Replies

1. GBA Editor
   Martin Holladay | Aug 10, 2012 12:35pm | #1

   Sue,
   1. Where are you located?

   2. Do you have an unconditioned attic? Or do you have insulated sloped ceilings?

   3. If you have an unconditioned attic, are there any signs of moisture problems?

   4. If you live in a snowy climate, does your roof have ice damming problems?

2. 
   suestou | Aug 10, 2012 01:11pm | #2

   1. I live in Atlanta, Ga. Roof is a 20-yr roof and is at year 22.
   2. Attic is not heated or airconditioned, & there's no insulation on sloped ceilings.
   3. No signs of moisture problems in attic. I have several, small spots where roof is leaking, but not
   at attic under main roof, which is steep.
   4. No ice damming problems

3. Expert Member
   Dana Dorsett | Aug 10, 2012 01:38pm | #3

   Installing turbines will not improve the roof ventilation without providing a path for air to enter.

   It will cool the roof deck by sucking more conditioned air from your house up into the attic space- but at a significant boost to the cooling bill.

   It will continue to pull conditioned air into the attic during the heating season, adding to the heating bill too.

   A ridge vent will have these effects too, but at levels orders of magnitude below that of a turbine-vent.

   Given that this place has gone 70 years without venting and shows no moisture problems, there is no rationale for changing the attic venting scheme, since any opening in the top depressurizes the attic relative to the conditioned space below, increasing the whole-house stack-effect driving air infiltration.

   If you DO add ridge venting, you MUST add at least as much cross-sectional are of either soffit venting or under-shingle vents (eg SmartVent ) low on the roof (1.5-2x the area is even better), to be able to avoid increased stack-effect driven infiltration. If adding soffit venting is out of the question, take a serious look at under-shingle roof-edge type vents mounted as low on the roof as possible, and oversize them relative to the ridge vent area.

   dana

4. GBA Editor
   Martin Holladay | Aug 10, 2012 02:04pm | #4

   Sue,
   Dana has given you good advice. If your attic has survived for years without any ventilation, there is no need to worry about ventilation.

   Whatever you do, don't install any whirlybirds (turbines) on your roof.

5. 
   suestou | Aug 10, 2012 02:44pm | #5

   Your answers are very helpful!

   One concern: I plan to sell the house next spring. Will lack of a ventillation system be a red flag for for potential house buyers?

   If not, in light of your answers, I'm inclined to forego any ventillation system and negotiate down on the roofing proposal cost.

   Thank you so much!
   Sue

6. GBA Editor
   Martin Holladay | Aug 10, 2012 02:48pm | #6

   Sue,
   Q. "Will lack of a ventillation system be a red flag for for potential house buyers?"

   A. It shouldn't be if the buyers are knowledgeable. It may be, however, because ignorance abounds.

7. 
   suestou | Aug 10, 2012 02:58pm | #7

   Thank you! I'll save your answer to share with anyone leery of my ventless attic! I appreciate your help!

   Sue