Garage workshop - moisture on concrete floor

Sorry... kind of a long winded poster here. I live in rainy Vancouver in an old house that has poor drainage. We had a big storm yesterday with enough rain to keep the basement sump pump going frequently until late evening. I've been thinking of using my attached garage as a workshop and today while cleaning out some junk I found small puddles underneath some non-porous items lying on the floor (buckets, plastic garbage bags etc). It seems there was enough moisture under the concrete slab that some migrated up to the top and condensed in these few spots. This has happened a few times before during these really intense downpours we get 3-4 times a year.
I dread the thought of digging up around the garage perimeter to attempt fixing or enhancing the existing drainage system. Will this periodic excess moisture present many problems in the shop, even with good heat and ventilation? I've been thinking of laying down a wood floor anyway because the existing slab is quite sloped, so any power tools I plan to buy would be a few inches above the concrete.
Your suggestions and comments would be appreciated.
Glenn {Please remove the [nospam] for email replies}
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Glen,
The moisture you found under the items (buckets, etc.) is evidence that the floor has probably never been sealed. All cement floors will wick moisture to some extent and its the sealer that prevents it from getting thru. Use a cement cleaner and then apply the best concrete sealer you can find for aged concrete. This needs to be a sealer, a topcoat of some floor paint (that isn't a sealer) will soon deteriorate and peel.
As for digging up around the garage perimeter - first find the source of the water. Is it because of a lack of rain gutters or bad drainage (look up French Ditch).
Bob S.
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Glen,
An un-related thought here...
If your going through the trouble of putting in a wood floor, you might want to consider making it about six inches from the concrete if you can spare the head room. This will allow you to run wiring and/or ductwork (for dust collection) under the floor to those 'middle of the shop' machines like your table saw.
Of course, this is assuming your planning on a permanent garage shop. You know, without those pesky cars getting in the way!
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My parents garage also had a moisture problem like that. In the summer, I would leave open the hatch to the insulated attic, and the convection would keep the floor very dry. I never did come up with a good solution for the winter. Neither could I explain the cause of the moisture. The garage was well above grade, and the lot sloped away from the garage.
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<"gh1[n??????????? wrote...

Aside from any other suggestions you get, if you place a wood floor down over the concrete, make sure you use a vapor barrier. I would even make sure that the edges of the plastic sheeting (where two sheets meet) over lap with plenty of room to seal them with a couple beads of silicone. Of course the fact that Bob's advice on finding the source is excellent goes without saying. I just wanted to throw in the idea of a well sealed vapor barrier.
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Howard
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I would use a combination of the solutions, I would seal the concrete, use a vapor barrier and seal it with silicone and then drop in your floor of choice. Anything from 1x on flat to 2x6 on edge if you have the room.
If dampness is still a problem, you could resort to a dehumidifier but I doubt that you will see a need for that.
BRuce
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BRuce


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Glenn;
Sounds like you need to look after your perimeter drainage problem before you consider laying a wood floor. Otherwise the moisture will warp your floor.
In my house I had puddling in my crawl space. I replaced half the perimeter drainage about 8 or 9 years ago when doing a backyard patio project. That cost about $10,000. Still had puddling and finally did the front half a year ago for another $10,000, including new front stoop, sidewalk and a strip across asphalt driveway.
Now, a year later, the puddling is gone from the crawl space and a moisture test indicated that the main floor is at a moisture level ~12% (was over 20% a year ago). At that time a floor installer warned me that he would NOT install wood flooring until the moisture problem was solved.
Next door, a new neighbour installed wood flooring right after buying the house and without the installer checking moisture concerns. A short time later it started to warp. Need I say more!
Brian
| | > Sorry... kind of a long winded poster here. I live in rainy Vancouver | > in an old house that has poor drainage. We had a big storm yesterday | > with enough rain to keep the basement sump pump going frequently until | > late evening. I've been thinking of using my attached garage as a | > workshop and today while cleaning out some junk I found small puddles | > underneath some non-porous items lying on the floor (buckets, plastic | > garbage bags etc). It seems there was enough moisture under the | > concrete slab that some migrated up to the top and condensed in these | > few spots. This has happened a few times before during these really | > intense downpours we get 3-4 times a year. | > | > I dread the thought of digging up around the garage perimeter to | > attempt fixing or enhancing the existing drainage system. Will this | > periodic excess moisture present many problems in the shop, even with | > good heat and ventilation? I've been thinking of laying down a wood | > floor anyway because the existing slab is quite sloped, so any power | > tools I plan to buy would be a few inches above the concrete. | > | > Your suggestions and comments would be appreciated. | > | > Glenn | > {Please remove the [nospam] for email replies} | | -- | --- | | BRuce |
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