Powered roof vent and how to pick a contractor…
Hello all –
I have a 1979 colonial(ish) house. I have a truss attic (tall, 20′?) over the bulk of the house and a smaller rafter attic over the garage and bonus room. When I moved in, there was NO venting in the smaller attic. Clearly insulation had been stuffed into places that was supposed to let the air flow. I removed that and it dropped the temperature significantly in the bonus room. House is in Norther Virginia.
The main attic has no eave venting. Only two vents, one at each end of the attic, in the side of the house, right up by the peak. There is a powered vent – it runs a LOT. I can’t (or can’t without a ladder) change the temp setting since it is really high. there is an on/off switch down low.
I can’t be sure, but it looks like most other housees in the hood have sealed soffits.
Problem:
1) clearly the vent sucks in tons of cool air from the house and sends it out the attic. This costs me money and a/c and comfort in the upstairs.
2) I think this is why I have fireplace smell in my living room, as it is sucking in cooled air from the fireplace to replace the lost air. (This causes the wife great consternation, nashing of teeth and ultimately leads to me being less happy!)
I just finished a six figure addition at the house and now officially hate all contractors (present company excluded of course). They were terrible. We did NOT go with the cheapest outfit, we vetted them, got references and everything. They still used a circular saw right in my media room and coated the whole house with drywall dust. I couldn’t sit at home and babysit them – that is why I hired a GC. In the end, I would have done better to just get my own subs.
So. What do I do? Is there any legit person I can hire? And how on earth do I make sure they do something that will actually FIX the problem which will take some thought and expertise.
Replies
The first question...
...is this: What problem are you trying to solve? Power vents frequently create more problems than they solve, by exactly the mechanisms you described. I'd turn the fan off, particularly if the foundation is dry. I'd also look into air sealing the attic.
Check out Allison Bailes' blog on greenbuildingadvisor.com where he addresses this very issue.
Re: the vent fan
If both ends of your house gables have vents ... seems the vent fan would draw air through those vents and much less so from inside the house (through the ceiling). Maybe I misunderstand where and what configuration the power vent is. I assumed you ment it was through the roof and maybe you ment through the ceiling into the attic? (there's that ugly word ... ass u me ...
Contractors who don't know how to work in an occupied space don't seem to really understand the other half of renovation contracting ... WOW. We've all put up w/ our own messes and learned that in hindsite failure to work properly around an occupied space ends up a pain in the butt. 'Course we pay ourselves nothing ... so you get what you pay for. But to higher someone to do work ... seems that he's either going to tell you to 'clear out the space' or he's going to mitigate a substantial part of making a mess.
You lookin' to hire someone for the fan thing?
You have it right. Powered vent in the roof. Gable vents. I just think the powered vent is probably pulling in air from the house too.
I'll be hiring someone, but not until I can figure out what really needs to be done... And I will sure be telling him to 'mitigate'!
thanks for the help!
Read Allison's blog
Really, power vents rarely save enough energy to justify their own existence. If you want to cool your house, add more insulation. You already know the power vent is drawing inside air into the attic because it backdrafts your chimney, and that's costing you comfort, money, and maybe health. If you've got a combustion appliance running, say a water heater, then it's also drawing the stack gasses from that into your house. Very bad.
Much of the conventional wisdom about attic venting is just wrong. Air movement in attics doesn't really do much to reduce attic temperature. Research (Google William B. Rose) has shown attic venting makes only a few degrees difference in shingle temperature. And if it's moisture you're concerned about, the better solution is to air seal the penetrations leading to the attic that admit moisture. Spend some time at Greenbuildingadvisor.com to really understand the issue.
Vent Fan Losing Money
Get some diffrent quotes and see some pics of the finish product. I would say if the fan is pulling cold air to the roof you are losing money and would shut it off. Most contractors will clean up with the project is done ...be bold when talking to them and tell them your wants and needs...You are paying them for thier service ...Get what you want.
http://www.roofingsanrafael.org
Sounds like a classical east-coast house with no eaves. (A really dumb design, when using standard attic construction.) There are several schemes to introduce eave venting into such a roof, but they generally require reroofing.