I am currently building a custom shower, and have been following the
directions from a DIY book, and getting useful information off the web.
For the most part, the instructions from all sources are consistent:
1. Layer of mortar sloped to the drain
2. Felt paper over mortar to protect membrane
3. Membrane, with proper seal around drain assembly
4. Backerboard on walls, down over membrane, but 1 1/2 inches off the
5. 2 - 2 1/2 inches of mortar with pea gravel around weep holes to
prevent cement from getting in the holes
What I haven't seen explained is what happens to the inside of the
threshold to prepare it for tile? Should a narrow strip of backboard be
screwed to the inside of the threshold (but kept 1 1/2 inches off the
floor), and mortar over the top like the other interior walls? It
seems like screwing the backerboard on the inside of the threshold
would compromise the membrane? I've seen a few pictures of the steps
involved, and it seems that everytime they get to the final bed of
mortar, the threshold and inside of the threshold appear to be exposed
membrane. Can you simply tile over the membrane???
Any help would be greatly appreciated!
Thanks and Best Regards,
At the thresholed wire lath in a single or double layer is bent to fit
snugly over the lumber framing the threshold, NO FASTENERS PENETRATE
Mud is trowelled on and pushed through the lath and a slight inward
slope is created.
Thanks for the reply! That makes total sense!
Would it be adviseable to put the lathing in place before I mud the
floor (with the thought that the floor mud would hold the lathing in
place at the threshold), or does it not really matter?
Another question I had was with respect to the threshold sides (and
top)... Is green-board sufficient, as a base for tile, or is
backerboard typically used in those places as well?
Thanks again for any advice!
I would use mud on the threshold inside and top. You want no nails through
the membrane. I wrapped the lath over the top and down about 1" on the
outside of the shower, so that it would hold itself in place over the
I nailed backerboard below that to help guide the trowel for shaping the
I did see a pro who glued some kind of backerboard (siliconized gypsum?)
to glued down membrane over the threshold. I believe he clamped backerboard
to the threshold to press the membrane into its glue to attach it, with
the top. He used special glue for this.
Thanks Bob! This seemed like a logical thing to do, so I did exactly
that last night, except I didn't wrap the lath over and down, on the
outside. I mudded the floor, which seems to have held the lath in
place, just fine. Tonight, I will mud the threshold, and get ready to
move on to tile! ;-)
I'm sure I'll be back soon, with some tile questions!
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.