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Finishing A Basement
I live in the southeast and have a
basement that I am about to frame around the concrete walls. I am going to
use 2x4 wood.
Do I need to use PT (pressure treated) wood other than the bottom? Or do I
use it all the way around. I read somewhere that I frame it up like normal
(PT on the bottom and white wood elsewhere), but line the concrete with ½
foam sheets and don't use a vapor barrier on the insulation. What are your
thoughts on this.
Thanks
John C.
There
are many different methods of finishing basements. Using Pressure
Treated lumber for the sole plate (the bottom board) is necessary
because the concrete will wick moisture out of the soil and into the
wood. It wouldn't hurt to use treated lumber for the entire wall... if
the basement ever floods, there will be less repair work.
About 10 years ago I did a little research on basement finishing methods
for my own house, which had a damp basement. I concluded that the best
method was this approach:
- Wash the walls (and floor) with Muriatic acid, diluted 50/50 in water.
This is hazardous! Wear eye protection, or a face shield. The acid
cleaning is necessary to remove lime from the surface of the concrete.
My old house had little white puffs of lime that formed as moisture
passed through the walls and evaporated. I rinsed the walls with a
garden hose, and I used a shop vac to suck up the rinse water. This was
a lot of work, but a very necessary step. Without this acid wash,
nothing will stick to the concrete.
- Paint the walls with a quality basement paint. In 1991 Consumers
Reports had just done a study of basement paints. I don't recall the
specifics, but their guide books may still have the info. I used Glidden
oil-based basement paint, which had a high content of Portland cement in
it. This stuff really stunk, so ventilation is required.
- Paint the concrete floor with oil-based concrete floor paint.
- Attach a sheet of ordinary 4 mil polyethylene plastic to the wall. The
trick was finding a glue that would stick to polyethylene. I tried many
different glues on some samples, and 3M super 77 spray adhesive was the
best. It costs about 10 bucks a can and only covers maybe 100 to 200
square feet.
- Build an ordinary stud wall. I just built the wall laying on the floor
and tilted it into place. But watch out for uneven heights in your
floor-to-ceiling dimension.
- Install wiring as normal. If you use UF (outdoor rated) wiring, you
may not have to replace everything in the event of a flood. It's just a
pain to strip the cable jacket.
- Insulate with regular fiberglass insulation. I couldn't find anything
other than kraft-faced insulation, so that's what I used. Here in the
north, they recommend only one vapor barrier, and on the inner-most part
of the wall. But a basement is a little different. The kraft facing is
really just a vapor retarder, not a true barrier. The polyethylene is a
true vapor barrier.
- Install a finish wall surface. I used T1-11 plywood with grooves at 4
inch spacing. It looked okay, kinda rustic. Good for a basement, and
very durable. If I used drywall, I would only use MR (moisture
resistant) wallboard, at least on the lower half.
- Finish trim with colonial casing and rough-sawn 1x2's.
I noticed right away that the humidity in the basement was much
improved, because the dehumidifier no longer ran continuously.
I visited my old house recently. The basement remodel is holding up
pretty good, but I did notice that the quality of my work has really
improved over the last decade!
There are more ways to finish a basement, more than I have time for. A
lot depends on the age of your house and any moisture problems you may
have. My old house (built in 1950) had no damp-proofing on the outside
of the concrete, so moisture entered readily. Newer houses always have
some form of damp-proofing, at least around here. You may not need the
basement paint, the acid wash, and the plastic sheet. But if you are
experiencing a lot of dampness in your basement, these steps should
help.
Bruce W. Maki, Editor.
John Replies:
I checked with the local building codes on this, and with people who do
this in my area, and this is what they suggested:
The wall is going against a poured wall (8" thick)
Use ½" sheets of insulating foam board and glue on the concrete
wall, seal all seams with tape.
Build the wall as normal, and use UNFACED insulation.
Install sheetrock as normal.
The house is 9years old and has the normal waterproofing stuff on the
outside when it was built. The area I live in is NOT known for floods (not
in a flood plan or anything like that) and the basement does not have any
moisture problems to begin with...
Thanks again
John
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