Bricks and mortar are not 100% waterproof, and even modern homes built with cavity walls and impermeable materials can still be affected by penetrating damp. Damp and excess moisture within brick and stonework can lead to internal damage and the deterioration of the masonry construction. To waterproof a masonry wall, it is important to seal and protect the brick on a home’s exterior. Unsealed brick can absorb water, leading to structural damage.
Brick sealer is a clear or tinted waterproofing sealer that penetrates the pores of the brick and masonry surfaces. Applying a waterproof sealant not only prevents against damage but also eliminates the gritty feel of interior brick floors and outdoor paved surfaces. Strategies for waterproofing concrete brick include applying masonry protection cream and sealant, using DRYLOK Siloxane 7 Brick and Masonry Penetrating Sealer when both air and surface temperatures are 50°F or higher, and using flashings under window and door sills to collect water that leaks.
The best practices published by the Brick Industry Association call for flashings under window and door sills to collect water that leaks. A light coat of polyurethane, preferably matte finish, should be applied all over the bricks to seal them and prevent groundwater from penetrating the masonry walls. The surface of the walls should be covered with a waterproof membrane or dampproof coating to help prevent groundwater from penetrating the masonry walls.
📹 How To Fix A Sunken Sidewalk With Spray Foam
It might come as a surprise but you can actually use a standard can of Great Stuff spray foam to support a sidewalk that has settled …
Is waterproofing brickwork a good idea?
In areas with high humidity, such as kitchens and bathrooms, it is of paramount importance to seal brickwork in order to ensure its longevity and facilitate cleaning. A water sealant can protect internal brickwork from light, moisture, and wear and tear, thereby facilitating maintenance and upkeep.
How to make clay bricks waterproof?
The application of a water-repellent or sealant specifically designed for masonry surfaces can effectively protect bricks from water absorption and minimize moisture damage.
Can you seal clay bricks?
Clay Imports handmade pavers are made from 100% natural clay, which is porous and prone to water and oil absorption. If not sealed properly, this can lead to staining and patina development. To reduce this, clay pavers can be sealed. Sealers can darken pavers significantly or only slightly change color. To preview the effect, either you or your installer should apply sealer options to sample pieces. A bin or bucket can be used for easy application of sealer.
How do you keep water from coming through concrete blocks?
Crystalline Waterproofing is a cementitious substance that can effectively waterproof a concrete block foundation by penetrating into the concrete and reacting to moisture, forming crystals and blocking micro-cracks or pathways. Concrete block foundations are crucial for home structural stability, and unattended water ingress can pose serious risks. Waterproofing provides a great useable space under the house and peace of mind.
However, concrete block walls have inherent problems in keeping things watertight, as gaps form over time as buildings settle and hydrostatic pressure from the surrounding ground exerts itself. Mortar displacement, cracks, and even the best waterproofing systems require maintenance and repair.
How do you waterproof clay bricks?
Water repellent creams and sealants can be applied to un-painted brickwork to protect it from water penetration for up to 30 years. These creams work by soaking into the substrate, reducing water absorption and providing a long-lasting invisible barrier against water penetration. They line the capillaries of the masonry, reducing water absorption and protecting the substrate. Additionally, they allow the walls to breathe, allowing damp to evaporate and drying out. One coat of façade cream, such as PermaSEAL Facade Cream, Remmers’ Funcosil FC, or Microshield Ultra, can protect up to 30 years of exposed brickwork.
Can you waterproof masonry?
Silane/Siloxane sealers are effective in protecting masonry materials like stone, brick, paver, and concrete by creating a hydrophobic barrier within pores. They minimize water absorption, mold and mildew formation, staining, and moisture deterioration. High Gloss sealants, with a high concentration of acrylic solid content, produce a glossy finish, darkening faded pavers and adding a brilliant sheen. The number of solids in these sealers determines the high-gloss shine, with 25 solid content sealers being semi-gloss and 30 solid content sealers being gloss.
How to stop water from coming through bricks?
Breathable sealant can help repel water and release moisture from brick walls, making it ideal for homes with occasional water seepage. Preventative measures include regular maintenance checks, consulting professionals like All Weather Coating for periodic inspections, and choosing a reputable service provider. They have extensive experience in exterior wall coatings and weatherproofing services, and their team of experts can provide a comprehensive assessment and tailor a solution that best fits your home’s needs. Choosing a professional service can save homeowners from costly repairs and ensure their property remains water-resistant.
Can you waterproof over bricks?
Crommelin 2L Dampstop is a waterproof product that can be applied to the inside of a wall, but it is not a great solution as it traps moisture within the wall, potentially causing damage to the roof structure if moisture travels up the wall to the top. Access to the outside of the wall may not be possible, but it is best to ask neighbors for permission before applying the waterproofer to the inside of the wall.
If access to the other property is permitted by the council, it may be possible to perform maintenance work on the wall. It is essential to consider the potential risks and benefits of applying a waterproof coating to the inside of a brick wall.
Which brick is best for waterproofing?
The construction of waterproofing for old government buildings, schools, and colleges employs the use of mud bricks, a layer of brick bats, lime, and sand (surki mortar) due to their ability to absorb and retain water for extended periods.
What is the strongest waterproofing?
Silicone sealant is a highly effective waterproofing material that can be used to protect concrete and make it waterproof. It functions as a crack filler and sealant, suitable for cracks up to a quarter inch or 0. 6 cm thin. Silicone sealant is suitable for pearl works, detailed waterproofing, and renewal of already protected concrete structures. It can be applied using spraying or extrusion with a paint roller.
Silicone sealant is an adhesive liquid form, typically looking like a gel, with a different chemical structure than other organic polymer-based adhesives. It maintains flexibility and balance at both high and low temperatures, and is resistant to other chemicals, moisture, and weather conditions. It reduces the likelihood of failure in creating and repairing objects.
However, using silicone sealants requires patience, as the temperature should be between 4°C and 37°C, and the humidity should be between 5 and 95°C. It may take up to 24 hours or several days for thick sealants.
Membrane is another functional and common waterproofing material, which is sprayed generously to the protective concrete structure to protect the interior from weather conditions. Membrane has flexible properties that form impermeable layers on the concrete, providing protection against external conditions. Membrane is preferred for waterproofing basements, foundations, substructures, large drainage pipes, and ducts, as it can be applied in many different places.
How to make brickwork waterproof?
Brickwork sealers are eco-friendly and odor-free, making them suitable for use on walls and preventing water penetration. However, brickwork and traditional stone walls are susceptible to water ingress due to their porous voids. Old, poor-conditioned walls or damaged mortar can allow water to penetrate and cause problems. Areas most exposed to rainfall, walls that don’t benefit from natural sunlight, and rooms that aren’t adequately heated are prime sources of water penetration.
To ensure proper dampness, professional advice and a survey should be carried out, as brick sealant or penetrating masonry cream alone cannot rectify dampness. Before applying a sealer, check for small cracks or holes in the mortar joints, as damage typically occurs to the vertical joints between the bricks. The pointing is generally not solid and only provides limited resistance to moisture.
To repair damaged mortar, it is recommended to repair the damaged mortar before applying a sealer or coating. This will help prevent water penetration and ensure the longevity of the property’s damp proof membrane.
📹 Don’t Make These Errors! Sealing Small Concrete Cracks Correctly
I will walk you through the complete process of sealing a small crack in your concrete driveway, sidewalk, or patio. There is a …
As a concrete and foundation inspector employed by a company specializing in poly foam lifting and leveling, I can attest that this method is highly effective. One crucial step not to overlook is the curing time. While commercial-grade poly can solidify in 15 minutes or less, as mentioned in the article, Great Stuff will require a longer curing period. Excellent article, my friend!
With all due respect to your ingenuity, which I applaud, I had this exact problem, but had a much easier – and cheaper – solution. I grabbed my neighbor, and together, we struggled up the broken off, but intact, 4’x2′ slab until it was resting on its edge. I then shoveled the requisite amount of dirt onto the area, then struggled the slab back down to slightly above level, allowing for compacting of the new dirt. Less than an hour, no jacks, no support beams, no chains, no j-hooks, or drill needed, and didn’t spend $16 on spray foam. That was over a year ago, and the slab has now settled to level.
We had a company come out and do the same thing, but if I was to do it again, I wouldn’t let them drill the holes because we got a few cracks now between a couple of the holes. When I was a kid we’d use a breaker bar and just lift the sidewalk and put dirt under it and then put it back down. I think overall, that is the better option and no drilling holes in the cement and trying to match the color later
I have done this and it works very well, although I didn’t use the jacks, I simply raised the sidewalk slabs with the Great Stuff foam. It will expand and raise the slab on its own, but be careful not to inject too much, because then it could end up being too high. The only thing I would recommend is to save the concrete dust from drilling the holes. Then you can put that on top of the caulk that you put in the holes so it blends perfectly with the existing sidewalk and the holes won’t show.
The most valuable part of this demonstration to me was the use of C clamps, jacks and timbers. Raising the slab with such control allows the use of a variety of fill-in support methods. The tip about drilling concrete with a rotary hammer is valuable too; I learned that after struggling with a simple hammer drill.
I did mine differently. I clamped angle iron on the adjacent slab and left the overhang over the slab that I raised. Used this a a stop so it can only be raised to the same level. I used an air hose and a piece of pvc to blow out a few websites under the slab. Simply added foam in the void. It lifted the slab until it hit the angle iron and then the excess simply flowed out the sides. No holes. No jacks.
This seems like a great method! Previously, I’ve worked on a slab jacking crew. We would do the same thing. We however wouldn’t use “foam” but rather a mixture of Portland cement (to harden), ag lime (as filler), and bentonite (to aid in flow- not sure if it has a purpose out side of that). This mixture was touted as “safe for the environment”. The 2 problems with slab jacking are: 1) cracks happen sometimes 2) typically can’t get things back to “original” but close. With smaller pads, lifting them up with a couple bars and packing dirt under is probably the best bet. Be mindful of erosion and you’ll save yourself a lot of money
I did something like this about 5 years ago. I had to raise a pad in front of a two step porch/entry. I did all I could to raise it, tracktor & loader, crowbars (big ones), and more. Got it to about right, close as I could get it and stuff all I could under it, including several cans of foam. I also repaired two broken step corners with a concrete mix and forms. It was pretty good, but didn’t match. No one complained but I wanted more. So I got some of that polymer resurfacer and did it all plus the 40 ft of sidewalk. All looks great now. And I made the polymer a bit thicker to get the rest of the leveling I couldn’t get before. This was a 60 year old sidewalk and step.
Very interesting, but I have seem multiple occasions where Great Stuff deteriorated over time, just turning to dust. Also, it was never meant to be load bearing. I’d be very interested in seeing this slab in a year or so to see if this works. Our HOA contracted a company years ago to repair the neighborhood sidewalks and they used grout pumps to both raise and support sinking slabs. It’s still working after maybe 15 years. A manual grout pump can be rented for about $75 per day in my area.
I love how you quickly found out your cordless drill wasn’t cutting it. I had the same revelation a couple nights ago trying to reattach loose furring strips behind drywall in my basement. Started off with masonry drill bits and my Milwaukee hammer drill, 45 minutes 2 holes and a dull drill bit later I got a ramset tool and got 10 more done in 15 minutes
Anyone concerned the foam might get compressed over time. There is another product made by Loctite called Tite foam. It is advertised as being 4 times as dense as other expanding foams. It has been a long time since I purchased it but it should be comparably priced as other foams and available at many of the same stores.
Thanks for the article. I tried lifting a sidewalk slab with a 6 foot prybar but wouldnt budge. Good idea to use a jack. I think others may be right that it could be a lot less complicated BUT I’ll try another way first and post a article before I either suggest an alternative or eat my hat. Thanks again.
1) did you fix the drainage problem that caused it to sink in the first place? If not, it will continue to sink. 2) the foam will compress over time, it’s not a structural product. I’ve tried similar things with a retaining wall and straightening a mailbox on a pylon underground and both failed due to compression of the foam after a couple years.
Great article. We had enough issues that we had sections aligned by a company that pretty much did the same thing. Although I wonder if the foam was the same or less susceptible to long term degradation. You also covered a key thing about dealing the joints, prime point of water entry under the slabs. I used backer rod with Seka sealant, both regular and self leveling, for this. I also lightly spread sand into the sealant while wet, then brushed excess away after fully cured. Makes for a nice appearance.
I have a garage with 6×6 slabs that make the floor. each slab has sunk in different directions. After perusal you do this I think I could take a laser and mark where the top of slabs need to be and hoist them into position. I would pump grout under the slab until it is completely full and give it a few days to cure before releasing the tension off the hoist. I have been looking for a way to do this without demoing the floor and poring all new. After perusal your article I clearly see the way to do it. Thanks
Foam lifting is for large slabs. It won’t help much if you have other problems such as an ant nest under the slab. Better would be to just lift the small slab, deal with any problems that would cause the issue to reoccur, add the appropriate fill material, and lay the slab back down. I’ve also seen places where the issue isn’t settling, but uplift. In those cases, you have to remove tree roots under the lifted section.
Interesting idea but much simpler; I lifted each side with a heavy 1″ x 6’ breaker bar from HDepot, temporarily stuck a few large rocks to hold it up, removed the bar and dug under with a hand shovel a bit then mixed concrete and shoved it under wherever I could. Next day took out my temp rocks and dressed the dirt edge back up.
I did this with my sidewalk out front to avoid the city charging me $625 to replace 2 5×5 slabs. Worked perfectly with the c clamp method. The 2nd block had some obstruction so I could not dig on each side. I had to lift by installing 2 5/16 tapcon bolts. Because there was no outlet for the excess foam I ended up overlifting by 1/2 inch so I had to lift the adjacent slab. I used the drill dust and some fine gravel over the self leveling sealant to blend into the existing sidewalk. Looks great. Also found out the foam doesn’t yield after it sets up(less than 1 hour). No need to leave everything up overnight.
I had a professional company try foam under my brick paver front porch after it started to sink in the middle. After 120 lbs of foam, the sides leveled off but in the front near the steps, it was rising. They refunded my money (very expensive) & I had my contractor rip out the pavers and pour a stamped concrete floor with rebar. Turned out great.
Great article. I would even consider letting the closed cell foam do the work for you. In a rennovation, I added a new tub. The overall contractor doing parts I was not wanted to spray foam under and around the tub instead of my concrete base. Thinking that a metric ton of water is heavy, I said okay, but you own the mistake if there is one. We came back the next day to see how all the work was and the tub was lifted about 1.5″ upward breaking the seal to the marble slab it sat on. If we go better at this, we could measure out and do this with spray foam and bypass the manual lifting. I do appreciate the control your way has though.
Great article thx! My buddy and his father do driveway leveling and house leveling down in Texas. They actually dig holes on the end needing to be jacked up. They then put inexpensive bottle jacks in the low spots and Jack them up. Afterwards they pump concrete in encasing the jacks and creating a pier. Works really well with large areas on driveways too. No callbacks. Just FYI.
Great article for small projects. Nice process for curing the problem. The last project my company did before retiring was to raise pavement slabs on US 75. Of course we had industrial grade pumps and the foam pressure lifted the pavement. Your methods work really well for smaller projects like walks and smaller patios! (And the joint sealant article is also really good.)
Amazing amount of engineering. I have lifted pieces of concrete as well. Generally for a sidewalk piece – this size – a large crowbar or 2×4 used as one will lift the slab. Spray foam definitely can lift the slab as well as hold it. What i do – You can lay a couple 2x4s that are min 2’ long each – each side on top of the side walk pieces so their spanning the other unheaved sidewalk. Get your large clamp or even a bar clamp – squeeze the concrete two the 2×4 lifting the slab with a crowbar if even needed. Throw dirt or your foam under there. The pieces are heavy but way more movable then you would first think. Generally if piece is in good condition it goes quick. If cracked you may have a bigger project. The best foundation to put under the lifted concrete is usually add some sand. I pile it into the gap under the lifted slab. You can usually soft the sand in well by using a garden hose and just blast sand from the side – swishing the sand mud under the slab until full.
Being as the steps were attached to the slab that was lifted I get why you did it the way you did, it needed to be exact lifts with minimal pressure applied. All of these people commenting about pry bars and such should do some FAFO research. Very nicely executed and with minimal breakage to back or slab.
Did a similar project a few years back, but went very simple – dug down front and rear trenches along each side, used a 6 ft pry bar to lift and level the sidewalk slab and supported the now lifted corners using several large “locally sourced” sandstones set on crushed gravel (created a pier) and then backfilled under the slab with flowable fill I purchased at the local big box store. All in costs were about $30, and the hand digging/levelling/backfill took me about 2 hours from beginning to end. This is a very precise approach, but I’m not sure on the great stuff foam CBA long-term.
Clamp a timber on the top and as you lift the slabs, clamp it tight to get the top flat, clean the joints out,, then you can either use the foam, or pour free flowing grout to the underside of the slab – shutter the sides to prevent leakage. Remember to heavily grease the end of the clamps that end up under the slab (best to wrap them in plastic too) and yank then out as the fill sets)
pro tip with these cans … use needle nose pliers to grip the base of the dispenser ‘nub’ at the top of the can while you are screwing on the dispenser tube … this will allow you to create a tight enough seal that foam will not creep into that seal … also, you can use the cans a second time but to do so, it’s best to clean out the plastic tube (assuming you only have the one) before the foam cures … a long metal wire and/or an air compressor come in handy for this (*only after tube is removed from the can*) … clean the semi-cured foam out of the nub gently as to not damage the nub and the seal inside that is holding back the compressed gas … wear safety glasses for this … *even with care, sometimes the cans are still one-use no matter how well you clean them
I don’t have a sidewalk to fix, but you just gave me the perfect method to lift a small shed to put in a new crusher run pad and new floor beams! I knew bottle jacks were part of the equation, but fixing 4X4’s to the shed and then lifting the 4X4 with chains might be the ticket. I’ll run some calculations to make sure I’m not doing something stupid, though. Thanks – love the website!
I did the same thing but no drilling! I dug the low corners out and put C clamps and a chain joining them. Then with a harbor freight farmers Jack I easily picked it up slightly higher than the other slab. I washed sand and water along the sides into the underside of the slab. Let it dry a day and Dropped the Jack and jumped up and down on it, success!!!
Note to those attempting this, one of the problems not encountered in this article (but you might have) is that the edges of the slab may end up beneath the adjacent sections. Due to shifting, the space where the sunken slab was had contracted, so it wasn’t possible to simply lift the sunken one. I had to put a masonry blade on my circular saw and carve away enough of the jagged edge so that there was a clean path for the slab to rise through. I’d also agree with other commenters who advised against drilling through the slab. I never went that route, so I didn’t end up with cracks, but let me suggest an easier and cheaper approach. The sidewalk is only a few feet across, so you can probably reach the middle from either side. Shove some concrete pads, gravel, and/or whatever else you have handy into the void. If you absolutely must use foam, you can start with several large chunks (i.e., paving stones and the like) and then add the foam between those. At the very least you’ll spend less on foam. Rocks are far cheaper and all-natural. Also, I can 2nd the article on the concrete caulk. I applied it all over my 100+ years-old property almost 5 years ago now, and it has held up perfectly. I wasn’t willing to repave all the areas with old and badly installed concrete. I used it on the curb alongside the driveway, gaps and cracks in the sidewalk, patio, next to steps, etc., and and in all cases it has not lifted out of the cracks, even after lots of rain, intense summers, and even pressure washing the areas at least 3 times since I applied it.
I did this, The slap had dropped at the front near the house under the steps. I let it set over night at first it was nice and flat but over a day or two it compressed foam maybe a half inch listen I raised it like 3 inches still looks better than it did. Next time I go a little past level then if the foam compress it will be level. ( Was redoing my front porch)
Nice well done article. You can save money and time by just wrapping the chains around the beams. No need to buy and install the J-Bolts. I did a similar repair. I did not use great stuff, I would be concerned how it would last over time. I got High density foam sheets and cut to size and slipped in from the sides. This also removes the requirement to drill the holes.
I loved the apparatus that was created to raise up the slab in the article. However I guess the slab was only worth about $5 as opposed to the value of the equipment and materials used being maybe $200. Surely just lifting the slab manually and putting an extra layer of sand underneath would have been simpler?
Good stuff! I have the opposite problem. I have a sidewalk slab that has risen about 2 inches on one end. There’s no tree roots. it just lifted for some reason. Any Ideas? The only thing I can think of is, lifting it up somehow and digging some of the Dirt away underneath and then setting it back down. Is there a better way?
I have found that “great stuff” deteriorates over time. My question is why not just use 4 bricks ( or something similar) positioned at each of the 4 corners of the lifted slab all flush and leveled equally. You can also use foam filler to give support in the center by drilling one center hole but otherwise the bricks will do most of the support.
Lifting up a small concrete slab can be done in a million different ways; one must simply be commonsense-cautious to not crack it. Then, once raised, it’s not too difficult to dig a bit to gain access to the underside, from the sides, and then manually fill the cavity with gravel or similar fill. The advantage of the process that I’m describing here is that it does not require procurement of all the items being shown here (wood, jacks, chains, hardware, hammer drill, drill bit, and two cans of foam).
If you lift the section of sidewalk back to original . There will be an open void beneath. Without supporting eventually i believe it will crack from use. I am just not sure if great stuff foam would last over time with the weight, weather and use ? I know that great stuff has several different strengths and maybe one of those would work ? I would think an exterior suitable foam would work for a while ? Probably work ok over the long run ?
Before everyone “rips into me”, let me tell you where I’m coming from. I’m a licensed general contractor for over 30 years so I do know a few things.While I applaud his ingenuity, I cant agree with the material choice. Foam compresses, Its as simple as that.That section of sidewalk probably weighs about 500#. Also, you have to look at why the sidewalk sank in the 1st place. Improper compaction of the soil beneath or something else? Has it stopped sinking? Foundation repair specialists would never repair with foam. They will either use a non-expansive grout or a cement/sand slurry mix. I hope this works, but I think this guy will be making another article in a few years about fixing a sunken sidewalk again.
for all the work done on this project and COST of materials- you could have removed the small section of sidewalk for 1/4 the cost and less time. The issue with the foam solution as well – it is a temp solution because it will compact and the slab will once again sink. I was a remodel contractor for 15 years. But if you like the idea of this project then by all means this works as a costly fix that the average weekend warrior will take 3 weekends to get it done. Oh and the C claps could very well snap the edges of the sidewalk when you do the lift. NOT a FAN of the project. Sorry!
Recommendation: If the slab is “hanging-up” at the 2 end locations (where the suppressed slab butts up against the other slabs) due to jagged “areas” along the faces of the 2 slabs…. get a Circular Saw with a diamond edge blade… and “run” the blade along the gap area between the 2 slabs. The “cutting” from the diamond blade will remove any jagged areas. This will give smooth faces to each of the abutting slabs and will allow them to “slip past” each other. The gap here is fine, because you will fill this with caulk. If you don’t want to fill the full depth, you can fill the void with sand UP to the final 1/2″ of the void (as it reaches this surface of the slab). NOTE: The slabs MUST be able to move.
Nice article. But my issue is that only a portion of my driveway has subsided. Attempting to raise it is my problem, since I can’t get to the edges to put C clamps on the edges like you did. I think my only option would be to drill holes and put bolt sinkers into the holes in order to grab the slab to raise it.
Good job on article. For a single slab like that I’d first lift with breaker bars and fill. If result wasn’t satisfactory I’d jack out old slab and pour new one, linking it to the rest of walk. What caused the problem to begin with is presumably one section or the other was poured first with a newer section poured later, with no attempt to ensure stable height consistency. Holes should have been drilled the side of the old slab, with short pieces of re-bar inserted that extended into the new pour.
Good article, interesting idea, but I’m skeptical that great stuff was a good choice for this. Rodents love the stuff, and I’m just imaging them chewing away at the base, living in it, and also carrying away the foam to line their nests, all the while it’s slowly sinking as more and more of the stuff is removed. Plus, lots of things meant for indoors will break down when “exposed” to the elements, and I doubt great stuff is an exception.
Interesting idea. My side walk sank making it lower than the concrete on both sides of it (as part of a drive way) Can’t really use c clamp method but it might stir up some ideas on how to raise it. In my case not so much a tripping hazard as it is a drainage issue. My roof drain is right there and water pools up in the sunken part. My fear is with no where to go it will seep into the cracks making the problem worse. I’ve sealed the cracks and try to sweep the water out if I can. Not sure what to do that would be budget friendly (prefer not to call in the professionals lol
#1- an 8 foot 2×4 and a block as a lever is all you need to raise slabs. Block slab in place.# 2-Dig under and use a bottle jack.tapper edges of slab. Then raise. Once raised, use grout or loose mortor mix. So it pours and flows under slab.. Once filled and stiffening, take extra over fill off side of slab. Replace with dirt n grass seed.
Hi. That Tremco Vulkem 45 SSL One-Part Semi-Self Leveling Sealant has a near perfect color match to your existing (older/aged) concrete!!! Looks good. How did you do that? Is that the exact color right out of the caulking tube? Or did you add something to that caulk sealant to better match your existing concrete? I’ve been using SikaFlex grey self-leveling sealant WITH some sand sprinkled after on top, to better match the existing concrete. Not perfect, but decent compared to stand alone grey/or limestone sealant. Which doesn’t look to appealing at all. Thank you very much.
I followed your instructions to the letter. I applied the foam and watched it seep out the sides of the slab over the next several minutes. However, the foam actually raised my slab 1-1/2 inches. I started placing all the weight on it that I could find, but it didn’t help. Now I’m screwed and sitting here thinking I’m going to have to bust the entire slab up and re-pour it.
Note for the cost of renting a rotary hammer drill, you can purchase a cheap one from Harbor Freight. Yes the professional ones are a beast and will last for years, but I grabbed a corded 8Amp Bauer for me $67. I’m sure I’ll die randomly but I’ve gotten 7-8 projects out of it and even resorted to doing things I normally wouldn’t abuse a drill for (like digging holes and churning compost with auger bits).
For anyone who has not drilled concrete, the rotary hammer drill is the way to go, and it uses an SDS concrete (masonry) bit. The SDS allows the bit to move in and out of the chuck by ~1/4-3/8″ while rotating. (N.B. don’t use these on mortar). If you rent one, the size used here is perfect. Many places rent the larger Bosch (other makes?), which are much heavier and difficult to control for this size bit. I’m not sure about the GreatStuff retail foam’s properties for this use case. It does expand rapidly, and depending on the age and make-up of the concrete as well as the consistency of the base material (sand, soil, gravel) on which the slab was poured, it may cause problems with cracking or sinking. There are commercial/professional grade injection ‘foams’ that are specifically engineered for this. They remain liquid longer and expand more slowly, allowing them to flow into the substrate and fill any voids that one obviously can not see. The cost is higher (of course). Another thing to consider, find, and remedy is the underlying (pun intended) cause of the sinking. (I.e., water drainage). If, say, this was caused by water, the foam injected will cause the water to seek another route. If you have an older home, espessially pre 1930s, the concrete may be extremely hard as concrete continues to cure for decades. There are graphs and charts on line showing curves for concrete curing (hardening) times and depening on where you live and the aggregate used (mine is from 1914 and the aggregate ranges from granite to what almost seems like coal – I’m in Chicago).
I do it differently. I raise the Slab, About 5mm higher than level) which leaves a “void” section underneath. I then pile heaps of Builders Sand at either side of the Slab. With a very fine water Jet Nozzle, you ‘transport’ the Builders Sand – underneath your Slab. Lower the Slab. Tamp it down with some timber, to achieve level.
this is very interesting coming from an automotive background and not repairs like this as we use something similar in removing a fwd transmission as the sub frame is shared with the engine and transmission using a tool called a engine support bar that had J bolts that supports the engine after the removal of the subframe. I see no issue in this process other then questioning how long the foam will last before breaking down
1. Use farm jack to lift one edge, lean on edge tilted away from workspace on solid object. 2. Raise and level bed with 3/4 inch gravel. Yes, gravel. It doesn’t compress, except a little of the bottom layer sinking into earth. Best long term bed. 3. Place 4×4 over void. This will be last thing slab rests on before laying it all the way down. 4. Walk down slab to 4×4 using 2 piece triangular framing lumber support. (Hard to explain in a comment.) 5. Attach farm jack to middle edge again, lay it down. Whole thing takes 20-30 minutes, tops.
Cost of 4×4 lumber, big bottle jacks, drill bits, c lamps, j bolts, 2 cans of foam…cup brush, etc: That adds up. You may say lots of people have much of these things already but that would be a stretch. My father would have had that sunken square busted into pieces with a sledgehammer and out of there in 10 minutes. Make a simple concrete form, add some busted up old crete from the old square as filler, tamp it down, and mix up a couple bags of concrete to pour a new square. Float it out with a nice 2×4, and you are done. If was me, i’d dig down the sides, pry it up with leverage bars, and pack a layer of sand under it to level it up. Great Stuff is not made for weight support or ground contact like that. I don’t think it will last that long.
My two issues is the holes and the foam. Holes seem unnecessary given the size of this concrete, it could’ve easily been dug up on the sides slightly more than needed for the C clamps and foam injected from the sides OR gravel. Second the foam. I question whether this is suitable for weight baring applications and wont compress over time and thaw freeze cycles. Those two critiques aside, I enjoyed the article as someone who appreciates out of the box thinking and resourcefulness.
I’ve used the great stuff to do the same thing,but it does expand quite well under the slab so that many holes for such a small slab is excessive! Also it will expand and lift it itself without having to lift it! If your gonna lift you might as well just flip it up and fill in with gravel or just lay down dry concrete to level it and it will harden up itself ! Just my opinion I’m a professional Truck and Auto mechanic not a mason!
My “drooping” slab is up against a raised concrete porch. If you’re standing on the slab, looking towards the porch, the left side of the slab is right up against the side of the house (CBS with stucco) and there is no place to get a C-clamp there. The other side is a flowerbed, so no problem on the right side. What do you recommend to raise the side of the slab that is both up against a wall and the concrete porch? The slab is about 4 ft. x 4 ft. concrete.
Hey the foam is not concret or cement and soft. You will compress the foam over time and then you have the same situation like before. Am for the clamper I recomennd to cover the arms which will be contaminated with the expanding foam in a e. g. polyethylen freezing bag bofor you clamp it in position. This will reduce the workload of cleaning the clamp arms from the stickimg foam afterwards. Regards from Germany
Excellent strategy and presentation. You do very nice work. A section of my concrete driveway subsided and cracked so I went looking for companies who do mud jacking. Couldn’t find anyone local but did find a service that uses foam to raise slabs. They quoted me about $1000. I said “screw that” and went and bought a masonry product made specifically for repairing concrete walks. I built up the sunken area to be level and it’s held up remarkably. Also, the materials were less then $50.
Looks good how it was raised up level again with the technic used though any spray foam will break down in time & give, I would have trenched under the slab both sides added some bricks though in doing so when the slab is being lifted I would have raised it up approx quarter inch or so then work bricks in tight in center & both sides therefore the slab in time will settle making it even with the other slab.
bigger trip hazard is that brick step, it suffers the same issue my moms old house had, years after the porch was built someone came behind it and poured a concrete sidewalk up to the step without excavating to maintain the same finish grade so the first step is way shallower then the second riser, I ended up demolishing the sidewalk and doing a brick paver walkway at the proper elevation.
After viewing all the tasks you had to do in order to lift up a small slab I’ve decided to redo all of my slabs by simply making them at least 6 inches thick of formed, one piece stainless steel that is shaped and angled to conform to the walkway path and these “slabs” are fitted on top of a “roadway” that runs beneath them using a very similar design to what the ancient Romans used (to avoid under the roadway moisture issues potentially bleeding out the material under the walkway). That ought teach them slabs not to misbehave!
for this situation I would have just lifted up the sidewalk section higher and then poured some watery cement mix under it, rodding it under it until I thought it covered most of the area. then lowered it until it was flush with other sections and waited for 2 days. no drilling no foam no real screwing around
When I worked (after my morning coffee break, American Postal Workers Union break, and then recuperating from being exhausted from walking to the breakroom, and then the used coffee department break), we raised up sunken concrete flooring slabs using hydraulic cement. We raised them up so they slanted toward the overhead doors. It helped get the 1st class mail out of the warehouse faster. Too bad the truck wasn’t at the loading dock though.
I’ve done some foundation repair and such but I’d ask the life span of foam compared to puming mud seems the mud stays if you mix the portlaine correctly but for seems holds up to water damage whitch is usally what cause such damage water can destroy anything. Portlaine the simple bye product of ash or crushed rock natrual earth material not chemicals
The hardest part is being able to raise the slab. With that being said, I wonder if you couldn’t have simply sprayed the foam directly underneath from the sides, with the attached straws? You could have raised it higher than needed, sprayed the foam underneath, then lowered the slab to the desired heighth and let it cure. Any excess would flow out the sides.
To the naysayers, it really doesn’t seem to be a complicated repair. The lifting apparatus looks like a great way for a single person to raise the slab without worrying too much about cracking it with prybars. I agree with those who say drilling the holes for the foam was unnecessary. Attach a long tube to the foam nozzle along with some type of reinforcement and you could probably inject the foam from the sides, although you’d have to dig a bit more to provide good access. There may be better products to use other than Great Stuff expanding foam. You might even be able to flow a cement slurry or concrete repair mix in from the sides. If you only had one or a few sections to raise, I think this is a great method, and you don’t get the mismatched color from pouring a new slab.
Unfortunately, my sidewalk runs next to my brick house and there is a raised brick planter running the length of the sidewalk on the other side, so I have no way to get a clamp under the sidewalk. My only choice would be is to hire a mudjacker or resurface the concrete walk level to meet the rest of the walk. If I resurface one section, I’ll have to do the whole length, otherwise it will just look like a patch.
How about trenching along damaged side. Then driving thick rebar underneath w/heavy hammer. Hook chains to however many bars used and lift w/car jack placed on 3/4ply, on ground across from rebar. Insert big stones to hold slab. Remove jack and rebar, then fill with 70/30 dirt/cement mix by packing tightly w/2×4 and sledge hammer. This insures cavities are filled!
For all the work, why not cut the slab, lift, level the substrate and restore the removed slab. The method in the article is excellent for larger slabs, but for something this small, the removal method could help identify any leakage/drainage issues to correct. Still, I like how you suggested drilling out the foam from the holes, many articles seem to lack this important step.
For the DIYer, it might be more cost effective to break out and replace the slab. A 3 x 3 foot by 4 inch slab would be 6 bags of concrete mix which would cost under $20. Probably less than the foam and crack sealer. Now throw in the cost of 4 x4’s, clamps, j-bolts, chain, bottle jacks, drill bits that you may or may not have. That said this is a clever trick if the sidewalk was patterned or colored which would be hard to match. Or in my case I have 15 or 20 feet of sidewalk that is tilted and sunk differently between slabs. In which case the investment in tools would be worth it.
Couldn’t 4 large tapcons be used to screw the chains to the cement side walk on the four corners then pull up the slab using 4 x 4 support with a Jack? However, this is one man doing this job on a very big slab. A small slab you would just use a pry bar to lift and fix it the good old hillbilly way and just fill it with dirt and rocks after lifting then bring it down jumping on it a few times to get it done. Love your ingenuity! It will be great on heavy applications.
Used Great Stuff Foam to fill in a void which had eroded under my back porch patio concrete slab. It’s very sticky when initially applied so I’m pretty sure I managed to trap the mother copperhead under that slab and filled in the void completely. Allowed the Great Stuff Foam to expand until it likewise came out the front edge of the slab. No more copperheads! 👍 (DFW, Texas)
I’ve read a bunch of comments, at which point I probably would use the “lift and fill” method, filling in with SOMETHING added right under the existing sidewalk slab. HOWEVER…if I used this article’s method, I would put squares of plywood between the C-clamp feet and the concrete. I see pieces of concrete breaking off with metal to concrete contact points.
Assuming most people do not have bottle jacks, hammer drills, masonry bits, large C-clamps and 4 x4’s laying around, it would have been way cheaper to bust that with a sledgehammer and re-pour concrete. All you need is the hammer, sakrete, a 5-gallon bucket and a piece of scrap wood for screeding. Foam will collapse in a year or 2 and allow water into voids which will heave in freezing climates.
Hmm. I was hoping that the spray foam application was going to be like the professional ones where it would lift the slab when injected. Would be cool to see a home kit for that style fix. Maybe someone could throw a kit together that utilizes an air compressor and port for those style spray foam cans. Idk 😅
I’m in the process of trying this on a larger section (5×8) at my home. I’ve seen other using the Great Stuff – Gap and Crack vs the Large Gap that was used here. Does anyone know which might support more weight, be better in the long run? The number of cans doesn’t really matter to me. I know that the “Large Gap” is Closed cell, so it won’t suck up water. Not sure about the “Gap & Crack”.
Humble opinion: the real problem is not being addressed, the soil under the foam will continue settling because there is not compacted roadbase under the slab, organic soil is sensitive to the water that will enter through the sides and will continue settling, there is no rebar or dowel bars connecting to the rest of the walkway or the foundation, therefore, when the soil settles (and it will) there is no rebar to hold the slab up. I stoo hiring the foam services as i was always getting a warranty call in less than a year. It is cheaper to install a mortar ramp to alliviate the trip hazard, but if you want a real solution, remove, install road base, comoact it, install rebar connecting into surounding slabs, and new concrete. In the long run, it is cheaper to replace with nice structural reinforced concrete.
This guy is definitely an engineer and not a contractor. Ingenious way to lift a slab but wat too labor and cost intensive. A simple 5′ pin bar and a few 2 x4 or concrete pavers would have tis done in half the time. Also, the step that the concrete buts up to is only 2 -2/14″ high and is also a trip hazard. Its also not to standard building code, which states that a series of risers can not differ individually in height by more than 14″. The next riser is clearly much higher than this one making this first riser a trip hazard as well. I would have ripped the walkway out and replaced to to be level with the first step. .
2:17 just a small safety tip I learned in the military, never have any part of your body in line with the plane of the blade on the grinder. Having the guard on is obviously a must, but your knee, leg, and feet were in danger. I never trust the guard on it’s own, and assume the blade is effectively a grenade with a shrapnel plane. Just keeping your entire body out of plane with the blade is pretty easy to do and a good habit to get into.
Great intro and explanation of how to do this Scott. I did this on a number of client concrete patio / walkway / driveways in the early 2000’s through 20-teens. The first ones from 20 years ago are still holding up! Like other forms of sealing – painting or other forms of calking, it is 80% prep. The most important thing is to follow the directions on whatever product you use! I think the second or possibly most important part of this procedure is to know WHY the crack formed. Many times there is poor drainage so there is soil erosion and frost cycles.. Is this crack going to continue or new ones going to form? Easy to solve when there is a downspout next to / near the concrete – get that water further away, re-route the downspouts, install a french drain if needed to help lower the after-rain water table. Where I have done this the crack stopped widening, and the sealant has held up for in upwards of 20 years!
I’ve used this method on my driveway. Asphalt. After a few years the cracks start to expand more and they open up.. leaving you with another crack next to your sealant. I believe one step id recommend to prevent this is to bind the sealant to each side of the crack, so smooth it out with a putty knife for example, so it isn’t just sitting in the crack but also is able to bind to each side. If you don’t then you’ll end up with my issue..
Nice vid, thanks! I would not use a graphite pencil to pack the backerod in as any graphite that gets on the concrete sides of the crack will affect the bond with the concrete. In fact, to improve adhesion I have used a toothbrush and alcohol to literally clean the sides of the crack prior to packing the rod in. I’ve also used play sand instead of backer rod for wide cracks or those that have irregular widths. Again, Thanks for the EDU!
I’m going to give you all a tip on product use. The Quikcrete product in the bottle will dry, hard and will pull away from even properly prepped concrete, when it moves seasonally. The other products do about the same and I’ve had failures at one or two years with all but the product I’m about to tell you about. Don’t laugh though. Clean and prep your concrete, you can even carefully use a wire brush, or pressure wash the cracked area a couple days before the repair, make sure it’s dry. Backer rod when used properly, needs to be down in the crack, not just below the surface, remember the concrete is cracked ALL the way through the thickness, so get some product in there to stabilize the crack, not just a dribble at the top. My secret concrete crack filler product is… Grey Flex Seal ! Yep, the stuff from T.V. I have used a large hobby syringe to draw the liquid Flex Seal from the Pint, or Quart can and just let it flow into the crack. It will self level very well. The difference with using Flex Seal is, it is Liquid Rubber, so when the crack joint moves, and it will, the Flex Seal will flex, and not pull away like the other products do. Flex Seal sticks to the clean Concrete really well. And it Stays Flexible for years. I repaired my first driveway that was full of cracks about 9 years ago, and it is still as good today as the day I finished. You can sprinkle some sand in the Flex Seal right when you put it in the crack, to help blend it in if you want too. I installed a new sidewalk at our new home last year, and used the Flex Seal on the Sidewalk Expansion cuts, to keep water out, and it looks beautiful.
Good things first. Silkaflex is a great product, don’t use on any slopes. I have not used the Tremco, nice to know it will do a slight slope. Bad part. The plastic bottle I have tried to use. The issues I had were, shaking it does nothing. There’s a lot that settles in the bottom that will never loosen with shaking. I have tried a spade drill with the point and corners ground off. This works well however there always seems to be lumps in it. It does not come out of the bottle very well when squeezing. Good information on the article 👍
The reason thick elastomeric joints fail is not because they are too thick to cure properly, but the real explanation isn’t easy. The bigger something is, the more distance it moves when it expands and contracts at its edges. And adding depth to a 3D space increases its volume more than you intuitively think because volume is all 3 dimensions multiplied together. The result is like a muscle that has gotten so big that it can rip itself from the bone. Since the adhesion of the sealant doesn’t change when you add more, one temperature cycle can simply make the sealant rip itself loose. Public and industry resources about sealant application explain this by placing hard limits on joint sizes, so installers can do their work properly without knowing why. The documentation for the various DOW and Henkel sealants I’ve used have recommended max joint sizes in the neighborhood of 1″, usually less. So pouring a bottle of sealant into a concrete joint is self-defeating, just like this article says.
I was just looking at your previous article because it was on my home page and I hadn’t seen it before, despite full notifications (“All”). I scrolled back in my notifications to everything between “11 days ago” and “13 days ago”, and it was missing. Clicked your website, saw this article! No notification either… dammit YouTube!
My method might be overkill but I would grab a bag of Cemetall (very inexpensive) and put it into the crack – just the dry powder, no water. Fill the crack with it but leave about an inch from the top of the crack. Then, mix a batch of Cementall with water to make a watery slurry. Pour that into the crack above the dry powder but again, don’t fill the crack all the way. Leave yourself about 1/2″ to 1/4″ from the top of the crack. Let that dry for 24-48hrs. Finally, use the Sika or Tremco to finish it off.
What you want to do (and he is doing it) is get the correct “shape factor.” If you go too deep the adhesive capacity of the sealant can’t hold on to the sides. It’s sort of like a rubber band if the shape is deep and narrow there is a lot of stress on the edges, while if its shallow and wide there is less adhesive adhesion stress. I just watched it fast to see if he would give the explanation of why you do this prep.