DIYbanter - "Springy" subfloor and tile

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"Springy" subfloor and tile

Thank you for reading my post.

I want to know if I should pull-up the entire sub-floor of my guest
bathroom.

My house is a 1982 tri-level (kit?). 50 foot x 25 foot. Most floor &
ceiling joist are 24" OC. The joist run the width of the house.

The guest bathroom (full bath) had a tile floor on a mortar bed, that I
removed.

The sub-floor that's under this tile floor is 1/2" plywood with some
sag on the outer ends and very springy between joists.
Is this normal after removing a mud-tile?

I ran a "stud-finder" along the floor, and
found that the joists are NOT 24" OC and more like 16"OC it a
hit-and-miss pattern... (guest bath is in center of the 3rd floor/
Master bath is on opposite wall of guest bath.) Is this ALSO normal?

~BUT~ my question IS ....
Should I set my circular-saw at just under 1/2 inch, and THEN replace
the entire floor.... or should I just add exterior-grade plywood over
the exisisting sub-floor?

For more information... the "basement" (1st floor) Den, 1/2 bath and
office are 8 foot ceiling, but the basement hallway is 7 foot.
(Bunch of duct-work, plumbing. ect.)

Thanks,
Dave

"DaddyMonkey" wrote in message
...
Thank you for reading my post.

I want to know if I should pull-up the entire sub-floor of my guest
bathroom.

My house is a 1982 tri-level (kit?). 50 foot x 25 foot. Most floor &
ceiling joist are 24" OC. The joist run the width of the house.

The guest bathroom (full bath) had a tile floor on a mortar bed, that I
removed.

The sub-floor that's under this tile floor is 1/2" plywood with some
sag on the outer ends and very springy between joists.
Is this normal after removing a mud-tile?

1/2" plywood is too thin for a floor, also since it's a bathroom floor it
may get moisture, which may have further weakened the 1/2" plywood

would go with minimum 3/4" thick plywood for floors

I ran a "stud-finder" along the floor, and
found that the joists are NOT 24" OC and more like 16"OC it a
hit-and-miss pattern... (guest bath is in center of the 3rd floor/
Master bath is on opposite wall of guest bath.) Is this ALSO normal?

~BUT~ my question IS ....
Should I set my circular-saw at just under 1/2 inch, and THEN replace
the entire floor.... or should I just add exterior-grade plywood over
the exisisting sub-floor?

sounds like existing 1/2" subfloor is unstable, removing it and replacing it
with 3/4" exterior grade plywood will be more stable

For more information... the "basement" (1st floor) Den, 1/2 bath and
office are 8 foot ceiling, but the basement hallway is 7 foot.
(Bunch of duct-work, plumbing. ect.)

Thanks,
Dave

Should I rip-up the 1/2" plywood and THEN install two sets of 5/8"
exterior grade plywood?

OR should I just install 3/4 exterior grade plywood OVER the 1/2" that
I already have?

And what about "blocking" inbetween the joist if I remove the old
1/2" plywood?
A waste on time/material?

Deep felt thanks to everyone,
Dave

I guess I should have stated in my original post that I am going to be
adding 1/4" cement backer/hari-board ONTOP of the subfloor BEFORE the
tile.

Thanks,
Dave

1 1/4" is the recommended thickness of the sub floor under ceramic tile.
That could be 1/2 +3/4.
Ripping up the existing 1/2" is not a good idea. There will always be an
edge with no support under it. If there is no damage to it leave it, vacuum
it real good, screw (make sure screws are long enough and go into the
joists) and glue 3/4 right over the top.
Screw and thinset the cement board to the new 3/4 ply.
Hardest part can be raising the toilet flange to the new level.
"DaddyMonkey" wrote in message
...
Thank you for reading my post.

I want to know if I should pull-up the entire sub-floor of my guest
bathroom.

My house is a 1982 tri-level (kit?). 50 foot x 25 foot. Most floor &
ceiling joist are 24" OC. The joist run the width of the house.

The guest bathroom (full bath) had a tile floor on a mortar bed, that I
removed.

The sub-floor that's under this tile floor is 1/2" plywood with some
sag on the outer ends and very springy between joists.
Is this normal after removing a mud-tile?

I ran a "stud-finder" along the floor, and
found that the joists are NOT 24" OC and more like 16"OC it a
hit-and-miss pattern... (guest bath is in center of the 3rd floor/
Master bath is on opposite wall of guest bath.) Is this ALSO normal?

~BUT~ my question IS ....
Should I set my circular-saw at just under 1/2 inch, and THEN replace
the entire floor.... or should I just add exterior-grade plywood over
the exisisting sub-floor?

For more information... the "basement" (1st floor) Den, 1/2 bath and
office are 8 foot ceiling, but the basement hallway is 7 foot.
(Bunch of duct-work, plumbing. ect.)

Thanks,
Dave

Thanks Calhoun/Paul !!!

I'm a little confussed on the "gluing" part.

Should I first put down #15 roofing felt over the 1/2" plywood, and THEN
3/4" exterior grade plwood over that --- with glue inbeteen each layer?

Help!
David

If you are using the felt than no glue. The felt prevents squeaks from the
two floors rubbing against each other and compensates for any grit you
didn't get cleaned up. If you glue you don't use felt. One or the other not
both. I always have preferred glue (construction adhesive in the caulk gun
tubes) on a real clean floor. It locks the two plywood pieces together so
they don't move against each other.

"DaddyMonkey" wrote in message
...
Thanks Calhoun/Paul !!!

I'm a little confussed on the "gluing" part.

Should I first put down #15 roofing felt over the 1/2" plywood, and THEN
3/4" exterior grade plwood over that --- with glue inbeteen each layer?

Help!
David