Today’s market offers many insulation choices, but the most popular and easiest to use is polystyrene rigid board. This comes in 2ft x 8ft sheets with interlocking grooves along their edges, and has the minimum insulation level that is recommended for rigid board, listed at R13/RSI 20. Your local dealer can recommend the most suitable insulation for your building in your area if you explain clearly your required R/RSI ratings. Although it is termed ‘rigid’, this board insulation is fragile when over-flexed or subjected to wind. Protect it before and during installation (and avoid walking on it if laid flat). Install special flashing trim on the foundation wall’s top, clipping it snugly to the insulation board. You can also apply pressure-treated plywood to hold the insulation in place at the header joist on the foundation wall top.

Ensure that every insulation joint is well-sealed and they clip together neatly. Your material supplier can help with flashing and clip requirements – there are many different types on the market. The insulation should overlap wall corners to avoid exposure of concrete areas.  The insulation should also be protected from intense sunlight by a covering, which also serves to preserve it from animal or traffic damage if it juts out over the grade. There are off-the-shelf coverings which can be purchased easily or custom-made from pressure-treated plywood vinyl or aluminum siding to match the house metal lath and cement.

Backfilling the Excavation

Once your drainage pipe is laid and insulation installed, now is the time to fill up the excavation. Do not use heavy clay soil or other types that drain poorly. Remove these and fill the hole with "pit run" sand for good drainage. This type of backfilling sand helps direct water away from the foundation wall for a dry basement.

The finished grade should slope away from your home once the refilling work is completed. This is good for drainage, especially from the foundation wall. Always install eaves-troughs with their downspout pipes directed away from the house.

Problem Basements

Older buildings usually present obstacles, such as:

• packed-stone or dirt floor surfaces;
• low-ceilinged basements;
• either no basement or slab-on-grade construction;
• building done on piers or by blocks.

Basement insulation problems may require the assistance of a professional contractor who can give you a better grasp of your specific requirements. With numerous variations in climate and construction types, it is impossible to give general requirements and still be correct about individual scenarios. Consult a professional if you’re not sure.