Old Slate Roof Repair

Often I come across a slate roof that’s just not worth repairing.   

Today I received a call from a local home construction contractor asking if I could give an estimate on installing a new pipe flashing on a plumbing stack he was replacing. He was remodeling a bathroom in a century home nearby. After a cursory inspection of the roof it was decided to replace the stack flashing and also the cast iron soil pipe. The lead stack flashing looked like it was the original and was in terrible shape and there had already been prior repairs.

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The roofing slate is soft low quality gray slate. The slate material itself is wearing out, spalling and delaminating. The repair that needs to be done, replacing the soil stack and installing new flashing, would also require replacing about 9 pieces of slate around the pipe. The original workers drove nails through the flashing flange and through the slate. Each of the slates now has a hole or is cracked and will need to be replaced. The cost of that repair alone would run about $350. But there are also other repairs that need to be done. There are numerous broken slates and quite a bit of damage caused by the gutter installers. The gutter crew drove nails right through the slate to secure the gutter hangers.

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Where the slate was not immediately broken, it was damaged enough to be weakened and later broken by heavy ice on the eave.
Besides the slate, it is evident that the roof has been leaking for some time, so there is also a good chance of deteriorated rotted roof decking under the slate that will need to be replaced.
Now once all these repairs are made and the roof is sound, there is still soft old low quality slate on the roof that is still deteriorating and could fail at any time. It’s just not worth doing the repairs and trying to save the old slate roofing. For the cost of the repairs, this roof could be replaced with a decent quality asphalt roofing material, or for a little more a new slate roof could be installed.

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