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Clothes dryer vent to outside — material of construction

user-958947 | Posted in Building Code Questions on

I’m trying to find a better way to get the vent through the wall in a brick veneer home—new construction.
The standard cheap thin wall vent from the big-box store ends up somewhat squashed during the brick installation, so that any future replacement is difficult. Also, sealing any future replacement to the water barrier behind the brick is not possible. I suppose that when you had to replace the flapper portion only you could cut it at the brick line, but then you have an odd shape to match up to.

So, in a haste to get the brick in, I put in a piece of 4″ PVC (4.5″ OD) thinking I could tie the vent hose to this. Its an electric dryer, so I decided that if the clothes could get that hot, then so could the PVC. I checked with several code inspectors who don’t like it but aren’t sure if its disallowed by code. Note that I put the PVC pipe through a polymer roof vent attached to the wall so I could swap out the PVC if it were deemed unfit, and still maintain my water barrier.

So, my question—-does the PVC meet code?
Possible remedies–put the cheap thin wall metal device through the ID of the PVC (would that meet code?), or replace the PVC with a piece of thin wall stainless pipe.

Would a plastic flapper outside meet code? The metal ones are very noisy and flap in high winds.

On a related issue, I used 3″ PVC (3.5″ OD) for bath fan vents through the side wall. The only problem here is finding metal downspouts/bug screens on the outside to match the size. Any recommendations here other than custom sheet metal? Note that these pipes were taped to the water barrier to maintain seal.

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  1. user-969424 | | #1

    Our residential code prescribes dryer exhaust ducts shall be constructed of 0.016 inch thick rigid metal ---equipped with back-draft damper. There's more but this address your main concern. I would advise you to check with the dryer manufacturer for further information. If you can get the manufacturer to go along with your PVC then take that info to the local building department and ask the chief building official to consider it as an alternative material.

  2. GBA Editor
    Martin Holladay | | #2

    2006 IRC, section M1502, "Clothes Dryer Exhaust," -- specifically M1502.5: "Duct construction. Exhaust ducts shall be constructed of minimum 0.016-inch-thick rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct."

  3. user-958947 | | #3

    So, if I leave the PVC pipe in tact, and install the .016" thick metal duct inside the PVC, it sounds like that would meet code. Right?
    Does flapper have to be metal?

  4. GBA Editor
    Martin Holladay | | #4

    All code interpretations are local -- subject to the ruling of your local inspector.

  5. dickrussell | | #5

    For the outside part, look at the Heartland Dryer Vent. It's solid construction, will last, won't have the noise of a light metal flapper, and provides backdraft protection.

  6. user-958947 | | #6

    Thanks, I just ordered a Heartland on-line for about 20 bucks.. It appears to be plastic and has good reviews. Does code allow plastic for this check valve?

  7. scpnvvZeAy | | #7

    Hi guys,

    I found this innovative dryer vent cap while browsing around. It actually looks like quite a winner. What are your thoughts?
    (The "low profile" one seems to be their newest model. -


  8. dickrussell | | #8

    JW, I think you'll like the Heartland. It is hard plastic, and not flimsy either. One might argue that it has a more noticeable profile than an ordinary wall cap, but I prefer function to looks on that. A leaky device would bother me more than something I just won't notice after a while. I painted mine Hunter Green to match house trim. For that I used Krylon Fusion spray can paint, and the result looks like it came delivered that way.

    I can't say for sure that the cap can be plastic and meet code, but I suspect it can be, since so many of these cap products are plastic. The difference is that it is accessible externally for cleaning, whereas the duct usually can't be. Code says no fastener penetration to avoid lint buildup, and I suspect code calls for metal also is to avoid lint collection from static electricity as could happen with plastic duct. As Martin said, ask the inspector. Or just install it and see if he notices it at all.

    DV, my thoughts on that Tec Products cap is that it still could be subject to lint buildup at the hinge, as happens with typical hinged flappers. I can't say for sure that the product would or wouldn't be apt to collect lint, but I don't trust advertising. I do know that the Heartland cap can collect lint at the floating shuttle (I think the Tec ad must be referring to that cap). My daughter bought a house that has one, and when I popped the cap off it looked like it had never been cleaned. However, the lint buildup was uniform around the perimeter of the shuttle, and it didn't prevent the shuttle from opening or closing properly to prevent backdrafting. I did clean it while I had the cap off. Overall, I like the design.

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