Q. I need to replace the roofing on an approximately 19 year old house. Can you give me some "dos and don'ts" to be aware of when selecting a contractor? For example, I have heard good and (mostly) bad things about applying new shingles over existing s hingles. Is there anything wrong with that or is it better to remove everything down to the wood and re-install all new roofing? How about the quality of shingles? Is the 25 or 30 year guarantee worth the additional cost?
A. My initial bit of advice is a donít. Donít apply new roof shingles over the old ones. Sure, itís legal under the code to do it but any good roofer will tell you itís not a good practice. For some reason the ďroof overĒ, as itís called, doesnít seem to perform as well and when it comes time to replace that roof both layers will have to be torn off and carted away. Obviously any savings that may have been realized by leaving roof number one in place will be lost tearing them both off in preparation for roof number three. Many folks chose the roof over because they figure they wonít own the house when the next roof is needed so they just pass the hidden additional cost along to the new owner.
Most shingle problems that occur before a roofís legitimate time are either storm or workmanship related so chose your roofer carefully and shop your shingles for looks. Shingle warranties are worth just about the paper they are printed on because if you read the fine print the suits write to cover the manufacturers youíll see itís a pretty slim chance to get a claim honored, although I have seen some manufacturers stand behind a bad run of shingles. But itís rare.
The one thing I would pay a little extra for are the shingles that come with magnesium and copper granules added to aggregate-- the top layer of tiny pebbles that impart the shingleís color and help protect the shingle from the sun. These metallic granu les will prevent the dark streaking that you see all over the place. Itís an algae and these metals inhibit their growth and the roof will remain the color it was when it was put on.
Next Iíd create a specification sheet to provide roofing contractors to bid from so you can compare apples to apples. Youíll want to talk to the roofers about whether or not they can save your existing gutters or will they likely get destroyed by the rer oofing process. I would specify the tear off and removal of all old roofing materials. Youíll want drip edge installed around the roof edge. It may not have been on the original roof. Itís not a code issue but itís a good idea to use it. It protects the wood roof edge from wicking water over time and creating rot near the edge.
What many folks donít know-- and even a certain population of roofers--that is a code issue is protection from a wintertime leak situation called ice damming. The building code states that if an area is where there is a possibility of ice forming at the eaves causing a back up of water that preventative measures must be taken to roof against that. We are in such an area and for that I like an asphalt product called Ice and Water Shield to be used from the roof edge to at least two feet up the roof insid e of the building line. The building line is an imaginary line that goes strait up from the outside wall of the house and does not include the overhang of the roof.
Specify that plumbing stack flashings be replaced and if any flashing is to be reused that it be in very good condition or have it replaced such as at chimneys and wall intersections like a garage roof meeting the side of a house. Once youíve selected th e roofer, checked his references, seen on his paperwork that he has a Maryland Home Improvement Commission license number and has supplied you with a valid insurance certificate, be sure that the maximum amount of money that you give him at contract sign ing is only one third of the contract amount. Thatís the law in Maryland. And before you write the final check make sure the job is one hundred percent done, all trash and equipment cleaned up and hauled from the site and double check for any ďcollateral damageĒ that may have taken place such as cracked or broken windows, damaged landscaping etc. Itís perfect weather for roofing right about now.