Best walkway / threshold support

[Dodgyrog]

Hi,

Tidying up this walkthrough in to my new extension, new floating floor will be raised up to be level with existing floorboards.

I'm probably over thinking it but it will be a main walkway so do not want issues or it start squeaking.

Void beneath as there was an airbrick there - telescop vents now installed behind where I'm standing.

so I'm thinking either :

Treated timber or concrete lintels on to the (repaired) DPC on both inner and outer walls.
or
Just one timber / lintel on outer wall (nearest in photo) and screw some treated joist stubs to the side of those 3 existing ones and ones at either side to then extend out to sit on the timber / lintel.

Any advice which is best?

...and yes I think the rad could eventually do with moving

 

[RonnyRaygun]

Take the wall down to level with beam and block floor, then DPM and insulation??

 

[Dodgyrog]

Take the wall down to level with beam and block floor, then DPM and insulation??

Yep there will be the DPM and insulation going on to the block and beam and maybe flowing it in to that area would be an option - but I need some kind of decent support bridging that central void which needs to be left to allow the airflow underneath. Would insulation not buckle under any weight?.... or maybe I'm misunderstanding.

Also the current brick levels do actually suit dropping some standard size lintels straight in - a bit of cost yeah but not much compared to the faff off taking out bricks to then build up part way - due to the way they are all laid.

 

[RonnyRaygun]

Oh yeah, you could use some air bricks to fill the void but if you can fit a couple of lintels over the top and get the levels right then it should work fine.
You could fill the cavity with a bit of concrete or more insulation but the insulation slabs will span the cavity if thick enough.