I want to brace a portion of my stairway using two boards that are 2x4x8
inches each. They will be under the tread and the tread and riser will be
carpeted. The back access to the stairs is sealed off. Is it OK to use a
couple of pressure treated boards I have? I.e. any prohibitions on use of
these small pieces of pressure-treated stuff, inside the house?
It depends on how old the wood is. Older pressure treated lumber contained
formaldehyde. If it's the newer type, it should be OK, but you can't use the
same fasteners, because the new pressure treated lumber rusts them out right
I read that the new treated lumber has copper in it
and the copper will supposedly dissolve an untreated nail
on another subj, talking about building materials
when I was on a frame crew, when the hurricane hit
nags head a couple years ago...plywood was in big demand
long about winter time, we were getting in hacks of fresh plywood
once you take a few pieces off, the plywood starts to get warm
it is actually hot to touch towards the center...
and, I did enjoy the heat seeing that it was at least 40 below that day
oh yeah! 40 below
or he could get a box of galvanized 16's
i use the drill alot when making something like this
i pre-drill the hole, and use vinyal coated deck screws
you really need at least a 16 when binding 2x4's together
end to end, like I say, the drill is the only way to make them
stay without splitting the ends...sometimes you are very
close to the end...or! if I had a good nailer, I could shoot
it with some 16's...
I'll raise a red flag. I built a shower enclosure and tiled it about 3
years ago. The "curb" and side supports for the shower door were built
from 2x4 PT purposely picked to resist mildew and rot even though no
water should have been able to reach it. The boards were held together
with a few 1/2 screws and washers counter sunk into the exposed
surfaces. Exposed surfaces were covered with WonderBoard strips before
tiling with thinset mortar.
After about a year it appears that the PT lumber was expanding and
cracking the tiles and grout. One of these days I'm going to have to
redo the whole enclosure. But first, I'd like to understand what
happened and what the "right" material to use is.
the pressure treated lumber is wet so it shrank at first
this caused cracks
once the craks were there, water did get in and
the pressure treated lumber swelled up
probably cracking the grout more.
next time, regular lumber will be fine for subframe
__ this may have posted already, i hit the stop send button
i wanted to add... if you can keep the area dry for a couple of
months...the treated lumber will settle, it will dry and pull all
it's going to pull...at that point you could just re-grout
rather than have to tear the whole thing out
Wood will only "expand" if it's getting wet, in which case you have a
bigger problem than just using pressure treated wood. You have a leak
that needs to be fixed. You didn't mention any kind of waterproofing
material in your construction details, so that would be my first guess.
The entire shower should be waterproofed before tiling, including the
bed, partway up the walls, and up and over the curb. Vinyl membranes are
common, but I used Schluter Kerdi to waterproof my own shower.
In addition, PT lumber is often a lower quality wood (hemlock around
here) that is injected with the chemical treatments. This makes PT
heavier with a relatively high moisture content. As it dries it often
warps and cups badly, which could also explain your tile cracking.
Shouldn't be a problem if it was properly screwed down, but if you had a
single row of nails down the middle or something, it could be an issue.
Viewed from another perspective, wood WILL shrink and expand with changes
in moisture content. Unless the wood is kiln dried, it will probably
shrink later. That's why many "pro's" build curbs out of bricks or other
material that won't shrink and cause the tile to crack.
I wouldn't worry about using pressure-treated wood in this case. There
isn't enough to cause problems even if it were to off-gas somehow (which
is unlikely if you've had them a while). And it's probably fully dry by
now if you've had it in storage for a while.
One problem with treated lumber is contact contamination. For example,
kids would play on playsets made of PT lumber, touch it with their hands,
then put their hands in their mouths, eyes, etc. Since the old PT
contained arsenic, this was a potential poisoning problem.
A second problem was "leaching" when used for things like raised garden
beds. The fear was the arsenic would leach into the soil, be taken up
into the vegetables, and poisoning the consumer. I don't remember ever
hearing a case of that happening, but it was a concern.
A third concern is breathing in the PT sawdust while cutting the boards.
Probably not an issue for the occasional weekend handyman, but a
different matter for carpenters who deal with it on a daily basis.
Anyway, I wouldn't hesitate to use the PT wood in your stairs.
Thanks for all the replies. Other than the actual handling of it, it seems
to be no problem. It will be in an area where no one has access to it and
the associated sawdust from installation will be properly take care of.
Thanks to all.
In most cases its actually recommended when in direct contact
with concrete. Especially in basements!
Only thing I can recommend is to cut it outside and wash
your hands when your done. Other then that, its safe to use.
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