Comments on: How Hot Is Your Roof? – Insulated Rooflines and Shingle Temperature

By: Richard Beyer

Richard Beyer — Fri, 30 May 2014 17:48:35 +0000

Oops.... Correction
Oops.... Correction warranted: I meant to say Closed Cell. Sorry for the type error.

By: Benoit Rulleau

Benoit Rulleau — Fri, 30 May 2014 17:31:34 +0000

Hi Allison, great article and
Hi Allison, great article and great website, keep up the good job!
Was wondering if there is a good roofing solution for a country like Japan with cold and sunny winters (where you you want to get as much sun's radiation as possible inside your building) and darn hot summers at low latitude with frying sunlight.
Is there any strategy to change the albedo of the roof according the seasons? To block that radiation in summer, but let it in in winter?

Thanks,
Benoit

By: Richard Beyer

Richard Beyer — Tue, 27 May 2014 17:55:47 +0000

9 degrees can make a huge
9 degrees can make a huge difference if you were describing 1st -v- 2nd -v- 3rd degree skin burns. Why would it be much different with a roof shingle? I have a roof with a 2/12 pitch, aka hot mop roofing. It layed perfectly flat prior to open cell foam being installed against the underside. (No pebble protection) By August, the roof had more blisters and ripples than a man could count. Once the foam was removed from this area, the blisters settled but the damage was done.

By: ted kidd

ted kidd — Mon, 26 May 2014 18:50:42 +0000

"Hmmm. Today I think I
"Hmmm. Today I think I'll crush some wives tales..."

Out of the park with 3 guys on base!

Thanks for doing this Allison! So helpful!

I remember somewhere comments about color causing delta t of 30. Love to see that point in there.

Also, primary importance of venting is to avoid ice damage by keeping roof surface sub freezing in high snowfall areas.

By: Jim G

Jim G — Mon, 11 Oct 2010 05:47:41 +0000

What about increased moisture
What about increased moisture content under the roof sheeting?

By: Jeffrey Sauls

Jeffrey Sauls — Thu, 07 Oct 2010 21:01:10 +0000

Another great post Allison. I
Another great post Allison. I'll be sure to download the report. This is the first question I get asked when I discuss the topic with builders. We insulated the roofline of our 84 year old home this Summer.

By: Allison Bailes

Allison Bailes — Thu, 07 Oct 2010 17:41:13 +0000

Very true, Doc. You need all
Very true, Doc. You need all the heat you can coax into your home in Maine, wherever you can get it from.

By: Tom "Doc" Brudzinski

Tom "Doc" Brudzinski — Thu, 07 Oct 2010 17:39:29 +0000

THX
I
THX
I'll read the article. I have an insulated (closed cell) roof that needs its final finish. I have planned on standing seam metal. I have been reading up what Joe St. has to say, which is a lot.

BTW, dark roofs, way up here in the upper right corner of the US don't seem to have the same implications as where you are! :)

By: Allison Bailes

Allison Bailes — Thu, 07 Oct 2010 17:34:50 +0000

Tom, I think metal roofs
Tom, I think metal roofs wouldn't show as big a temperature difference because they reflect a lot of the solar radiation. White shingles keep vented attics more than 15 degrees cooler than black shingles, and a reflective metal roof would do more than that. I haven't seen anything comparing vented attic to insulated roofline with metal roofing, though. The best would be a metal roof on an insulated roofline with a one inch air gap to allow venting between the roofing and roof deck. They call that a 'ventilated double roof' in the FSEC paper.

By: Tom Brudzinski

Tom Brudzinski — Thu, 07 Oct 2010 16:50:12 +0000

THX, Allison. DO you think
THX, Allison. DO you think that the answer would be any different for other roofing materials, a metal roof in particular?