Soffits and Gutters


Old 03-03-15, 06:18 AM
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Soffits and Gutters


I live in Chicago and am in need of new gutters and soffits. I currently have aluminum soffits and fascia that were installed over the old wood soffits. Unfortunately there are not actual soffit vents in the old wood soffits. I want to make sure that whoever I hire to do the job will cut out vents in the wood and then cover with the aluminum soffit vent for proper attic ventilation. My question is how many soffit vents are needed and what distance should they be separated? Or should I remove the old aluminum soffits myself and then remove all the wood prior to them coming out to install new soffits?

Secondly, as I begin to price out new gutters and soffits can anyone give me a ball park of price per foot that is reasonable for this type of job?


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Old 03-03-15, 07:00 AM
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Can't help on the price, but the guideline for vent area is a choice either 1/150 or 1/300. That means 1 ft² of NFA (net free area) for every 150 or 300 ft² of attic floor. The 150 or 300 depends upon how well the ceiling plane is air sealed and if you have a vapor barrier under the drywall. Usually, only new construction qualifies for the 1/300.

Example: If you have 1,200 ft² of attic floor @ 1/150. you would need 8 ft² of NFA total venting. That number is then divided half high and half low giving you 4 ft² for your low vents. BUT, that is NFA so you will need larger openings depending upon the actual vents you select. Often they are rated at about 50% of the actual opening.

This is also dependent upon what you have for high vents, gable vents, ridge vents, or other.

Old 03-03-15, 10:13 AM
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Can you access or at least look at the soffits from the attic? A soffit vent is useless if it's blocked by the insulation. Baffles can be installed on the attic side to provide an air way so the vents will work.
Old 03-03-15, 10:15 AM
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If there weren't soffit vents in the old wood soffits, what makes you think you need them now, or that it's even possible? Some houses were built in a manner that blocked off those rafter bays so just drilling holes through your wood soffits isn't necessarily all that you would need to do. This is a hard question to answer without seeing the house or the manner of construction. It might be that your wood soffit could come down. But in a lot of houses, this method of ventilation was not part of the plan... and by opening up the soffits and rafters you are just creating energy loss at the top plate.

On new houses with trusses that have an "energy heel", it's a different story. They are made just for this purpose, so that a large amount of insulation can be placed over the top plate, between the baffles and roof deck.
Old 03-03-15, 11:03 AM
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My old man had aluminum soffit put in recently along with a ridge vent. The guys doing it just cut a basically continuous six in wide vent into the wood soffit before putting on the vented aluminum soffit.

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