We are planning to take everything out of the basement to re-do the foundation. One contractor is proposing to use polyurethane or icynene to fill up the holes and then rebuild the rest of it with new material.
Our concern is whether this polyurethane product is safe? What about the side-effects? I do not want to put anything into our bodies that we will regret later, especially our toddlers.
-- Henry Bissoon, e-mail
ANSWER: While you should have significant concerns over using polyurethane or icynene spray foam to repair your foundation, the focus or your worries are way off base. Both of these materials are now widely used for insulation and air sealing in homes and commercial buildings but are not designed for any kind of structural repairs.
The first thing to address is the advice given by the contractor that recommended this material as suitable for foundation repairs. I have heard of some bad ideas, but this one is right up there with the worst ones. I would send the person who suggested this packing and look for a real foundation contractor or mason to do the repairs. My reasoning behind this is that both of these materials can be very effective in providing high quality, moisture and air resistant insulation, but have no structural properties. Replacing deteriorated mortar with foam insulation will do nothing to improve the strength of the old foundation walls, which may continue to move and deteriorate over time. I don't even know if this would stop the majority of the moisture that is leaking into your basement, which should be your primary concern if you plan to finish the basement.
Old stone foundations like yours continue to perform well after many decades, even with considerable deterioration to the mortar that holds the stones together. The first problem normally to address is the seepage that occurs as the old joints deteriorate and turn to sand. If this seepage is minor, improvements to grading and drainage around the home and repairs to mortar joints in the interior of the foundation may be enough to hold the water at bay. If this has been neglected for many years, not only will the water be an issue, but movement in the individual stones may occur. If this movement goes on for some time, as you have experienced, structural damage to the home is inevitable. The only recourse, in that case, is major foundation repairs.
Foundation repairs on stone or rubble foundations, other than minor repointing or parging above grade or inside basements, are not in the scope of expertise of the home handyman. These repairs typically require major excavation, usually by hand, around the perimeter of the home right down to the base of the foundation. Once the exterior of the foundation is exposed, loose mortar can be removed and the foundation repointed. This may have to be done from both the interior and exterior of the foundation, if there is enough damage to the mortar joints. After complete, new damp proofing or membranes and drainage tile system can be installed outside the foundation, if no further structural repairs are required. If there is significant movement in the stones they may have to be removed and reset, or replaced with poured concrete, after the house floor structure is temporarily supported.
As you can see, this type of repair is not one to be taken lightly, or attempted with makeshift ideas using improper materials. Your concern over the composition of the blown-in foam insulation is a moot point, as these products should never be used for this purpose, anyway. What should be more of a health concern for the occupants of your home are the effects of excessive moisture intrusion into the basement.
The good news is that proper foundation repairs will solve both the problems of structural damage to the home and problems related with water leakage. This will not be a low-cost repair but will be money well spent, rather than blown away with the useless installation of foam insulation in place of proper mortar.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the president of the Canadian Association of Home & Property Inspectors - Manitoba (www.cahpi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P.O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358 or check out his website at www.trainedeye.ca.
