[RE-wrenches] Personal project: roofing colors

[Matt Lafferty]

Hi William,

I'm interpreting your question to be mostly aimed at finding out how roof
color affects the temperature inside your house. It makes a heckuva
difference. Conventional wisdom holds true... Lighter colors absorb less
heat than darker ones. If you are going to stick with comp, from a thermal
point of view, go with the lightest color you and your family can tolerate
looking at... Remembering that one day the whole house will be covered in
that same color.

Roof color is only one factor that affects thermal performance of your roof
& attic system. Using a "white" shingle will reduce the heat that is
absorbed by the roof covering, which reduces the amount of heat that
transfers into the sheathing and attic space. Adequate attic ventilation is
a larger issue. Same principle that Matt Tritt mentioned... Do NOT skimp on
attic ventilation!  Lotsa eave (low-side) and ridge (hi-side) venting is a
must. The most effective ventilation scheme is one where convection draws
the air across the bottom surfaces of the roof sheathing. 

A radiant barrier is also worth considering. There are various methods and
products available, depending on the framing configuration of your project.
Some of these can perform dual-duty by creating ventilation paths at the
bottom side of the roof.  And don't forget adequate and properly installed
insulation. (Don't block your ventilation pathways with your insulation...) 

All these things together are a system that will affect livability (comfort
& aesthetics) as well as energy use. The neat thing is that these are
passive... Once they are installed, they don't require maintenance (other
than roof replacement) or energy to operate.  It's worth it to do it right
up front.

Enjoy the remodel!

Matt Lafferty

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
Miller
Sent: Wednesday, September 24, 2008 9:06 AM
To: RE-wrenches
Subject: [RE-wrenches] Personal project: roofing colors

Friends:

I have an energy question on a personal project.  We are adding two rooms to
our house and it is time to select roofing colors.  Nothing will match the
weird comp shingles already on our roof, so we are going to not match and
re-roof the rest of the house later.  In the meantime, I need to pick a
shingle color.  How much difference does a lighter roof color make here in
our inland California (Mediterranean) climate?  We get over 100F frequently
in the summer.

Thanks for your insight.

William Miller