I'm replacing the lower level floor joists in a 135 yr old farm house.
Basically sitting 6" off the ground on a rock foundation. The current joists
(what's left of them) are rough oak 2x10 on 24" centers. Length = 15.5'.
If I go to 16" centers and support them in the middle, would a 2x8 Douglas
Fir be sufficient, or should I stay with the 2x10? Flooring will be
underlayment then 1x6 pine planking. (similar to original)
2x8 will hold but probably will be more "bouncy" even on 16" instead of
24" spacing. If it were me, for that application I'd stay w/ the 2x10
and use treated for the extra moisture resistance and still be far less
expensive than Doug Fir (unless you're in the PNW where it can still be
found--ask the average worker-bee at the local yards here for "fir" and
they'll think "fur" and when you tell them what you mean the response
will be "Never heard of it!" :( )
I'm no expert, but that sounds consistent with what I have seen used over
the years. While you have the floor open, I'd strongly consider doing some
digging and making that glorified sleeper foundation into an actual
crawlspace with a vapor barrier, and usable access for wiring and such. If
that isn't practical, I'd make all the new timbers out of treated wood, and
use a solid poured concrete pier up the middle for your center support. I
suppose house jacking and a proper foundation are out of the question?
Raising the whole thing would have been nice, but the "wings" so to speak
off the kitchen are on slabs. And it would be cost prohibitive. I've
already done about 80% of the wiring and have the plumbing planned and none
of it goes under. We even had a guy do a superb job of putting in a high
efficiency heat pump/furnace/ac unit with full duct work with minimal
hassles. I hadn't even planned for this floor fiasco, but we opened it up
to level it and found the joists in a bad way. My preliminary plan for the
center support is to dig out the loose dirt and get to some solid ground and
lay down a PT 6x6 and block up on top of that. I don't think pouring
concrete is possible. I'm on a bit of a time crunch and winter is moving in
here fast. I figger if what was there lasted 135 years, then anything I do
will out last me for sure. And we plan for this to be the last stop. <G>
thanks for your reply and input,
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