While the asphalt shingles will be the primary water shedding roof layer there are many benefits to installing a roof underlayment.
Roof asphalt shingle installation.
Although placing new roofing over old may be allowed by some codes roofovers tend to be inferior and won t last as long as a roof installed over stripped sheathing.
To install asphalt shingles start by installing underlayment and new flashing on the roof.
Below 40 f shingles are brittle and crack easily when hammered or bent.
Above 85 f it is easy to tear the shingles or mar the granular coating.
Continue to chalk additional guidelines based on the width of the shingle through at least four courses rows across the roof.
Use your chalk and tape measure to mark about 12 inches up on the roof for the first set of shingles.
The felt is laid in horizontal courses overlapping the eave ice and water protector by 4 and the valley membrane flashing by 6.
Installation temperature requirements for asphalt shingle roofs ideally shingles should be installed at temperatures ranging from 40 f to 85 f.
Installing asphalt shingles over an existing shingle roof it s not ideal to install new shingles without removing the old ones but follow this pro advice if you do.