This is because the membrane is more expensive to manufacture as well as the need for more specialized labor.
Pitched roof to flat roof conversion.
On houses new pitched roofs typically are supported by the exterior walls as with standard sloped roof construction.
However flat roofs require much more aggressive and consistent maintenance than a pitched roof.
Either way your home s existing design may interfere or affect the changes you can make.
There are several ways to convert a flat roof to pitched.
Realistically speaking to do it right would involve a complete tear off of the roof structure then a re engineering and rebuild of the new flat roof.
The typical way is to remove the existing roof and add new framing to the home that create a pitched roof over the old flat roof area.
You either have to raise the height of the eaves or lower the height of the ridge.
Pitched roofs have about a 40 longer life than flat roofs.
You can install a shallow pitched roof over your existing flat roof add a trussed ranch style roof to convert to cathedral walls or even build a new floor and install the pitched roof above that.
You can tear off the existing roof remove the trusses and strengthen the joists.
A pitched roof is more expensive.
It is a significant renovation if you are converting from flat to pitched.
They last 25 50 years while a flat roof membrane will last about 15 20 years.
This has to happen whether you re just removing the pitched roof or adding another floor with a flat roof.
Flat roofs also don t last as long.