U value questions regarding area weighted calculation.

[rssteve]

Hi, just in the process of sorting my building regs plans and need to work out what insulation i need to fit.

I've got over 25% glass area so going to use the area weighted calculation to prove my design is no worse that the maximum if complying with part L.

Q1. under part L does a bi fold door have to have a maximum of 1.8U, or is it classed as a window due to the glass and got to be 1.6 or under?

Q2. When working out my area m2 of wall, floor etc, do I ignor the wall that joins the house I am building the extension onto, since that is going to be an internal wall?

Q3. Do I class the wall that will attach the garage as an external wall? it is current single skin but will be knocked down and rebuilt as a cavity wall but will be internal to the garage on the other side, the garage is a simple single skin attached to the side of the house with a flat roof.

thanks in advance.

 

[wessex101]

Off the top of my head, so could well be wrong.

Q1. I always use 1.8 for sliding folding doors
Q2. Yes, you only use external walls
Q3. If the garage is unheated space I would take the wall between extension and garage as external wall.