Q: I have got an outbuilding that needs a new roof. We use the building to store equipment in for use around our hobby farm. I had a local contractor look at it and he insisted that the old roofing needs to come off before new shingles are installed. The existing roof is a three-tab shingle but is all intact with simply 25 years of use, so it needs replaced.
I want to use the same shingle that is on our house and garage and it’s an architectural style shingle. Does that make it so that I must remove the existing roofing? George
A: A three-in-one shingle really lays about as flat as any shingle there is. Given the fact that no areas of the existing shingles are missing or curled bad you should be able to simply lay new shingles over the existing.
Something to look for is if the roof structure is capable of supporting the additional weight. Sometimes out buildings that are 80 years old or so, might not be capable of supporting the added weight. If the existing roof framing shows signs of sagging or if the ridge board is sagging at all, it would be of concern for additional weight.
Often out buildings of years past were not framed to today’s standards and under-size rafters and ridge boards are common. There was a time, and I think you can still get them, when the use of a single layer shingle called a clip lock, were quite common, especially around farm and agricultural buildings. These shingles had a diamond pattern and hooked at the top and overlapped the edges of the bottom shingle, creating an interlocking single layer different than the half overlay of today’s shingles.
Also roll roofing, sometimes called salvage roofing, was used as a single layer low-cost type of roofing material. Both of these style shingles are about half the weight of a 3-in-1 shingle and a third of the weight of today’s architectural shingles.
Jeff Deahl is past president of the Builders Association of Northeast Indiana. Questions for the Square Corners column may be submitted to jeff@craftsman-design.com.
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