Various methods of install by different roofers

Andy
11/8/2005
Hi, I just wanted to say that the messages posted here are quite helpful. I'm trying to learn as much as I can, but I'm really new to all of this. I currently have a tar and gravel roof and would like to have a standing seam metal roof installed. My roof currently has 2 pitches, the steeper side has a vaulted ceiling, thus no attic space. The other side has a lower pitch, about 2-3:12. My roof just started to leak and I quickly went up there and did some patch work. I have asked for quotes from 4 roofing companies/contractors. But they have varying methods of application, so costs. Method 1, remove old gravel off roof, inspect for wood rot, install fibre board, install roofing paper/vapour barrier, install standing seam roofs using nails. Method 2, keep existing roof, strap horizontally with 1"x4" wood, install #30 felt, install standing seam roof using screws. Method 3, keep existing roof, lay down sheets of styrofoam, install roofing paper, install standing seam roof using screws. 2 contracters are using this method. Are any of these methods of installs bad, that I should stay clear of? If so, please explain why? Thanks alot for your time.
Allan Reid
Dura-Loc Roofing Systems, Inc.
11/9/2005
Knowing your climatic area would help but here goes. Th building codes now call for ventilation on roofs 2/12 slope and greater. In the case of your vaulted ceiling, it means you must provide a minimumof 1" of vertical vented free air space. This is best provided by strapping the roof vertically with 1 1/2" lumber over the rafters and fasten down through into them. Then choose a roof system designed to go on horizontal battens. You should ask to see their product approval report that will show that the system has been tested and approved for wind, rain etc. It is an ideal time to then look to see if you have insulation needs as it is an ideal time to add more. One does need to be carefull when you add insulation over the existing flat roof membrane as it could trap moisture in the assembly. Rule of thumb is that you should have at least 40% of the combined new R value on the top. The code does outline certain limitations when recovering as to types and layers. Also one needs to assess the structure as to the weight of the new assembly. Certainly, the gravel should be scrapped off if you go over to remove weight. If you now have leaks, you may of had them for a while. Theses areas should be opened up yo check for rot. Remember you if you leave the roof in place it will be difficult for it to dry out. In summarry all three methods are ruled out as they do not allow for vertical vented air space. Make sure they put on a good quality underlayment down as well.
Andy
11/9/2005
Hi Allan, Thanks for your quick reply. I live in Canada on the west coast. Mild and wet for most of the year here. I didn't know about the 1" vertical vented free air space requirement, and I'm suprised none of the contractors mentioned that I would need this. I shall consider insulation needs as well as check for wood rot. You mentioned that I need to put on a good quality underlayment. In your opinion, what is a good underlayment? (sorry still too new to this). Thanks.
Allan Reid
Dura-Loc Roofing Systems, Inc.
11/10/2005
In Canada the code calls for 1 1/2" and is very advanced in this regard. As your area probablt does not require a building permit to replace the roofing, it is somewhat free range for the contractors.
Guest User
3/4/2007
I need a graphic of how to correctly overlap valley flashing. Should I lock the valleys together by cutting them both down the middle and locking them together? Should I cut away the excess and let them overlap? It would be easier if I saw a picture of some methods used. This is for standard shingle application.
Todd Miller
Isaiah Industries, Inc.
3/4/2007
I assume by "standard shingle" you are referring to asphalt / fiberglass shingles. I would suggest contacting the Asphalt Roofing Manufacturers Association.
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