Slate at the end of its life
A great deal of the housing in this region was roofed in slate between 1890 and 1930 — and slate lasts roughly a century. That arithmetic is why so many houses across the collar counties are facing the same decision at the same time, and why it is the most consequential roofing choice a local homeowner will make.
Reading a slate roof honestly
Slate itself rarely wears out first. What fails is everything around it: the nails rust through, the flashing at chimneys and valleys corrodes, and the sheathing beneath softens where water has been getting past. A roof losing individual slates after a hard winter usually has decades left and needs a repair. A roof shedding them steadily, with slates that flake or crumble at the edges when handled, is telling you the stone itself has gone — and no amount of patching changes that.
The distinction matters because the two verdicts lead to completely different projects. It also explains why a general roofing contractor may steer toward replacement while a slate specialist sees a repair: they are not always disagreeing about the roof, they are disagreeing about what they are equipped to do.
The two roads, priced honestly
Keeping the slate means finding one of the few trades in the region who still work it properly — a small pool, booked well ahead, and priced accordingly. What you get is a roof that can outlive you. Converting to composition means a full tear-off, almost certainly sheeting over the original spaced boards (slate was nailed to gapped sheathing, and modern shingle cannot be), new flashing throughout, and a covering rated for a few decades rather than a century.
Neither is wrong. But a quote that treats a slate roof as an ordinary tear-off has probably not accounted for the sheathing, the weight difference, or the flashing work — and those are the lines where a conversion goes over budget.