On a historic house the stone or wood is often not what fails first. Fasteners, flashing and underlayment give out, and a roofer can usually replace them while keeping sound slate or cedar. Repair is usually the better first question than replacement, and the work needs a roofer who has done it before.
Key takeaways
- Slate can outlast the nails, flashing and underlayment holding it, so a sound slate roof with failing fasteners is usually a repair job, not a replacement.
- Cedar needs to dry between rains, so shade, moss and leaf litter shorten its life more than age does, and the shaded slopes wear first.
- Slate and cedar work is specialist work; ask the roofer how many such roofs they have worked on, what fasteners and flashing metals they use, and for photographs of earlier jobs.
- Never walk on a slate roof or a wet cedar roof, because slate cracks underfoot and wet wood is slick.
- If the house has historic status or sits under association rules, ask the town and the association about materials before choosing, since this guide does not state any local rule.
Why do old roofs in Washington, Kent, Woodbury and Roxbury need different care?
They are made of many separate pieces, each held by a pair of fasteners, so they fail one piece at a time. The houses are old, with several chimneys, dormers and additions, and the flashing has been renewed more than once. Care means knowing each piece and each joint, not treating the roof as one sheet.
Towns such as Washington, Kent, Roxbury and Woodbury hold a stock of Colonial and Federal houses, farmhouses and barns, many with slate, cedar or standing-seam metal roofs. Washington itself is a town of villages, including Washington Green, Washington Depot and New Preston, with long rooflines and several chimneys on many of its older homes.
That variety is the reason a one-size answer does not work. A roof laid in one century and patched in two others may have three kinds of slate, two kinds of nail and flashing in copper, lead and galvanized steel.
A roofer who looks at such a roof reads its history first. Where were the repairs? What metals are in contact? How is the water leaving the edges? Those answers shape the repair.
What fails first on a slate roof?
Usually not the slate. Iron nails rust through and let slates slip, copper or lead flashing cracks or lifts, and underlayment or old valley metal wears out. A slate that rings clearly when tapped is generally sound. Slate that is soft, flaking or splitting in layers is near the end.
The signs show from the ground. Slates lying on a porch roof or in the garden, gaps in the rows and rust streaks running down the face of slates point to fastener failure, which roofers call nail sickness. Stains on the ceiling below a valley or chimney point to flashing.
A repair replaces the failed slates and secures them with fasteners that will last, often hooks or copper nails, and renews the flashing in a compatible metal. Dissimilar metals in contact corrode, so choice of metal matters.
The table sets out what you see, what it usually means and what is done.
| What you see | What it usually means | Usual response |
|---|---|---|
| Slates on the ground or gaps in rows | Fasteners have rusted or failed | Replace slates and secure with durable fasteners |
| Rust streaks down slate faces | Iron nails corroding | Re-fasten; consider copper nails or hooks |
| Flaking or layering slate | Slate nearing the end of its life | Replace affected area; ask about the rest |
| Stain beside a chimney or valley | Flashing has cracked or lifted | Renew flashing in a compatible metal |
| Cracks where someone has walked | Slate broke underfoot | Replace; keep traffic off the roof |
What fails first on a cedar roof?
Moisture, not age. Cedar shakes that stay damp under shade and leaf litter grow moss and rot, split in freeze and thaw, and curl at the edges. The shaded north slopes wear first. Keeping the roof clear and the gutters flowing slows the decline, and split shakes can be replaced individually.
A cedar roof is meant to breathe. Air moving beneath the shakes dries them after rain, and a roof laid over solid sheathing without that airflow may rot faster. A roofer can tell from the attic whether the roof has the space to dry.
Moss lifts shake edges and holds water. It should be removed by a roofer, not scrubbed or pressure-washed, which can damage the wood. Where trees overhang, trimming where safe lets sun in.
See the guide on roofing under trees for how shade and debris wear all roofs, not only cedar.
Repair or replace: how do you decide?
Repair when the slate or cedar is mostly sound and the problems are fasteners, flashing or a few broken pieces. Replace when the material itself is failing across most of the roof, or when repairs have stopped holding. Ask the roofer for both options in writing, with photographs of what was found.
Replacement is a big step on a historic roof, in cost and in character. The roofer should explain why a repair will not do, and whether a partial replacement of the worst slopes is an option.
Do not be rushed by a roofer who calls every old roof dead. Also be wary of one who patches without ever asking whether the roof is sound. A balanced answer sets out the condition of the material, the fasteners and the flashing, and what each choice buys.
The service page on slate and cedar roof repair describes how the work is done.
- Is the material itself sound across most of the roof?
- Are the fasteners and flashing the main problem?
- Would a partial replacement of the worst slopes make sense?
- What do repairs cost over several years against replacement?
How do you choose a roofer for slate or cedar?
Ask how many slate or cedar roofs the roofer has worked on, what tools and fasteners they use, what metals they choose for flashing and whether they can show photographs of earlier work. A confident, specific answer is a good sign. A vague one is a reason to ask the line for another roofer.
Not every roofer takes this work. The call line puts you through to an independent roofer who serves your town; say at the start that the roof is slate or cedar, and ask whether that roofer does it.
Check registration before you sign. Connecticut has no roofing licence; roofers working on homes register with the Department of Consumer Protection, and you can look it up at elicense.ct.gov. See checking a roofer's registration.
How do snow, ice and trees affect these roofs?
Snow sliding off slate can break pieces below and tear gutters, and ice at the eaves can lift slates or split cedar. Roughly 45 inches of snow falls in a typical winter in the Danbury area. Good attic insulation and ventilation, snow guards where needed and clear gutters all reduce the stress.
Ice dams are as relevant to old roofs as to new ones. An old house with thin attic insulation can melt snow from below just as a converted cottage can. The guide on ice dams on Candlewood Lake homes explains the mechanism.
Trees add shade, moisture and falling limbs. Heavy limbs can break slate or crush cedar, and a fallen tree on an old roof is a specialist repair. Ask the roofer to plan for matching material.
What routine care keeps a slate or cedar roof going?
Keep gutters and valleys clear, remove moss through a roofer, trim limbs that touch the roof, check flashing each autumn and have the attic looked at for damp or daylight. Small tasks done on a schedule cost far less than a failed valley or a run of slipped slates after a hard winter.
The calendar below follows the year in this region. It assumes a tree-shaded roof, which most of the older houses have. It is a checklist for conversation with a roofer, not a substitute for an inspection.
Keep a log. Write the date of each visit, what was found and what was done. Over several years it shows a pattern, such as a slope that always sheds slates in late winter, and the pattern tells a roofer where to look.
| When | What to look at | Who does it |
|---|---|---|
| Late autumn | Leaves in valleys and gutters, flashing at chimneys and dormers, limbs touching the roof | Roofer, or you from the ground |
| After the first big snow | Snow sliding from the slope onto what is below, ice at the eaves | You, from the ground |
| Early spring | Slipped or missing slates, split shakes, stains inside | Roofer |
| After major storms | Wind and impact damage, flashing displaced | Roofer |
| Every few years | Attic: daylight, damp sheathing, insulation and ventilation | Roofer or insulation contractor |
What should an inspection of an old roof include?
A close look at the slate or shakes from the roof, not only from a ladder, and a look at the attic side of the boards. The roofer should check fasteners, flashing metals, valleys, chimneys and gutters, and give you a written note with photographs separating what is sound from what needs work.
A good report names the metals and says how they were found. It tells you which slopes are in worse shape. It lists repairs that should be done now and those that can wait a season, and it says plainly if the roof is near the end of its life.
Ask for the findings before any commitment to repair. The page on roof inspection describes what a full look includes, and a second opinion is reasonable before a large job.
What about matching, historic rules and the look of the roof?
Matching old slate or cedar takes time, and a repair may look different for a season or two. If the house sits in a local historic district or under association rules, ask them about material and colour before you decide. This guide does not state any such rule for a particular town.
Salvaged slate from a less visible slope, or from a supplier, can give a close match. Cedar weathers to grey, and new shakes will look brighter at first.
Ask the town building office whether any review applies to a roof repair or replacement, and note who told you. If the answer is no, write that down too.
Frequently asked questions
Can a slate roof last a very long time?
The stone can, provided the fasteners, flashing and underlayment are maintained. A roofer who inspects your roof can say how much life the slate has.
Is it safe to walk on my slate roof?
No. Slate cracks underfoot, and a slate that slides can fall onto anyone below. Look from the ground and let a roofer climb.
Can I replace cedar with asphalt?
Possibly, but it changes the look and may be restricted on historic houses. Ask the town and any association first.
How do I find a roofer who does slate?
Tell the line the roof is slate or cedar when you call, and ask the roofer about earlier slate or cedar work. Ask for photographs.
Will insurance cover slate repairs?
That is for your insurer to decide, and this guide cannot say. Keep photographs and written findings.
Sources
This guide is general information for Fairfield County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.