Creating an Alcove from part of a cavity wall

[fantom]

I this this is my first thread on here, so Hi all

Im planning an extension to my home which may consist of a 2 story addition to the side of my current home.

Where my current outside wall would become the inside wall of the new lounge I was thinking I could install a concrete lintel and remove the external 4" block and cavity insulation to give me a shallow alcove perhaps 2.5m wide.

Then I wondered if this would be structurally ok, any thoughts?

 

[ree]

If lintelled over, it should be structurally OK - the only reservation would be how wide is the knock thro doorway to the new extn?

Presuming cavity trays are installed at the roofline?

Essentially, you are cutting a new doorway but stopping half way thro.

 

[fantom]

If lintelled over, it should be structurally OK - the only reservation would be how wide is the knock thro doorway to the new extn?

Presuming cavity trays are installed at the roofline?

Essentially, you are cutting a new doorway but stopping half way thro.

the door knockthrough would be in a different location as the room would be around 5m long with the alcove in the middle and the door at the side (750mm door?)

Not sure on Cavity trays, can you please explain? I dont think it will matter as Im joining into roof level and will be the length of the house.

 

[ree]

Sorry, i was wrong, i missed the two story bit. You are correct to be puzzled. No cav trays are necessary.

You seem good to go but do make sure that the bearing ends of the two internal skin lintels have their own space for end seating - or maybe use a single internal wall lintel across both openings if it makes things easier. This has to be a site call.
BCO must advise.