Question: I would like to get rid of the wall to wall carpet in my basement, but am having trouble figuring out what to replace it with. Each vendor tells me something different. I’d like it to have a warm and attractive appearance. I have blond hardwood throughout my main floor, and would like to carry it down the stairs, but it doesn’t make sense to put hardwood in the basement.
Cynthia Stewart, e-mail
Answer: Unfortunately, carpets are not a good choice for installation directly over concrete due to the dampness often associated with cool basements. The carpeting or underpads have a tendency to absorb moisture and odours. In very wet cases, the carpets can become mouldy and may create a health hazard for homeowners susceptible to mould sensitivities.
The best way to prevent contact of carpeting, or other floor coverings, with cold concrete basement floor slabs is to install a subfloor. Traditionally, this consisted of thin strips of wood or “sleepers” which were laid directly over the concrete and covered with boards or plywood sheathing. Often the sleepers were made from cedar, which has natural resistance to rot but is still subject to moisture damage over time. The separation of the wood sheathing from direct contact with the concrete created only a partial thermal bridge and allowed a small airspace to prevent quick rotting from wicked-up moisture.
The separation and airspace allows for a much warmer floor surface to the touch and a much dryer floor to install carpeting. This system may work well for many years, but can quickly deteriorate if the foundation leaks or the sewer backs up.
A more modern approach to the use of untreated wood for this purpose is to use pressure treated plywood for the sleepers and the plywood sheathing. This will be very successful in preventing rot and mould growth, but may be a health concern from off-gassing of the chemicals in the treated wood into the living space.
Check with manufacturer’s specifications and local building officials before using large amounts of any treated wood or preservatives in your basement.
An even more recent approach to the problem of moisture damage and rot from subfloor contact with concrete is the use of specialized plastic membranes underneath the sheathing. These membranes are slightly raised with dimples or ridges that allow a good, moisture proof separation for the sheathing and sufficient space for air in the gaps between the ridges, which prevents trapping moisture underneath the subfloor.
The original installations were done by creative contractors who used exterior foundation waterproofing membranes covered by plywood or OSB. While these were somewhat effective, they typically had to be secured to the concrete, which did not allow for easy removal if excess flooding occurred.
Several manufacturers realized the value of this type of system and developed a hybrid that included the membrane already bonded to the sheathing.
The small size of the individual panels and the tongue and groove edges allow for very easy installation over most basement floor slabs. In most cases, securing the panels is not required and is a real benefit in case of a leak in basement plumbing pipes, hot water tank or sewer back-up.
Popular options like laminate flooring can be a good choice for the final floor covering in this situation as it is normally installed without permanent fastening and may be easily removed or sections replaced if damaged.
Every year there are many new products being introduced not only for new home construction but also for renovations or retro-fit situations like those in your question.
Care should be taken to employ new or old technologies that will work well in modern, well insulated and sealed homes without creating new problems like condensation and mould growth. I recently viewed the installation of one such new system designed by a local inventor for insulation of foundations that prevents moisture and mould growth. It works by employing a de-humidification system built into the design.
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.
trainedeye@iname.com
