[marsbar16]

I am replacing my shower stall. I need to add 1/2" on top of the existing subfloor, which means the shower drain pipe will be 1/2" lower. Can I still use this, or do I need to extend the drain pipe 1/2"? Is there an easy way to extend the drain pipe (it's only 2 1/4" to the p-trap... so not much pipe to work with... and I assume I need a certain length of drain pipe for the drain tailpiece and rubber gasket to fit over)?

[massplumber2008]

Hi Marsbar:

Best bet here will be to DRY FIT The shower base and see how everything lines up.

Install the drain as it should be installed... I recommend you use a silicone caulk and not putty at the drain. Then drop the new base in place over the pipe... level the base from front to back and from side to side and then gauge how the rubber will fit down over the pipe.

If needed you may have to extend the pipe or you may even need to realign the PTRAP altogether... rare for an exact swap out on shower bases.

Finally, are you planning to install the shower base in a bedding substrate such as mortar or structolite? Read the instructions that come with the base... if called for, I'd seriously consider bedding the shower base... makes for a better, longer-lasting job... and reduces squeeks and creeking... ;)

Back to you...

Mark

[marsbar16]

Thank you for a prompt and helpful response! The existing drain pipe is 16 1/4" from the rear framing and 24" from the side framing, which is exactly the same as the rough in dimensions for the new shower base, so hopefully it will be exact. When installing the new shower base and drain I won't have access underneath the drain cutout (to hold the pipe steady) unless I cut a hole in the first floor ceiling (which I'd rather not do). Is the best solution, to secure the drain to the drain pipe, to use a glue-on type (so that I can screw the other piece in from above once the shower base is down? I assume I can't put on the rubber gasket type unless I can get to the drain pipe from below.

I'm installing a sterling vikrell shower base... instructions do not call for a mortar bed unless the subfloor is not level... the floor is level within 1/8" across the 48" area. I was hoping not to use a mortar base... bad idea?

[massplumber2008]

Use the socket-weld type strainer assembly (see image) so, as you said, "that I can screw the other piece in from above once the shower base is down". Use silicone caulking in place of putty. I'm sure this will still be tricky but the other kind of drain (called a no-calk with rubber seal) has a much higher failure rate in the long run when copared to the socket-weld type.

In terms of a bedding substrate, I bed all my showers unless specifically prohibited by the manufacturer. The difference can be pretty significant as it can take a spongy floor and make it feel like a custom concrete floor... ;) Up to you, of course!

MARK

[marsbar16]

Thanks again... whe you mention silicone caulk... should I be using that on the top side and underside (i.e. in addition to the rubber seal) of the drain? I want to make this as leak-proof as possible, as I won't be able to check it once it's in place (unless I cut a hole in the first floor ceiling).

[massplumber2008]

Use it only on the TOP side only to guarantee no future leaks (see image)! On the underside be sure to install the rubber and cardboard washer if provided. Tighten all together by spinning the bottom and holding the top part in place... minimizes loss of silicone from under the strainer.

Note that the pic. Below shows putty... ignore that. Your best bet is definitely silicone!

Mark