Balcony extension - cantilever


Old 09-03-18, 06:24 AM
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Balcony extension - cantilever

We would like to extend a recessed 4 x 20 balcony on the front of our second story. By adding 2-3 in width the balcony would become a much more usable space.

Right now the decking is wood over a waterproof base. My understanding is that we would have to open this up and sister 2x10s along the 4ft span, cantilevering up to 2 ft. The roof over hangs 3 ft, so ideally we would be able to max out to the over hang. Id assume this would be possible if we can get the 2x10s into the house another 2-3ft to provide more stability for the cantilever.

Anyone have any experience with or ideas for this scenario?

I have also considered having a steel frame fabricated and have that simply secured ontop of the existing waterproofing. I have little experience designing with metal and would not have a clue how make this strong enough and how best to anchor it to the house. I have done some welding over the years and would love to do this myself if someone could provide specs on what would be needed? Any thoughts on this is really appreciated. Tks
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Old 09-03-18, 06:54 AM
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One thread, one forum please. What you are asking is not practical for this forum to answer. What you propose would need a structural engineers approval and falls outside the realm of diy due to the safety factor. Fasteners alone will not be allowed to support a cantilever, so that idea is not practical right from the start. To give you an idea on why WOOD cantilevers work, 3x the span is within the house, sistered to existing floor joists, while 1/4 of the joist length is the actual cantilever.

With little to no information about your wood structure and no photos of the framing it's impossible for us to give any suggestions. If you could include that we might be able to make a suggestion.
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