Adding insulation and new metal roof

Guest User
3/24/2008
I have a cabin built in 72. It has vaulted ceilings with less then R-19 insulation. Roof is shingled (4-12 pitch) We want to make the roof metal with hardware hidden and add insulation after we remove the current shingles. We are in a heavy snow area with very cold temps. Any suggestions on adding insulation to current plywood roof and then metal roof?
Todd Miller
Isaiah Industries, Inc.
3/26/2008
You will wnat to add insulation but also a vented airspace on top of that ... followed by decking underlayment and roofing in my opinion. You may want to look at vented structural insulated panels as one option.
David Moore
6/5/2008
We also have a similar issue yet we live in Austin Texas. Our composite shingle roof was destroyed in a hailstorm several weeks back. We have always intended to upgrade to a standing seam metal roof. The house was built in 1970, 5-12 pitch, vaulted ceiling, no attic, joists 2x10 on south side and 2x12 on long north side with 1-1/2" holes 8" apart on internal facia board and then joists continue to outer facia where roof overhangs perimeter walls 3 to 6'. Simple roof with no hips or valleys, just one ridge with skylight and (2) chimneys along with normal plumbing penetrations. I can't see any type of ridge vent or eave vent at either end of house. I'd like to add a thermal insulation on top of the existing deck and then a standing seam metal roof on top of that and maybe an air gap between the metal roof and thermal board insulation with a ridge vent. I have had trouble finding someone that understands the system that I think we need as the roof has very poor insulating qualities now. I'm an Architectural Engineer that is out of practice now 20 years as I'm in the vintage car business now. However, I sure would love to get some help getting back up to speed. Can you point me in the right direction for construction details of a system of this type?? Need help.
Todd Miller
Isaiah Industries, Inc.
6/11/2008
Your plan sounds pretty good. What I would suggest, though, is that you find a metal panel you like and then work with the manufacturer to finalize the details and help you locate an experienced installer.
Guest User
7/5/2010
I have a log cabin kit house. It also has vaulted ceilings with 2x6 tongue and groove with cellutex and shingles. I get a fine dust sifting through the 2x6s (the house shifts as it warms and cools each day and the boards move around). When I saw your posts about a felt underlayment, I was assuming that would go right over the roof deck and would help to keep the bits of synthetic insulation from also grinding and then sifting in. I was surprised to realize that it goes right under the metal roof. Do you have any suggestions of what could go over the 2x6s and under the insulation that would help keep it from dusting into the house? Would SIPs be better for this situation? (I do plan on using foam insulation in some form and a metal roof over all this. and live at 2,600' in the Sierra foothills.)
Eric Novotny
An informed customer is the Best Customer!
7/7/2010
You can put another layer of underlayment under the foam if you so choose and if you think it will stop the dusting. I doubt that you will get much dusting from the foam as it is very dimensional stable at temperatures. There will be no way to control the dusting as a result of the wood moving against itself. That being said, wood only moves with moisture content and not temperature. If you stabilize the temperature against the roof deck, that will likely assist with the moisture stabilization and hopefully the movement.
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