km roofing edinburgh are members of the national federation of roofing contractors- nfrc and flat roofing alliance (fra). find out more about flat roof specification or login to our members area where you will find a range of tools including our u-value calculator. importance of walk pads on flat roofs. if you have an old flat roof then simply contact with us for a free no obligation inspection. traditional 3 layer built up felt roofing system. residential flat base sheet residential flat base sheet residential flat roof . previousnext.