Get matched with top roofers in Humboldt, IA

You shouldn’t put a new roof underlayment over an old one for a few reasons. Old felt must be removed in order to assess the condition of your roof decking, such as rotting wood or other structural issues. Also, if your roofer doesn't install a fresh layer of felt as is required by shingle manufacturers, your warranty may be voided. Finally, old underlayment removal is often included in the cost of roof repair or replacement, so there's no real benefit to leaving it on before installing a new layer.

In most cases and locations, roofs with a single layer of asphalt roofing shingles won't require roof removal before installing a metal roof. However, underlayment may be necessary on roofs with moderate shingle damage. Heavily damaged roofs or ones with multiple shingle layers will most likely require removal before a metal roof can go on.

Underlayment is used between existing shingles and a new metal roof to prevent friction and wear from the shingle granules on the underside of the metal. The underlayment also helps prevent water intrusion and allows expansion and contraction without wearing away at the roofing material.

Whether you should choose a flat roof or a sloped roof depends on your particular situation. Flat roofs tend to be less expensive to install. However, sloped roofs have longer lifespans and stand up better to heavy snow and other inclement weather.

Keep in mind that even a flat roof needs to have a slight slope, usually around 1/2 inch for every foot. If it is completely flat, water will pool and cause damage, either from weight or leakage or rot.