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SC_1story_w_crawlspace 12-27-2011 07:21 AM

Sealing a ventwell (brick wall / concrete patio)
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Hi, this is my first post after joining the forum (and was impressed this site has an iPhone app as well). Was looking for some advice on a new house I bought in SC. It is a one story house on a crawlspace.

In the back, the previous owner installed a concrete patio that runs up against the foundation. In one spot, water collects against a vent well and is causing water to leak into the crawlspace through the vent.

Wanted to get some advice. Looks like the previous owner used a sealant at the interface that has since eroded away.

Any suggestions for a product that would give me a good seal at the patio/steel vent well/brick interface? Should I also consider sealing the whole brick foundation on that side of the house where I have the problem?

Some pics attached.

Also...we already have that specific crawlspace vent closed.


BridgeMan 01-12-2012 09:09 PM

You might try a good polyurethane sealant, something available at a masonry supply store as opposed to the typical big box place (although the latter might have something comparable). I've had good luck with Vulkem 45, made by Tremco. I like the large tubes, which require the big caulking gun (30 oz. cartridge). And doing the entire run of joint would be in your favor in terms of keeping water/moisture out of the crawlspace, although I know of people who've had "swimming pools" under their house where a crawlspace is supposed to be.

To avoid wasting your time and money, surface prep is absolutely critical in making sure all of the old sealant is removed, down to clean, sound brick or concrete. As I used to tell my inspectors--"Have the contractor make it clean enough to eat off of." Vigorous scraping, followed by wire brushing, should do the trick.

joecaption 01-13-2012 08:44 AM

That's messed up, what they were suppost to do is form a drain pit with stone in it for drainage before that slab went in.
Also the well should have been set so that hole was above the slab not even with it.
The holes to big to fill with caulking so I would use a Stainless steel short bolt with washers on both sides set in Buna N caulking.
Also seal around the well with the same caulking.
A window well cover would also keep out some of the water.
Basement Window Well Covers, Egress Window Wells, Basement Window Bubbles, Window Well Cover at Window Bubbles

nealtw 01-13-2012 02:39 PM

The water appears to be sitting on the deck, is there no slope to take the water away?
This vent into the crawspace, is it a cut away in the foundation or is it a cut away thru the rim joist? If it is a the latter sealing the well will not solve all the problems as the water sitting on the deck will migrate thru the brick anyway. As Joe has pointed out there should have been a drain at the bottom of the well. Wet sill plates or rim joist is a much bigger problem than water it the crawl space.

joecaption 01-13-2012 03:27 PM

If the crawl space stays wet then you had better be taking a look at the floor and rim joist. If there all moldy or fungus covered there going to need to be treated with Boric Acid.

SC_1story_w_crawlspace 01-14-2012 07:02 AM

Thanks guys...the vent itself is cut into the foundation and not the rim joist, though I will take your advice and spend some time looking at all the floor joists, etc around that vent to make sure I do not have a mold issue.

Water does collect against around this vent well...when they put in the concrete patio they did not get the slope right in that area. From everyone's suggestions, it sounds like the first attempt should be cleaning the joint between the vent well and the patio to get it down to steel and concrete, then apply a waterproof sealant around the edges. Then also clean/treat the brick wall itself with a sealant so moisture does not seep through into the crawl space that way.

I was interested in one posters comment about treating any mold with boric acid. How does that procedure work? I do have spots in the crawl space with a little mold (little pinhead sized dots slightly raised up off the wood) that 2 inspectors told me were common for all crawl spaces...but I would still like to treat it after I finish pinning down my vapor barrier and taping all the edges together.

joecaption 01-15-2012 07:52 AM

Boric acid can be used for hundreds of thing, insectacide, fire redarder, treating rotted wood, mold treatment, eye wash ect.
It's marketed under dozens of differant names.
For a small amount just go to Wal-Mart, any hardware store, Lowes or HD and look in the insectacide area. Your looking for Roach Away. Look on the lable, it's 95 % boron.
Mix it in very hot water a small amount at a time in a pump sprayer.
There will be a small amount or clumps that will plug the nozzle while spraying.
Just unscrew the tip and rap the wand on a floor joist while holding the valve open until it sprays out all 4 holes.
I use it to treat exposed wood where boring bees, carpender ants, powder post bettles are making holes, make a paste out of honey or sugar water and boron to kill ants that are showing up on countertops or the tracks on slidding doors.
If you ever went into a commercial kitchen you would see a white powder under some of the equipment, it's boron. Roaches step in it and when they lap it off it dehydrates them and they die.

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