Foundation and Basement Wall Cracks
|If you have a basement, finding cracks is a common occurrence. Concrete, and cement products are susceptible to the corrosive activity of water and the constant shifting and movement of soils surrounding your home. Therefore, finding cracks is common. Not good, but common. Poured concrete foundation walls, even in newly built homes, often have more than one, a multitude of cracks, which form within the first days, months, or years. These cracks are usually thin, superficial, and may not be a threat to the structural health or well-being of the home. There are three major types of foundation wall cracks:|
Vertical Wall Cracks: Vertical basement wall cracks will generally in their early years (1-20) not compromise the structure of the home, but they may cause water to seep in to your basement. They are commonly caused by the shrinking concrete as it is curing but are also known to be created by the backfilling process, poor craftsmanship, and other factors.
Horizontal Wall Cracks: Horizontal cracks are much more dangerous to your home than vertical ones and have the potential of leading to the complete failure of the walls. As the pressure of the soil and water outside combines with the weight of the entire home to press on the foundation walls, they can buckle and snap. If the crack is large enough that you can fit a dime into the gap, then you should immediately get a professional opinion from a foundation expert. Many options can be used to fix bowed walls, including rebuilding, braces, and reinforcement. These solutions can repair the walls, add strength, stop their inward movement, and redistribute the home’s weight cross the foundation. We always install drain tile at the base footing of any wall rebuild.
Bowing Foundation Walls and Sinking Floors: Often, basement walls will begin to bow before they crack. Not something difficult to recognize, simply look at it. Take something with a string attached, touch the top to the outward part of the bow, and see where the end of the string touches the floor. Right next to the wall? Or an inch or two away? Now you have structural issues. Call The Foundation Expert.
This foundation wall bowing is a strong early warning of a weakened basement structure. Brick and stone walls are just as vulnerable to these problems and are also susceptible to crumbling mortar. Bowing basement walls are serious and must be addressed as soon as possible or may become irreparable. Signs of a bowing basement wall include the following:
- Basement wall cracks are wider at the top instead of the bottom.
- Uneven floors
- Cabinets, windows, and doors that will not shut properly
- Cracks forming in upstairs drywall and plaster
- Exterior brickwork cracks and breaks in caulking seals
- Leaning chimneys and porches.
Please note that bulging foundation walls may be at risk of collapse. If you see this, call us immediately for advice (703) 762-2429
Monitoring Basement Wall Cracks
Generally, foundation wall cracks are discovered long after their formation. It’s easy for a homeowner to assume the worst and assume that these cracks have suddenly appeared. A realistic view on cracks is important- it is best to treat all wall cracks as potentially serious until a professional has looked at them. Cracks typically form at weak points in the foundation walls, including corners, pour lines, ‘cold’ pour lines (so called because the concrete got cold waiting for the next truck to pour); service holes, pipe penetrations, edges of basement window frames, tie rods, and long spans of wall in the basement foundation. Once you have located a crack, give us a call, and describe what you see. Call The Foundation Expert at (703) 762-2429for a Free Consultation with one of our experts.
Foundation Wall Cracks and Floor Cracks
All concrete structures will crack to some extent. Concrete will crack due to tensile stress induced by shrinkage or stresses occurring during construction, setting, or use. Contractors pour walls, or build block walls, and before the concrete and/or mortar can cure properly, or adequately, up goes the rest of your home, and there is the stress we are talking about. In many large structures, expansion and contraction joints, or concealed saw-cuts, are placed in the concrete as it sets to make the inevitable cracks occur where they can be managed and out of sight. In residential construction this rarely occurs.
Concrete members may be put into tension by applied loads. The size and length of cracks is dependent on the magnitude of the bending moment and the design of the reinforcing at the point under consideration.
Shrinkage cracks occur when concrete members undergo restrained volumetric changes (shrinkage) as a result of curing or drying, self-generated shrinkage or thermal effects. Once the tensile strength of the concrete is exceeded, a crack will develop. The number and width of shrinkage cracks that develop are influenced by the amount of shrinkage that occurs, the amount of restraint present and the amount and spacing of reinforcement provided. Some cracks are immediately apparent, visible within 0 to 2 days of placement, while drying-shrinkage cracks develop over time.
The first determination should be whether the crack in question is structural or not. The answer is usually degree – usually a measurement of an inch. For example, if you take a plumb bob or 4’ level on a bowed wall, and the displacement from the crack to the floor is an inch; or if one side of the wall is in or out an inch, or if the crack is one inch or wider in width, than you probably have a structural issue, and upon that determination, we would request the services of our PE – Professional Engineer, which we have on staff (see NADER). Don’t take a chance. Call The Foundation Expert today and
schedule an Inspection by one of our Licensed and Certified Staff Members.
Regardless, wall cracks, block cracks, cement cracks, and mortar cracks can be sealed effectively with the right diagnosis, and then if applied properly, the right product and system. Combinations of structural I-Beams, angle irons, waterproof and hydraulic cements, epoxies, urethanes, polyurethanes, carbon fiber, with or without Kevlar, and other products have been used for decades to fix structural cracks from the inside. However, it takes experience, and knowing which product to apply to your specific foundation material and situation.
One concrete wall is not necessarily identical in chemical properties as another. One concrete crack is certainly different from another. Carbon Fiber and other fixes have been applied to bridges, parking structures for decades, and for the last few years, to the residential market with tremendous success. We have carbon fiber products, and carbon fiber reinforced with Kevlar. We have carbon fiber stitches and staples to stitch and staple a wall or floor together, if we determine this is the correct approach and application.
Epoxies, elastomeric sealants, polyurethanes, and a few other excellent products have proven to be effective,when applied properly. We have also seen failures when other companies haphazardly apply these materials. There are a variety of systems which may be applicable in certain situations, although proper and adequate drainage, in our opinion (and those of most engineers), may possibly be a critical component of any solution.
Overkill is never enough when it comes to your foundation, falling short is not acceptable. Polyurethane foams, and waterproofing sealants that are elastomeric have some give as opposed to the rigidity but structural adhesion experienced with epoxy. Each is designed to seal walls to prevent moisture from passing through. Each has its differences which make them good, or not good enough of an, option to use based on experience.
If you have a block wall, sometimes your solutions are limited by what can be properly done. You either have to stop the water by waterproofing the wall, which truly means outside excavation, and depending on our analysis, maybe exterior drain tile to lower the hydrostatic pressure. We may only need to install an interior wall and floor management system, allowing the water to flow; this can sometimes be done by installing modern microbial vapor seal wall systems and directing it to a sub-floor drain tile system, and maybe using a dehumidifier or other types of systems which extract or manage the moisture from the air, which we always recommend for basements.
In the end, it is price; what you can afford and which solutions are appropriate and feasible. The solutions are many, some good, some great, some horrible, depending on the company (in our opinion). Also, the application. We can propose a solution or option for any situation and we are not only capable of the application, but would do so with excellence. I have seen, first hand, the flip-side of the coin – a builder, or sub-contractor for other companies install systems with no regard to whether it would work in 5-10 years, since they on’t be around.
Since all homes are different, and each problem is unique, often we propose a combination of materials and solutions, for example: to properly waterproof a wall we might suggest drain tile system, pump, epoxy with carbon fiber, or polyurethane. On another, a simple dig and seal from the outside. On another, an entire wall system (we have many) with a sub-floor drain system. On another, just a drain tile system, with a wall management system. Only a proper inspection can determine which solution works best for you. Find out now. Call The Foundation Expert today and allow one of our Licensed and Certified Inspectors analyze your situation and prescribe a permanent solution!
Basement Wall Damage
Soil Compaction Changes
|When your home was built, an area approximately 6 to 10 feet from where your house is currently located was excavated, footings were formed, your walls constructed, etc. (See Understanding Residential Foundation Construction). Then that area was in most situations, backfilled with the same clay that was originally excavated. Damage to foundation walls is caused when marine clays are used as backfill. This practice is now prohibited, but County inspectors do not sit around job sites watching as crews place backfill. Code violations are something that we find on a regular basis when conducting inspections – and it does not matter if the home is worth $100,000 or $5,000,000. New Home Building Contractors love to skimp and save money wherever possible.In any case, this soil was not properly compacted to what we call a pan hard density. It was loosely backfilled, and rightfully so. Otherwise, the compaction would have imploded the walls that were not fully cured to begin with. As the years went by, and your house aged, the soil around your home compacted. During dry periods, the clay shrinks, settles into the voids left by the moisture, and then when the moisture returns, swells again. Damage is caused from these yearly cycles of pressure exerted by shrinking and swelling of the marine clay in the backfill. Swelling pressure of the soil can be compounded by improper drainage around the house from rainwater.|
Porous Concrete Block
When concrete block is exposed to water, the concrete block soaks up the water like a sponge, at which point, the acid starts to corrode and weaken the block and the mortar that holds it in place. This can ultimately result in a weakened block wall, which can then bow inwards.
Structural Wall Cracks
Depending on the extent of damage, foundation walls may need to be replaced while others can be repaired. Interior solutions can be wall bracing, I-Beams, Carbon Fiber, epoxy and polyurethane injections, interior drain tiles, and other types of repair. We now have interior elastomeric applications to waterproof concrete blocks from the inside, if the block is unfinished. Outside solutions involve excavation, crack repair, wall rebuilds, helical piers and anchors, home leveling, waterproofing, drain tiles, etc. To prevent future damage, the clay must be removed and the backfill replaced with, according to code, a minimum of fifty-one percent (51%) sand and/or gravel.
Indicators of Expansive Soil Movements
Listed below are indicators you can look for to determine possible expansive soil related movement and / or structural damage. The probability that your foundation has experienced some movement increases with the number of indicators observed, their frequency, and location in the structure.
- Diagonal(stair stepping) Cracks in brick walls. Cracks may go through brick or mortar and vary in width
- Sagging brick lines when sighting along a wall
- Bowed or non-vertical walls
- Separation of wood trim joints at corner
- Separation of concrete driveway, patio, or sidewalk from foundation
- Tilting of landscaping/retaining walls
- Cracks in sheetrock walls or ceilings
- Bowed or non-vertical walls
- Bottom of wall separating from the floor
- Cracks at wall corners
- Cracks above doors
- Ticking doors.(warped door frames)
- Sticking windows
- Sloping floor surface
- Cracks in ceramic or vinyl tile
- Cracks in concrete floor
Soil Moisture Changes
|Observing soil moisture changes around your foundation is possible, but what about under it? Moisture can move from outside to under your foundation through a property of soils known as suction or capillary action. Soil suction is similar to placing just a corner of a dry, compressed sponge in contact with a puddle of water. In a short time, the sponge has drawn water throughout itself and grown in volume. While a water source is present, the sponge will continue to absorb water until it is saturated. If the water source is cut-off, then water already in the sponge will distribute itself evenly, but the sponge will not reach saturation.Water can move horizontally and vertically through the soils under your foundation in a similar manner. As clay soils draw water to themselves, they too grow in volume (swell or heave) causing your foundation to move. Drying outside your foundation reverses the process. The moist soils will lose volume (shrink) as soil moisture moves out from under your foundation, the clay will crumble and settle into the voids left by the moisture, creating voids under the footing, causing the foundation to settle. Shrinking and swelling soil motions can lead to damaging your foundation and structure.|
Structural problems, wall rebuilds, stairwell installations, egress window installations, outside dig and sealing of cracks – all of these may require excavation. Waterproofing in its purest form is outside excavation, sealing the wall with a waterproof and vapor proof material, installing a proper drain mat for the wall, and installing a proper drain tile system to alleviate any hydrostatic pressure build up against the wall. Then, backfilling with aggregate. The Foundation Expert can handle any size project. Allow us to resolve your foundation and structural problems with experience, quality, and a cost-effective approach. Get answers now. Call The Foundation Expert @ (703) 762-2429
Crack Repair FAQ’s
Q: How can I tell if the crack needs structural repair?
A: If you think you have structural issues, call us at The Foundation Expert immediately! (703) 762-2429.
Signs of structural cracks include horizontal cracks, cracks 1”or greater, significantly wider at the top than the bottom, and offset cracks. These are just a few signs of structural damage. If there is any question of structural problems, we’ll know when we have inspected; and if so, call the engineer on duty to develop an engineer’s Report, necessary for anything ‘Structural’, to pull the appropriate permits, to have an engineer’s stamp of approval, which will be critical if you ever need to sell your home. Don’t make a mistake by going with a company which does not understand the difference between structural and non-structural foundation problems. You don’t get any ‘do-overs’ with your foundation. Rely on Engineering, not contracting in this case, The Foundation Expert – Licensed Structural Inspection to evaluate your situation.
Q: When do cracks in concrete occur?
A: Some, right away, some within 7-28 days of when your house was built. Many poured concrete cracks develop within the first two years after the foundation walls are poured. Block can take much longer – twenty, thirty, fifty years? Longer.
Q: Can a crack in concrete grow?
A: Yes. Freezing, thawing, pressures from expansive soils and seasonal and daily changes in moisture content within the soil surrounding your home; just a few of the reasons that cause cracks in concrete to grow or move.
Q: Does a crack in a concrete wall that is not leaking need repair?
I am going to finish my basement and am concerned about ruining my renovation; ruining my material possessions, carpet, furniture, boxes, musical instruments, clothes, etc.
A: Cracks will continue to deteriorate over time due to continued settling, poor drainage and hydrostatic pressure, moisture penetration, and soil pressure against walls. It is recommended that all cracks be repaired prior to finishing a basement or storing valuable items there.
Q: How does crack injection work?
A: Sometimes a completed two-part application in one tube, or a two part liquid resin through a double barrel tube gun, which is then pumped to flow, under low pressure, into the crack in the wall from inside the basement through ports. This resin, or epoxy, or polyurethane is introduced into the crack through small ports glued over the crack. The resin travels all the way through the wall to the outside where the concrete wall meets the dirt. The polymer or hydrophilic reacts chemically with the water, and then solidifies filling the space within the crack. The ports can be easily removed by hacksaw or other tool.
Q: How long will a crack injection repair last?
A: It depends on who does the injection, what material was used, what material was sealed. When we do repairs using crack injection methods, it is done properly and the injection itself should last at least 10 years; but we double ‘proof’ our crack repairs with Miradrain – which is drain board run up the wall on either side of the crack and directed under the floor into something existing there; this could last 30 years or more if undisturbed. If the money is spent and the work is done ‘right’ the solution should last 10-15 years or more.
Q: When fixing a crack, what is the difference between an epoxy application and a polyurethane application?
Can you be more specific – when would you apply one or the other?
A: The answer is not as simple as the question. Either material may achieve the desired result with some cracks, and with others, it is definitely one or the other. Some companies doing the application may simply choose the material they have the most experience with. If a specific crack needs to be repaired only to prevent water seepage, or water is actively seeping through the crack, we usually will apply polyurethane hydrophilic foam; whatever we feel is the best choice. Here is a breakdown of when we might use epoxy or polyurethane:
Epoxy is available in a wide range of viscosity, from ultra-thin to paste-like, which can accommodate cracks of different widths. If we determine that we are going to use epoxy (we prefer Polyurethane when this fix will work), we will use whatever viscosity is necessary to inject a given crack at pressures less than 40 psi. The width of the crack will determine the viscosity. A wider crack requires thicker material.
The main advantage to using epoxy is the amazing compressive strength, which at 12,000 psi or greater exceeds that of most concrete. This is why epoxy is sometimes the better choice for repairing structural cracks. However, epoxy can cure very slowly, usually taking hours to harden and cure. This can be advantageous since it allows time for the epoxy to flow into even the smallest crevices.
On the flip-side, if the backfill outside the wall has separated from the foundation, creating a void, the epoxy may flow out of the backside (outside) of the crack before it has properly cured or hardened. This can happen as a result of settlement, poor compaction during construction, materials thrown into the backfill instead of soils, and erosion do to the water. This may be why the crack is leaking water in the first place – it is the path of least resistance! Also, epoxy might fail in a wet application, although we always ‘torch’ the bare wall with butane torches.
These elastomeric, fast-setting foams are effective alternatives for applications involving only crack sealing (waterproofing) and not structural repair. If we have a concern about material leaking out the back of a crack, if we determine during our material testing and application process that epoxy is indeed flowing out the back, we then turn to polyurethane foams.
Because of their elastomeric nature, they are able to accommodate slight concrete movement so the seal stays intact. They also begin to harden and foam within minutes of injection. This reduces the chances of the material flowing out of an injected crack while still in liquid form, and even if some does leak out, the foam will fill the void. Although they do not add any compressive strength, you usually do not need any.
Q: What is the best repair method for a cracked poured concrete basement wall?
A: Go outside and dig down, way down to foundation footing. Then seal the outside. Then go inside, and inject a low pressure epoxy or polyurethane – whichever we think is the best method, the best application based on what we see when we arrive, not diagnosed on the phone. While there are numerous ways to temporarily patch cracks, to get a permanent repair, you must do two things: stop moisture penetration from the outside and eliminate or accommodate any wall movement. Low-pressure injections are done from inside the basement. The procedure will fill the crack from front to back and bottom to top thus completely sealing the crack. In addition, when using urethane foam, you will fill any void behind the crack.
Q: Why do surface repairs using hydraulic cement, caulks, coatings, or patching always fail?
A: These types of repairs consistently fail within a short amount of time. Expansion and contraction movement of the wall, though minimal, causes these repairs to shadow the cracks movement and leak again. Low-pressure urethane and epoxy grout injections are permanent repairs since the crack within the wall is completely filled, not just the surface.
Q: What if the crack is very small?
A: Not so small you’re not reading this question. It is rare that a crack is so small it cannot be injected with a crack injection system. Cracks, which are barely visible to the naked eye, are good candidates for crack injection. Again, visual confirmation.
Q: Why does concrete crack?
A:See Causes and Solutions. Cracks in concrete are a result of shrinkage during cure and other construction practices when the house is built. Settling, structural overload, soil shrinkage and expansion / swelling, hydrostatic pressure due to poor drainage, and other factors. Almost all concrete poured basement walls will eventually develop cracks.
Q: What is “stapling” a crack and how important is it?
A: Stapling is the process of installing carbon fiber with or without Kevlar™ reinforcements on the wall across the crack that is being injected with epoxy or polyurethane. In my opinion, the jury is out. I can’t see these staples holding the forces of any crack, if the water wants in. The carbon fiber straps and staples are installed with epoxy securing them firmly in place. I think they have not stood the test of time – they are fairly new; and where do you hear about ‘staples failing’ unless you’re the company which has to service that ‘warranty’ call. What might be fine for 12 years, might fail in the 13th.
If a wall is structurally compromised, I believe rebuilding that wall is the best option, when possible. Structural I-beams to shore up from the interior also have historical success. I do occasionally use carbon fiber with Kevlar, but normally to prevent structural damage. A functioning interior drain system with a good pump is also a prerequisite of any interior fix. Again, each situation is unique and so are the options.
Q: I have two vertical cracks in a basement wall and I’ve been told I need a “complete drain tile system.” Do I have to spend $10,000+ – ten thousand dollars to keep my basement dry?
A: Maybe. Maybe not. We can’t possibly know how much until we visibly see how much needs to be repaired by our observations and calculations. We don’t estimate – we quote exact prices and conditions. If all you have is a crack (poured concrete), and no seepage at the cove (where the floor meets the wall) then probably not. At least, not spend $10,000. However, if the crack was caused by hydrostatic pressure (not an easy determination), then a drainage system may be the solution, along with proper crack repair. Only a qualified inspection will allow us to make a determination for sure. Call The Foundation Expert at (703) 762-2429 for a qualified concrete crack repair consultation and possible inspection.
Q: Will a low-pressure injection work on my cracked block foundation wall?
A: No, blocks are hollow and porous. We can recommend alternate methods of repair. Block walls that leak are serious. Moisture soaking through is serious, but if you have a crack in a block wall, and water is coming through, you may have a serious issue. Call us.
Q: Do you recommend injecting the leaking joint between my poured wall and the concrete slab?
A: No. You need a sub-floor, drain tile system if the floor cove is leaking or seeping water. If you already have a drainpipe system installed by the original builder or another waterproofing company, and it is seeping in that area, then the drain tile is clogged, or blocked, or the sump pump is not working properly. Regardless of your situation, The Foundation Expert can properly diagnose and prescribe a cost effective solution to your problem. sam@theFoundationExpert.com or (703) 762-2429