recovering tar and gravel with metal

Pierre Seguin
7/6/2011
Hi Guys I've been reading multiple FAQ ,going to different web sites and I'm still shy of bits of info . Maybe I can get the whole deal here , so here goes . I presently have a low pitch roof 1:75 / 12 ( 7" over 4' ) tar and gravel roof , cathedral ceiling , so no attic to speak of , and a low R-20 (at best ) in the joists space . The plan is to remove all gravel , inspect and patch any/all repair necessary , then use 1x4 strapping either east to west at 16" intervals or north- south on each joist , which I can see by removing the soffit . Then I plan on using 1" x4x8 styrofoam to cover the whole roof ( for sound insulation from the rain (for lack of attic and insulation) and heat penatration from the sun coming in through the roof , so my A/C will not work overtime for nothing ) and this should give me a 3/4 " gap between the tar and styrofoam , then re-sheet the whole thing with 1/2" plywood , seal the seams with Blueskin then cover the whole thing with metal roofing that is good enough for 2/12 roofing . I also would like to install a ridge vent , in the center that would expand 20' ( the remaining 25 ' is split between the living room and a carport ) . By strapping on the joist I can easally leave the 16" open for some ventallation and putting a facia to cover the ends of strapping leaving a 1/2 " gap at the back . I'm I on the right track or way off base Thank you for any info
Todd Miller
Isaiah Industries, Inc.
7/6/2011
Assuming you have some intake vents this sounds like a very well thought out plan. Good job! I would suggest a metal roof with a reflective finish for added efficiency.
Pierre Seguin
7/6/2011
Thank you very much . the intake ventallation would be at the lower part of the roof right behind the new facia which would stick out 1/2 inch away from the old facia and wrap itself on top of the strapping , and venting every 14" with the strapping going up to the vent cap . you could see the opening if you stood directly under it .one more thing , would any styrofoam do or would some type melt with the heat
Todd Miller
Isaiah Industries, Inc.
7/6/2011
Ultimately I think you want to pick up as much R value as possible. I do not think you would have an issue with styrofoam (EPS) melting but I would suggest polyurethane insulation for greater R value.
Eric Novotny
An informed customer is the Best Customer!
7/7/2011
+1 on using poly in lieu of EPS. Also, I would recommend some screening on the soffit and ridge vent to prevent the infestation of any critters of bugs. As a final recommendation, why not put some more insulation up there? R-20 in Canada is wholly inadequate and you will never get another chance to add more. Spend the extra bucks and put more up there. You can put a layer down and bolt your 2x4s straight through it and then put another layer in between the 2x4s to maintain your 3/4" vent space.

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