I’ve got to install some 1/2″ hardi backer for a shower, and am not sure what and where to find the right tape for the joints.
James Hardie web site says to use ” 2″ wide high-strengh alkali-resistant glass fiber tape”. when I asked at my yard the guy available at the time didn’t seem to really know. He thought I was talking about the “mesh” tape used for drywall. But I don’t think that’s it.
I’ve searched online and seem to have found the product. looks more like a solid fiber cloth like tape, is that right?
Does anyone know exactly what I should be using and what kind of local supplier to find it at?
Replies
We (myself, and now my tile guy) just use the fiberglas mesh tape.
And is that with Hardiebacker?
Also the other poster mentioned a membrane. Are you using a membrane as well, or tiling over the board. View Image View Image
Hardibacker and no membrane.
I don't bother taping the joints. I fill the joints with thinset and call it quits. But that's with durock, not hardibacker. I don't know if it would make a difference. The tape isn't going to stop anything from moving if it's going to move. Are you going to use any kind of waterproofing membrane over the hardibacker?
Steve
no membrane on walls or ceiling, only for the pan. View Image View Image
Do you put a shingle-lapped drainage membrane (ie: tar paper) behind the hardibacker?Steve
never heard of tar paper being used.
rubber membrane in the pan runs up the wall about a foot, hardiebacker overlaps that. View Image View Image
The books I've read on showers and tile say you should run tarpaper shingle lapped, behind the backer board and overlap the pan with it. That's the way I've done it till recently. I've started using Laticrete fabric and brush-on membrane over top of the backer board and skipping anything behind it. With that suff you could fill the shower top to bottom with water and it wouldn't leak. But it's pricey.Steve
yeah I never heard or seen the tar paper method before.
I've heard of the membrane over top before. ( I've seen Mike Holmes use that method alot on his TV show) Yeah it would be pricey. View Image View Image
The thinking on the tarpaper behind the cement board is that the cement board, thinset, and tile can all withstand indefinite wetness, but there needs to be a waterproof barrier to keep the framing behind from rotting out.Waterproof membrane over the cement board is the premium way to go, but a little more money. Not much in the overall scheme of things, especially when replacement costs for mold problems are factored in.Bill
I completely agree that the waterproof membrane is the ultimate way to go. But considering that the shower I tore out was in absolute perfect condition with only green board protecting the studs, I will have a hard time selling the membrane. I already upsaled the use of Hardiebacker.
I know that many shower tear outs reveal alot of water damage and mold issues. what is the difference between two showers built without a membrane where there has been water penetration. Is it a breakdown in the grout where it begins? View Image View Image
Honestly, I do not know what causes the difference in every case. Often it comes down to patterns of usage. Some showers never dry out, due to constant use by multiple people. Therefore, evaporation through the back cannot keep pace with the introduction of more water.Grout is one place water gets through. Even intact grout is not designed to be a water barrier.Bill
In a tub install with tile walls, should the Kerdi membrane be extended over the lip of the tub, or is it adequate to let the tiles overhang? Also, I've read/heard about paint-on membranes. Is there and advantage to the Kerdi over these?View Image
I don't know what the situation is at your supply house, but if you go into Home Depot (or maybe Lowes?) they sell the branded 2" tape right next to the panels. Not sure if it's any different than regular mesh drywall tape.
Justin Fink - FHB Editorial
hmm.....looked one of my local HD's could even find the Hardiebacker only Wonderboard. View Image View Image
I hate to reveal my depth of knowledge concerning
H.D. and Lowes. So on the down low... HardiBacker-Lowes Kerdi-H.D.
It's entirely regional.
HD here/Hardi and Wonder, no Kerdi, no Denshield.[email protected]
I'm glad to lose
my HD creds.
I've bought the two tile books from FHB. One from mike and the other I don't remember. In mIke's book he puts tarpaper behind the cement board and in the other book Tom Meehan doesn't put anything. Another article in the book by Dennis Hourany puts cement backerboard down over OSB with mastic and if I read him right he has even put tile just on OSB.
These guys, I guess know what they are doing but they sure seem to be doing it differently and it obviously works for them. At least I don't feel quite as bad thinking about the way I have done things in the past.
roger
Edited 3/12/2008 10:28 am ET by roger g
No Lowes here in Canada. I'll have check out Rona. View Image View Image
The difference is the alkali resistance. Maybe drywall tape has that now, I don't know. But early versions of drywall mesh tape were not alkali resistant, so I've heard, as there is no need for it with drywall compound.
"Not sure if it's any different than regular mesh drywall tape."
so far as I know ...
it is completely different stuff ...
and drywall mesh should never be used with thinset.
(good idea for Whats the Dif column ... send the check to Pgh)
and ... shower walls should have a vapor barior.
either laped roofing felt or poly.
and said VB should extend down and overlap into the shower pan.
and yes ... the backer board seams should be taped and thinsetted.
I now save the tape till I'm setting the tile ... as the tape is self adhesive ...
just stick it ... then trowel the thinset as per the norm.
helps keep from forming the dreaded hump in the wall.
which ... can happen when ya tape/mud one day then set tile the next.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
All cement backer boards require a vapor barrier(6 mil poly) be installed behind them.....
The VB should lap just over the tub lip or into the pan, depending on your situation.......
As for the joints/seams .....horizontal seams, I run a bead of caulk (ureathene) along the top edge of the first board, then bed the next sheet into that, then smooth the face, It's also recommended to caulk/seal the fastener heads.......Vertical seams (inside corner) I leave an 1/8" gap, then caulk and smooth......
backer board should extend to within 3/8"- 1/4" of tub deck/floor( in a shower the floor should go down 1st), then tile to with 1/8"-3/16", then caulk, no grout, same on inside corners, no grout, use matching caulk.
IMHO ......use Densshield, no need for VB and easier to work with, 4'x*' sheets can usually be found at yuor drywall supply house.
Geoff
Moved to new thread to avoid Hijack
Edited 3/12/2008 10:35 am ET by Dagwood
The way I do it is that my rough stud opening for a 5 foot tub is a little over 5 feet (for wriggle room). I cover the wall with whatever you are using (green board or cement board etc) and bring it down so it comes down to but not cover any part of the tub. Which means, after doing the walls you could, if you wanted, still pull the tub out.
I then tile the walls and it is the tile that overlaps the tub.
As far as membranes and vapour barriers, see my previous post.
roger
Thanks Roger. My thread has moved here
http://forums.taunton.com/tp-breaktime/messages?msg=102104.1
View Image
Saw your pic where you put the cement board all the way down. Hmmmmmmmmmmm.
When you go to tile this, the bottom tiles are going to kick out as they overlap the tub unless you use hellish thick thinset.
I think I would correct the problem by putting a 1/4inch cement board on top of what you have and butt it up to the tub then tile. Pretty quick fix
Your mixing valve may not have to be moved or it can be forced over abit.
PS I used to live in Alliston.
roger
Thanks RogerView Image