Covering over old roof without checking for damage?

Guest User
1/4/2010
One metal roofing company says that they would install stone-coated steel shingles over the existing 3 (yes, 3) layers of asphalt shingles after putting on 2 x 2 battens, and that despite the fact that about 30 square feet of roof has loose or missing shingles and looks like it's sagging (there are also leaks at various flashings), there is no need to remove the shingles to see whether the wood decking is damaged and needs replacing. The guy said, "Your rafters are fine." How can he know that? Or does he? Even if the rafters aren't damaged, is it a good idea to simply cover over any damaged decking? (We also have possible damage from having no ridge venting, no soffits and therefore no soffit venting, and fiberglass insulation crammed in under the decking without any baffles.) How fast and how far should I run in the other direction, if at all?
Todd Miller
Classic Products, Inc.
1/4/2010
First of all, a fourth layer of roofing probably is in violation of building codes in your area. Next, if the roof has bad dips in it, please be aware those will still be apparent after the new roof is installed. Going over old roofs is not unusual but in this case I certainly would not do it without a good attic inspection. I would also ask him how he is going to mark the rafters and make sure his battens are fastened into them.
Guest User
1/9/2010
Thank you.
Guest User
1/9/2010
The same company that says that it isn't necessary to remove the 3 layers of asphalt shingles has now sent me a description of what they propose to do (for $18,000) if they install a stone-coated steel roof with Steelrock Pacific Tiles. The proposal reads: 1. Cut back the edge along the entire roof. 2. Install a ice and water barrior at edge 3. Install a 30lb felt over entire roof 4. Put 1x4 battons from bottom of roof to top on every 24 inches 5. Install 2x2 counterbattons across roof from facia to ridge at 14 1/2 on center( reinforceing the entire home) 6. Install 1 inch ridged foam inbetween all 2x2 (7 channels will be left open to vent from Facia edge to ridge.) 7. Install facia metal with grill inserts for air intake 8. Install all new metal valleys,flashings and trim ass. 9. Lay all roofing panels screw as per manufactures spec. 10. Leave air venting at ridge ( under barrel trim) 11. Finish all trim and compleat To recap: As I've explained before, we have no soffit venting (because there are no soffits). We have no ridge venting as far as I know (when the proposal says "leave air venting at ridge", I think they must mean they would install it). We have 6 inches worth of fiberglass batt insulation crammed into the five and a half inch deep spaces between the 2x6 rafters, under the decking. And the upstairs has cathedral ceilings, already finished with sheetrock. What I understand: I understand a vented roof (with both soffit venting and ridge venting). And I understand an unvented roof (with no venting, and with closed-cell foam either added as a layer on top of the decking, or sprayed onto the underside of the decking from inside). What I don't understand: I don't understand this company's proposing to use rigid foam in some places and nothing in other areas, supposedly to allow ventilation (after adding in venting in the fascia boards and at the ridge). Maybe since we have fiberglass insulation we probably don't want to remove (because of the sheetrock), this is some kind of hybrid between vented and unvented? But I don't get how it's supposed to work. How would getting air flow going in the seven air channels help with the rest of the roof? And doesn't leaving these air channels empty ruin the whole idea of adding the rigid foam insulation? I thought the purpose of adding the rigid foam was to keep warm moist air from the inside of the house from coming into contact with any cold surface)? Am I missing something here?
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