Slate or shingle: what the decision actually costs
If your house was built between roughly 1890 and 1930 in this region, there is a good chance it was roofed in slate — and slate lasts about a century. That is why so many owners across the collar counties are facing the same question at the same time, and it is the most expensive roofing decision available locally.
First, establish what you actually have
Three situations get confused with each other. A slate roof with decades left that is losing slates because the nails or the flashing have failed — that is a repair, sometimes a substantial one, but the roof stays. A slate roof whose stone has gone soft, flaking or crumbling at the edges — that roof is finished regardless of what is spent on it. And a composition roof that was laid over slate decades ago, which is a different job again, because the slate underneath adds weight and has to come off with everything else.
Getting this wrong is expensive in both directions. The honest test is someone handling the material: sound slate rings and resists, spent slate flakes between the fingers. A photograph from the ground cannot tell you.
What each road involves
Keeping the slate means finding a trade that still works it — a genuinely small pool in this region, booked well ahead, and priced for the skill. In exchange you keep a roof that can outlive its owner and the architectural character that goes with it, which on some streets is also what the house is worth. Converting to composition means a full tear-off with heavy disposal, almost certainly sheeting over the original spaced boards, entirely new flashing, and a covering rated in decades rather than a century.
The arithmetic that matters is not the two quotes side by side — it is each quote divided by the years it credibly buys, and then weighed against how long you plan to own the house. Neither answer is wrong. But a conversion quote that does not mention sheathing, disposal weight or new flashing throughout has not been priced properly, and the difference will surface once the roof is open.
Next step: How long a roof actually lasts here
A no-cost look offered by a firm that only installs composition is a sales visit, not an assessment of your slate — sometimes a perfectly honest one, but the incentive is what it is. If the answer will steer tens of thousands of dollars, pay for an opinion from someone who works the material.