Slab heave can be fixed. The cracks in your house that open and close can be stabilised. Cornell Engineers has the experience and knowledge to help you fix slab heave.
What is Slab Heave
Some signs of slab heave are:
- Diagonal or stepping cracks in brick and blockwork walls.
- Cracks coming from the corners of windows and doors.
- Doors and windows stick and become difficult to open and close.
- Cracks, gaps or compression of cornices.
- Gaps under walls.
- Visible unevenness in floors.
- Rarely, cracks in floor tiles.
Do This First
If you are a homeowner and your house is starting to move and crack, do this first:
- Start a Crack Diary.
- Find water sources that are entering the ground around your house and eliminate them.
- Fix leaking pipes. Get a plumber to help find and repair these pipes.
- Repair dripping taps. Replace the tap washer or relocate the tap into your yard.
- Fix broken pipes under your house. See a plumber.
- NEVER plant trees near your house. Consider removing any really large trees that are near your house (seek help from a structural engineer and/or arborist).
- Fill in dog holes next to the footings with tamped, moist clay sourced from elsewhere on the block.
- Capture condensate from air-conditioners and hot water systems and divert it away from your house.
Do these things before you talk to your builder. Do them before you lodge a claim with your insurance company. Do them before you start paying for engineers and expensive chemicals. Do them before you fix ANY damage.
The problems associated with slab heave can often be overcome by one of these solutions:
- Improve the tolerance of the building to uneven movement. This solution includes articulation gaps and joints and wall strengthening but is only appropriate if the slab doesn’t feel uneven.
- Remove the cause of the uneven movement. Identify sources of soil moisture and eliminate them or isolate the building from them.
- Isolate the building from uneven movement. This method includes jacking and underpinning so that the house is supported clear of the ground movement. Not all houses can be fixed this way.
- Demolition and reconstruction of the house using one or more of the above techniques and/or a stiffer/stronger footing system.
Do it Right
I’m sad to say – unless slab heave damage is repaired correctly, it will come back again, and again, and again. Concrete slab repairs have to be done correctly.
Some builders think that houses with slab heave damage can’t be repaired. Houses with slab heave can be stabilised!
Cornell Engineers have engineered successful repair and rectification projects many times. Matt Cornell has never had to recommend demolition of a whole house because of slab heave.
Let me say that again: In twenty-eight years of full-time practice as a structural engineer, Matt Cornell has never ordered the demolition of a house because of concrete slab heave.
Should You Start Watering Around Your Home?
Changes in soil moisture levels in reactive clays cause ground movement. When clayey soils become wetter they lift. When clayey soils dry out they drop.
I’ve seen the results of engineers recommending to clients that they start watering around their home. I’ve seen homes where the owner has installed boreholes that they fill up daily in an attempt to solve slab heave. I have seen automatic watering systems with the valve pit full to the brim.
Let me say this: The addition of water to the soil around your home by manual or even automatic methods is too uneven and too difficult to maintain for it to provide lasting results.
- Do you stop watering when it rains?
- Do you know whether you are changing the soil under your house?
- To what degree is the moisture-wicking sideways?
- Who will water for you when you are on holidays?
- What will you do when there are water restrictions?
Do you see? It is just to hard to maintain even soil moisture conditions around a house by adding water to the soil.
The better way to solve slab heave is to eliminate all abnormal sources of soil moisture. Go back and read the Do This First Section. All these things are aimed at providing long term, stable, normally dry soils. No user intervention. No automatic watering systems or boreholes.
Make the soil dry around your house in a way that does not require your intervention. That is how you can protect your home from slab heave.
Cornell Engineers can Fix Slab Heave
If your house has moved and cracked because of uneven soil moisture conditions, I can diagnose this problem and help you fix it. I can help you fix your concrete slab heave, reduce cracking and reduce ongoing movement.
In time you will be able to fix the cracks and enjoy your house.