We plan to extend at the rear of the house. The existing house is shaded red.
I understand permitted planning stops at 4metres for a detached house. Would it start from the external wall from the kitchen on the right or the garage wall on the left?. All part of the orginial house when it was built.
Are you planning to extend behind the garage too (so a side extension)? If so, I am not sure whether that is covered by permitted development. Ordinarily to answer your question, the 4m would be from the back of the kitchen.
Plan to add a utility room to the back of the garage. Not sure it actually counts as a Side extension as it is still on the rear of the house but staggered (IYSWIM) The garage is Intergal to the house and has a bedroom on top.
Interesting that you say the Kitchen ( as we thought). Meeting with an architect tomorrow who on a telephone chat though it may need planning as it might count from the garage wall?
The planning portal just says the "rear wall of the original house" as it was built originally or how it was in 1948! I'd take that as the kitchen wall (but I'm not an expert) if you say the house and the garage are as they were previously built.
It's from the rear wall you're building from, so you've done the right thing by staggering them and not trying to do a wrap around. The main extension should be fine (as long as it fits all the other criteria). The smaller extension is both a rear and side extension, not necessarily an issue unless you're in article 2(3) land or it's more than half the width of the original dwelling.