How to support subfloor repair, beams 24 O.C.


Old 10-10-05, 04:23 PM
Visiting Guest
Posts: n/a
Need to support subfloor repair, beams 24 O.C.

My house is a 1963 ranch-style, single story, original subfloor is 2 x 6 T&G laid on 4 x 6 beams that are pretty far apart, at least 24" to my knowledge.

I had to take out part of rotted master bath floor on one side of toilet. A beam goes right under toilet, and the flange is attached to it. Toilet leakage went all the way thru subfloor so beam is moist on top and soft near the flange - maybe you could remove 1/2" material with a pocket knife. Any structural concern there?

Anyway back to the hole: when I cut back the rotted T&G boards about 12" parallel to the beam under the toilet, I expected to find the next beam at the 16 or 18 inch mark - but there was none. I reached a ways up under there and still couldn't touch the next one. So I'm hoping these beams are no more than 24" apart, but unfortunately the tub sits over where that would be. Don't wanna disturb the tub, it's not in the budget. Is my only option to hang 2 cross joists between the beams, and create a box to attach the edges of the cut floor and the repair panel? Should I support the cross joists from below with jack posts? The crawl space is extremely tight, so if I can't reach the next beam to tie in, is it feasible to build a "flying" frame - a short piece of beam under the side of the opening that lies between the existing beams, jacked near the far corners of the hole, and tied back to the one beam I can get to? Or is something like that not a good idea?

Last edited by jwfsmith; 10-11-05 at 09:53 AM.
Sponsored Links
Old 10-12-05, 12:00 PM
Visiting Guest
Posts: n/a
Update: these suckers are 48 inches apart!!

Had a chance to get a look under the hole with a tape and flashlight, turns out the beams (aka joists?) are a full 48" apart. So I got a framer in to take a look, he says the 2 x 6 decking can take that kind of span, that's why they built it that way (seems cheap to me, was there any kind of UBC in 1963??). So this framer says I just need cross joists between the two beams, meaning 4-foot sistered 2x6 on each side of the opening, then frame in the rest of the opening from below. No jacking required. He'll do the job.

Is that sufficient support for the bathtub, and the floor in general?
Old 02-08-06, 12:16 PM
Join Date: Feb 2006
Posts: 1
subfloor replacement in bathroom; joists 48" apart!

I am in CA; house build in 1958, exactly the same situation - 2x6 t&g subfloor on 48" center joists (4x8's). I need to make the same repair; how did yours turn out?

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes