Framing a Basement shop...?

[lkazista]

When framing a "dry basement", everyone tells me to go PT on the floor, and then frame conventionally up to the ceiling. This is advice that EVERY builder I have EVER spoken with has told me.

Enter Fine Homebuilding Magazine MARCH 2005 issue.

The writer states that PT will keep thr rot at bay, but can still develop mold and mildew from the concrete contact. He instead says that a 1 inch layer of styrofoam be put down, with a double layer of offset plywood on top. Once that is complete you just frame with yellow lumber, no PT needed. The styrofoam boards allow water to enter and exit and dry easily.

He recommends the same process on the walls only using 2 inch styrofoam. This keeps fiberglass out of the basement and away from any potential water. He goes on to say that the plastic wall liner between the concrete and the fiberglass is a bad way to go.

Any thoughts...?

Lee

[Duff]

I can't say 100%, but I thought PT was only required on the exterior wall contact points. . .

[jonmulzer]

I have always just framed with ground contact rated pressure-treated lumber for the sill plate and yellow lumber the rest of the way. Floating walls when necessary and on the demo work I have done on basement rooms I have never noticed mold or mildew really. I would hesitate to reinvent the wheel, below grade framing has been done this way for years. Ground contact rated PT wood is supposed to resist mold and mildew because of the higher concentrations of preservative chemicals and mold and mildew will grow on styrofoam if they wish, given the right conditions.

Why no vapor barrier? I have always been a fan of tarring the exterior of the wall, sealing the inside with a good oil-based concrete sealing paint, vapor barrier and then spray-in expanding foam insulation. But I am a belt AND suspenders sort of person.

[lkazista]

Jon,

He says that a "barrier" doesn't allow moisture a way to get out if it gets in. Bascially saying that mostuire WILL always find a way in, and trapping it in the vapor barrier will lead to problems. He does say that it could take 20 years or so for issues, but that issues are fairly certain to found at some point.

Duff,

Yeah, just on the concrete points for the PT, but this author is saying to go against that, and do the styrofoam trip on ALL concrete surfaces, and then yellow lumber, hence breaking the concrete contact.

Lee

[Brian G]

Local building codes may differ, so what the guy says in the article may not apply to your area. For example, in my city, code requires that plates are either PT or redwood. There also has to be a vapor barrier between block walls and the framing. Furthermore, the basement walls must be insulated to at least R-5.

So, check with your city.

[lkazista]

Local building codes may differ, so what the guy says in the article may not apply to your area. For example, in my city, code requires that plates are either PT or redwood. There also has to be a vapor barrier between block walls and the framing. Furthermore, the basement walls must be insulated to at least R-5.

So, check with your city.

I spoke with my inspector today, the 2 inch foam board gives you an R7, and he finds it to be an acceptable "vapor barrier" as well. He is only looking for the barrier to stop the capiliary action. If the floor were covered as described, he would be fine with the lack of PT.

He had never heard of anyone doing the basement in this method, but did remember the article, and researching it back then, and not having any issues with it.

Lee


_

[JimD]

I've done two basements with PT bottom plate and framed from there. I haven't torn them down to look but have had no noticable problems. Usually the conventional way to do things is a pretty good idea. It is wasn't, it wouldn't stay the conventional way to do things.

Vapor barriers are different in different parts of the country. If you plan to put a plastic vapor barrier under the drywall, I would put one between the concrete and the framing too. You could get moisture from the concrete in the wall and the vapor barrier under the wallboard will trap it in the wall. Around here, they do not put vapor barrier under the wallboard (air conditioning is the main load and the reasoning is humidity from the outside becoming trapped) and I don't think you need plastic to protect the movement of mositure from the concrete into the wall - because it can get out throught the wall board.

I like rigid foam insulation but it is kind of expensive. If your budget will accomidate, I think that is a good idea. I would use a normal PT floor plate, however.

Jim

[LinuxRandal]

I asked about this a while back, and talked about Cedar as a possiblity as well. The use of tar paper was mentioned.

http://www.bt3central.com/showthread.php?t=33551

[Russianwolf]

I'm planning on using the 2x2 flooring squares from HD. they have a plastic layer on bottom that has spaces for air to flow and raises the surface layer off the floor. The top is OSB. It's specifically designed to go on concrete floors.

[LarryG]

Any framing in direct contact with concrete or masonry, whether interior or exterior, should be PT (considered good practice even if not required by code).

No wall or floor assembly should have more than one vapor barrier. Where to put the one VB varies depending on the construction type and climate. In recent years much new information has come to light that challenges the traditional thinking on where it should go; in many cases (like the humid southeast), it's a lose-lose situation no matter where you put it. But it's a sure thing that if there's two VBs in the assembly, condensation will form between them and have no way to escape. As an example of this, we no longer specify a vinyl wall covering finish on exterior walls. The VWC, which is intended to be decorative and low maintenance, has been found to act as a VB and that leads to problems with condensation and mold.

I don't see anything wrong with the proposed system in the OP, but I don't think it's a case of the water that "will get in" having a way to get out. If actual water is getting in, the first priority is to stop that from happening. The reason the rigid foam insulation will work better is because it better isolates the mass of the concrete slab from the tempered air in the basement, and thereby does a better job of controlling condensation.

[ejs1097]

I'm planning on using the 2x2 flooring squares from HD. they have a plastic layer on bottom that has spaces for air to flow and raises the surface layer off the floor. The top is OSB. It's specifically designed to go on concrete floors.

Instead of the HD 2x2 squares at HD, my neighbor went with a different product. basically it's just the plastic but comes in huge rolls, you then supply your own plywood/OSB/etc. It's a lot cheaper with this method and the end result is the same. I think he said Lowes supplies it as well.

here's a link.
http://www.doerken.de/bvf/ca-en/prod...loor/index.php

[mschrank]

This thread over at JLC Online hits on a lot of your questions. This is a mostly pros only site, so should be a good source of info:

http://forums.jlconline.com/forums/s...ad.php?t=25634

[lkazista]

Mike-

Great Site, talk about a wealth of information on a topic.

It directed me to this site; http://www.buildingscienceconsulting...r_Renovate.pdf

Sort of like a Bill Pentz site about your house.

A lot of info, thanks!

Lee

[Cheeky]

Instead of the HD 2x2 squares at HD, my neighbor went with a different product. basically it's just the plastic but comes in huge rolls, you then supply your own plywood/OSB/etc. It's a lot cheaper with this method and the end result is the same. I think he said Lowes supplies it as well.

here's a link.
http://www.doerken.de/bvf/ca-en/prod...loor/index.php

they carry dricore at HD.

my brother is in the initial phase of finishing his basement. i'm helping him as much as possible.

we might be going overboard, but we painted the floor and walls with water-proofing paint. we're going to set the framing 2" away from the walls, use a vapor barrier for the bottom plate, with PT.

after it's framed, and plumbing and electrical pass inspection, he's going to have somebody spray 2lb expanding foam insulation. benefits include: as close to air-tight as possible, resists rot and mildew.

[crokett]

I framed my basement with 2" foam glued to the concrete block walls. The stud walls were put against that. I used treated for the sill plates. I have a few spots where I left access for wiring, etc and 2 years later, still dry and no mold, even after the flood we had in '06.