The dog days of summer are not here yet, but an old construction oversight make it seem that they have arrived early and will stay longer than normal. Here’s one way that cooled things off quickly, for under $40, took less than 30 minutes to build and deploy. Parts list, drawings, step by step DIY instructions, and installation photos that you can download. Topics: Background; A Small Heat Problem; Tiptoeing Through The Attic; Found It; Some R & D With A Dash Of Procurement; You Can Have It Too; Conclusion

Background
We did a lot of upgrades to our current house when we bought it, particularly things that would reduce our operating costs, particularly energy. We put in new double-paned windows, replaced the conventional hot water heater with a flash unit, and insulated the walls and attic with the latest cellulose insulation system. It has worked out very well for us, but there was one room that has always been an occasional problem during July and August.

A Small Heat Problem
The room was added by the previous owner, was built by a reputable contractor, and had all the inspection tickets punched. Still, if we had more than two or three successive hot days then the room would get uncomfortable. It was always a puzzle because of the insulation we had done. The walls would always be cool, but the line where the ceiling meets the west wall was always a bit warm. There is more than two feet of insulation in that section of the attic, so I did some detective work.

Tiptoeing Through The Attic
First I looked at the architectural drawings, and noticed that the walls’ top plate was in line with the bottom of the attic’s plane. Making a trip up there, I discovered that there were no peripheral attic vents around the room, and in fact the only vent was at the north wall, some 25 feet away from the closest peripheral attic vent in the original part of the house. No air movement through that section at all.

Found It!
The insulation in the rafters at the attic’s top, and the R40 insulation over the ceiling joists in the attic’s bottom, bottled heat. It would build up during the day, but not be completely dumped at night. The heat density would increase with successive hot days, typically during July and August.

The walls’ top plate made it impractical to add peripheral attic vents. Installing an additional attic blower wouldn’t really accomplish anything because of the distance to the nearest peripheral vent. A metalized tarp over the roof won’t work because its absorbed heat could damage the shingles or worse. What I needed was a way to reflect radiant heat only in that area where the west wall meets the ceiling, would be quick and easy to build, would not cause collateral damage, and could quickly be put up and taken down.

Some R & D With A Dash Of Procurement
With these somewhat vague requirements I went to the local home improvement store, which for us is Lowes. I wandered the aisles looking for the things that could be used, regardless of their original purposes. Eventually I found it: three feet by 12 feet galvanized aluminum metal roof sections, to be mounted on top of 2×4 runners that would keep the metal panel off the roof and allowing for air movement underneath, tied down at the corners with synthetic rope to keep the completed assembly from moving in a wind.

You Can Have It Too!
The materials costs is less than $40 retail, it took less than 15 minutes to assemble, and about ten minutes to install. You can download the complete bill of materials, including Lowes part numbers, drawings, assembly instructions and some photos of an installed assembly, as a three page PDF file.

Conclusion
The improvement was immediate and dramatic. The temperature drop from the previous days was a cool 12 degrees, the shingles under the heat shield are cooler than they were without it, and I have a quick fix for this year. Perhaps next year we’ll take advantage of all that energy being reflected back into the atmosphere and have a solar system installed. I’ll let the pros do it this time.

Tags: dog days of summer, home air conditioning, home improvement, Lowes, summer heat

This entry was posted on Sunday, July 13th, 2008 at 18:05 and is filed under Potpourri. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.