Calculating volume of roof space

[^woody^]

I think the use of "space" is clear enough. If someone doesn't know what that means then they must surely have it between their ears.

 

[wobbly2]

A local LPA, have told me this week that when calculating the additional roof volume you include tiles, eaves, overhangs and anything that protrudes forward from the original roof plane. They even said that there is reasonable argument that the volume created by projecting down from the eaves/overhang to the roof slope and back to any side cheek can also be included i.e. the fresh air below the eaves.

The odd thing is that the Planning Portal volume calculators appear to ignore eaves etc and just us the external wall and roof slope measurements!!!

 

[tony1851]

They even said that there is reasonable argument that the volume created by projecting down from the eaves/overhang to the roof slope and back to any side cheek can also be included i.e. the fresh air below the eaves.

That's absolute nonsense because in Part A (extensions) it specifically says you can omit projecting eaves from extension measurements so by
inference, the same applies to roof enlargements.
If any applicant in that local authority area puts up with that, they deserve all they get.

 

[wobbly2]

I know very little about Permitted Development and Planning Permission etc but I think it would be very unwise to rely on ones understanding of an inference when spending 10's of thousands of pounds on a PD dormer enlargement that is close to its maximum volume. Whilst an LPA might not normally be worried about the eaves etc volume being excluded would that be the same if a disgruntled neighbour made a complaint? Ok, if the enlargement was over volume by that of the eaves you could possibly cut them off and rework the structure but that gonna cost.

 

[tony1851]

I know very little about Permitted Development and Planning Permission etc but I think it would be very unwise to rely on ones understanding of an inference when spending 10's of thousands of pounds on a PD dormer enlargement that is close to its maximum volume. Whilst an LPA might not normally be worried about the eaves etc volume being excluded would that be the same if a disgruntled neighbour made a complaint? Ok, if the enlargement was over volume by that of the eaves you could possibly cut them off and rework the structure but that gonna cost.

Fifty m³ is a big volume, and it's unlikely you would get near that. If they are saying you should include the volume of the air from the underside of the eaves to the surface of the roof, then you either tell them to get lost, or put up with a smaller dormer.

 

[tony1851]

PS: there was a planning appeal case in March 2016 where it was determined that the airspace under the eaves was not to be included in the calculation of volume.

 

[wobbly2]

The volume calculated is a gnats under 46m3 so it is getting close, plus 3 or 4 small dormers on the front would be nice but I know planning is required for that.

Have you any pointers to that appeal case?