Asked on Dec 1, 2011

My 1927 house has minimal attic insulation so I'm about to add fiberglass bats.

Woodbridge Environmental Tiptophouse.com3po3Southeast Solar Co


The problem I have though is that there is also minimal ventilation in the attic too. There are no eave vents and not enough sofit overhang to create them. Currently I have two gable end vents (about 3 sq ft each) and that's it. The attic space is only about 1000 sq ft. I'm guessing my options are 1)have a ridge vent cut in when I have the roof replaced but I question whether the two gable vents are enough, 2) put an electric exhaust fan over one of the gable vents to pull air from one end to the other or 3) add one of those mushroom type of elec vents although I hate cutting holes in anything.
Any ideas on my 1), 2) and 3)...or a better idea?
5 answers
  • 4. Do nothing, unless you observe visual moisture issues within the attic itself. If there is no black staining, or rust on the protruding nails there is no reason to put any additional ventilation in. By installing additional insulation your preventing any heat build up from getting into the home from above, or heat or cooling escaping from below. I would however before you put any insulation in the attic air seal the top plates, any light fixture boxes in ceilings, and any wire or pipe openings where they enter into the attic area. Then install and reset the insulation in the attic. By doing so you will give the fiberglass insulation a real chance to do its job. Last thing. You have a very old home. Chances are quite good that there is or was Knob and Tube wiring. You cannot safely cover this with any kind of insulation if its still active. So if you have any, or think if any that is there is still operational then get this fixed first or you risk the chance of burning down your home.

  • Danno L
    on Dec 1, 2011

    The old knob and tube was replaced a long time ago at various times so I have a mixture of flexible metal jacket and romex. Thanks for the advice.

  • Southeast Solar Co
    on Dec 2, 2011

    1. I suggest calling Southface .( They will come by and see it for a small fee and give you a correct assessmentquote50071 of the situation. They also rain in HERS rating. It may be worth attending. 2.If the insulation is inadequate, please look into having spray foam insulation installed. Venting the attic is truly not necessary unless you do not have adequate ventilation to take the moisture out of the home (such as vent fans from your bath room) Almost all the heat loss and gain is from the roof. Doing nothing does not sound right.

  • 3po3
    on Dec 2, 2011

    I think your best bet is to get an energy audit. Can't vouch for Southface, of course, but somebody should come out to your house and assess both your insulation and ventilation needs.

  • A HERS rater can do this for you, however you really should contact a BPI envelope shell professional for this type of work on older homes. As far as foaming the attic I agree and disagree. If any of the heating or cooling equipment is located in this area, then bringing in the equipment within the shell by foaming the attic roof and end walls plus removing any ventilation is the way to go. However if you do not have any equipment within this area, Install the insulation or use blown in if you have no intention to use the attic for any storage in the future. Also be sure that whoever does this is independent of any company that may be trying to sell you a service by simply using a check list format and not a blower door and CAZ evaluation of the home.

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