Trying to decide how much work I need to do to accomplish my goal here. My house is 100+ years old. It’s 1-and-a-half stories and the construction choices were probably questionable even at the time it was built. First floor ceilings are joisted with 2×4 lumber. That’s actual 2″x4″ not nominal, on 24″ centers (sort of, 22 here, 25 there). The underside of the joists are covered in tongue and groove pine or fir, which might help explain why the thing hasn’t fallen down. My bedroom is over my living room, contains a king bed and several dressers full of clothers, the span is 172″ and there is only 1″ of sag. In the dining room, I removed the t&g ceiling, and when my 40lb daughter bounces up and down in her bedroom above, the ceiling flexes at least a half inch. (Obviously, removing that t&g was stupid, but it’s done, there were good reasons at the time, and I’ll address that problem some other year).
Now I want to add a bathroom in part of the space that currently makes up my bedroom. This presents any number of problems which I will have to solve. One of the biggies is how to fit drain pipe in that floor. There will be three fixtures, tub, lav and toilet. I think I can run a 3″ drain for the toilet between joists and into an actual 4″ stud cavity to the crawlspace. And although I haven’t checked to be sure (I will) I seem to recall code allows me to get away with 1.5″ for lav and tub drains. However, drilling 1.5″ holes through 4″ joists really seems to be pressing my luck, especially in light of the next problem.
Here’s the bigger problem, however, which depending on your answer might solve my drain problem. I wanted to put a shower stall in this bath, SWMBO wants a tub, but she’ll settle for a small one. So, to my question. The tub would be a 48″ model (I know, why even bother at that size, but did I mention SWMBO?), and would run perpendicular to my undersized joists. Although my floor/ceiling is holding up just fine, should I worry that the addition of a tub full of water (let’s guess 600 lbs total in an overflowing scenario) is going to create structural problems that don’t exist when the space above is just general living space? If so, what’s the remedy?
Obviously I could sister in larger joists, and double up on the spacing, glue and screw a new subfloor and I’d substantially increase the strengt of the floor in the area that is to become a bath, but doing the same in the rest of the bedroom would require removing the 100 year old doug fir flooring that I lovingly refinished, and not doing the whole room would result in a higher floor in the bath, awkward. I could add all kinds of blocking, but I’m not sure 4″ deep blocking is going to do all that much. Reducing the span is not an option.
I realize that few if any of you guys are structural engineers, so I guess I’m asking for your “gut” feel on this. Like I said, there have been zero problems with this underbuilt deck in 100+ years. Will it survive this possible large, new load?
Replies
Seems to me unless theres a way to add a partition below adding to the strength of the floor joists the only think you could do is sister up some joists in which case I'd use TJI's. Very easy and safe to make holes for plumbing and electric.
Is there any way you could run a dbl fj with a steel flitch plate the span of the room and header off where the tub goes? Pictures would go a long way here but as you say...I think an engineer on site is the safest route to go.
also for a shower you'll need a 2" drain pipe whatever another 1/2" would make I don't know..
As far as the flooring goes you "could" use it over if you want to spend the time hassling with all of that...if thats worth it all.
I'd think any additional weight would most definatly add to the floors integrity. Only an engineer could tell you on close inspection.
Only thing I can think of is if you could put the bathroom somewhere you could partition in the room below giving you the extra strength above.
sky hooks might help too : )
andy...
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2x4 floor joists are a major problem. Short of using steel in the floor I don't see how it could be properly supported unless a deeper joist is used.
Even so, you might have to shop around for an engineer that would even look at a 2x4 floor.
Good luck.
Beer was created so carpenters wouldn't rule the world.
You are insane to consider this without tearing down the ceiling and sistering al those joists to make them deeper and doubled at least. Something like 2x10
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Hold on, this is a terrible idea.
A new floor needs to be designed.
Probably balloon framed, so a ledger and joists w/hangers may be a start.
If it is ballooned then fire blocking will be needed as well.
And the 1-1/2" drain line will need a 2" hole, removing half of the joist. It sagged an inch at full strength, with half of it removed failure immediatley comes to mind.
At the span you have posted I would use 2x12's at a minimum, especially with plans of boring 2" drain line holes in them. 2x10's would be minimum without the drain line.
Whats your current ceiling height in the room below the proposed bathroom?
Do you have the head room to sister on 2X10's? Your going to lose approx 5" of height to your existing room.
Doug