We’ve been considering the March 2005 article by Andy Engel for doing the flooring in our daylight basement conversion. But it bothers me that it’s being attached to the concrete by screws (thru plywood and eps), thus giving an immediate “passage” of underground water pressure to seep up the screw holes. That underground water pressure is the source of the water sheen we get on that floor during rare multi day rains. We have doubled all the drain lines around the basement to offset this effect, but still because we are the last property down hill before the stream, 20 feet lower, the water pressure builds up on those wet days and gives us the sheen.
anyone want to comment on the use of this installation versus the possible water transmission?
We’re inclined to use the Building Science for Healthy Homes method instead. A dimpled membrane goes against the concrete, then eps, then plywood, then breathable flooring. … or even dri-core.
Anyone with experience want to jump in here and compare? Thank you?
Replies
Given your slab is wet, I think a dri-core like product is your only solution, short of removing the slab and laying down plastic, or drain tile ... ps maximum tapcon screw depth is 1 1/4 inches, your slab will be allot thicker than that ..
Very old house ... probably insufficient vapor barrier under the slab ... poured together with the footer ... don't want to disturb floor ..risking footer/foundation... have doubled the drain piping all the way around the house ... insulated subgrade walls on outside, waterproofed walls on inside ... made keyway at base of inner wall and added hydraulic cement ..... did these before 2000 ... no water from walls ever ... but in very heavy days of rain ... will get a sheen on the garage floor ....
Is there no good way to handle this situation and keep it mold free? We've heard and read of some options ...
Is the conclusion here still a no go?
The room is my pathway from base of gorgeous basement stairs across the garage into my laundry room. Need some environment control so as to balance the good situation at base of stairs and in the laundry room.
Is there no good way to handle this situation and keep it mold free?
Sure. Keep the RH below 50%= no mold. We live in what amounts to a walkout basement and do just that. But we never have wet floors even though we have hill above (and on top) of us. We also constantly monitor RH, as you should.
How important is your landscaping? The two underground houses I've built both had hills above (and over) them. Both got an umbrella extending 20' from the perimeter. Neither have a water problem. The client insisted on a standard drainage system behind the buried wall. Never saw a drop come out of it. I'm extremely careful to direct surface water around the houses. BTW, no special waterproofing necessary, just 6 mil poly.
Leaving your basement wet and keeping RH below 50% might get interesting. Get the biggest honking dehumidifier you can find. And maybe find that you occasionally need a second. Then your problem is you want to isolate the water under a finished floor. Doesn't sound good to me.
You haven't filled in your profile, found by clicking on your name, which would tell us where you are. This time of year, most of the North America (not Pacific NW) would have low RH from simple air changes, which you should have anyway. PAHS Designer/Builder- Bury it!
The rest of the basement is dry and the RH stays below 50%. Doors close off this 10x20 area which gets the occaisional sheen. We do plan to put a dehumdifier in here, because adjacent storage closets need the help. They have louvered doors.
Now we're looking at putting in the dimpled plastic, eps, ply, and wood floor plus a forced air source in the dimpled layer which we'd turn on when needed. it could vent to oudoors or inside the room, either one. Plus dehumidifier. The closets get up to 58% RH. No current record on the 10x20, but it is signficantly lower.
sorry, initially only saw the tapcon issue, I don't think humidifiers etc, are going to help, the concrete will keep wicking the moisture from the ground under the house, I think your looking at removing the slab and installing a vapour barrier, or breaking channels for drain pipe, maybe even a sump .. it's only a matter of time till mold and mildew will begin ..
I'll jump in, but you might not like my opinion. If you've got a water sheen on your slab, I don't think you should finish the basement. That's too much moisture for any interior system to handle.
Andy
Andy
Never try to teach a pig to sing. It wastes your time and annoys the pig.
I'm not disagreeing with you, but the other half of my marriage thinks it should be a go ahead. Mold makes me ill. It does not make him ill.
The sheen on the 10 x 20 area former garage under the house is the only part of the basement floor which ever show moisture. It takes many days of hard rain for it to show.
Why won't these air pocket sub floors like dri core be a good enough solution?
Won't the sheen just dry? Or do you think it will just make mold?
There will be a dehumidifier in there.
If there's water, there's mold. Maybe legionella, too, particularly when there's not much air. Don't count on air to dry it, even using the dimpled plastic.
I'd still advise against proceeding, and I wouldn't take the job on a bet. That said, if you're set on proceeding, get the biggest, baddest duhumidifier you can.
AndyAndy
Never try to teach a pig to sing. It wastes your time and annoys the pig.
>>I'm not disagreeing with you, but the other half of my marriage thinks it should be a go ahead. Mold makes me ill. It does not make him ill.I'm with Andy: tell your other half that guys can really get themselves in trouble by plowing ahead without due consideration of other views <G>Pointing out where he can grab some blankets on his way to the couch might drive the message home <G,D&R>
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