I just purchased an eight year old home that is in good shape.
My concern is that the dryer vent blows underneath my front steps, which
are made of wood.
Could this be a fire hazard due to lint buildup?
I am seriously considering hiring a builder to re-vent the hose.
I went into the crawl space and it is neat and clean, no moisture.
The owner's manual will tell you the maximum allowable distance that
you can run the vent. You may be over that limit either way - 90 bends
creat much more drag on the air flow.
Having a too long vent run could be dangerous. The dryer won't be able
to exhaust the heat as quickly and there is an increased danger of
fire. Try and burn some lint some time - it burns beautifully.
There are inline vent fans to boost the air pressure in the duct and
help exhaust the air. The fan blades are designed to prevent lint
build-up, but they should be installed so you can access them to clean
off the lint anyway.
What about venting it into the crawlspace below? We don't have any
insulation between the floor joists down there, and the ground is
bare. The crawlspace is well ventilated (as is our drafty 50+ year
I ask because to get the vent down and out through an outside wall
will require about 3 90 degree bends along with about 40+ feet of
ducting. My only other alternative is to vent through the roof which
would be 2 90 bends and about 20' of ducting but I've read that it's
not good to vent vertically because the lint will clog easier.
You don't want to vent a dryer ANYWHERE inside the house, including the
attic or the crawlspace. That's a lot of moisture that could cause rot,
mold, etc. I also believe it's a code violation.
Unless your house is 80'x80' and the dryer sits right in the middle, I'm
guessing you can find a shorter route to an outside wall. I believe the
maximum length is supposed to be under 25 feet, which you have to subtract
5 feet for every 90 degree elbow (just going from memory on this).
I had a similar situation when I built my house. My initial options were 16
feet up to the roof, or about 20' out to a back wall. Once I stopped
overthinking the situation, I ended up with a short 5' duct run to a side
wall. I went down to the crawlspace, under the joists, then out through the
rim joist in the crawlspace. Two 90's, two 45's, and about 4' of actual
duct. I wrapped the whole thing with metal foil tape and insulation. It
flows wonderfully and can be cleaned easily from outside.
Check your options further. You'll probably find another route that is much
Well, the dryer will be sitting in a bathroom which is just about dead
middle in the house (which is appx 60' long and 40' wide). It will
take two 90 degrees to get it pointed to the foundation for exit, not
counting an additional 90 from the dryer to the proposed vent's hole
in the wall. Closest foundation wall would be appx 15' from the
vent's hole in the floor but that's right next to the front porch. Add
another 3' for the duct from the wall hole to the floor, so min run is
just at 19-20 feet.
According to the mfg's ducting chart, the max for 2 90's rigid 4" duct
run is 16'.
Funny, I watched "Ask this Old House" Thursday night. A homeowner had
an exhaust fan installed in their bathroom. The electrician claimed it
was unnecessary to vent it to the outside, so he just installed the fan
so it vented into the attic.
The homeowners ended up having water damage to their bedroom ceilings.
It was winter when they went into the attic to see if they could find
the problem, and they found sheets of ice on the inside of their roof.
The temperatures from a dryer vent will not create a fire hazard.
Neither is the lint a fire hazzard. Lint may burn, but it will not
self ignite. If the porch crawlspace is enclosed, you may have a
moisture buildup there, but I see no other problems, except the lint
may be unsightly.
Well, it is vented sort of outside, as it vents underneath my front
steps which are made of redwood, and there are spaces between the wood
I spoke with a builder today, and he suggests drilling through the
concrete and venting it outside.
I find it hard to believe that this is code, and that the home passed
the building inspection upon completion.
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