Question: I found a couple of your articles in old issues of the Free Press regarding sow bugs, and I was hoping for some further advice. I own a duplex, and my tenants live in the main floor and basement. One of them sleeps in the basement, and has recently complained of numerous sow bugs. I know they are harmless, but she has been finding them on her bed and is understandably disgusted. I intend to clear away as much organic matter from the foundation as I can, but that may have to wait until spring. In the meantime, I thought I would seal any interior gaps and cracks I can. Is that a fool’s errand?
In one of the articles, you mentioned sealing the floor drain in the basement. Could you elaborate on how I would do that? Would it involve getting one of these "waterless trap seals", or is there another method you had in mind?
I would appreciate any advice you can give.
Best regards, Thomas K.
Answer:
The solution to eliminating sow bugs and other crawling insects from your basement area is to ensure the area remains as dry as possible. Sealing a damp catch basin below the floor drain is a start, but ensuring the basement walls are properly insulated and air-sealed may prevent them from propagating near the foundation walls.
You are correct that small, pill-shaped sow bugs crawling around a basement are primarily a nuisance and not much more. To my knowledge they are essentially harmless as they don’t bite humans or pets, don’t transmit any diseases, and live for a short time before dying and leaving behind messy but innocuous remains. To see a few crawling around a typical basement is nothing out of the ordinary, but if they are more numerous and constant then the infestation may be more concerning. Not because they are harmful, but because they are a sign of a condition in the home that should be addressed.
These tiny insects, and some other crawling bugs often seen in homes, multiply in large numbers when there is a wet area that is accessible. You are correct that these small critters are often found inside and crawling out of a basement floor drain. That is typical in older homes that have catch basins for the weeping tiles below the floor drain cover. The cover is normally perforated, so that any water that spills or leaks onto the basement floor will easily drain into this small cavity in the concrete. At the bottom of this catch basin is a trap, filled with water, that is attached to the waste water drains. Because this trap is always full of water, and the weeping tile terminations above are often damp or dripping water, this is an ideal environment for the insects to live and reproduce.
One solution, as you have discussed, is sealing the top of the floor drain to prevent the bugs from escaping into the basement and living space. This is often done by homeowners with plastic sheathing, a garbage bag, or other water-resistant material placed under the cover. This may help keep the pests out, but it also may prevent basement water from draining if there is a leak. If this occurs when nobody is in the basement it could lead to a serious flooding issue. So, installing a floor drain seal that will open in case of flooding, but which will be closed at all other times, would be an ideal solution. While there may be several types of products available for this purpose, there is a locally owned company called Dranjer that manufactures floor drain seals, primarily for radon gas prevention. Fortunately, these devices should also work for the protection of your basement from creepy-crawly insects entering via the catch basin. Installing one of these, or something similar, should help minimize the problem, but is only one step in the solution.
Because basements can be substantially cooler than the upper floors of a home, there is always a chance they will be somewhat damp. This is because warm, humid air from the rest of the home may condense when it hits colder areas and surfaces in the area below grade. This is more prevalent along the perimeter of the basement, as the air contacts the always cool foundation walls. Since many basements still have sections of bare, uninsulated foundation walls, this is often a problem. Also, many older basements are poorly insulated, with missing or improperly sealed polyethylene air/vapour barrier over the insulated walls.
When warm air penetrates through these poorly sealed insulated walls it will almost always condense on the concrete foundation, because that will be even colder than normal with the thermal insulation keeping heat from the basement warming the surface. In winter, this condensation may freeze, leaving a layer of frost on the foundation, or in the insulation itself. Once this melts, when the weather warms in the spring, it leaves a perfect wet environment for the sow bugs to thrive. This will certainly be compounded with an older foundation with plugged weeping tiles, cracks, or deteriorated damp-proofing, but can also occur in one that is in otherwise good condition. So, ensuring the basement walls are properly insulated and air sealed, to prevent these damp conditions, may be even more important than sealing the floor drain.
Installing a Dranjer, or other device, under your floor drain cover may help keep some of the sow bugs out of the basement suite in your home, but ensuring the insulation is well sealed, and the foundation dry, is even more critical in preventing nuisance insects’ numbers from getting out of hand.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
