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Flat roof engineer needed

user-6610113 | Posted in General Questions on

I’m remodeling a 100 year old home with flat roofs/parapet walls.  The house is in the shape of an ‘H’ with a second story covering part of the central area.  The pitch is less than 1/8″ per foot.  The roof has sections that are uniformly slanted in one direction and others where there are complex curves.  Roof needs to be replaced but every roofing contractor I bring to the job is recommending something different.  I would like to work with a roofing engineer who can make recommendations on increasing the pitch based on the roof topography.  My architect and structural engineer don’t have any ideas.  Any recommendations of someone who would fit that bill?  I’m in the Los Angeles area but should be able to work distance on this. 

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  1. GBA Editor
    Martin Holladay | | #1

    You wrote, "My architect and structural engineer don’t have any ideas." Really? That's very surprising. If you are paying an architect and a structural engineer, you need to sit them both down and ask for advice. If these professionals are in over their heads, they should at least be able to refer you to a colleague -- or, better yet, to consult a colleague on your behalf -- so they can suggest a solution.

    Remember, your architect and engineer are working for you. That's why you're paying them.

  2. Peter Yost | | #2

    HI Matt -

    Can you say more about the different recommendations of the roofing contractors you have asked about your roof? I think we can give better/more specific guidance if we know just what the differences/the issues are (besides the slope of 1/8-inch per foot)?

  3. Jon_Lawrence | | #3


    I think what you are looking for is a flat roof designer. Assuming you are not planning on changing the framing of the roof, your Architect does not need to be involved beyond specifying the insulation, wind lift and pitch requirements. Your structural engineer should be able to confirm whether the existing design is adequate to handle the expected roof loads. If you plan on adding a rooftop patio or green roof, then the existing structure may need to be reinforced. Your roofing contractor can then provide the roofing supply house with the roof dimensions and insulation requirements and they will provide a design plan comprised of layers of polyiso boards of various thickness and pitch. The choice of adding a cover board and what type of membrane can be decided between you and your contractor and will be dictated by what you plan on putting on the roof. If it just a roof that will not have solar, garden, patio, etc., than you can usually skip the cover board and go with an EPDM membrane. If the roof will have solar or other things, then you may want to include a cover board and a PVC or TPO membrane. Your roofing contractor will know better than your architect or engineer what to specify based on the expected use of the roof.

  4. seabornman | | #4

    A search for "Los Angeles roofing consultant" gives lots of hits. Call around until you find someone who does your kind of work. Not all architects are flat roof experts, especially for renovations such as yours.

  5. jhonnyToretto | | #5

    I recently did some repairs to the flat roof of my house myself. Installing a flat roof - is a fairly simple and safe process, so you can handle it yourself. First, the roofing includes far fewer elements than in the case of a pitched roof and, therefore, easily assembled. And secondly, the builder, during the roof installation, is on a flat surface, not on a sloping surface. If you're looking for a good roofing engineer, look to local artisans or an Indianapolis roof contractor. Only an experienced person can find the answer to your question.

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