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Discussion Starter #1
So I ripped up the old diagonal floor boards in the bathroom (1950s ranch), mainly because it will be easier to work with plumbing that needs moved around. We extended the bathroom out a little but ran into the floor being in between joists.Here's a pic of my situation, I have ductwork in the way that doesnt give me much room to add on anything.

I was thinking maybe 2x4s cross ways with joist hangers to help support the existing floor wall and new sub floor.
Also bought 3/4" plywood for the subfloor and was gonna add either 1/4" or 1/2" cement board for the travertine tile. This suitable? Joists are 16 center. My only dilemma with adding another sheet of plywood is the 3/4" plywood 1/2" cement board, thinset, and the tile already puts the height of my floor over the edge of the hardwood floors, if I add another sheet of plywood I feel its gonna be well over.

http://imgur.com/U90AIZi

Also forgot to mention, I've been trying to get multiple opinions and was told the travertine tile with the flooring underneath may need extra support cause of the weight. I feel it cant be a huge difference considering the old flooring, concrete slab, tile, cast iron tub, old heavy sink etc weighs a lot, would this really make a big difference? 2x10s 16 center
 

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retired framer
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You can change the duct to an oval shape.
Lay a long piece of 2x4 on the ceiling for now. Place blocks from joist to joist on flat 16" OC , screw down thru that wall plate into the blocks with 4 1/2" or 5" screws.
Pull the longer 2x4 up tight under the blocks and screw it to the joist. Add more blocks on the flat between those blocks half under the old floor. That is there to support the edge of the plywood and provide fire stop at the edge of the floor.
I would look at sisterring the joists, you want all the support you can get.


Once you have one layer of plywood down set a glass of water on the floor stand in the middle and bounce the floor a little, see what the water does. Concrete board will not help with stiffness.
 

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And you should be using 1/4" not 1/2 tile board, 1/2" is for walls.
Make sure to use constrution adhesive on top of the joist when installing the subfloor.
I would have used Advantech instead of plywood.
 

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Discussion Starter #5
I can still return the plywood and go with the Advantech. From the joists, should I get the 3/4" and 1/2" then the 1/4" cement board?

My biggest concern now seems to be people telling me that the travertine will be too heavy according to the john bridge calculator. Suggestions on fixing this?

Trying to figure out how much heavier can this stuff be opposed to all the old heavy stuff used back in the day with the floor boards, concrete, tile, cast iron tub, heavy sink, etc. and held fine for 60+ years
 

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retired framer
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I can still return the plywood and go with the Advantech. From the joists, should I get the 3/4" and 1/2" then the 1/4" cement board?

My biggest concern now seems to be people telling me that the travertine will be too heavy according to the john bridge calculator. Suggestions on fixing this?

Trying to figure out how much heavier can this stuff be opposed to all the old heavy stuff used back in the day with the floor boards, concrete, tile, cast iron tub, heavy sink, etc. and held fine for 60+ years
The old mud base was thick enough to add to the structure and if it was heavy enough, the joist could sag to max. no bounce left. You have relieved them and they now have bounce again.
Doubling the joist with the same or close to will stiffen them up.
Advantech comes in thickness a little thicker to a whole bunch thicker, I would go with as thick as you can go and still keep the threshold close to the other floor reasonable.
1/4" cement board.
 

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Discussion Starter #7
I appreciate the help. Im still fairly new to the deflection stuff. I think I was confused before. So what I was originally thinking, the joists wouldn't support all the weight of the tile. Now I'm figuring out its more about the bouncing of the sub floor, correct? So the thicker the plywood the more suitable for the travertine tile.

With a garage underneath and the ceilings covered up for the most part plus duct, water lines etc in the way, it would really be tough for me to add another 2x10 against each joist. Do you think blocking in between the joists would help support the floor better also for the tile? Trying to think of other solutions that could help me.
 

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retired framer
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I appreciate the help. Im still fairly new to the deflection stuff. I think I was confused before. So what I was originally thinking, the joists wouldn't support all the weight of the tile. Now I'm figuring out its more about the bouncing of the sub floor, correct? So the thicker the plywood the more suitable for the travertine tile.

With a garage underneath and the ceilings covered up for the most part plus duct, water lines etc in the way, it would really be tough for me to add another 2x10 against each joist. Do you think blocking in between the joists would help support the floor better also for the tile? Trying to think of other solutions that could help me.
any span more than 7 ft should have bridging or solid blocking and that does help spread the load, some.


We built a house with 16 ft 2x10s that the floor bounced to much, It had 2 sets of bridging. I cut two strips out of the floor and added 2 rows of solid block and repaired the floor. Made no difference. :vs_mad:
 

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Discussion Starter #9 (Edited)
any span more than 7 ft should have bridging or solid blocking and that does help spread the load, some.


We built a house with 16 ft 2x10s that the floor bounced to much, It had 2 sets of bridging. I cut two strips out of the floor and added 2 rows of solid block and repaired the floor. Made no difference. :vs_mad:

Heres a few more pics of my situation. Scab in some 2x10s where I can and I should be ok? Also at the edges I have 2x4s, should I leave those or switch those to 2x10s also?

Also just realized the original joists aren't level lol cant catch a break.
 

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retired framer
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Where ever possible those blocks should be flat half under the wall, The idea is to make the fire take another 1/2 hour to get to the next cavity, wall or floor as well as support the edge of the floor. .





Not sure what the tin baffles are for but as you are over the bathroom I would insulate and if the tile floor was always cold this would be the time to think about a heated floor.
 

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Discussion Starter #11
So turn the 2x4s sideways and half under each side. I have no idea what the tin is for in the middle I was confused too.

My wife and I really thought about a heated floor but our bathroom isnt very big to begin with we decided it really wasnt worth the extra money for the size and time really spent walking on it. The garage is pretty warm so the floor never got too cold, with the vent right there and all too. Definitely gonna insulate though, and add sound insulation for the hallway and bedroom side walls

Should I change those 2x4s out flat and use 2x10s or leave it? Also gonna stagger a few 2x10s tomorrow in between each joist bay
 

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retired framer
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So turn the 2x4s sideways and half under each side. I have no idea what the tin is for in the middle I was confused too.

My wife and I really thought about a heated floor but our bathroom isnt very big to begin with we decided it really wasnt worth the extra money for the size and time really spent walking on it. The garage is pretty warm so the floor never got too cold, with the vent right there and all too. Definitely gonna insulate though, and add sound insulation for the hallway and bedroom side walls

Should I change those 2x4s out flat and use 2x10s or leave it? Also gonna stagger a few 2x10s tomorrow in between each joist bay
Solid blocking between joists is loose term, they don't have to be a full 2x10
When we do them from below they are often 2x4s on the flat at the bottom.
A 2x6 or 2x8 would be fine.
Should I change those 2x4s out flat, yes or sneak something else in there to plug the gap

Vacuum the dust out where you can, in a fire that stuff explodes.
 

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Discussion Starter #13
We've been vacuuming the dust out, learn something new every day though didnt know that a fire can cause it to explode. I'll do some stuff tomorrow and update with pics.

Suggestions on easiest way to level the joists?
 

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retired framer
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We've been vacuuming the dust out, learn something new every day though didnt know that a fire can cause it to explode. I'll do some stuff tomorrow and update with pics.

Suggestions on easiest way to level the joists?
I saw a demonstration with dust of all kinds and most explode under pressure only, so a closed cavity with lots of heat the pressure goes up and the dust explodes and blows cracks in the drywall below and the fire has access.
 

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Discussion Starter #16
Would 3/4" rtd plywood work for subfloor and 1/2" bcx work on top?

Or should I get the 3/4" osb?

Was also told blanke permat could take the place of the 1/2" underlayment, so just the 3/4" and blanke permat would work?
 

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retired framer
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Would 3/4" rtd plywood work for subfloor and 1/2" bcx work on top?

Or should I get the 3/4" osb?

Was also told blanke permat could take the place of the 1/2" underlayment, so just the 3/4" and blanke permat would work?
Or go with 7/8 Advantech and 1/4 CB or the permat.
 

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Discussion Starter #18
They don't carry advantech around here unfortunately.

Think I'm gonna go with the 3/4" rtd plywood and the permat

Maybe add the 1/2" bcx on top of the 3/4" to be safe. Lol so confused on what to do to make this right
 

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They don't carry advantech around here unfortunately.

Think I'm gonna go with the 3/4" rtd plywood and the permat

Maybe add the 1/2" bcx on top of the 3/4" to be safe. Lol so confused on what to do to make this right
There are other brands of Advantech. I guess I am spoiled with material we have available.
 
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