form ply + cement sheeting OR 19/22mm cement sheeting

folks, for a raised platform in the bathroom we are currently building, can formply and 4.5mm cement sheet be used instead of going to the 19/22mm cement sheeting products? the bathroom is on a concrete slab and we need the raised area to get the right fall for the drains from shower and bath. we are doing it this way to avoid having to dig out the slab, retermite protect, etc. The raised platfrom is 3m x 1200 with joists (?) every 40 cm. the area that is under the bath will also have noggins to stop any twisting (and because i am a huge fan of overkill). the top surface will tiled when complete.

NO !!!!
Use the correct compressed sheet either 19 or 22 is ok and a minimum of 3 coats of waterproof membrane

cheers, i was both hoping and not hoping that that would be the correct answer.

what is used to cut drain holes? will a regular hole bit do the job if the sheet is wet at the time?

Quote:

---

Originally Posted by ajm

cheers, i was both hoping and not hoping that that would be the correct answer.

what is used to cut drain holes? will a regular hole bit do the job if the sheet is wet at the time?

---

Just a moment...

pick your size in this style, TCT tungsten carbide for better cut
cheers

cheers

Make sure you use the mastic sealant NOT SILICON for joints/junctions of wall/floor/step/bath with the reinforcing fabric.

Quote:

---

Originally Posted by ajm

cheers, i was both hoping and not hoping that that would be the correct answer.

what is used to cut drain holes? will a regular hole bit do the job if the sheet is wet at the time?

---

You can also drill a series of holes around the circumference as close as possible together with a small say 5mm masonry bit not on hammer function with the sheet fully supported. Tap out the center and clean up with a diamond blade. We also recess the puddle flange in flush with the sheet with the diamond blade