AboutBrad Zacharia Expertise All aspects of residential Roofing. This includes shingles and flat (low slope) roofs. I have knowledge in the installation as well as the design of roofs from an engineering standpoint.
Experience I have been doing roofing for 40 years. This was my father's business and I took it over in 1980.
Publications I have written responses to artcles that I felt needed a response to and those responses have been published in roofing trade magazines.
Education/Credentials BSEE Drexel University
www.ZachariaRoofing.com
Expert: Brad Zacharia Date: 7/7/2008 Subject: replacing woodshake shingles with asphalt shingles on an a-frame home
Question QUESTION: Hello Brad, we are currently trying to replace our old roof with asphalt shingles, and have run into a bit of problem. My husband decided to do the roof himself, mainly because the price a roofing contracter wanted to do it was way out of our pricerange. He's been a roofer for about 5 years, but never has done an a-frame. My questions are this: The rafters/trusses are 4ft. apart (6x4s). How do we keep the decking from waving? There is not anything else that is "stable" to nail to between the rafters. Could it even hold the extra weight that decking/shingles would add to it. It's a 16/12 pitch 2 story home, didn't have any previous decking on it, so we're pretty much starting fresh. The cedar shingles were nailed onto 1x4s to that were nailed onto the hard foam insulation. Those boards were extremely warped. Do those need removal? Any help would be greatly appreciated, we are really struggling with this. thanks
ANSWER: If you have a warped deck and you put a roof on it then you will have a warped roof. That would be a cosmetic issue only if you could put up with it. I don't see how you're going to nail shingles to the shakes as it will leave big lumps in the roof. The only thing I can see is to strip it down to the rafters, put on insulation board and plywood. They do make systems with insulation board and plywood attached.
Brad
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QUESTION: I reread my question and smacked myself in the head. We started on a small side 2 days ago. He tore off about 10sq. There wasn't any decking underneath the woodshake shingles, just 1x4 boards running horizontally about a 12in. apart going up the roof that the shake was nailed onto. Our concern (well, his, I'm no roofer)is that do we leave the 1x4s that are nailed into the insulation on there and apply decking over them (removing/replacing the warped ones, of course)? Hes concerned about having wavy decking due to the studs being 4ft apart, and is not sure if it's safe to nail to the 1x4s the cedar shakes were previously nailed to. I am personally worried about the gap that will be left between the insulation and the decking caused by 1x4s. Wouldn't that create a save haven for condensation, if it's not vented? He said he could put ridgevent on the top, but i am sure you need at least an inch of unrestricted airflow for that to be effective - and the horizontal 1x4s rule that out, making so only the top 12" of the roof were vented. Summing it up, do you think it would be okay to remove the 1x4s that are nailed into the insulation and trusses, and would it be structurally sound putting all that weight on trusses that are 4ft apart? I'm not positive, but I thought perhaps decking and asphalt shingles probably weigh more than cedar shingles. I'm not going to let him continue without knowing, and the man has too much pride to ask another contracter himself.
Answer You can't nail to the 1x4s. You'd have to screw to them. If you remove the 1x4s the rafters are too far apart to hold up the plywood between them. Four feet apart for the trusses is awfully far apart. You don't insulate the roof rafters unless you're living directly under them. You insulate the ceiling of the room below. You insulate the closest you can get to the living space. Weight should not be an issue unless the trusses are undersized. No one makes a building that is borderline about to fall down if you add a little more weight. You probably need to come up with some idea to add extra support between the rafters.
