Calculating Volume Of A Hipped Roof Extension

[Renovation]

Hi,

It's been a while since I was at school and the online calculators don't seem to cover this scenario.

Planners want a volume trade off



I'm building a first floor extension over the railings - even I can remember how to calc the room volume but for the roof:

Effectively I've laying a triangle over at 45% x the width of the room

1/2 base x height x depth

Height = END HIP length measured down the hipped end (as I'm laying it over hence it's NOT the loft height)
Depth = room width
Base = room length

Is the above correct ?

[Renovation]

I think I might have over thought that

Effectively I'm adding a 3.6m wide section.

As the end hip already exists, if I cut it off and add a 3.6m wide section to the middle, the existing hip will cover the end.

So the height I need to measure is the ROOF height.

Correct ?

[Escort3500]

I'm rubbish at maths so can't answer your query However there's a useful volume calculator on the planning portal - www.planningportal.gov.uk that might help you. It's under the 'useful tools' tab.

[Renovation]

Escort3500 said:

I'm rubbish at maths so can't answer your query However there's a useful volume calculator on the planning portal - www.planningportal.gov.uk that might help you. It's under the 'useful tools' tab.

Thanks, I'd found that and it is handy - just doesn't cover my type.

[Shaolin]

Not sure what you mean?

The new roof will have a slanted end that matches the slanted end of the house it butts up against? So from the side elevation in your photo it will look like a pushed over rectangle (a parallelogram). If this is the case and the cross section triangular, then the slanted (hipped) ends will be identical and so you can treat it as a triangular prism the full length of the railings bit. You need the vertical height of the triangle, not the length down the sloping hipped bit. Then it's 0.5 x width x height x length and you can ignore the hips as long as they are identical.

[Renovation]

Shaolin said:

Not sure what you mean?

The new roof will have a slanted end that matches the slanted end of the house it butts up against?

So from the side elevation in your photo it will look like a pushed over rectangle (a parallelogram). If this is the case and the cross section triangular, then the slanted (hipped) ends will be identical and

so you can treat it as a triangular prism the full length of the railings bit.

You need the vertical height of the triangle, not the length down the sloping hipped bit. Then it's 0.5 x width x height x length and you can ignore the hips as long as they are identical.

Yes

Thanks.

Yes that's what I thought (in my second post)