Investor · Denver, CO · Member since 2014 · 128 posts · 23 votes
I recently had to do some research (read: cutting into the wall) on my clothes washer drain. I found that there is no p-trap, either in the wall or below grade in the crawl space. The washer plumbing drains straight down in the crawlspace, and then does a 90 degree turn into the main line.
What would the plumbers here recommend in this situation and what might be the code requirements?
Investor · Silver Spring, MD · Member since 2014 · 178 posts · 60 votes
10y
Interesting read. How old is the construction? I ask because if you have no smell you might have a running trap. They are illegal in most places now along with S traps and certainly in the national codes the local jurisdictions use as models. (some local exceptions) The distance of vent from the trap maybe limited by code. But the function is limited by the diameter of the drain line, the slope and the length of the drop (added velocity=greater siphon). The depth of the trap (a deep seal trap) can help. Like the trap on your AC's condensate drain, the depth determines how much negative or positive pressure it can handle before it siphons completely. Bottom line you should have a trap.
Investor · PA · Member since 2013 · 1k+ posts · 602 votes
10y
I would probably add a p-trap in the crawlspace or where ever it is easiest to do so to avoid sewer gas coming in the house. If there is no smell now it could be because what it's connected to now has a trap somewhere.
Investor · Southern Pines, NC · Member since 2014 · 339 posts · 171 votes
10y
I would be surprised if no trap. You would usually smell that. I don't know how much of the wall you cut out bit generally the traps are toward the bottom of the cavity. What size pipe and what kind is it? Pictures would be great. I did plumbing for a living for about 6 years and have seen a lot of rigged stuff.
Investor · Denver, CO · Member since 2014 · 128 posts · 23 votes
10y
I have not noticed any smell. The tenant in the other side complained at first about "exhaust fumes" but never did she mention that it smelled like sewage. This was before I added an exterior dryer vent and haven't heard anything since.
I attached a few pictures. 1 is looking inside the wall down from where the water connection and wall drain box would be...no ptrap. 2 is where that plumbing comes thru the floor into the crawlspace...no ptrap. 3 is where the line does a 90 degree turn and then ends at photo 4, which is just a t-joint to the main sewer line. Sorry for some crappy quality. Some are video screenshots.
Agent/Investor · Murphy, TX · Member since 2013 · 542 posts · 304 votes
10y
Pics are there now. There should be a trap in there somewhere. Should be quick and easy for a plumber but the lack of a vent may cause the trap to get siphoned empty anyway. I'm assuming this was done as part of a remodel? If there aren't any there now, I'd suggest putting a couple hangers on the drain pipe to take the stress off the rubber coupling, prevent the weight of the water from pulling the fittings apart, and to ensure proper downward pitch on it as well.
Investor · Denver, CO · Member since 2014 · 128 posts · 23 votes
10y
So a p-trap without a vent is worthless due to the siphon effect, am i understanding correctly? In that light, the vent would go downstream from the p-trap, correct?
Investor · Southern Pines, NC · Member since 2014 · 339 posts · 171 votes
10y
that is exactly correct. Has to be very close to trap as well. Could use a running trap if you make it deep enough. The problem with too big of a drop before the trap is the momentum of the water will empty itself regardless of vent. Best place for trap is up top straight into a vertical pipe vented out through roof or with full size studor/mechanical vent in the room or wall vented cavity. I can try to draw picture if that's not clear
Investor · Silver Spring, MD · Member since 2014 · 178 posts · 60 votes
10y
Interesting read. How old is the construction? I ask because if you have no smell you might have a running trap. They are illegal in most places now along with S traps and certainly in the national codes the local jurisdictions use as models. (some local exceptions) The distance of vent from the trap maybe limited by code. But the function is limited by the diameter of the drain line, the slope and the length of the drop (added velocity=greater siphon). The depth of the trap (a deep seal trap) can help. Like the trap on your AC's condensate drain, the depth determines how much negative or positive pressure it can handle before it siphons completely. Bottom line you should have a trap.
Investor · Southern Pines, NC · Member since 2014 · 339 posts · 171 votes
10y
@Doug W. That is exactly what he needs. 6 dfu should cover a washing machine by itself, but the minimum vent and drop through the floor is supposed to be 2", and the drain is supposed to be 3" within a few feet of hitting horizontal as well, but no use changing everything out. That is just new codes. @William Morrison, That is right, but a lot depends on local jurisdictions. Functionally it will work just fine. Some inspectors will allow it if it only serves the washing machine. At least that is what I have run into. Ideally run it out of the roof, but in an application like this, I would probably just throw a studor on there.
@Doug W. That is exactly what he needs. 6 dfu should cover a washing machine by itself, but the minimum vent and drop through the floor is supposed to be 2", and the drain is supposed to be 3" within a few feet of hitting horizontal as well, but no use changing everything out. That is just new codes. @William Morrison, That is right, but a lot depends on local jurisdictions. Functionally it will work just fine. Some inspectors will allow it if it only serves the washing machine. At least that is what I have run into. Ideally run it out of the roof, but in an application like this, I would probably just throw a studor on there.
I'm with you Joseph. In most cases for existing construction you don't have bring up to code. I might use it too. Or maybe large deep seal trap at the bottom. Can't see that part too clear in picture. The line looks larger under the floor. The couple places I looked had a process for getting permission from the inspector but that's a pain <Grin>. All said you want it to work and not stink. More Grins. The code issue in some areas can block a sale later. The fun part of this site is it covers a wide range of place. Had a friend have to fix plumbing code violations before he could sell. He lived two blocks from the Baltimore county line in Baltimore City. His plumbing met the county requirements but not the city. It was the type of water supply tubing. Yeah I helped all night. <Grin> The other is the insurance issue. Out of code installs done by owner or handy man can invalidate your insurance, probably not the case here. More important in electrical and gas work. My son lives in your circle of influence Southern Pines, interesting change going on there.
Investor · Denver, CO · Member since 2014 · 128 posts · 23 votes
10y
That being said...in the MEANTIME, I would like to do laundry.
Is there a short term fix (i.e. just gluing the pipes back together and maybe supporting the hanging pipes under the crawlspace) that will hold me over until I can get a few people to look at it?