Home & Garden Columns
I was out with a young contractor at the home of a client he wanted me to talk with the other day. The homeowner had a wet basement and garage that never seemed to dry out. We walked around and I looked up the hill to find a line of extraordinarily healthy and prolific trees and shrubs marching to the crest of the hill. They ran in a line from north to south, roughly. “Creek”, I cried, “Well, maybe an aquifer.”
Well actually, that’s the easy part (diagnosis). The hard part is draining the site effectively, but, indeed, the first things is to see if you can figure out where the water is coming from and it helps to understand the kind of source you’re dealing with. I knew that there was a lot of water and it came all year long, although, obviously more in the rainy season. The homeowner readily agreed with this assessment. That’s the way our creeks, streams, springs and aquifers work. They can run all year long, although more so in the winter. Some springs run copiously all year round, and this can change the way we think about moisture issues.
Why do we want dry properties? Does it really matter? What is the downside to inaction?
The answer to these questions is not consistent from one house to the next. It’s site and owner specific. Like many things in life, the answer requires some personal inquiry and the acknowledgement that most of us live within a range of imperfect conditions. We’d all go nuts if we tried to fix everything and it seems to me, at times, that the folks who actually do fix absolutely everything are a little nuts.
Here are some guidelines: Does your house show signs of current settlement? Is the foundation rotated or cracked? Does it appear to be drifting this way AND that at the same time? It’s best to involve an engineer or inspector to help make a determination about this but some cases are really obvious. If your floors make for great fun with marbles or topple small children, you might have a settlement problem. If these things are true for you, you might want to invest in drainage because it can almost always slow this process, although there are surely soils which will move despite our best efforts. In some cases it can make a huge difference, however the time scales are such that it may not be apparent for some years.
If you have water or damp soils under your house for part or all of the year, this may contribute to fungi growing in the crawlspace, basement or the house proper.
This varies a lot, but if you have windows that are perennially coated with condensation, this is one likely cause (don’t ignore this because there are other possible causes including faulty gas appliance venting which might prove quite serious).
When drainage is installed properly, it can help damp houses dry out, lessening the effects of these various microscopic organisms.
Fungi (which includes molds and most mildews) and Protists (which include at least one mildew) nearly all require elevated humidities to propagate and when things are dry, most of them simply will not grow, throw spores or otherwise annoy.
If you’re ready to really attack this problem, the type of drainage system that seems to be most effective and popular is the “French” (or, more properly, subsurface) drain. This is essentially a moat. The notion is this. If you can give the water that is heading toward your house a faster and easier path around the house via gravity to a point beyond harm’s way, you’ve won the battle. This usually takes the form of a trench around the entire perimeter of the structure, though a horshoe shape often works well on a hillside since the water on the downhill side tends to be moving away from the house anyway. Usually.
Given that water travels toward your basement or crawlspace from below ground as well as from the surface, you want to be able to catch it as it approaches your basement and so must cut this moat deeper than any portion that might be wetted within the bounds of your home. Since water is generally traveling through the soil in roughly the incline of the hillside, it is not typically necessary to make a trench at the uphill end as deep as one might think. If your basement is 6 feet below ground and near the lower end of the building, you do not necessarily have to make a 12 foot deep trench at the back. A 6 to 8 foot trench might do just fine. This is tricky stuff though, since we just don’t know exactly how the plates of clay, silt and rock are layered below your house and we also don’t know how waterways have crafted themselves over the eons (especialy springs, eek). But, all that said, if it looks like a wet, slimy frog, it’s probably a wet, slimy frog.
Nonetheless, the smart money tends to be on making the trench a little deeper than everyone thinks is enough and when you’re already digging, the cost usually isn’t much more to trench another foot or two.
A moat will still work just fine if it’s filled with something that leaves big voids for water to flow, so rather than having a trench around the house (to go with the pikemen and the drawbridge), we fill it in with gravel. To be sure that there is an extra big void, most systems include a large perforated pipe that works simply by providing a space where water can flow. Water flows in the entire body of gravel and pipe as it chooses. A fabric encasement is wrapped around the pipe and gravel to keep soil from slowly nullifying this diaphanous mechanism.
The trench must be sloped to direct water to one or more safe end points. On a hill, this might be down to the street-gutter, but on a flatter lot, it may be necessary to end the slope in a sump (or well) where it can be pumped out to the gutter. Sometimes there are other safe places to dump the water but not usually and please don’t dump it anywhere near your neighbor if you want to get invited back to the annual BBQ.
There’s too much to say about pumps to get started in this forum but let it be enough to say that these require many carefully considered details and the oversight of an electrician.
Clearly, these are heady, complex issues and when funguses and wet basements are involved, this is not the time to try and go it alone. So if this sounds like your home, get some professional help and put the fungi on the dinner table where they belong.