How to ventilate a hip roof with a widow’s walk?
I have a question about a relatively new home (4 years old) in Massachusetts with a ‘four-square’ hip roof that terminates in a widow’s walk (it is flat inside the railing and covered with Bituthene).
There are soffit (eave) vents at the perimeter, insulation in the attic floor (between the ceiling joists) and a ‘prop-a-vent-like material’ to hold the insulation back from the soffit vents, so as not to impede airflow towards the top of the hip portion of the roof.
HOWEVER, there is no ‘visible’ vent to the outside where the hip roof joins the flat widow’s walk area. Where would one expect the venting element (i.e. ridge vent) to be in this situation? and/or how should it be vented? The attic space gets very hot.
Additionally, the HVAC unit for the 2nd floor heating and cooling is in the unconditioned attic space. How can this be rectified and still provide fresh intake air for the HVAC unit? The area of the attic space is +/-40 feet square with an 6-8/12 slope/pitch up to the widow’s walk.
Elizabeth Nichols at [email protected] or Kenneth Minklei at [email protected]
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Replies
Elizabeth,
Unfortunately, finding a way to ventilate your attic is the least of your problems. In theory, you could always install a bunch of ugly "mushroom" vents in the upper portion of your sloped roof, but I don't suggest that you do that.
Your main problem is the fact that the builder of your house has decided to install the heating and cooling units for your home in an unconditioned attic. This is outrageous enough in Florida, where winters are mild; in Massachusetts it is, in my opinion, unethical. Whether or not it is illegal is up to a jury to decide.
I bet you don't have any snow on your roof, do you? Not with a furnace in the attic.
If your house is only 4 years old, it's time to talk to the builder. You might want to have a good consultant and lawyer along with you for that conversation.
There is a solution, but it isn't cheap. You need to install insulation along the plane of your roof to bring your attic within your home's conditioned space. Needless to say, you'll also have to seal up your soffit vents.
Good luck!
Martin,
I think you are being a Cold Climatist again ;-)
Give the South some credit.
We(the South) use/waste more(source) Energy than New England!
http://www.buildingscience.com/documents/digests/bsd152-building-energy-performance-metrics/files/BSD-152%20Energy%20Metrics.pdf
Why is the practice(mech in attic) merely outrageous in the South yet borderline Criminal in the North?
If Elizabeth chooses to "condition" the attic...
The furnace will also need to be replaced with a sealed combustion furnace.
John,
I concede. The South and the North are equally nuts.
Thank you Martin and John for your comments. Because I was asking the question for my son I did not get all the facts correct. When he said HVAC I misunderstood.
The HVAC unit in the attic is an hydronic air-handler receiving hot water and/or freeon from the primary boiler in the basement. It is not a 'combustion' unit. It supplies heating and cooling to the second floor.
Thank you again for your comments. Elizabeth
Elizabeth,
At least it's not a furnace. I suppose that's small comfort.
Since you don't have a furnace in your unconditioned attic, you probably won't be able to get your builder to pay for the needed upgrades to your attic. It's up to you to decide whether you want to live with the high energy bills, or bite the bullet and pay for the roof insulation to solve your problem once and for all.
What Martin said is 100% correct.
But I always like to ask when people want to retrofit roof venting.....What problem are you trying to solve?
-Rob
I don't disagree with any of the comments here. But I wouldn't want anyone to get the impression that it's hard to top-ventilate a 'widow's walk' roof. In fact it's very easy, and absent the air-handler/ductwork issue it would be a simple retrofit too.