This is my first time plumbing a standard bathtub and I have a basic question on the necessary hole size to access to the tub’s plumbing. I’ve already cut a nice neat 2-1/4 ” hole in the subfloor for the drain line to connect to the PTrap below. I’m now realizing that if I have trouble with the tubs overflow seal or other components I wont have access to fix them short of ripping out the tub.
Before I go any further with the tub install what is the smallest but reasonable size access hole to cut in the subfloor for a tub’s plumbing access?
Thanks
John
Replies
It's best if you have access from the back of the wall. The overflow seal in particular often fails (especially those crummy foam ones). You can maybe save yourself some agony if you can find a hard-rubber replacement. (I found one for our tub, after it wrecked the ceiling below, but it was dumb luck to find it in the random odd gaskets drawer at the local HW store.)
Generally, a 14.5"x14.5"
Generally, a 14.5"x14.5" panel that can be removed somehow is all you need, either in the tub skirt or in the drain side wall. You should be able to reach the P trap as well as the overflow.
I believe the others are talking about a wall access, but you are asking about floor access to install or replace the waste and overflow assembly and be able to connect it to the p-trap.
You need a rectangular hole about 8" x 12" thru the subfloor. The thru-the-wall access is also a good idea for future maintenence and replacement purposes. The hole thru the floor allows the drain ell and tube to sit lower than the subfloor level, which is the way most tub drains work--the link below shows how the tub waste and overflow need clearance below the floor level.
.http://review.us.kohler.kohler.com/onlinecatalog/pdf/1087852_1.pdf
Both accesses are needed to to let you reach down into the the p-trap connection if needed, after the room is finished.
If I understand correctly, an 8" x12" hole centered with the tub with the 12" length parallel with the tubs longest length will provide a reasonably good hole for future repairs working from the crawl space.