enter image description hereI am adding a covered deck and attaching to my house. I want to attach it like the project about which funtastic asked this forum May 20 '14 at 6:47 and was given a response to his question by shirlock homes a few hours later.

My question is: How are the beams that support the rafters supported at the house? I have seen house roof decking, soffit, and fascia removed to expose the top of the exterior wall. This seems dependent on needing proper studs in the wall to support the beams and in the above mentioned access method I have never seen the side wall opened to accommodate this.

If the beams are supported by support posts from the ground and then the roof tied in like funtastic's it appears that this may lead to deck roof movement independent of the house roof which it would seem to lead to shingle interlacing failure.

Sorry if I am too long winded but I have tried to think this through and be confident in the outcome. Thank you for your expertise

  • 2
    It would help to add some pictures of your own. As it is, we can't really see what you have to work with and that makes it difficult to answer.
    – gnicko
    Nov 23, 2021 at 1:15

3 Answers 3


In general, such beams are let into the existing structure's wall and supported by studs or an adequately-sized header (as over the window in the example above). Rarely are they supported only by posts outside the wall at that location.

They could also be supported by suitable building hardware fastened properly to the existing wall. This would only work if there's adequate framing in the wall already. If there's not, taking the former approach is often just as convenient since the wall needs to be opened anyway.

If all else is out of the question, a post outside, set off the existing wall slightly, could be used. Rather than putting it tight against the wall, creating potential moisture issues, you may give the beam a slight cantilever of a few inches. Any such posts must be supported by full frost footings to prevent movement that would be detrimental to the adjacent structure.

Details matter. You'll have to provide a good description and/or photos of your situation for more specific help.

  • +1 for describing how the beam is typically connected to the house. I would just add that the top of the new beams should match the top of the wall (top of top plate) and the new roof should have the same pitch as the existing roof in order for the addition to match. Also, they should calculate the new roof load on the footing to make sure it can support the new load.
    – Lee Sam
    Dec 24, 2021 at 16:46

You have to tie the deck roof to the existing building framing. In the picture below, the red lines are the existing joists and studs; the yellow lines are either new additions (joists/studs/lintels in locations that do not have those supporting elements) or strengthening/modification of the existing structures.

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Similar to:

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  • 1
    Note, the addition will add some loads on the house, however, you've reduced some loading area as well, which essentially offsets the impact to the extent that you might not need an engineer calculation to validate the work, but you would still require a permit from the local building official. I would hire a reputable builder to handle this modification. Good luck.
    – r13
    Dec 25, 2021 at 21:57

The problem I see with what's you've sketched is that load of approximately 1/4 of the added roof is going to be carried by the existing roof rafters, unless you make some structural changes there. This may,or may not be acceptable.

You can avoid this if you use a scissor truss of some sort for the deck roof. With a truss like that, you do not need a ridge beam/board on the deck roof, and the load of the new roof is carried by the beams coming out from the house. Of course, they have to be sized appropriately.

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