Suspended Slab Bearing On Existing Masonry Wall With Lintel?

[Redacted]

Hi there, I was recently tasked with doing the structural design for a new laboratory. One portion of this design is a very small storage room extension as shown in the attached images. The room is only about 4x7’ with a concrete slab as the roof. The client wants to utilise the existing walls of the building to support the suspended slab.

My main concern with this is that there is a lintel above a 3’ opening that will need to carry the additional weight of the 4x7’ slab (although this is a low load). I am not sure of the condition of the lintel, so I did put a note in the drawing that it be inspected and replaced at the discretion of the engineer prior to pouring the slab.

I was thinking that as an alternative, I could just have the slab spanning one way (longer span), to remove the need to bear onto the wall above the lintel but would deflections for a 7’ span be an issue? I could always stiffen that side with an L beam if required.

I am interested in utilizing the simplest construction approach, can you provide any advice?

 

[r13]

I wouldn't worry about the lintel. You have a two way slab supported on 3 sides, stiffen the lintel side with a few additional bars should do.

 

[KootK]

I also wouldn't worry about the lintel:

1) with 16" of wall/header left over a 36" opening, the header will just arch over it.

2) most would consider it valid to allow the slab to be the lintel as you've suggested. Obviously, it creates a bit of a stiffness incompatibility issue if the stiff opening header would have to deflect meaningfully in order to let thee slab-beam engage as proposed.