Custom Shower pan: A Step-by-Step Guide
This is what you need to pour a custom shower pan.
Dry-pack (pre-mixed sand and cement mixture)
Pan liner which serves as moisture barrier over sub-floor and six inches up behind tile backer-board.
Backer-board for high moisture and backer screws (preferably backer with moisture barrier) or paint backer board without moisture barrier (this includes cement board or hardi-backer) with a waterproofing paint coating.
The process to pour a shower pan includes removing drywall where the new pan will be and also go down to the sub-floor if there is carpet or old tile on current floor surface. This is the hard part yet worth the effort to pour a custom pan.
The next step is to decide on the front edge and do the framing. If you want to include a bench in the shower the pan liner needs to be installed first so your framing of the bench will sit on top op the pan liner.
Be careful that all nails and sharp edges on sub floor are removed to prevent damage to the new pan liner. For extra protection you can also install along the back or any area where the bench is, additional pan liner lapping over the bottom liner to prevent moisture which might seep from some unseen crack behind the bottom pan from the back of the bench.
This however is not needed if you do a great job with the seams between the panels of your backer and seal the seams and backer well.
After setting a new drain fitting (for those not comfortable with this part you might call a plumber) for your shower pan(this drain should have three or four screws below the adjustable drain cover where you attach the pan liner.
When all plumbing and the framing is done and for this I assume you don't want a bench, you can seal the sub floor and pour the first part of your custom pan at a slope of 1/4" for every 12" from the drain fitting (the first pour is done to ensure the liner you install rests on top of a slope and that the water that penetrates thru the tile or grout lines will be able to drain towards the outlet without pooling underneath the tiles on the pan liner.
After the first pan is ready (in most cases after 72 hours) the liner can now be installed 6 inches up the bare studs and over the front entry edge. Make sure you staple right at about inch 5 1/2 from the bottom of the pan up the studs to prevent any leaks below the water line.
The pan liner gets glued to the drain with plumbing weld to make sure there is no chance of leaking. Best to gently cut the hole for the outlet in the liner after attaching the pan liner to the outlet fitting.
Tip: Leave the screws in the fitting and cut small X cross on top of the screws before removing the screws and putting the plumbing weld on the liner and on the drain fitting. After all is attached the center hole can be cut without any possibility of a misaligned hole in the liner.
The next step is to install the backer on the walls over the pan liner which are attached to the studs already. Also install the backer on the edge. The bottom backer screws should be no lower than six inches from the bottom where the backer touch the pan liner.
A easy idea is to now mark along the backer the level slope to where the new pan will be poured after measuring the further-est point from the drain outlet to the wall. The outer edge of the pan will be one level so all new tiles will start on all sides at the same level. This will mean that the slope of the pan might be more on shorter sides than on the longer sides.
You are now ready to pour the final pan on top of the liner using dry pack again. The slope still should be 1/4" every 12" from the outlet.
Dry pack should not be totally wet like when pouring concrete. Instead it should be easy to pack and to pat down without the mixture runny like concrete. To work the dry pack use different length leveling tools like very straight 1" x 1/2" sturdy wood planks.
This part of your pan is very important and should be near perfect at slope and evenness. After this pan is dry again about 72 hours you now can proceed to tile. Use a v-notch trowel and smaller grooves if mosaics is thin to prevent thin set mortar mix to squeeze thru grout lines. The tiles should be installed normally without any need now to add thick thin set to adjust the slope or to get even surfaces.
Very important to get the second pour perfectly tile ready and it's easy to gently work the surface while still damp and get the right slope and even tile surface area.
Feel free to shoot us a email if you need more information. Good luck with a awesome custom shower pan!