Can I put a dryer vent duct under a concrete slab?

RSKY · Mar 7, 2012

As I said earlier mine has been in use many years and I have never had a problem with condensation. But you will have lint build up in the pipe and it must be flushed yearly.

dmccarty · Mar 7, 2012

Our vent goes up and exits at the roof. I wish we had gone to the outside wall instead.

Our dryer's specifies how long the dryer duct can be. Our vent stack is within the dryer's specification but if we had run to the exterior wall it would be that much shorter....

Later,
Dan

KennyG · Mar 7, 2012

As long as you can slope down and still be above grade, I don't see why this wouldn't be OK.

My first thought was to go up and into the ceiling joist space. You said that would be too long of a run, but it seems like there should be a path as short as the path through the slab.

If you do embed it, definitely use plastic and not metal. When I installed a few heat duct systems in slabs a few years back, we used transite (concrete) pipe for the ductwork.

rtimgray · Mar 8, 2012

You're right - the distance would be the same if we ran parrallel to the joist - but it will be even shorter to go to the outside wall if we run perpendicular to the floor joists (can't run the dry vent perpedicular to the second floor joists - it would have to run parrallel and between them).

Also, I would have to go up (add 7' or 8' to the run) just to get to the second floor joists, and them come down some one the other side (at least low enough so that I could reach the screen without having to get a ladder) so as to clean the lint off.

Thanks for the ideas, fellas.

TRR · Mar 8, 2012

If you decide to go with PVC you may want to consider using the gray electrical conduit type. It has the UV inhibitors, is a thick wall (sched 80 i think), and has the long sweep elbows mentioned in the previous posts.

rtimgray · Mar 8, 2012

Good idea about the gray PVC.

Incidentally, if I could lay hands on either large aluminum conduit or stainless steel pipe, would those be good options? The aluminum conduit has pretty thick walls, but I don't know how "permanent" it would be. Both of these options may be available to me, and it's not like a need alot of it (less than 20').

Thanks.

KennyG · Mar 8, 2012

My thought would be that, with all the potential variations of moisture and chemistry, aluminum might corrode. Also, any metal is probably going to cause more condensation in cold weather because it will transfer more heat from the vent. I would stay with the plastic.

kenmac · Mar 8, 2012

KennyG said:
My thought would be that, with all the potential variations of moisture and chemistry, aluminum might corrode. Also, any metal is probably going to cause more condensation in cold weather because it will transfer more heat from the vent. I would stay with the plastic.

Your correct . alum. will corrode over time. You could wrap the outside but, it won't help the inside. If you can't go up & out. ( best in my opinion) use plastic.

Fixemall · Mar 9, 2012

Drive right over to your local in ground swimming pool dealer and get some direct burial flex line in the right length/diameter and bury it, it will resist anything you throw at it and outlive all of us.

the chimney sweep · Dec 5, 2014

rtimgray said:
From what I've read in a quick Google search, looks like PVC is frowned upon because of both breaking down from heat and static electricity/static cling to lint. What do you guys think about putting metal ductwork down under the slab? If I use aluminum will it still eventually corrode or will it live forever?

Thanks again.

I clean dryer vents for a living and find these monsters often. The builders who put a dryer vent in the slab should be made to clean them. With 4 90 degree turns it makes it impossible to clean. I have seen those in the slab with only 2 90 degree turns out of the wall behind the dryer and then another 90 heading it toward an outside wall. Then instead of going up and out with two more 90's it just goes straight out the wall. Those are a breeze to clean and they are tilted a little downhill and water drains easily when the plug is taken off. Other than that all slab vents should be rerouted. I never see PVC that has broken down. Aluminum in the slab is asking for trouble as any brush you put in it has a chance to wreck it as is it so pliable. PVC works best but get a good grade, not the thin cheap stuff.