OK, thanks. I like "no temporary repeals of the law of gravity".
The long story, based on the comments. Layout at
formatting link
I did the diagram eight+ years ago while buying the house, but it's still correct in what matters here. I don't think it says, but the front of the house is about 100' to the road, 70' my property and 30' ROW (the paved road is butted against the far side of the ROW).
House was built in 1953. French drain and gutters installed in 2002 as part of my purchase, based on inspector's and contractor's recommendations. The seller was paying most of the cost, and I didn't pay a lot of attention to the details. Obviously should have paid more attention. (And in the end I may have paid most of the cost, as total required repairs exceeded the seller's contracted maximum.) The seller had been given the same report (same inspector even) when she bought the house three years prior, but had not taken any action.
Symptoms at that time:
1) Fungus on a few joists. Inspector could not say how old, but saw no change in three years.
2) Standing water or wet sand in the crawl space after rain.
3) Standing water at the south end of the house after a rain, pretty much covering the space between this house and the one next door.
Contractor, who came with multiple good recommendations, recommended a) the French drain, b) gutters, c) a low wall to protect the crawl space access door, and d) a berm in the back yard to divert runoff. (The crawl space access is at the SW corner of the house -- upper left on the diagram -- so water flowing from the back yard could enter easily.) AFAIK, the only evidence of water intrusion was on the south end and the south part of the back (west) side. Work was completed and we closed on the house. Though I paid less attention than I should have, I saw enough to know that they did install the French drain, and of course the other items are visible.
The French drain is against the foundation -- I didn't make that clear before -- on the west, south, and east sides of the original house (as marked on the diagram), about 110' total. The outlet pipe runs from the SE corner of the house to the ditch at the road, just off the bottom of the diagram.
Short term followup: though the berm was a good short term remedy, in a few months I completely solved the backyard runoff problem -- by doing nothing. Previous owner hired a "gardener" who came in with his lawn tractor and scalped the yard to within an inch of its life, then pulled out his leaf blower and took away the fallen leaves (the yard is shaded by large oak and sweet gum trees) and grass cuttings. I mowed as seldom as possible and at 3" height when I needed to, and never removed any organic material. Wonder of wonders, in a few months the ground was absorbing even the heaviest rain with no runoff at all (remember, this is Florida, very sandy soil). Neither the inspector nor the drainage contractor had noted this simple solution.
I got a remote-reading thermometer/hygrometer. Asked both the inspector and the contractor what RH was needed to prevent damage to the wood (fungus or rot). Neither could tell me. IIRC the inspector had noted that the wood itself was dry enough, just had this old fungus on it. Contractor basically said "I know how to dry it out, I don't know how dry it needs to be". He was proposing forced ventilation, which to me would just bring more hot moist air under the house, where it would cool since the house now has A/C (of course it did not in 1953, I think A/C was first installed in the late 1970s) and make it damper. I finally found someone who said the figure is
70%. My hygrometer shows that the RH is usually under 70% in the crawl space, and is only higher when it's higher outside. My conclusion is that the fungus observed on the joists probably grew 30+ years ago, before the house had A/C. No way to prove it of course.
I still had some trouble with water pooling, but it was clear that some of it was backing up from the road. The ditch had not been maintained, and water from uphill (north) was coming into my yard instead of staying in the ditch. After several calls, I got the city to pull the ditch and sod it. (The workers love throwing those sod staples, or whatever they are called, into the sod. I'm sure those do the job of holding it in, but I need a metal detector to get rid of them. Just yesterday -- some six or seven years later -- I found another one.) Since then, I've kept the ditch clear -- I learned that a narrow channel is better than a wide one, because the slope lessens in front of my house and the water drops its load of sediment if I don't keep it running fast. Neither the inspector nor the contractor noted the problem with backup from the road.
Long term followup: eventually the shingles made it clear they had reached end of life. Also had continuing problems with a "homeowner job" (a term I've come to use as a pejorative even as I continue to do some things myself) on the screened sun room (see diagram), including a valley with no slope. This year, had a new roof built over roughly the north half of the house, redecked the rest (was only 3/8 at most, not up to code), and metal roof put on the whole thing. Looks great, and only a single puncture through the roof -- got rid of two unused chimneys, used air admittance valves for two vents and ran the third through a gable, leaving only a skylight over the porch.
But I didn't plan adequately for replacing the gutters, and they didn't tie in well to the way we did the lower end of the metal roof panels, so I spent a good while figuring out how to add flashing and leaf guards to get all the water into the gutters and keep the leaves and acorns out. Finally completed that last week and got to test it the next day in a big thunderstorm. The gutters, flashing, and leaf guards seemed to work fine. Three downspouts were spewing water from joints, indicating blockage. The base of the downspout at the SW corner was a veritable spring, water gushing up from where the downspout entered the drain pipe. Not surprisingly, there was a puddle at the south end of the house. (Which verified that the original recommendation to install gutters was absolutely correct, since the flooding reappeared when the gutters didn't work, even though the backyard runoff and front ditch backup had been fixed.)
Checked the downspouts, only one was blocked, and that was above where it was spewing. So I started working with the drain pipe, which is that black polyethylene corrugated crap. Pulled out one downspout, reached in, and pulled out a 4' long hairball. (OK, root ball, but I have cats and it looks like a hairball.) Not enough to account for the symptoms, but told me that roots were readily invading. I had seen roots one other place, where a joint had been added later, so I wasn't totally surprised.
Experimenting, I found that putting a hose down one of the front downspouts got water flowing at the ditch, though it took about ten minutes to get there. Putting a hose in a back downspout, however, never got anything to the road, and the water was well above the top of the pipe, but the hose could not put out enough water to make it overflow. So there was a blockage along the south side, serious enough to prevent significant flow. Yet there was an outlet large enough to consume the input from an wide-open hose at less than 1/2 psi. Puzzled.
By this point I had decided, both from these observations and from reading various places, that the corrugated crap had to be replaced with PVC. So I started digging it up, no longer being careful to avoid making holes (and it's nearly impossible to dig the stuff up without making holes anyway). Got about half way from the SE to the SW corner, saw where I'd made a pretty big hole, and decided to test again. Water came spewing out of the hole. So I'd exposed the part with the blockage. Only took a minute to find a root as big as a finger growing into the pipe. Had to cut open 2' of pipe just to pull out the hairball, which ran 10' downstream and 4' upstream. After that, another test showed that water from the back flowed to the road, though it still took about ten minutes to get there.
(I still don't know why the drain was working before the gutters came off and were replaced, and not after. My guess is that it's a combination of it wasn't working very well before and that if I'd looked carefully during a hard rain I'd have seen some backup, that 3 months with no flow allowed the roots to grow tighter, and that some debris got in and plugged the remaining gaps before I got the gutters protected again.)
So yesterday I started digging full speed (which for me is not very fast) to expose the rest of the corrugated crap for replacement. I was about 6'-8' from the SE corner (going toward the road) when I noticed that I was hitting two corrugated pipes instead of one. I found that they were tied together in a tight Y -- both pointed toward the road, perhaps with the idea that this would mean one wouldn't back up into the other. Still more digging revealed that the one I hadn't seen before dove into the ground under the other. I didn't try to follow it, but it's surely connected to the French drain. There's certainly no other outlet from the French drain -- remember, I saw the work being done, so I know it's not draining into a reservoir, and although there's a little bit of slope, there's no place to hide a drain pipe and lead it to an unexpected location.
So slow-moving water could back up from the gutter drain into the French drain. Even some fast-moving water, especially with the corrugated crap. And if the corrugated crap is partly blocked farther downstream, a LOT of water could back up into the French drain. Possibly this has something to do with the long time for water to reach the ditch, though I haven't figured out any way to determine that.
So that's the background for my post last night. In eight years, no one has asked me for a recommendation on the inspector or the drainage contractor, so probably it will never happen. I'm unlikely to act to publicize what happened -- heck, I haven't even checked whether they are still around, and the worst I can make it out to be is incompetence, not fraud. But still there's this nugget in my brain that wants to make sure I've got it right in case someone asks.
As for my belief that the French drain was not needed ... well, obviously I have no way to remove it for testing. The fact that the situation seems to be under control even though there's no effective outlet weighs strongly in my mind. Of course, since the soil is sandy, it's possible that the French drain is acting as a reservoir to get the water to the bottom of the foundation to percolate, instead of being against the foundation wall. (The foundation wall is brick, painted on the outside. I think the paint was there before the French drain was installed, but I'm not totally certain.) I know, as described above, that the French drain doesn't solve the puddle -- blocked gutters alone re-created that, even with no backyard runoff or backup from the ditch.
As for installing a French drain with the idea of adding an outlet or pump later ... well, I've explained that I know that was not the case here. But in this environment, a French drain with no maintenance is just a mass of roots anyway. If I dug up my French drain now, I'd probably find solid roots in the pipe -- after all, that pipe has to have holes in it, which are invitations to the roots.
Now, aren't you glad you asked?
Edward