First floor extension - extending blockwork up

[Mack]

Hello all!

Long time reader of this absolutely brilliant forum, so I thought who better to give advice for some potential building work!

 

I have a 1960's semi (J Maunders, Trafford) with a single story garage extension built i think in the late 80's or early 90's.

I'm looking to build on top of it, and wondering where I should start looking in terms of planning the project and getting the plans drawn for a pro team to do the work.

The garage originally had planning permission for an extension on top of this, and I think there must be plans still in a cabinet, and there is some level of building control that was submitted for this.

The previous owner it seems was both a cantankerous old bastard and extremely fastidious in his approach- everything he's built seems above and beyond what would be required and quite a lot of attention to detail... But his wife left him and he boarded everything up around Nigel Lawson's budgets (judging by the newspapers) and gave up then. A flat roof was put on top of the first story.

The original excavations for foundations are only partly filled in on the inside, and I've dug down 7ft and it's still blockwork so haven't hit foundation yet, much deeper than the original house. So I think it's probably good for going up. All the steels above garage door and windows are humongous but currently holding up 3 courses of brick.

The construction is cavity with 2 skins of brick (yes even internal skin, no breezeblock) with a ~2inch finger cavity, uninsulated, with stainless cavity ties. It looks like nice work.

I had a private planning professional tell me I would need a steel installing internally around the perimeter, so that I could put blockwork on top of this to open the cavity up for insulation for modern regs.

Is that necessary? If the current construction is perfectly suitable for building upwards.in brick and block, surely the best method would be to just build on top using the same construction, and internally insulate? I want to go above and beyond regs for insulation and don't mind losing internal space.

I'd love some advice on this please! 

My ideal scenario is to have some proper plans drawn up for planning and BC and engage a professional for the works.

Thanks all!

[MikeGrahamT21]

Plenty of ways to meet insulation standards of today, not sure a whole load of steel is very ecological or economical, but as you rightly say you can add internal wall insulation, as long as you achieve the stated U value requirements with your build up then you are good. Just don’t forget to have the cavity pumped with blown beads too!