Why is a house roof so jolly big?

[pillj123]

Just curious...some I have seen are really enormous..do they actually need to be so vast?....wouldnt a gentler angle work just as well ?
This is obviously one of lifes deep mysteries.....

[The Builder]

Right, pilly ........... are you sitting comfortably?

Lots of countries use flat roofs. No problem with that at all. In this country, as ever, we're traditionalists. We regard pitched roofs as the only "proper" construction.
Thatched roofs need 45 degrees to shed rainwater properly
Clay tiles (small ones) need 45 degrees (usually)
Slate needs at least 35 for small slates ....................
............... 25 for large slates.............
Concrete tiles can go down to 15 degrees, which is why modern roofs and bungalows have lower roof spaces...............

I'll bet you wish you never asked now ;o)

[pillj123]

Well actually that has gently made my afternoon....(yes ...slightly sad really!)
Well I never...now I too can claim to be one of the worlds foremost understanderers of roof angles!
I do thank you Mr Builder for giving such a prompt and succinct reply...I will share my newfound knowledge as soon as the occasion arises!

[Mosaic]

Even without additional insulation, the roof space acts as insulation between the outside world and your bedroom. Obviously lots of additional insulation is better.

There's only really three options for spanning a space: flat, arch / dome, or pitched roof. Once you go into dome or pitched, the simple geometry means you end up with something big in relation to the area it is covering.

[pillj123]

Thank-you , Mosaic....now thats rather amazing stuff too.I always knew there were real reasons...now I begin to see it all more clearly.

[atalanta]

In countries where they get lots of snow, rooves must be steeper so the snow slides off rather than building up intil the surface is overloaded and threatened by the weight.

[Booldawg]

Drive through Belgium - they have some mad rooves there!

[buildersmate]

................. or even mad roofs.