How large a hole shall i knock in an external wall for french doors?
Changing the exterior of a building would typically require planning permission. You may also need to submit a building warrant application for the work – things to look out for are typically with regards to insulative properties of the new french doors and energy conservation (what type of glazing, its overall U-value, etc.). You’ll also be asked to produce details to show that your proposals are in line with the building regs. Call up your local council to confirm. It’s best to keep it legal as it would complicate any possible sale or transfer of the property in the future. That sorted, you’d best find out the size of the doors you’re going to fit as the others have suggested. It’s pretty much common sense – you don’t want to knock an opening too small or the doors won’t fit, and you don’t want to knock an opening too large or you’ll have another job with filling in the gap. That said, it’s best to make an opening slightly larger that the overall dimensions of the door itself (with t
