Hello all,
I’m getting ready to reroof a building that I recently converted into a duplex. It used to be a Masonic Lodge/church. The existing ceiling/roof deck is 2 1/2″ cedar T&G. On top of that is 3/4″ fiber board. I’ve seen it called celotex sheathing also, I think.
Two layers of shingles on now…I’m assuming that when we tearoff, most if not all of the fiber board will be damaged. We’ll see how it goes at first, but we’ll make a good effort to save it.
I’d planned on trying to get some insulation on top of the roof deck and covering with osb. It cost me $190 to keep the upper apartment at 54 degrees last month (2200 sq. ft). Although the heat is not my responsibility when rented, I liike to keep that cost down for future tenants. How much foam would you put on to make this worth doing?
Do you see any need for nailers between these sheets of insulation? I was going to tack the foam in place and secure with screws through the osb, foam, fiber board, and into the roof deck. Around the perimeter I would run a nailer for fascia installation, etc. Sound good?
Repair/Replace the fiber board, call it good?
SW Michigan
Thanks,
Jim
Replies
There are SIP (structural insulating panel) systems that are specifically designed for this application.
The panels are designed with nailers on one side... insulating foam... and even include ventilation mechanisms.
Personally. I have never installed these things... but I have had several rather trusted persons recommend them to me. From a logical perspective... they make sense. From an ease of use perspective... looks like putting together a jig-saw puzzle.
The only major issue I see is with my innate desire to put a deck over these panels... but I have not yet contacted any of the manufacturers to see what the options are.
edit... HARK... here is a current thread about this very product! http://forums.prospero.com/n/mb/message.asp?webtag=tp-breaktime&msg=54012.1
Edited 2/11/2005 11:28 pm ET by Rich from Columbus
I've considered them but the cost is too high for me. Great product from what I hear though.
Jim
just a bump
hey
Jim,
I think the question is really one of how thick a layer of insulation you want to pay for.
I assume we are talking about styrofoam and then a layer of decking on top of it. Off the top of my head, styrofoam has an r-value of about 5 per inch.
Off the top of my head, where I live in Indiana attic insulation is usually expected to be R-19.
So by those numbers, you need four inches. Now the screws are expensive!!
I would do two inches at a minimum.
For the record, I've done some roofing, but I have no experience with what you are doing.
I wonder at what point of thickness you start running into issues of too much distance between the 2 1/2" cedar T&G and the roof sheathing.
Rich Beckman
Another day, another tool.