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DACarey
Attic Insulation - No Soffit or Eave Air Holes
DACarey

My attic does not have enough insulation and I would like to add some but my attic is a little different from what I have seen on ATOH and other home improvement shows.

Specifically, my attic does not have any air holes in the eaves or soffits. Instead, my attic has two windows on opposite sides of the attic that have louvers (always open) and screening to vent the attic.

Most of the time that I see on TV, the requirement for attic insulation is to place some type of 'channel' near the base to allow air from the soffit vents to circulate up to the top of the attic. This channel keeps the insulation away from the lower roof.

My question is this: since my attic has different venting, do I need this channel?

I don't think I need it but I want to hear what other people say before I add insulation to my attic.

Thanks.

MtMan54
Re: Attic Insulation - No Soffit or Eave Air Holes
MtMan54

Hi, Are you getting ice dams? Venting is used to stop ice dams when there isn't enough insulation in the attic to keep the heat inside the house. The venting will let the lost heat escape to the outside. Thanks

ed21
Re: Attic Insulation - No Soffit or Eave Air Holes
ed21

Besides helping to prevent ice dams by keeping the roof deck cool, vented soffits are used in conjunction with ridge vents to promote airflow in the attic. If you don't have any soffit venting, baffles at the soffit probably won't do much.
Sometimes soffit are are vented from under and behind a fascia board, not an overhang.

keith3267
Re: Attic Insulation - No Soffit or Eave Air Holes
keith3267

You still need the baffles, or a gap at least. Even though you don't have soffit vents, there is still some infiltration. Insulation will trap some warmth escaping from the house, that's its job. You do not want this trapped warmthe against the bottom of your roof or you can get ice dams. It will also keep the shingles in this area hotter during the summer and shortening their life.

You do not need to add soffit or eve vents unless you start having other problems. Its an odd relationship, but the less insulation you have, the less ventilation you need. With less insulation in the attic, the more heat escapes and the more heat that escapes, the stronger the air currents in the attic, so smaller vents are still effective.

As you increase your insulation level, less heat escapes into the attic so the air currents are weaker and you need more ventilation. The old rule of thumb of one square foot of vent for every 150 to 300 square feet of attic floor was OK for the days of R-19 or less insulation. With todays recommendation of R-38 or higher, you need to be a lot closer to the 1/150 or even lower.

The soffit/ridge vent system is superior to the older gable vents, but retrofitting is not always an economical choice. You just need to keep that gap (1" or more) between the roof and the insulation and if necessary, increase the size of the gable vents.

Mastercarpentry
Re: Attic Insulation - No Soffit or Eave Air Holes
Mastercarpentry

I agree with Keith. There will be some convection even without soffit venting and you need to make it possible, so leave space at the bottom of the rafter bays then see what happens. If you have problems I'd add soffit venting first. If you still have problems then add a ridge vent and close the gable vents. The old-fashioned 6X12 louvered metal surface mount soffit vents aren't pretty or as effective as a full strip vent or perforated soffit, but they are cheap and easy to do. Another approach is to cut out or demo the existing soffit and go with ventilated vinyl soffit; again easy and cheap but has the benefit of never needing maintenance.

Many times existing attic venting will be enough and many times it won't, but upgrading attic insulation to today's standards is always a good idea even if a little more work is needed with it.

Phil

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