We are applying to build a semi detached house on the side of an existing detached house. Because the houses are to be linked together we're limited to ceiling heights by the heights of the existing rooms as the new house will be a mirror of the existing one. We'd like to build loft rooms in the new house roof when we build it but the existing house only has a roof space height of 2260mm which would give a finished ceiling height of only about 2000mm. The house is a victorian style detached with a front and back gable (so the roof slopes from side to side) and the plan was to do dormers on the roof sides just from the middle to the rear to give a large dormer room, then have another room in the front section that would have a roof that slopes on both sides so only the centre portion would have a high enough ceiling to be usable.
I've become aware of national space standards which designate that minimum floor to ceiling height needs to be 2.3m over 75% of the house. But I also find references here and there that this only applies 'if your council enforce it'. I'm struggling to find out if this is true or whether my council (Reigate and Banstead) enforce it, or whether there are any circumstances where it is more subject to interpretation? There doesn't appear to be any reference to it on their planning website. I also don't know whether loft rooms when built as part of a new build also count in this calculation (even though they don't for conversions).
My question is, if the space standards are enforceable and we convert the loft including the double sloped roof section, is there an area of roof height under which rooms are not counted as habitable and are therefore excluded from calculations? I'm also a landlord, and I know on some of my properties in London where I have to conform to minimum space standards, I am not able to count any floor space with a ceiling height under 1500mm as usable space for instance. So this could work in my favour as if this space doesn't count as usable rooms for planning purposes, but we can still add velux windows and we can list it as storage and then the remaining dormer room would only be about 20% of the house and therefore would bring the calculations into the right percentages. We're conscious that a new build very likely will have its PD rights removed so we wish to maximise the space at time of the initial planning application.
Thank you