NEED HELP ASAP RE GAMBREL ROOF INSULATION

**RockEngineer** · 08-13-2005, 07:00 AM

You can't go wrong ventilating the insulation space but if you leave an air gap you need to make sure there is an air flow (eve vents and ridge vent). Air gap with no air flow can be a problem from the information I have read.

I don't claim to be an expert on all areas of home building. I'm just an engineer who likes to make sure log homes stand up and it pays better than flipping burgers at McDonalds. I have done a little research and tried to apply common sense. There are definitely strong and differing opinions when it comes to insulation and ventilation. You will have to make the decision in the end based on the information you have been given. Either way you go now you at least have some warnings of what to do and what not to do. If you take those warnings you should have no problems either way. It sounds like a cop out but it isn't. Both ways work if you take the proper precautions for each method.

Good Luck. Enjoy Life. Don't be a workaholic like me.

**Lolo-Steve** · 08-13-2005, 06:54 PM

you could use this product made by owens corning

it's called Raft-R-Mate®** attic rafter vents

The site located at http://www.owenscorning.com/around/v...mate_attic.asp

**starrlady5** · 08-13-2005, 07:18 PM

Thanks, Rock. I think I'll stick with the solid foam, no air space, as you suggested. I specifically asked the bldg center owner if any special venting was needed and he said no. We worked all day today doing wall insulation. I checked the roof out well from outside inside lower floor, and upper loft. I just don't see a good air flow the way it is without adding a lot of venting. I think I'd be asking for problems. There is a LOT of Gambrel ceiling coverage. I really do NOT want to put it up, only to tear it down to tackle a mold problem. (Actually had this experience before. It wasn't pretty.) Thank you SO much! D We'll probably be tackling the roof insulin this next weekend. If you have any other tidbit suggestions, let me know before then! ) I'll let you know how it goes. Made a LOT of progress just last night and today. It's so exciting. Going to be a very cozy little place! ) Thank you, again, endless thanks! Really, really, really!

**spin05** · 08-15-2005, 03:33 AM

I used RMAX poly-iso sheets in my home.They are 2 1/2 in thick.That gets you a R15.30. I just doubled it up for a total of 5in. thick to meet my R30 reQ. here in washington state. Atlas roofing is another brand

**starrlady5** · 08-15-2005, 03:40 AM

Thank you. What type of ceiling do you have? Open, cathetral, Gambrel style, etc? With air space and venting, or filled all solid airspace and cracks as Rock suggested? How long have you had it this way? Are you really happy with it, no problems? Thanks for the brand names. Our building center owner is supposed to be calling this morning for prices for me. Thanks! D

**starrlady5** · 08-17-2005, 10:05 AM

Hey Rock,
Haven't received the foam insulation board yet. Read up on the foil type insulation while waiting (Insulation 4 Less web site).

Question on possibility...
On the waferboard roof decking (tin roof, tar paper, then waferboard decking), on underside interior ceiling area could we do something like VAPOR BARRIOR PAINT TO SEAL THE WOOD, THEN FOIL INSULATION (HIGH R (FFMF) FOIL FOAM FOIL - INSTALLING IT FLAT AGAINST THE ROOF DECKING TO SEAL. THEN add 5" solid foamboard FLAT up against the foil to fill the air space, then seal all cracks? Or do you think this work better than if we used only the foamboard by itself?

I keep reading while there is still time. I found a couple other internet posts from people with similar situations.

EMAILED INSULATION 4 LESS with basically this same question to see what they would say. See their responses below

THEIRS
Yes apply per your fist method Apply Prodex High R underside of interior ceiling VAPOR BARRIOR PAINT TO SEAL IT, THEN FOIL INSULATION (HIGH R (FFMF) FOIL FOAM FOIL. Make sure you have ¾??? or more air-space for optimal performance. Tape seams with metal tape. For additional install ideas click http//www.insulation4less.com/install_methods.asp and http//www.insulation4less.com/quick_installation.asp and http//www.insulation4less.com/installation.asp.
Staff
www.insulation4less.com

MY FOLLOWUP REPLY
Thank you for the quick reply. I need it as I need to get some of this ordered asap IF it will work. HOWEVER, please make sure you have read carefully and understand before selling me anything.

I did read your website (including all of the links you sent me) prior to emailing you. My BIG question and dilemma is I will NOT have VENTED air space. There are no eave vents. And if the interior ceiling is done this way there is room to leave air space, but it will be DEAD AIR SPACE. Plus you are saying to use this foil as a stand alone and DO NOT add the solid foamboard below it? I am in Montana right up by the Canadian border and our ceiling R-values are usually in the 30's.

If you do not know the specifics of this, PLEASE be sure to forward it to someone who does. I really want to do this correctly PRIOR to the ceiling being all closed up! ) ) ) It will have a finished ceiling over it.

THEIRS
Not able to give more specifics. We aren???t installers. All the advice we have is posted on website. If you don???t see it on the web, than we don???t know it. We would never state to not use additional insulation. That will always be a personal call. If it???s a residence we would suggest you contact your code official or local contractor.
Staff
www.insulation4less.com

**RockEngineer** · 08-17-2005, 05:09 PM

I don't know anything about the foil beariers. I know a couple people who have used them but I haven't heard good or bad. The manufacturer's data and the salemens statements are good but I tend to be a skeptic when it comes to salesmen.

I have shared with you all my limited knowledge on roofing and insulation. Any information I might share beyond this point would be pure conjecture. Sorry I'm not much more help. I know it is frustrating.

I don't think the foil can hurt your situation but that is just a wild guess. In Engineering terms it is a WAG (Wild Ass Guess) not even a SWAG (Scientific Wild Ass Guess).

Good Luck.

**rreidnauer** · 08-17-2005, 05:12 PM

Is it really possible for this Prodex insulation to really have an R-value of 14.5 per 1/4 inch layer? That sounds ridiculously high for the thickness. Maybe it could be for radiant energy, but seems hard to believe it could insulate thermal transfer.

Thoughts?

**ets80** · 01-01-2013, 11:49 AM

2 x 6 rafter spaces are clearly not sufficient amount of space for the adequet amount of insulation needed for your area. But theres nothing much you can do now that the metal roofing is installed. You need to have the roofing people come back and install a vented ridge cap to help or at least make an attempt to move some air out of the confined 2 x 6 spaces.