Replies

1. 
   FredB | Oct 13, 2000 07:05pm | #1

   *
   How is this for a quick answer? The answer is yes and getting R30 isn't any problem. There are a couple ways to do it that I've used.

   You can do it either by a cold roof with soffit to peak venting in each rafter bay, or by a hot roof where you pay particular attention to maintaining a seal. Probably you are going to want to use a foam for the insulation. Construction sequence will depend on just what you want to see on the inside. If it is rustic T&G you would start there and build up. If is something like sheetrock you could do the whole thing and put the rock on last.

   This is general so you may have more questions?

1. 
   Mark_Herrera | Oct 14, 2000 02:18am | #2

   *If I understand you correctly, you will have an exposed ceiling. Rafters and the underside of roof covering exposed. Typically the insulating materials would be stuffed in each of these rafter bays. Since yours will be exposed, the insulating materials will be laid on the top portion of your roof in the form of rigid insulation panels. Once these rigid foam panels are laid in to place, they shall be covered yet again by another layer made of plywood, with screws long enough to penetrate both plywood and foam and attach to the framing below. At least that is my exposure to this situation. I understand spray foam could possibly be another option. I am not familiar with it's benefits or draw backs. I hope this helps.

1. 
   Jason | Oct 15, 2000 08:20pm | #3

   *Another method is to lay your ceiling lumber across your purlins or trusses (whether 1 or 2x), and then build up with foam insulation. Use 2x4's, with appropriately long fasteners through them to the purlins to create an airspace, and then lay your sheathing over the 2x4's. Shingle or whatever over this. We've done a couple timberframes this way, and it seems to work out pretty well. Post again for more details (e.g., rake, eave, or vent detail).

1. 
   S_Edwards | Oct 15, 2000 10:04pm | #4

   *Jane: Locate a log home manufacturer who has a log home on display. The type of roof you desire is common to log homes. Ask if they have an exammple available you can examine. Their three foot by three foot example piece will help you understand what the previous builders have written about.

1. 
   David_Myers | Oct 15, 2000 10:52pm | #5

   *I have a full attic space in my new home and wish to insulate it with R40, an I value required up her in northern ontario, Canada. Our code indicates that r20 is all that is nessisary for an exposed, be cathedral ceiling. why the miff,. And why can't anyone up here tell me why. Is it just so the insulation will fit? if someone in Canada reads this please tell me who I can contact, our local Building inspector does not know and I do not want to do anything unless I understand the variables. Thanks

2. 
   Phill_Giles | Oct 16, 2000 07:22am | #6

   *Because the dummies who wrote up the code figure that a cathedral ceiling should be treated as a wall and not a ceiling. They can dance lots of reasons, but they sort of stress the fact that the R40 in an attic is open at the top and probably doesn't effectively deliver R40 while a wall-like unit (enclosed on both sides and completely filled with insulation) delivers greater than it's required R20. Or you can believe my jaded friend who figures it would just be too much hassle to build an R40 cathedral, so the code reflects what everyone wants.

3. 
   Nick_Pitz | Oct 16, 2000 12:53pm | #7

   *The most straightforward solution would be to use structural insulated panels (SIP's). They can easily be had with R-32 urethane insulation, and blueboard on the inside and OSB on the outside, as well as other configurations.Try http://www.winterpanel.com

2. 
   Jane_Huesemann | Oct 16, 2000 12:53pm | #8

   *
   I am looking for advice or experience from people who have built rooms that have exposed trusses. What method is used to insulate the roof? Is there a way to get an R30?