Steels onto return brick for new opening?

[cdbe]

If it's running through flush there is no return, the spreader (in my case) just spans the new/old join.

If you're "attached", it's difficult to avoid a return unless your new external wall is literally on the boundary:

 

[baker332]

Thanks CDBE, appreciate the pictures and drawing.

The issue I have is that the external walls are up, onto/attached to the external that I'd like to knock through, this would leave me with the cavity.

Therefore the spreader assuming cannot span over the cavity without building up a brick pier (could be wrong?) - Or can one steel rest on the internal wall, and the second steel rest on the brick return of the external wall?

Or second option, have a single beam with overhang, resting on the internal wall with it being more supportive than the return wall (this is just an idea).

This is what I have today, from a quick drawing:

Yellow being the extension walls.

If the brick pier needs building up between that cavity, does it need to be 'toothed' into the brick work to make it structurally sound, or can it simply be built block by block to fill the void effectively?

 

[baker332]

In your drawing CDBE, what does PW reference/stand for?

 

[baker332]

Think I may understand further - using the spreader onto the return and the newly built extension wall, the question then begs what to do with the cavity, fill the void as per tony's diagram (toothing bricks in/or block by block) or simply use a cavity closure.

 

[tony1851]

@op, I suspect you are over-thinking this.

You need to maintain the cavity - ideally the outer skin should have been bonded to the existing brickwork rather than using strips.

Internally you will get a gap where the cavity is, but you need to get rid of this by bonding the new inner skin to the existing inner skin. The ultimate aim should be to carry the two skins on uninterrupted.

The spreader padstone straddles tthe old and new work and further helps to bind old and new together.

 

[cdbe]

PW= party wall (between you and neighbour if you have one).

What you have at the moment is a path for damp to cross into the building and a thermal bridge for heat to escape - but it seems to quite common to do that, close the cavity with a closer and get away with it. Whether there is an issue with the stability of the end of the inner skin is a question for the SE, but the cavity could be closed with bonded masonry to mediate this - but you're still left with the bridged cavity - but then I suspect so are many other extensions round the country - chopping load of bricks out is hard work!

 

[baker332]

Tony thanks for taking your time to draw up and post the diagram it makes sense really appreciated.

CDBE, thanks for also explaining and the PW explanation. I will ask the builder then to cut out the return, as I'd prefer not to have a bridged cavity,

Thanks all, finally got to the bottom of this!