Question from this week’s radio show:

Dear Dr. Roof:

Please tell me if I have totally messed up!!!! About 5 years ago we had a steel roof installed. When they did the work they said they could either remove our old shake roof or leave it on. I thought “Gee, two roofs are better than one” so I had them leave on the old shake roof. Was that a huge error? I don’t have any complaints but now I wonder if possible bad air could not escape properly. There are vents but….

Please let me know.

Thank you very much. Penny H.

Dear Patient Penny,

You ask this question after you had roof installed because you want to know if you should be worried. Well, please don’t be worried, air still gets through the seams of the steel roof. Whether it is stone granule covered steel or clean steel like made by Classic Metal Roofing Systems, the steel is water tight but it is not air tight, so air does escape and you also say that you have vents coming out. However, if I had to do a steel roof, or any other kind of roof, I like to remove the original roof anyway because it is the only chance you’ll have to see the wood base of your roof deck and know if any wood needs replacement due to dry rot. Also, if it is steel over wood, it is not class “A” fire rated unless you have fiberglass underlayment between the steel and the wood. The steel won’t burn, but it does transfer heat which is why you cannot get an “A” fire rating, the highest and now usually required in many areas of the country. But you already have the roof up and it is only 5 years old so relax and live with what you have. You didn’t say it leaks so be happy, as many roofs leak and yours doesn’t. But if you had to do another roof like this one, I would recommend removing the old roof first, or at least making sure that there is a fiberglass underlayment so you would have a class “A” fire rated system, the best fire rating.