Yep this is another post in the long tradition here of people asking for engineering advice.
Here’s the situation-the red dimensions are the free spanned lengths of the joists that I don’t want to replace…the grey is the outline of the floor below
What I’ve got is 22′ 2by6’s unevenly supported by a bearing wall in the ‘middle’ one side has a span of 9′-1″ the other side spans way too much at 11′-10″. The joists run in the short dimension and are 16″ oc.
On top of the joists is 7/8″ T&G floor nailed directly to the joists. The joists on the rest of the floor are 2by10’s so there is a step down to get into this room which used to be a covered porch.
We were originally planning on putting down warmboard in this room which is 1.25″ thick but I’m told it has the same strength as 3/4″ subfloor.
My initial reaction is to try to rationalize not ripping up the T&G subfloor and sistering new joists to the old..I just want to put the warmboard down directly on the existing floor and be done with it…The floor does feel pretty solid right now but we are going to be tiling and I can’t have a flexi floor for that. The tub is on the well supported side…
Or, my span calc says 2by8’s should do it…if I use select struc.
So, should I rip up the old floor, sister on new 2by8’s and attach the warmboard directly to them?
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Edited 5/16/2008 2:15 am by madmadscientist
Replies
Shoot I forgot to ask.
What's a reasonable live-dead load for a bathroom?
thanks,
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
bump
Yea I know its pathetic to bump your own thread but I need help with this.
My radiant guy says he needs to know how the joist situation is going to work out so he can design-spec the warmboard...
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
If it was mine I'd use the 2X8s. But I'm really conservative, and like a stiff floor.40 PSF is the normal live load for residential floors around here. I think that's pretty wide spread, but don't know about your area.
According to a new survey, women say they feel more comfortable undressing in front of men than they do undressing in front of other women. They say that women are too judgmental, where, of course, men are just grateful. - Jay Leno
So would a reasonable load be 40psf live and 10psf dead for a bathroom?
thanks,
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
I can't find them now but there was some good online calculators that dovetail had. I think one was bradco supply.com
I think this is what you want, yes?http://www.martindalecenter.com/Calculators1A_5_Co_FJ.html#HOMER-JOIST'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
That was it!
Yes: 40psf live and 10psf dead is fine.
What Matt said - 40PSF live and 10 PSF dead.
Champions take responsibility. When the ball is coming over the net, you can be sure I want the ball. [Billie Jean King]
With Struc Sel 2gy8's on 12" centers this span calc says I'll have L/720 deflection. I would attach the warmboard directly to the new joists.
Would this be enough for tiling on top of?
thanks,
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Tile isn't something that I have any experience with...
If a person could find a better way to kill bugs, they would not only get rich, they'd probably get a lot more dates. [Red Green]
L/720 should be fine.Try this calculator: http://www.johnbridge.com/vbulletin/deflecto.pl'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
The John Bridge calc is a little bit un-ideal I think. The one I link to lets you specify the grade and species of lumber which is really important I think to get a real number. With the JB calc you don't know what assumptions its making so how can you believe it really?
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
I've used the JB span calculator for years and have never had a tile job go bad due to the specs it has given me. My assumption based on that experience is that whatever assumptions the JB folk made in programming that calculator were sufficiently conservative to ensure safe results in the very great majority of cases.
Your mileage may vary, of course....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Well it looks like I'm going to have to pull up the T&G subfloor and sister on new joists...damn I was hoping someone here would give me a rationalization for not doing it...but I'm pretty sure we are going with slate tiles and that means L/720....dang
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
Try this site: http://www.awc.org/calculators/span/calc/timbercalcstyle.asp
Yep that's the one I linked to in my first post. It seems to be the best I've found and it comes from an org that should know what its talking about.
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer