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Fastening down Wonderboard to floor joists

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Fastening down Wonderboard to floor joists Sammy bin Snoozin 10-20-2007
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Posted by Sammy bin Snoozin on October 22, 2007, 11:46 am
I see. My building vocabulary is not that good. It already has 2x6 =
boards on the joists, if that's what underlayment is. They are in good =
shape.

> Sammy bin Snoozin wrote:
> > I meant... what kind of underlayment, how thick, etc? Makes sense, =
but adding any thickness will bring the new section higher than the rest =
of the floor.
>=20
> Please don't top post.
>=20
> Underlayment thickness is determined by what you intend to put=20
> on it, spacing of the floor joists and material used for=20
> underlayment, including how it is installed.
>=20
> > Ah so! Thanks. What is underlayment?
> >=20
> >=20
> >>Sammy bin Snoozin wrote:
> >>
> >>
> >>>What's the best way to do this? Below is from Eric Gurney =
7/21/2000 which is the best I could find with google...
> >>>
> >>>From =
http://www.custombuildingproducts.com/onlyproducts/WonderBoard12.htm=20
> >>>(link no longer good)
> >>>
> >>>Fasteners: Galvanized roofing nails, 1 1/2" (38 mm) long with =
hot-dipped=20
> >>>galvanized coating for use with wood framing. Nails should meet =
Federal=20
> >>>Specification #FF-N105B/type 2 style 20. Custom Concrete =
Backerboard Screws=20
> >>>or equivalent, 1 1/4" (32 mm) long, for use with wood or 20 gauge =
steel=20
> >>>framing.=20
> >>>
> >>>Underlayment: Using a 1/4" (6 mm) square-notched trowel, apply a =
setting bed=20
> >>>of latex-modified mortar to the subfloor or base. Immediately =
laminate 1/2"=20
> >>>WonderBoard Concrete Backerboard to subfloor base, leaving a 1/8" - =
3/16"
> >>>(3 - 5 mm) space between boards at all joints and corners. Stagger =
joints so=20
> >>>they do not line up with underlying substrate joints. Fasten =
backerboard=20
> >>>every 6" - 8" (15.2 - 20.3 cm) o.c. throughout board field and =
around all=20
> >>>edges while setting bed mortar is still workable. Around perimeter =
of each=20
> >>>board, locate fasteners within 1/2" - 2" (1.2 - 5.1 cm) of edge. =
Fill all=20
> >>>joints and corners solid with latex-modified mortar. Taping of =
floor and=20
> >>>counter joints is not required.=20
> >>>
> >>>Sam
> >>
> >>If you are trying to fasten wonderboard directly to floor=20
> >>joists, then there is your problem. The reason that you can=20
> >>find no instructions on how to do it, is because you cannot do=20
> >>it. Wonderboard cannot bridge floor joists, so you must have=20
> >>and underlayment to support it. Then you fasten the=20
> >>wonderboard to the underlayment.
> >>
> >>
> >>--=20
> >>Robert Allison=20
> >>Rimshot, Inc.
> >>Georgetown, TX
> >=20
> >=20
>=20
>=20
> --=20
> Robert Allison=20
> Rimshot, Inc.
> Georgetown, TX

Posted by Manster on October 21, 2007, 3:58 pm
Sammy bin Snoozin wrote:
> I meant... what kind of underlayment, how thick, etc? Makes sense, but adding
any thickness will bring the new section higher than the rest of the floor.

There are several things to consider for a floor tile installation as
Robert indicated. Not the least of which is the potential for
deflection or flex. I learned this the hard way once. I've done a few
tile installations over wood sub-floors since that snafu and I've
referred to this when I have.
http://www.ttmac.com/deflection_limitations.htm

Sometimes it's just no feasible for tile to be put over a sub-floor
given the existing construction, etc.

Posted by samurai on October 22, 2007, 12:05 am

>Sammy bin Snoozin wrote:
>> I meant... what kind of underlayment, how thick, etc? Makes sense, but
adding any thickness will bring the new section higher than the rest of the
floor.
>
>There are several things to consider for a floor tile installation as
>Robert indicated. Not the least of which is the potential for
>deflection or flex. I learned this the hard way once. I've done a few
>tile installations over wood sub-floors since that snafu and I've
>referred to this when I have.
>http://www.ttmac.com/deflection_limitations.htm
>
>Sometimes it's just no feasible for tile to be put over a sub-floor
>given the existing construction, etc.


I'm just getting tile put in.
I have an older home, with wood laths that run diagonally across the
floor joists, they are 5/8" thick.
My tile guy installed 3/8" plywood over the wood laths, then a
thinset ontop of the plywood, and then the wonderboard. Then used
special screws to fasten the wonderboard to the joists.

Then the tile in a 'subway' pattern. Looks great.

samurai.

Posted by Manster on October 22, 2007, 10:25 am
samurai wrote:

>> I've done a few
>> tile installations over wood sub-floors since that snafu and I've
>> referred to this when I have.
>> http://www.ttmac.com/deflection_limitations.htm

> I'm just getting tile put in.
> I have an older home, with wood laths that run diagonally across the
> floor joists, they are 5/8" thick.
> My tile guy installed 3/8" plywood over the wood laths, then a
> thinset ontop of the plywood, and then the wonderboard. Then used
> special screws to fasten the wonderboard to the joists.
>
> Then the tile in a 'subway' pattern. Looks great.


Sounds adequate, assuming the floor joists are spaced properly. Say 16"
o.c. or close. You can check yourself using the L/360 criteria as
prescribed at the web site I posted before. I doubt that you will have
any problems. I'm not sure; what is a "subway" pattern? A staggered or
offset joint, a basket weave pattern?

Posted by Sammy bin Snoozin on October 22, 2007, 11:46 am
Thanks, there's no flexing in the floorboards. I'm just replacing =
1/2-inch water-damaged particle board with cement wonderboard. =
Evidently I put down some kind of mortar or cement on the floor boards, =
then the wonderboard on top of that, then fasten with roofing nails or =
screws. At least that's what they told me at home depot.

> Sammy bin Snoozin wrote:
> > I meant... what kind of underlayment, how thick, etc? Makes sense, =
but adding any thickness will bring the new section higher than the rest =
of the floor.
>=20
> There are several things to consider for a floor tile installation as=20
> Robert indicated. Not the least of which is the potential for=20
> deflection or flex. I learned this the hard way once. I've done a =
few=20
> tile installations over wood sub-floors since that snafu and I've=20
> referred to this when I have.
> http://www.ttmac.com/deflection_limitations.htm
>=20
> Sometimes it's just no feasible for tile to be put over a sub-floor=20
> given the existing construction, etc.

Page 2 of 4       < 1 2 3 > last >>
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