• Are there any cracks in concrete walls or floors?
  If so:
  • How many are there?
  • Where are they located?
  • How wide are they?
  • Are they vertical or horizontal?
  • Have they remained the same for a long time or are they changing?

• Patch unchanging, small cracks from inside with cement-based material or use an injection-type repair material.
• Fill unchanging large cracks from inside (and outside if possible) with "hydroscopic" concrete patch material that expands as it dries or use the polyurethane or epoxy injection system.
• Consult a structural engineer or basement specialist concerning multiple, severe or expanding cracks.

• Minor cracks only require attention to prevent water or soil gas entry.
• Major cracks can allow large quantities of water or soil gas to enter.
• Severe or active cracks (particularly if they’re horizontal) may be an indication of future problems or even present unsafe conditions that could lead to collapse.

• Is there any porous, powdery or crumbling concrete or mortar?
• Are there honeycombs (voids) in the concrete?
• Is the surface layer of concrete breaking off (spalling)?

• Patch small areas of crumbled, honeycombed or broken concrete with a cement-based material. Consult a structural engineer for widespread problems.

• Small areas of crumbled, honeycombed or broken concrete will allow moisture and soil gas to enter. Deterioration may continue, affecting the structural strength of the foundation.
• Large, damaged areas may be unsafe if they don’t adequately support the existing house or proposed renovations.

• Does the foundation seem to be sinking or settling?
• Do floor joists and beams seem to be uneven?
• Was the foundation built on fill or disturbed soil?
• Are the foundation walls warped or bowed inwards?
• Do concrete floors appear to be lifted up?

• Determine the cause of the problem and make immediate repairs. If any of these situations is severe, get help from a professional.
• Uneven settlement can cause concrete cracks or uneven floor joists and beams.
• Footings on different soils can cause uneven loading. Pressure from the soil or from groundwater can warp or bow foundation walls inward, cause horizontal cracks and floors to rise.

• Uneven settlement may continue to disrupt the house structure. Bowed walls may collapse.

• Is there cracking and heaving pressure in winter (often found at below grade basement entries or house and garage connections)?

• Cracking or uplift may indicate adfreezing (frozen soil adhering to the foundation and lifting it) or frost heaving. Solve adfreezing by installing a drainage layer, polyethylene sheet or free-draining backfill around the foundation. Prevent frost heaving by installing better foundation drainage and insulating above footings. For serious problems, consult an expert.

• Adfreezing or frost heaving will continue to cause seasonal movement along with water and soil gas leaks. The resulting foundation instability can continue to damage the existing house and any proposed renovations.

• Is there enough headroom below the floor framing and any ductwork to allow the basement to become useable living space?
• Can the foundation adequately support the existing main floor system and any proposed renovations?

• For greater headroom, lower the floor and underpin the foundation or raise the house.
• Seek professional advice to assess whether the foundation is adequate and to plan structural changes.
• If converting attics to living space, or adding an extra storey, assume that the foundation will not support the added loads. Consult with a design professional to verify that the width of the existing footing meets current building codes.

• Lack of headroom will make it impossible to use the basement as living space.
• Changing structural elements without sufficient planning can lead to unsafe conditions, including the sagging or collapse of main floors or foundation walls.
• Adding extra loads may cause sinking, uneven settling and cracking.

• Are other houses in the area known to have high levels of radon or methane?
• Is there a bad smell or high humidity in the basement?

• Measure average levels of radon concentration, if you are concerned. Test services are available in most major cities or through public health departments.
• Air-seal the foundation completely.
• Provide ventilation in the winter and dehumidify in the summer to lower humidity levels.

• Radon can accumulate in houses, causing unsafe exposure limits for occupants and a higher risk of lung cancer.
• Moisture and other soil gases can contribute to humidity, odour and mold problems.

• Is there any evidence of termites or other insects?
• Are there rodents present or have they caused damage?

• Call an exterminator to get rid of termites.
• Eliminate hiding places, food and water sources. Set baits and traps. Destroy nests. Seal entry points.

• Termites, cockroaches, rodents and other pests are not only a nuisance and potential health hazard, but they can also cause serious damage to your home.

Rewards

• Fixing foundation structural problems will help greatly to ensure the continued safety and durability of your home.
• Other planned renovations are much more likely to be successful when they are based on a sound foundation.

Skills to Do the Job

A handy homeowner can patch small, unchanging cracks or other minor concrete problems, deploy a radon test kit or deal with minor pest problems. A skilled homeowner can attempt repairs to large, unchanging cracks or undertake a thorough air sealing project.

Professional help is essential for:

• Assessing and correcting changing cracks.
• Lowering floors and underpinning or reinforcing foundations.
• Adjusting structural elements.
• Assessing loads and structural capacity.
• Correcting adfreezing and frost heaving problems.
• Correcting major pest infestations.