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Building Code for a Dryer Vent?

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  • Nov 14th, 2012 11:53 pm
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Sr. Member
Mar 25, 2003
778 posts
1 upvote
Binbrook

Building Code for a Dryer Vent?

From what I can tell, our dryer vent is venting from our 2nd floor laundry room up to the roof and not to an exterior wall. We're having issues with the vent getting plugged with lint though and it's causing our dryer to over heat and shut off. Is there a specific building code for the vent? I'm thinking that we might need to add a fan to help pull the warm air our of the vent. The house is less than a year old, I wonder if I can approach the builder to fix this?
17 replies
Sr. Member
Nov 24, 2004
948 posts
42 upvotes
A dryer vent can be run to the roof, soffit, or through the wall. I've seen all those kits on the shelf at building supply stores.

Maybe you need to clean out the dryer itself? Lint can build up in the fan inside and reduce it's performance. I clean mine out once a year or so. Also the vent tube past the dryer may be clogged. Not sure how to resolve that.

If its reasonable to access on the roof, I'd also check the exterior vent. There may be a clog of lint there, or even a birds nest.

CM
Deal Addict
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Mar 24, 2008
1028 posts
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Etobicoke
The vent has to vent to the outside.

As for Code? The only other thing I can think of is that it should not be one of those plastic flexable ducts.
Deal Addict
Jan 5, 2003
2917 posts
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Toronto
Don't know about the code, but in terms of the venting, in general:

- minimal length and bends so lint doesn't get trapped
- ridgid metal is best, followed by flexible metal, but stretch it out to minimize folds where lint could get trapped. Don't use plastic because of the hot air might melt it
- sharp bends will greatly reduce airflow

If there are too many sharp bends and it has to go far up, I could see how the air might not be strong enough to defeat gravity and some lint would float back down when it shuts off.

Don't know if venting to the outside is required per the Canadian bldg codes, but in many southern areas, venting to an attic is fine. However, in colder climates, warm air meeting cold air = condensation if your attic doesn't have enough ventilation and your rafters, etc. will degrade and rot faster, so it's always better to vent outside regardless of code. Maybe it'll be okay in moderate areas like Vancouver.

I assume you're cleaning out the lint trap after every load, right? And the lint trap doesn't have any holes or rips in it and is securely fastened along the edges? That has to be a lot of lint that isn't captured by your lint trap to have your vent "plugged with lint".
Deal Addict
Sep 11, 2006
1918 posts
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KELOWNA
Also check your lint trap to see if it is blocked. It may look fine but if you use dryer sheets like Bounce, they can form an invisible barrier that won't allow air through (thus overheating the machine). The test is to take the trap and see if tap water will run through it freely. If it doesn't, the thing is coated and you need to get some soap and wash it off until water will pass through.
Deal Fanatic
User avatar
Oct 10, 2006
7741 posts
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Georgetown
Hehe....our builder didn't even put one in! For the last 13 years I pull my dryer out monthly, and vacuum out the vent they retrofitted :mad:

If you are experiencing issues, there is a kit at Home Depot that is mean for ventless installations. You put water into it to assist.

See this button :confused: :confused: Learn how to use it PLEASE ;)
Deal Addict
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Mar 24, 2008
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Etobicoke
jm1 wrote:
Apr 10th, 2008 2:45 pm
Don't know about the code, but in terms of the venting, in general:

- minimal length and bends so lint doesn't get trapped
- ridgid metal is best, followed by flexible metal, but stretch it out to minimize folds where lint could get trapped. Don't use plastic because of the hot air might melt it
- sharp bends will greatly reduce airflow

If there are too many sharp bends and it has to go far up, I could see how the air might not be strong enough to defeat gravity and some lint would float back down when it shuts off.

Don't know if venting to the outside is required per the Canadian bldg codes, but in many southern areas, venting to an attic is fine. However, in colder climates, warm air meeting cold air = condensation if your attic doesn't have enough ventilation and your rafters, etc. will degrade and rot faster, so it's always better to vent outside regardless of code. Maybe it'll be okay in moderate areas like Vancouver.
I assume you're cleaning out the lint trap after every load, right? And the lint trap doesn't have any holes or rips in it and is securely fastened along the edges? That has to be a lot of lint that isn't captured by your lint trap to have your vent "plugged with lint".
I would recommend against leaving the vent in your attic, unless you are will ing to seriously jepardize your health. Mold will grow in no time.

If you have no choice but to vent up through your attic, the duct should also be insulated to lessen the chance of condensation in colder weather.
[OP]
Sr. Member
Mar 25, 2003
778 posts
1 upvote
Binbrook
Thanks for all the replies everyone! We clean the lint trap every time we run the dryer. From what I could tell when I took the "flex" tube that connects the dryer to the wall, it looks like the L connection that's directly in the wall is getting plugged. The builder installed a vent fan (like the one in a bathroom), I wonder if we can tap into that to help assist getting the air up the vent to the roof? I used the vacuum to suck the lint out of the vent and the flex tube as well and there was A LOT of lint in there. The house is only 9 months old as is the dryer.
Deal Addict
Jan 21, 2008
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Oakville
I've seen secondary lint traps you can buy that hooks up onto your flex hose, that just means you have an extra one to clean every time. But it saves from your hose getting clogged, I believe they sell them at HD.
Deal Guru
Mar 23, 2009
11657 posts
1470 upvotes
Toronto
Old thread but...
Techhead wrote:
Apr 10th, 2008 12:54 pm
The vent has to vent to the outside.

As for Code? The only other thing I can think of is that it should not be one of those plastic flexable ducts.
Isn't use of the flexible foil stuff not recommended either?

The reason I ask is my contractor put in rigid metal for the entire vent except for the last 4 feet or so before it heads outside. For this last piece he used flexible foil. I'm going to ask him to change it to flexible metal but I was wondering if the flexible foil actually met code. (I think the intent was to use the foil temporarily in that spot since he didn't have the flexible metal one handy, and the flexibility was needed because of a mild angle there, but then he forgot about it.)
Sr. Member
Mar 6, 2007
950 posts
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EugW wrote:
Jun 9th, 2011 2:58 pm
Old thread but...


Isn't use of the flexible foil stuff not recommended either?

The reason I ask is my contractor put in rigid metal for the entire vent except for the last 4 feet or so before it heads outside. For this last piece he used flexible foil. I'm going to ask him to change it to flexible metal but I was wondering if the flexible foil actually met code. (I think the intent was to use the foil temporarily in that spot since he didn't have the flexible metal one handy, and the flexibility was needed because of a mild angle there, but then he forgot about it.)

I haven't read any actual code on this, but from what I recall, you can use the flexible metal (not the foil type though) as long as it's not concealed behind a wall. The flexible metal is ok if there's a removable panel. The concern is that it can still be easily punctured, and if it's hidden, you'll never know. I used the rigid metal ducts except for the last couple of feet to my dryer so that I can slide it in and out a bit more easily (and plus, the total run from my dryer to the outside is < 10 ft).
Deal Addict
User avatar
Mar 8, 2002
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Ottawa
You need to clean the dryer duct out regularly, because even the best dryer lint filter will not catch everything. You can buy a dryer vent cleaning kit from Home Hardware, Item #3721-671 and optional extension Item #3721-670. Other places may carry it, too.
The code does not prohibit dryer vents through a roof, although they are more problematic. If still under warranty, definitely contact your builder.

2006 Ontario Building Code

6.2.3.1.(2) This subsection (Part 6) does not apply to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems that serve individual dwelling units within the scope of Part 9.

EXCEPT!
9.32.1.1.(5) A clothes dryer exhaust duct system shall conform to Part 6. (the key parts of which follow)

6.2.3.2. Materials in Air Duct Systems
(1) Except as provided in Sentences (2) to (4) and in Article 3.6.4.3., all ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of steel, aluminum alloy, copper, clay, asbestos-cement or similar noncombustible material.

6.2.3.8.(7) Exhaust ducts connected to laundry drying equipment shall be,
(a) independent of other exhaust ducts,
(b) designed and installed so that the entire duct can be cleaned, and
(c) constructed of smooth corrosion-resistant material.

Vinyl is combustible, so it does not meet the requirements of Part 6.
Sr. Member
Mar 6, 2007
950 posts
59 upvotes
MacGyver wrote:
Jun 9th, 2011 5:34 pm
You need to clean the dryer duct out regularly, because even the best dryer lint filter will not catch everything. You can buy a dryer vent cleaning kit from Home Hardware, Item #3721-671 and optional extension Item #3721-670. Other places may carry it, too.
The code does not prohibit dryer vents through a roof, although they are more problematic. If still under warranty, definitely contact your builder.

2006 Ontario Building Code

6.2.3.1.(2) This subsection (Part 6) does not apply to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems that serve individual dwelling units within the scope of Part 9.

EXCEPT!
9.32.1.1.(5) A clothes dryer exhaust duct system shall conform to Part 6. (the key parts of which follow)

6.2.3.2. Materials in Air Duct Systems
(1) Except as provided in Sentences (2) to (4) and in Article 3.6.4.3., all ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of steel, aluminum alloy, copper, clay, asbestos-cement or similar noncombustible material.

6.2.3.8.(7) Exhaust ducts connected to laundry drying equipment shall be,
(a) independent of other exhaust ducts,
(b) designed and installed so that the entire duct can be cleaned, and
(c) constructed of smooth corrosion-resistant material.

Vinyl is combustible, so it does not meet the requirements of Part 6.

I guess smooth material means that the flexible metal ducts are out of the question, eh? :(
Sr. Member
Jul 26, 2010
827 posts
54 upvotes
eastern Ontario
I believe that joints must be taped, no sheet metal screws that would project inside and catch lint.
Deal Guru
Mar 23, 2009
11657 posts
1470 upvotes
Toronto
This site states:

http://www.gtahomeinspector.com/1Reside ... ltant.html

"The IRC will defer to the manufacturer’s instruction, so if the manufacturer’s recommendation permits a longer exhaust vent, that’s acceptable. An inspector probably won’t have the manufacturer’s recommendations, and even if they do, confirming compliance with them exceeds the scope of a General Home Inspection."

My Samsung dryer installation manual states that flexible non-foil metal venting is permitted, but flexible foil metal is not. And yes, no screws, just aluminum tape. For the flexible non-foil metal duct, it cannot be enclosed behind a permanent wall. It must be accessible. Only rigid metal ducts are permitted to be enclosed in a wall.

In my case I'm sort in a grey zone. It is behind a permanent wall, but it is also accessible from the side, because right beside it the wall opens to an open space at the electrical panel. My contractor didn't close that part of the wall off, which in retrospect works to my advantage.
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