Opening in a block wall for addition

[mr richard]

1st post, great Forum!
Want to cut a 7'-6" wide opening in a 8' high block basement wall.Wall is load bearing 8" block hollow,with exterior brick veiner.This supports one floor above, 2"x4" wall and 4/12 pitch roof, Ranch House design.

The plan is temporarily support the roof and floor.Remove the brick and block 8' wide.All brick above the basement will be removed also.Cut back floor joist to make room for new header. Install a header made up of 5 2"x10"x 10'long (can go longer if needed), which would leave 12" per side to rest on the block wall.Existing floor joist would tie back in to new header/rim joist with joist hangers.The question is should I make the opening wider and add additional trimmers like for a garage opening or would the hollow block wall be enough support for the header ? Would two trimmers per side be ok?

[Don_P]

There's not enough information to make an informed decision and not real sure I'd want to make a guess. You'll be dropping some pretty substantial point loads to the footings that would need to be considered. Most girders are 3 ply or less, not much joist load will make it to the 5th ply although wall and roof load will. I'd call an engineer.

[Studio43]

Richard
Sounds like a good plan. It's difficult to get a structural header requirement without knowing the loads it is carrying. To size the header, at the very least, one would need to know the area of the floor and roof that is being carried by that member. As well as, the material load or "Dead Load and the design allowable "Live Load" which includes snow loads. You could provide more info and it would be helpful. Please note, for good reason, most professionals on this forum or any forum will be reluctant and more than likely not to give specific sizing or to design a structural component without alot more information. Unfortunately, your situation like most would be best served for the professional to make site visit to witness the conditions for themselves.

One issue I have with your plan. The header can be put in place the way you suggest. But, You would like to side load, which means, attaching the floor joist with hangers to a built-up header. Side loading is fine . But, the the built-up memeber is not something I would suggest. Just too many laminations. To side load a header you should use a single piece header. A double lamination should be the max. Due to that fact, you should consider either engineered lumber and a Steel wide flange beam. I prefer steel on block anyway. An Untreated wood header in contact with masonry is not something I would suggest.