I am performing a fabric upgrade on our house. Work to be done includes:

 

- EWI

- New windows, doors

- Establishing AT layer

- Digging out foundations for EWI

- Designed ventilation

- Resizing of window openings (enlarging and shrinking)

 

I have done:

 

- Overall aesthetic look (it's not really changed much, but thicker walls and more contemporary look to the joinery)

- Energy model

- Generic details for important installations, e.g. window installation, treatment of eaves (before deciding on manufacturers)

 

What I need to do:

 

- BC approval

- Planning approval (don't think there'll be much of this, not listed nor in conservation area)

- Choose suppliers and products

- Update details to follow systems chosen

- Arrange finance

 

What should my ordering be next? I don't want to get BC approval only to find our budget won't work for what we have got approval for! Should we finalise the entire design first?

Yes, get the design and budget sorted.  Get plenty of quotes.  If within budget, refine, finalise and go ahead, if not, revise spec.