I mentioned earlier this week that my yard was torn up for a pretty good reason. That reason: french drains. Or maybe, French drains? I’d better go ahead and capitalize it, I think if anybody is like to be offended it’s the French.
You might recall the issues of water in our basement that precipitated our (presently stalled) renovation project. Part of that renovation was solving the water problem, which we attempted to do with a product called DryLok. Well, long story short, it failed, perhaps predictably enough. Thankfully, none of our work was lost, but it did mean that we needed a final solution to the moisture problem, and quickly. Hence the French drains.
If you don’t know, French drains are designed to relieve hydrostatic pressure on sub-grade foundation surfaces. In other words, it’s an underground gutter. First things being first, you gotta get underground.
I should say here that I hired someone to do this work for me. I was immediately thankful that I did once I saw how much dirt I would have had to move all on my lonesome.
A lot of that is because I had him go a lot deeper than usual. A foundation in our region only needs to extend 42″ below grade. However, the back of our house is completely below grade, so the footer is 96″ down. We probably could have gotten by without going as deep as we did, but take a look at that first picture again, paying attention to the wall. That’s bare block, not waterproofed. I’m going all Walter White on this one: no half measures. Had to get down to that footer and tar that whole wall.
And insulate it, too. That’s a few inches of rigid board, not enough to turn my house passive, but it should help to keep some of the chill off. And down there in the bottom of that trench, that’s the gutter I was talking about. It’s a perforated pipe, which means it has holes in the top of it. Remember, water follows the path of least resistance. When you’ve got clay soil like mine, it’s actually easier for water to push through the concrete block than it is to flow around the house. Now, the water that would be pressing against the house instead can find its way into this pipe, where it will flow harmlessly around the house and into the front yard.
That’s the side of the house where it now flows; the pipe and insulation were added after this photo was taken. After the pipe is laid and sloped properly, the trench is filled with two kinds of gravel. The first is large gravel that won’t clog up the holes in the pipe, then a finer gravel that will keep dirt from settling down between the larger stones. Any water that gets close to the house will trickle down through the gravel, instead of being held against the house by the clay soil.
So all that’s done and now we’re hopefully better off for it. Basements are inherently damp places, I’ve come to realize. Water will come through masonry, through walls and up through the slab itself. That’s why foundation drains and under-slab vapor barriers are standard in new houses. For old houses like ours, you just gotta make do and bite the bullet. Unfortunately, this is the kind of improvement that makes a house much more liveable, but doesn’t show up in the value of a home. Apparently, the moisture problems in my basement were legendary, like the French dragon Tarasque; I met someone who knew the previous owners and the first thing they asked me was, “basement staying dry?” With luck, these French drains, like Saint Martha, will have soothed the savage beast.