There are all sorts of things you have to take into consideration depending on where the building is.
Pitched roof to flat roof conversion.
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.
It is a significant renovation if you are converting from flat to pitched.
You can tear off the existing roof remove the trusses and strengthen the joists.
Pitched roofs have about a 40 longer life than flat roofs.
Either way your home s existing design may interfere or affect the changes you can make.
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.
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.
This is because the membrane is more expensive to manufacture as well as the need for more specialized labor.
You either have to raise the height of the eaves or lower the height of the ridge.
A pitched roof is more expensive.
However flat roofs require much more aggressive and consistent maintenance than a pitched roof.
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 a few ways to dealing with a pitched roof if you choose to convert to a flat roof.