CMU wall to Wood Wall Connection

[omoreno80]

Hi all. I am working with a contractor on removing an existing CMU wall on a house built in the 50's. The roof is a rafter system supported along the building perimeter. The ceiling joist are supported along the perimeter and at an interior CMU bearing wall. The ceiling joist are lapped to resist thrust forces. From the my inspection it looks as if the perimeter tie-beam goes towards the inside of the house about 7'. The owner described the area as an enclosed sunroom. The rafters are supported at the edge of this area. The contractor is proposing to remove this wall entirely and replace with a wood beam and post systems. I have some concerns over maintaining the structural integrity of building by cutting off a tie beam, but I do not see a problem with using my new header as a tension chord strapped into the remaining bond beams perpendicular to this new header. Does anyone have any options to this system? The client wants to stick to wood. Thank you

 

[omoreno80]

I have added a sketch.

 

[dik]

A section through the wall would provide more useful information. How is the ceiling/roof/floor above framed? why is the wall bearing? What sort of load is it taking? Do you want to replace the wall from ceiling to floor?

Dik

 

[omoreno80]

The roof rafters span from side wall to ridge. The ceiling rafters span from sidewall to sidewall and are lapped over the interior wall location, bearing over the interior masonry wall. The wall only takes the ceiling joist dead load and a 10 psf attic live load. The wall will be replaced from floor to ceiling, but the concern is the continuity of the tie-beam. the entire wall and tie beam is proposed to be removed. The new beam will provide support for the ceiling joists at the lapping ends supported by posts on either end. The header will be strapped strap to the bond beams perpendicular to it. I had another contractor who says there are familiar with houses constructed in the 50's and indicated his concern. At this point I agree with the original contractor, but I want to make sure I am not missing anything. I can upload a sketch if this does not clarify my question. Thanks

 

[msquared48]

If you are worried about the continuity of the collar ties, make the beam upset into the attic space, hang the ceiling joists from the beam and install metal straps across the bottom of the ceiling joists at the bottom of the beam. Continuity maintained.

Mike McCann
MMC Engineering

 

[dik]

Is the tie beam you refer to a bond beam within the masonry wall? From your comments, it appears that the masonry wall has no purpose other than supporting the ceiling rafters. If this is the case it would appear that this is a simple matter of providing a new support for the ceiling rafters and removing the masonry wall.

Dik

 

[omoreno80]

Yes, the tie beam at the top of the masonry wall...it frames into to perpendicular masonry walls at either end, which then are perpendicular to the exterior walls. Yes, I agree that it solely supports the ceiling rafters, contractor is concerned with maintained wall continuity, but I just don't see how it applies, if it were an exterior wall I would agree about maintaining a tension chord continuity, but on a wall 7' inward I don't see it.

The collar tie continuity is not affected.

 

[dik]

If there is a concern about lateral stability of the remaining walls, a couple of feet of the interior wall can be left in place and grouted to provide the lateral restraint. These stub walls can be used as a bearing for a beam between them to support the ceiling rafters and the area can be 'clear spanned' with no intermediate wall.

Dik