Do you suspect foundation damage in your house? If you are feeling dizzy thinking about the cost involved, then this article will tell you whether it is really foundation damage and what you can do about it.
Did You Know?
It is a myth that new houses do not require foundation repairs. In fact, foundation repairs have been carried out in houses as young as 2 years old!
The foundation of a house is affected by several factors, like moisture content in the soil, season, and presence of trees near the house. The most common reason for damage to the foundation is weakening of the soil around and below the foundation. This is either because of drought conditions which cause the soil to dry and contract, pulling at the foundation, or due to air voids in the soil, due to which the foundation sinks, causing the outer wall to revolve, thus damaging the foundation. The best way to check the safety of the foundation is to call a third party structural engineer, who will advice you on the further course of action. For informative purposes, this article will give you the common signs that a house with a bad foundation shows, along with a description of the various methods of repair that can be undertaken.
Signs of a Damaged Foundation
☛ Sloping/bowed floors
☛ Doors/windows that stick when opened or closed
☛ Gaps between door/window frames and sills
☛ Leaning/cracked chimney
☛ Gaps between walls and the floor/roof
☛ Leakage from the roof
☛ Cracked foundation walls
☛ Bowing/cracked walls
☛ Nails popping out
☛ Wallpaper peeling off on its own
☛ Cracked floors/concrete with or without water leakage
☛ Water accumulation around the house after a spell of rain
☛ Uneven roof
☛ Raised/lowered stairs or porch
☛ Mold on walls/roof
☛ Soil separation near foundation OR cracked soil near foundation
☛ Wall rotation
☛ Sunk/lowered foundation
Repairing a Foundation
Patching is used to fill up cracks in walls. Epoxy resin is used to fill in such cracks. First, injection ports are fixed to the cracks to enable the resin to enter them easily. After curing, the resin hardens, preventing further widening of the cracks and moisture entry. After inserting epoxy resin, the injection ports are removed using a hammer. Polyurethane foam can also be used to keep out moisture.
This is a method in which a house with a weak foundation is supported by inserting steel piers or piles underneath it. It begins with excavation of the ground around the foundation, followed by inserting the piers and filling the shaft with concrete for strength. Grout is inserted below the piers to remove void spaces and give additional strength. To be stable, the piers should reach the bedrock or load-bearing strata. There are several variations of this method, as explained below.
Push piers is a system in which additional support is given to the house by hydraulically inserting steel piers below it. The piers shift the load from unstable soil to more competent soil or bedrock. This method is used to either stabilize an existing structure, and even raise a sunken structure, making it a long-lasting solution. It is used when the bedrock or strong strata is near the top soil.
Helical piers are steel shafts with intermittent helices or screw-like turns. They are driven like a screw into the ground, as opposed to being pushed in. These are used in regions of challenging soil conditions, to transfer load from unstable upper soil to stronger load-bearing deep soil layers. It is a deep foundation system that is used more for industrial foundations, rather than residential ones. Helical piers take less space to be inserted, and are used to overcome compressive forces or forces arising due to tension. They are generally used for bearing lighter loads, like porches, staircases, etc., and can even be driven using hand equipment, if there are space constraints.
Steel piers are used to stabilize or raise houses with weakened foundations. They are driven into the ground, similar to push piers, and are weighed down by the load of the house. The steel pipes used may be subject to corrosion, misalignment, and bending problems, along with being quite expensive. It requires less space for operation.
Slab piers are used to stabilize or raise concrete foundations that require support. It is a very costly process, and has high space constraints. The slab piers may be driven by helical systems or pushed by push pier systems. The method transfers the load from unstable top soil to deeper, stronger layers. When the slab breaks, further raising of the foundation becomes a challenge. Success rates in lifting slabs have been low.
This method involves drilling of shafts directly into the foundation, after which the bottom of the shafts are widened like a bell shape with the help of special bits. Steel rebars are inserted into the shaft, before concrete is poured into it and allowed to dry. This may take anywhere between 1 – 2 weeks. Afterward, the house is lifted and placed on the bell piers. The disadvantages of this system include requirement of heavy equipment, danger of water seepage, and long-time requirement.
This method helps stabilize bowing foundation and basement walls. Bowing occurs due to increased lateral pressure from soil on a wall. Once this pressure increases beyond a certain limit, the wall begins to bulge. In this method, a several-feet deep hole is dug into the ground, a couple of feet away from the foundation wall. Then a steel rod is inserted into the foundation wall from within, such that it reaches the hole. A steel plate is fixed to the end of the rod within the hole, and another is fixed to the other end. Then the rod is tightened, pulling the wall back up straight. This method requires periodic rod-tightening.
This method involves placing precast concrete cylinders one upon another, below the foundation, to be stabilized. A hole is dug below the foundation slab, and the cylinders are inserted, followed by placing the slab upon them. The driving force here is the weight of the house, and hence, there is no prior indication of how deep the cylinders will go. Despite being one of the most economical methods, it has several disadvantages, like misalignment of cylinders due to lateral pressure of soil, cracking of pilings, cylinders inserting too low for support, and so on. One major disadvantage is that, in case the pilings sink very deep (beyond the refusal point) they may cause the slab to crack. This method is less time-consuming though.
This is a variation of the above method. The only difference is that, in this technique, a cable or rebar is inserted along with the cylinders, thus keeping them in alignment. The time required in this method is less, as there is no need to wait until the cement gets consolidated. However, there are certain problems with this technique, the most serious one being that, due to the cable or rebar, the entire column itself may be skewed, as opposed to individual cylinders in the pressed piling method. Another is that, the holes made in the cylinders for inserting the cables may cause water incursion.
This method is pretty similar to the pressed pilings method, with the exception that, in place of concrete cylinders, steel pilings are used. The weight of the house is again the driving force. The technique aims to minimize the disadvantages of the pressed pilings method, by using steel in place of concrete. The time required in this method is shorter, since one doesn’t have to wait till concrete consolidation. However, the method may fall prey to corrosion of the steel pilings, failure to reach the refusal point, thus compromising stability and incurring high cost of materials. Also, due to the reduced width of the columns in this case, the stability suffers. One important disadvantage is that, when heavy objects in the house are reassembled, an uneven load is placed on the pilings, which may cause misalignment.
This method is used to raise or stabilize sinking foundation slabs. Certain well-placed holes are made in the slab, and using a hose or some other equipment, a cement grout is pumped under the slab. This fills any spaces below the slab, and when the mixture hardens, the slab is raised or given support. This method is non-disruptive, has low cost when compared to slab replacement (ranging from half to one-third), and requires little time. However, sometimes, the mixture can get into sewer lines, which can be a bit of a problem.
This technique is similar to slabjacking, with the exception that, in place of cement, polyurethane foam is pumped below the slab. This foam expands on consolidation or releases gas bubbles, which helps raise the slab. However, due to the use of foam, the process does get much costlier. The holes made in the slab for foam jacking are much smaller than those made in slabjacking, thus reducing the need to cover them up.
Carbon fiber reinforcement is used to bind cracks on walls, floors, and restore bowed walls. It uses carbon fiber strips and strongly-binding epoxy resins, along with steel angles. First, the part of wall to be strengthened is identified, and epoxy resin is applied over the work area. Then, the carbon fiber is glued over it. Finally, the job is finished by fixing steel angles at the top of the wall. This method requires little time and is cost-effective.
Sagging beams, uneven floor tiles, and reduced crawl space can result from weakened soil conditions. To rectify this, metal support beams are installed, which raise the crawl space to an optimum level. These metal supports can withstand a lot of weight.
Choosing the right method depends on the area of damage, the amount of damage, and whether the damage is internal or external. The average cost of foundation repairs in the US is anywhere between $5,000 and $7,000. If the foundation of your house is still strong, you can make sure it remains so by simply looking out for the warning signs given above. If foundation damage is ignored, then the problem becomes more severe as time goes by, and you may end up shelling out more in future.