Need Advice- Dryer Vent/Drywall Issue

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jenny8484, May 21, 2012.

  1. jenny8484

    jenny8484 New Member

    Messages:
    6
    Location:
    ny
    Hi, I am hoping someone has some advice for me. We are remodeling our basement, and our washer and dryer are down there. The old owners of the house previously had the dryer vent into a crawl space underneath the house. We got a new washer and dryer and converted to a gas dryer (since we had a gas line) but the nearest outside wall is 20 feet away (since most of what is behind the wall is an extension with crawlspace underneath). We used rigid galvanized pipe and ran it along the wall, and as a result I probably have 2 elbows and maybe 15 feet of horizontal duct work currently behind 2x4s (we have not drywalled yet). The last 4 feet or so are exposed where it vents out (we are leaving a section of the basement unfinished). I purchased a dryer booster fan as well was a lint trap since the duct is very long. I noticed with the new gas dryer that the pipe gets a lot hotter than when we had our old electric dryer. Now my concern is putting drywall over the wall where a lot of the duct runs. Is this a bad idea? Not sure what else I can do, my options are limited since we can't move the washer across the room (consulted a plumber and he said its not possible being that the washer is near the waste line).
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    It is ok for dryer duct to be enclosed. The rigid galvanized is the correct material. Code will also specify NO screws in the joints, since they catch lint.
    The duct booster is an excellent idea.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,056
    Location:
    Cave Creek, Arizona
    The "duct booster" IS going to accumulate lint, so it should be accessible for cleaning. Your dryer's manual should have shown how long a vent duct could be without using a booster. As far as enclosing it is concerned, almost ALL dryer vents are enclosed inside a sheetrocked wall.
  4. jenny8484

    jenny8484 New Member

    Messages:
    6
    Location:
    ny
    Thank you both, The dryer duct fan is accessible (it is put on maybe before the last 5 feet of duct line that goes straight up and outside, which is in our accessible/unfinished part of the basement). I figure I exceed the manufacturer's recommendations without the fan since I have 2 elbows which subtract 5 feet each plus another long run of horizontal duct which is about 15-20 feet. The reason why I was nervous is because my husband's coworker (who is also a volunteer fireman) told us putting such a long duct behind drywall was a fire hazard, and I was just nervous because the gas dryer has made the pipe even hotter. I don't think we will even insulate that wall just in case... The other alternative would be running it basically the same length, but up into the crawlspace (where our previous dryer vented out into) with a long length of vent pipe through the crawlspace and outside a foundation wall. Well, I appreciate the advice!
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Your dryer will work a LOT better with the booster. Your fireman is probably cautious about dryer fires, because they do happen. On submarines for 22+ years, fire was always a major concern. The only fires I ever did experience were in the clothes dryer exhaust duct, due to lint buildup!! Keep the lint cleaned out and you minimize the risk.
  6. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Your fireman friend doesn't know that drywall is used for fire-separation in homes?
  7. SteveW

    SteveW DIY Senior Member

    Messages:
    1,053
    Location:
    Omaha, NE
    Following up on the OP's question -

    what is the best way to secure the joints in the dryer vent pipe?
    No screws, as Jimbo says.

    "Duct tape", of course, is not really used on ducts and would be a poor choice for this application since it will fail eventually, allowing the joints to separate, which could lead to lint being blown into the wall space.

    Is there a better, more permanent, type of tape to use?

    I would be concerned that you would really want to have those joints very well secured, and the pipe itself tightly secured to the studs, so that when you run a cleaning brush through the pipe, you won't dislodge the joints. Dryer fires are one of the biggest causes of household fires, and you want to make it safe and easy to clean out the vent pipe.
  8. chefwong

    chefwong New Member

    Messages:
    710
    Location:
    District of Columbia
    There is good *duct tape*. It's more like a PE blend if I recall.

    I normally lap 2X with Duct Mastic and then wrap it with the foil mastic tape
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,270
    Location:
    New England
    RE the gas dryer exhaust being hotter than with an electric...yes it is if it is working properly! On max, a typical gas dryer produces in the order of 45K BTU while an electric one produces the equivalent of around 20KBTU after you convert watts to BTU.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,056
    Location:
    Cave Creek, Arizona
    IF the duct is properly secured, there is NO WAY it could "separate" with or without duct tape. But a metallic tape would be better if you were really concerned about it. "Fire rated" drywall is used for "separation" in buildings, but standard sheetrock has a limited fire protection. And "dryer duct" fire is going to be INSIDE the pipe, not outside.
    Last edited: May 22, 2012
  11. jenny8484

    jenny8484 New Member

    Messages:
    6
    Location:
    ny
    Thank you all for your responses. I was worrying myself over this, so I am glad to have some advice/reassurance.
  12. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Can you explain to us the difference between Type X and "standard" drywall please?
  13. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    [h=3]USA and Canada[/h]Drywall panels are manufactured in 48-inch (120 cm) and 54-inch (140 cm) wide panels in varying lengths to suit the application. Common panel thicknesses are 1/2" (12.7 mm) and 5/8" (16 mm), with panels also available in 1/4" (6 mm) and 3/8" (10 mm). Both 1/2" (12.7 mm) and 5/8" (16 mm) panels of TYPE 'X' (a gypsum board with special core additives to increase the natural fire resistance of regular gypsum board[SUP][14][/SUP]) are used where a fire-resistance rating is desired. Regular 5/8" (16 mm) panels are used (with or without light gauge resilient metal channels) where additional mass is needed for the reduction of sound transmission.[SUP][citation needed][/SUP]
    Drywall provides a thermal resistance R-value (in US units) of 0.32 for 3/8" board, 0.45 for 1/2", 0.56 for 5/8", and 0.83 for 1" board. In addition to increased R-value, thicker drywall has a higher sound transmission class.[SUP][citation needed][/SUP]
  14. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
  15. jacobsond

    jacobsond DIY Junior Member

    Messages:
    59
    Location:
    ND
    Your appliance and your appliance repairman are going to THANK YOU for your incite on your dryer vent.Rigid vent with and assessable booster GREAT. Use the silver tape on your joints and you should have no problems. Make it secure enough so you can clean the vent at least once a year with a vent cleaning brush. Sheetrock is used as a fire break and while the vent seems hotter I find it hard to believe it would get to combustion temps of wood. The dryer high temp on the safety stat is usually less than 200 degrees.
  16. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    You asked the question because you already had an answer in mind? You mentioned Type X and "standard" you did not mention Type C.
  17. dlarrivee

    dlarrivee New Member

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    1,172
    Location:
    Canada
    I just find it funny how people think that fire rated drywall is so much different than the "regular" stuff.
  18. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Well I don't think anyone said it is SO much different. It is WHAT you use if the code says so. Like if the code wants blue primer, you use blue primer. Not because we give a bleep about the color of primer.
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