extending patio roof

[Michael Flattery]

I want to remove the 2 center posts on a 21 ft span of patio roof. Rafters are 2x6 24"O.C. They tie into house roof rafters and extend out 8' with a 12" overhang. Support beam is now a double 2x8 sitting on 4x4 posts. If I make that a triple 2x8 beam can it span 21'? It has 7/16" decking with roll asphalt roofing.

 

[dcg9381]

If I make that a triple 2x8 beam can it span 21'? It has 7/16" decking with roll asphalt roofing.

Can you get a 2x8" that's 21' long? That'd be a triple. I think you're talking about bolting something together and extending the length.

I think you're well into LVL territory.

 

[Michael Flattery]

Correct. The existing 21 footer is a 16 ft plus a 5 ft glued and screwed to the same opposite it. I was hoping to add the same with a third.

 

[nadogail]

A 21 foot long clear (no knots) wain, checks or splits will not be found any where but a specialty supplier, probably a supplier of aircraft lumber or a marine yard.

I doubt if your ordinary sawmill would be able to fill the order.

 

[dcg9381]

Correct. The existing 21 footer is a 16 ft plus a 5 ft glued and screwed to the same opposite it. I was hoping to add the same with a third.

I don't think you're going to get engineering on that. Will it work? I dunno. I think LVLs are less expensive than you think and I wouldn't risk a roofline.