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.
A pitched roof is more expensive.
There are all sorts of things you have to take into consideration depending on where the building is.
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.
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.
There are several ways to convert a flat roof to pitched.
You either have to raise the height of the eaves or lower the height of the ridge.
This has to happen whether you re just removing the pitched roof or adding another floor with a flat roof.
On houses new pitched roofs typically are supported by the exterior walls as with standard sloped roof construction.
It is a significant renovation if you are converting from flat to pitched.
Either way your home s existing design may interfere or affect the changes you can make.
Pitched roofs have about a 40 longer life than flat roofs.
They last 25 50 years while a flat roof membrane will last about 15 20 years.
Flat roofs are about 10 20 more expensive to install than a pitched roof after the conversion.
Flat roofs also don t last as long.
You can tear off the existing roof remove the trusses and strengthen the joists.