Slate and Historic Roof Repair in Trenton and the Old Towns

Should a slate roof be repaired or replaced?

Usually repaired, as long as the slates themselves are sound. The common failures are rusted fixings, corroded flashing and individual broken slates, all of which can be fixed. Replacement makes sense only when the slate is brittle and flaking throughout. A specialist's written opinion should settle which applies.

A common trap is the roofer who recommends a full replacement because slate repair is harder than shingle work. Ask the roofer to explain what is wrong with the slate, not only with the roof.

If you decide to replace, ask whether salvaged slate can be reused on the visible slopes and new material used on the rest.

Do historic districts regulate roof work in Trenton and the nearby towns?

They can. Mill Hill in Trenton may require Historic Preservation Commission review for visible exterior changes, and other historic districts such as those in Bordentown, Princeton and Allentown work in similar ways. Ask the local office before changing material, color or the look of the roofline.

Review rules vary by town and often by the type of change. A like-for-like repair may need little or nothing, while a change from slate to shingle is likely to draw attention.

Do not assume your house is or is not covered. Ask the municipal office, and let the roofer know the answer.

Who can work on slate and copper?

A roofer with specific slate or metal experience. Ask whether they have repaired roofs of the same material and age, how they match slate and how they fasten replacements. Slate is brittle underfoot, copper must be soldered and the wrong approach can cost the roof more than the repair saves.

When you call, say the roof is slate, cedar or copper so that the line puts you through to a roofer who handles it. Not every contractor does.

Ask for photographs of previous slate work if you are unsure.

What about built-in gutters on a historic house?

Built-in gutters on older houses are lined with copper, lead-coated copper or other metal, and they leak when the lining cracks or the seams open. They can usually be relined or repaired, but the work is part metalwork and part carpentry, and visible changes may need review.

The gutter repair and installation page covers box gutters in more detail, including why a leaking one damages the wall and ceiling beneath.

A careful roofer will also check the cornice and fascia for rot that has developed behind the gutter.

How do I find a roofer who really knows slate?

Ask directly: how many slate roofs they have repaired, how they remove and replace a single slate, what fasteners and metals they use and whether they can show photographs of earlier work. A roofer who answers specifically and calmly is likely to have done it. Vague answers are a sign to keep looking.

Slate repair has its own vocabulary, and a roofer who knows it will use it. They talk about slate hooks, copper nails, headlap and sources of matching stone. They also tell you which slopes they would not walk on and what they would do from a ladder or a roof hook.

Ask for the registration number and check it with the state before you sign anything. On the New Jersey side, home improvement contractors register with the Division of Consumer Affairs; on the Pennsylvania side, with the Attorney General. The guides on how to check a roofer in New Jersey and hiring a roofer on the Pennsylvania side explain what to ask.

If your house is in a historic district, mention that on the call. A roofer who knows the local review process can help you prepare a short description of the work, with photographs, for the commission or the municipal office.