Replies

1. Expert Member
   Dana Dorsett | Jul 10, 2015 05:27pm | #1

   Which is more likely to leak and cause expensive damage to the interior?

   In most cases the answer would be "roof", but I haven't seen your house.

   Any time you're replacing roofing or siding is a once in 25-75 years opportunity for improving the thermal performance and moisture resilience of the house with exterior insulation. But getting the R-values and material stackup right is important, or you can be working against yourself.

2. 
   charlie_sullivan | Jul 10, 2015 08:57pm | #2

   In many cases, insulation upgrades to the attic can go on the attic floor, allowing re-roofing to be done independently of the insulation upgrades. But it would be worth understanding that for your house before proceeding. Roughly speaking, if you have an unconditioned attic with insulation on the attic floor, and you don't have ducts in the attic, you can separate those decisions. But if you have conditioned space in the attic, with the insulation just under the roof, you'll want to consider exterior insulation in conjunction with the re-roofing.

3. GBA Editor
   Martin Holladay | Jul 11, 2015 05:27am | #3

   David,
   You've been given good advice here. The answer is almost always to address the roof first.

   But if there is any chance that your roof plane will be insulated, do your research before replacing your roofing. If you finish installing new roofing before figuring your your insulation details, you can end up painting yourself into a corner. (Here at GBA, we get a question almost every week from a reader who has painted himself into a corner with a bad roofing decision.)

   For more information, see:

   Roofing and Siding Jobs Are Energy-Retrofit Opportunities

   How to Build an Insulated Cathedral Ceiling