Question About Vent Work

licensed-trim

I've installed cabinets and microwaves, but I've never installed vent work before. The homeowner wants their microwave vented to the roof. I told her it doesn't need a vent, it's in the microwave itself, and she said her daughter's kitchen caught on fire because she didn't have it vented to the roof and is determined her microwave will be vented to the roof. She said she already has a bunch of roof vents up there; meaning she wants to tie into an existing vent on the roof. My question, can this be done? Can you tie into an existing vent pipe, or run the vent tubing close to the other vent without actually tying into it, sorta let it hang close to a roof vent?

I'm thinking you can't do this; that it's not code. So I'm thinking I'll have to make a new roof vent. I looked this up on how to do it. I have a question about this. I'm not familiar with roofing too much, the vent is circular and of course the roof is inclined, what's the best way to draw this circle from the attic, or the roof?

Any advice on this subject is appreciated.

Tom Struble

your trying to put a wall mount vent on the roof?

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Tom

seifconst

I could see trying to use the existing vent hole for the new roof louvered vent flashing. My concern would be taking away the existing roof vent without putting another on the roof somewhere. Roof vents are there for a reason. This would be the first thing i'd calculate. I would definately not let the range vent close to a roof vent (under roof). The greases will cling to everything on the bottom side of the roof and most likely plug the existing roof vent. As far as drawing a circle ..............a compass?

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Tom Struble

i think he thinks he needs an ellipse,i don't no how to do dat

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Tom

mics_54

The instructions that come with the microwave are pretty clear and usually accurate with various options for installation. If you've installed microwaves before I'm almost sure you've seen them.

I seriously doubt a room vented microwave caused a fire because it was room vented. In Michigan you are more likely to have a fire caused by poorly installed venting into a cold attic from condensation dripping into the electric appliance. No, do not hook the microwave vent into other existing vents. No, do not vent the microwave inside the attic "near" an attic vent penetration.

The best way to vent is not through the roof but through a gable endwall with insulated metal duct.

goneelkn

Broan makes a dampered roof vent for different size ducts. assuming the micro needs a 3 x 10 to round duct converter, and the cabinet above has room for the duct to go straight to attic and no obstructions(joists etc)? be sure to change exhaust on back of micro to vent outside. just a matter of installing micro, attach converter, then duct to attic, once in attic be sure to use insulated duct to control condensation. for dampered vent, it is easier to line it up on the roof to get under a shingle(asphalt) for flange. with the other vents in the roof you should be able to measure over to get between rafters. just drill a small hole thru roof to be sure you are between rafters, then cut full hole. tell customer that they will be loosing some room in cabinet above micro

licensed-trim

Thanks everyone for your input. I talked the lady out of doing this option. I did explain to her that she didn't need a roof vent for a microwave and that she would actually cause more of a problem installing one.

cinty1986

• Installing attic vents in an existing roof is a relatively simple job that most of us can handle. Remember to follow basic safety procedures when working on the roof:
  
  
• Wear loose clothing and rubber-soled shoes with good ankle support.
  
  
• Only work on the roof in dry, calm weather.
  
  
• Be alert for slippery or loose shingles or rotten decking that you might put a foot through.
  
  
• Avoid power lines and TV antennas.
  
  
• Keep children and pets away from the area so they aren't hurt if something falls off the roof.
  
  
• Your extension ladder should be angled so the base is away from the wall a distance equal to 1/4 of the ladder's length plus the width of the soffit.
  
  
• Intake Vents–To install intake vents, set your circular saw blade to a depth about 1/8" greater than the thickness of the soffit (soffit materials are usually 1/4" thick). Lay out the location of the vent between the rafters, then cut the hole with the circular saw. Screw the vent to the soffit, covering the hole.
  
  
• If you have fiberglass blanket insulation in your attic, make sure the blankets are positioned so they cover the top of the exterior wall but still allow at least a 1" space between the top of the insulation and the underside of the roof sheathing. Otherwise, the insulation will block the air flow and your soffit vents will be useless.
  
  
• If you have loose fill insulation in your attic, you'll need to install baffles in each rafter cavity that contains a soffit vent to keep the air space clear.
  
  
• Roof Line/Turbine Vents–To install roof line or turbine vents, first locate the vent between two rafters. Use a utility knife to cut away the shingles and felt paper, then use a saber saw to cut a hole in the roof the same size as the throat of the vent.
  
  

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flyjaysun

get some new smart a@* comments this style is getting old

world llc

you cannot tie 2 vents together because some of the air can blow back down the other pipe...

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