Cleanline p-trap installation @ wall
This is a plumbing question. It is regarding the clean, attractive installation of an exposed p-trap for a pedastal sink or other exposed p-trap application. In his book on “Installing and Repairing Plumbing Fixtures” Peter Hemp descibes (and shows in pictures on page 117 and page 126) an aplication where there is simply a nipple protruding from the sanitary tee (protruding by not much more than 3/4″) and he uses a slipnut & washer to attach the p-trap after installing an escutcheon plate around the visible part of the nipple. This creates a slimline installation that is clean and attractive. My question is this, what is the nipple screwed into and if he is using ABS as a plumbing material how far back must it be from the finished wall surface in order to glue in a threading adaptor and then a 2″ nipple? It seems as though it would push the san-tee right through the back of the wall. Is there such a thing as a threaded ABS san tee?, Do I need to use like a 2″ galv. san tee with threading? is there such a thing. Does anyone have ideas about clean installation ideas for p-traps? I would like to avoid having an abs adaptor sticking out of the wall covered by a giant escutcheon. Any help or insight would be appreciated.
Replies
The protruding nipple you see is a one-piece trap adapter that comes with a threaded nut and the seal is part of the nut. There are 2 common sizes for the waste arm - 1 1/2" and 1 1/4". There are two styles I am familiar with: one is a standard fitting size that is glued over a pipe and the other is a street fitting that will fit into the end of another standard fitting. You could glue the second one directly into the san tee but you would have to have the stack precisely placed to get the position you needed at the finished wall. Usually, the sanitary tee is a 2"-1 1/2"-2", which means the 2" waste pipe is reduced to a short 1 1/2" arm within the wall cavity which then turns out via a sweep (not a 90* elbow). You then have the option of using a very short length of pipe to come thru the finished wall where you glue on the first adapter or you glue the second adapter right into the sweep. The escutcheon can go over the threaded portion as long as it allows complete tightening of the nut and seal over the p-trap waste arm. For a bathroom sink you could use the 1 1/4" size.
John
Up here BOW plastics makes a 1-1/2 x 1-1/4 ftg x slip joint adapt. the 1-1/2 ftg end is about 2" long so you can cut it off to the length you need prior to glueing it in to your elbow or tee. Adjust it so your threads just protrude thru the finished wall, you may have to trim drywall to allow the nut to go deep enough to allow your chrome escutcheon to fit flush to the wall. this is usually the fitting I use
Kevin
Edited 7/17/2002 11:37:39 PM ET by KC