Is this bad?

[solarbird]

We have a little water in the garage. I think this is not a problem but I wanted to ask. Let me describe the house, first, starting from the garage and basement, and working up.

We live on a steep hill, and we have a basement-level garage. (Technically something like 80 square feet of it is officially "basement" and the rest is officially "garage," this having to do with whether there is more house over it. But really it's all connected, which makes this confusing.) 1/2 level up (and substantially but not completely offset - that 80 square foot overlap again) there is the ground floor, which is two to three three feet below ground in front, and is completely underground in back. The main floor above that is completely above ground in front (actually about seven or eight feet above the ground) and about three feet underground in back. If it wasn't for the retaining wall, it would be completely underground in back, too. Then above that is the top floor, above ground everywhere, even without the retaining wall.

Now, back down to the garage: the cement garage floor is a separate pour from the foundation/basement wall at the back of the garage. There's a small gap between the two pours, probably about, hum, 2mm? Along that gap, water wicked in from apparently below. I use the word "wick" because for the most part none actually made it even all the way up to the floor, except where a couple of floor mats were placed against the wall. These got soaked.

The foundation/basement wall segments stayed apparently dry the entire time, but a couple of rugs got soaked.

As far as I can tell, this is just a result of the near-record(?) water levels of the last couple of days showing up in our basement/garage level and is not actually a problem. But I could be wrong and would like to know that if so! I note that the stairwell down to the basement/garage bottom level is made of treated wood at the bottom stair, and not so at the stairs higher up, which indicates to me that the builders kind of expected this.

Also, the crawlspace behind the ground floor and beneath the main floor, in back, stayed dry.

So. I think I'm right and this is mostly okay, but am I wrong?

And is caulking that gap with industrial paving caulk a bad idea?

Comments

[westrider.livejournal.com]

My mom's garage got much worse than that, and the general opinion seemed to be that it was simply a matter of the record shattering rainfall, and that nothing really needed to be done about it. Unless, of course, we start having a regular monsoon season here, but that's an entirely bigger problem.

I can halfassedly speculate about potential problems with caulking that gap, but it's really not something I know about, so I will refrain.

[solarbird]

The first question that comes to my mind is, "is this an expansion gap and will filling it with anything create floor cracks later?" And I don't know.

[westrider.livejournal.com]

That was the first thing that came into my mind as well, but, like I said, I know diddly-squat about this sort of thing, so I can't make any recommendations one way or another.

[wrog]

...trying to remember what I can from my HS architecture class, keeping in mind that this was 30 years ago (i.e., I'm barely remembering and some tech may have changed) and back in NJ where certain prevailing conditions/assumptions may be different ("Never build on fill. always dig down to bedrock!" (since of course you almost never have to go that far to get down to granite -- yes, welcome to New England))...
... and also our experience of living in a house on a hillside where there were still interesting water problems.

standard practice was to seal the outside of the foundation wall as best you can, but for the basement slab, you just have a layer of crushed stone and pour it separately -- I don't recall there being anything about sealing it (it might even be actively bad to seal it -- you want moisture to be able to leave -- for that matter, basements often have an Actual Drain, which really is nothing more than a big hole in the slab... ).

From a physics of point of view this makes sense since the only time the seals underneath the house would matter is when your house is playing "boat" and at that point you're pretty much hosed anyway.

Most of the time, your house is just an obstruction in the middle of an underground stream/river, and as long as you give the water someplace else to go, you're fine. Given the choice between "under" and "around", you'll have a slight preference for "around", but under is okay as long as it isn't then inspired to go up. And the only way the water goes up is if something is blocking it from continuing down the hill. (Our own water problems were mostly solved by building french drains eminating from the downhill corners of the house -- which basically had much better water conductivity than the surrounding soil and kept water from collecting near the foundation wall.

So my 1st-order guess is your builders did everything right w.r.t. the foundation wall -- otherwise you'd have a horizontal geyser in your crawlspace or bottom floor somewhere -- and that's what matters.

I can't really see the gaps in the garage floor as being expansion gaps. Expansion gaps are what you need where stuff is going to be heating and cooling a lot, like, say, sidewalks exposed to sunlight, or where you're dealing with materials that expand/contract differently (e.g., concrete road surface on steel bridge frame -- if they ever actually do that, which I think they try not to...).

On the other hand houses/foundations also settle, which would be a legitimate reason not to have a monolithic structure or a big wide slab with no interruptions. On the 3rd hand, the stuff you fill the cracks with can be plenty flexible -- the real issue, I think, is, once water does get into your garage, is there a way for it to get out again? On the 4th hand, maybe having the slab sloped a teentsy bit is enough.

made of treated wood at the bottom stair, and not so at the stairs higher up, which indicates to me that the builders kind of expected this.

or it's required by code. I don't know.

[dustin-00.livejournal.com]

You have the same question I do -- except in my case, I have carpet and some finished walls over the crack in my cement slab. :-/

[solarbird]

Well, it's not a crack, really, it's a gap - it was never joined. I don't know whether it was even intended to join, it might be an expansion gap of some sort.

[solarbird]

Also, ouch, carpet and finished walls. :(

[(Anonymous)]

Preamble wherein she says: "please consider this advice in light of its source". I used to do municipal engineering in a building-inspection and construction-review group, and heard lots of geotechnical horror stories revolving around foundations and drainage. So, herewith, advice offered after checking available datasets for your locale:

+ + +

The major reason for the small open gap is so that it can be a control joint (which allows shear or dilation at a known point), since with the foundation style and site grading you have, and given the heterogeneity of your hill's native soils, the builders anticipated differential compaction and possible differential settlement, plus issues with locally-high groundwater pore pressure. (Almost certainly you have a substantial, and very deep, perimeter French-drain, plus completely concealed chevron drains under your slabs; take my word for it, if you didn't, you'd have flooded).

It's okay to caulk the gap; it would be better to use something with as low of volatile components as possible, and which retains some ongoing flexibility. A synthetic "asphalt" type of caulk **would** work, but because of ventilation and offgassing issues I would advise you to use a California-compliant low-VOC (low-volatile component) elastomeric caulk. Buy, and try, one tube first, make sure it goes in okay; might want to use an old butter-knife to slide it in more deeply. Ongoing flexibility is essential: your slabs need to be able to micro-move there.

Needs to be said, of course, "this is gratuitous and neighbourly engineering advice offered in good faith for public benefit without exchange of compensation; no warranty express or implied is here given." Which is to say, please do not sue me for trying my best to be helpful, and if you are feeling paranoid, drink some tea. ^_^

If more questions, have at it.

[solarbird]

We have a substantial drainage system indeed! And it does work very well and I do maintain it. (This is actually very little maintenance consisting entirely of checking the traps for debris buildup.) It actually drains to a wintertime creek and outflow ditch.

The plan drawings I have talk about 4" perforated "FTG." drains around the foundations. Next to the perf. drain there is '4" solid pipe tight lined ind. of ftg. drain,' and I don't know what that means.

One of the things I was worrying about w.r.t caulking was whether this was an expansion gap of some sort. (See above for previous reply.) Now I have a term to use. ("elastomeric.") Thanks. ^_^

[mattsnaps.livejournal.com]

I was personally going to give props for "heterogeneity", but "elastomeric" is better.

[angharads-house.livejournal.com]

Okay, no hay problema.

What does the 4-inch solid pipe connect to, on your drawings? I would expect a Y-shaped system with each arm running up to a dry well beneath one of your downspouts on either side of the house (there will be at least two downspouts, and most likely one for each straight run of gutter). Do the perforated drains eventually lead, downstream, into the main discharge system?

I'm asking because there are several ways that this can be done, and stay effective, and there are a couple of ways that screw up badly with time -- my friends over in building inspection used to reject plans over that.

Also to consider: Canadian national codes (at least the CSA versions) want all below-grade wooden elements in a residential building to be pressure-treated wood (what we'd call preserved-wood foundations). So seeing the bottom part of your stairs be made of preserved wood, well, that's just good practice done by a conscientious builder.

Glad to be of service, this counts for 0.5 PDH with my professional association. ---> just kidding... ^_^

[solarbird]

What does the 4-inch solid pipe connect to, on your drawings?
The drawings don't have the entire drainage system, just the bits near the foundation walls and footings. And even that is in sample form rather than complete. So I dunno. Could be SPACE!

[(Anonymous)]

can you make a scan and send? this is sounding very wierd, as if they only showed "typical details" but not a proper as-built.

back-channel okay; attachments okay too long as you warn me they are coming (i junk unecpected ones)

[solarbird]

Livejournal logged you out again. It does that.

These are absolutely not the as-builts, sadly. This these are a copy of the permit prints. I have another copy of the permit prints which is slightly earlier where you can see the changes from the original for-permit plans where they lied to King County about the grading. They are versions from after the City of Kenmore coming down on their asses, however.

They're still wrong in a few ways. 0) I think they show the garage/basement level as a little too low vs. actual construction. But I'm not sure about that. It looks lower than as-built but that could be a trick of siding scale, infill amounts done, things like that. So that might and might not be accurate. Things that are clearly different: 1) The server closet isn't there; it's an enclosed rectangle which appears to be unreachable from any point in the building as drawn. I don't even know whether they intended it to have a floor, or whether they just didn't draw in the doorway to it. The location of the current door is pretty obvious. 2) A second, smaller-in-both-axes enclosed rectangular area in front of the one just described. This would definitely not have been reachable (and would not have had a flat floor over the entire area had it been), and I think would have been purely ornamental. (And changed the way the building interfaced with the garage roof, not for the better.) It would have been under what is now a box protrusion from the top level. The house definitely looks better without it, but having it there was presumably the original quick-change for dealing with the lowering of the garage to match grade reality. 3) There's a Juliet balcony on the top floor that isn't in the drawings. I'm 99% sure it was added later as part of the introduction of the top-floor box, as an architectural echoing of that box.

Okay, so, here's a picture from when it was listed. In the plans we have, that rightmost window on the top floor isn't in a box, it's part of a sheer wall that goes all the way down to the garage roof, and the area under it is filled in. (Also, there's a beading board that runs along the whole house pretty much exactly where the box bottoms out in reality.) That additional enclosed area would have been (apparently) unreachable. Behind that area is the server closet, shown in the plans as unreachable, but built in normally. And the Juliet balcony on the centre window on the top floor isn't there.

There are other cosmetic differences; there's a decorative vent in the front wall under the high peak; they just didn't bother but I think it'd help. The build-out of the front porch railing is very different, with 4x4s instead of the as-designed 8" mostly-cosmetic square columns.

In the version of the plans that shows the changes (via whiteout, no lie) from the original, you can see that the garage section was supposed to be about 5' higher, and on the same level as the ground floor. The building would have had a much greater feeling of mass to it, and would have been more of a horizontal spread than a vertically-oriented assemblage of levels. The garages would also have been more visually prominent, peers with the rest of the building, rather than subordinate to it. While there are many things about this building I can... take or leave... this change is not at all one of them. From a symmetry standpoint, the flatter (and therefore wider, proportionately) version is better, but from all other standpoints, I prefer this one.

Also, it helps that this one actually gets built on the actual landscape as present, rather than in some fantasy-world flat plot, as described in my story link above. -_^

[jessie-c.livejournal.com]

Caulking is probably what you'd want to do. It'll keep the water in the ground where you want it and be flexible enough to allow for expansion and normal movement. You'll probably have to replace it every couple of years but that's better than the situation now.

It'll also serve to keep out ants ant the like in case they ever find their way into that crack.

[poodlgrl.livejournal.com]

I work for a building envelope firm you know. Our business is waterproofing. Let me know if you want me to run it by one of the engineers. I can sweet-talk!