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Community and Q&A

New roof cost? Upgrading from a low slope to a steep slope

crosis38 | Posted in GBA Pro Help on

I live in Ontario Canada. Im considering all my options to improve my old home’s attic space. You see, we get lots of ice damming each winter. The existing roof has a 3/12 pitch along with an 8/12 cathedral. Im wondering if it is cheaper to have a contractor build a new steeper pitch roof over my existing (or remove the existing for the steeper one).

For my existing roofing I’ve contacted local contractors. They said they’ll remove the existing barn board decking, suck out all the old cellulose to expose the attic floor and attempt to air seal (who know’s if they’ll do it well), open all soffits and add baffles, then install new OSB decking then shingle the decks. They would do all this to the troubled region (800 sqft). Price: $23,000 to $32,000 CAD. To be fair they would be adding new OSB and shingles to the rest of the home too for that price but not the same extensive attic work elsewhere since ice damming is only occurring at the low slope and cathedral regions.

What is the pricing to have a steeper roof installed + shingled? I would do this only over the troubled low slope and cathedral regions? This would make it possible to now have walk in access to the attic for me to insulate and vent how i choose.


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  1. crosis38 | | #1

    UPDATE: For the record, a detailed overview of my existing low slope roof and its problems can be read here:

  2. GBA Editor
    Martin Holladay | | #2

    If you want to reframe your roof at a steeper pitch, and install new roofing, you may need the help of an architect or designer.

    If you are capable of making architectural drawings, you can do that part of the work yourself.

    The next step is to share the drawings, the scope of work, and the specifications with three local contractors, and to wait for their bids.

    All construction prices are intensely local, so GBA readers aren't going to be able to guess on the cost of your project.

  3. AlanB4 | | #3

    I would not do this to fix an ice damming problem, Martin is correct in the other thread, no ice dam problem is unsolvable.
    If the OP is not feeling the solutions perhaps its time to contact an appropriate expert from CRESNET or BPI Canada?

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