Slate is forgiving. It sits up there for decades, shrugging off rain, frost and whatever the prevailing wind throws at it, giving you almost no reason to think about it at all. That is exactly the trouble. By the time a slate roof makes itself noticed — a brown patch spreading across a bedroom ceiling, a damp smell in the loft — water has usually been finding its way in for weeks.

You do not need to climb anything to stay ahead of it. You need a habit: a quick look from the ground most months, a proper check in spring and autumn, and a roofer on the phone the moment something genuinely changes. Twenty minutes with a pair of binoculars is the whole job.

How often is often enough?

For most slate roofs, three kinds of inspection cover almost everything:

• A monthly glance — two or three minutes from the garden, the drive or the pavement opposite. You are looking for change, not perfection.
• Twice-yearly proper checks — a thorough ground-level survey in spring, once winter has done its worst, and again in early autumn before it starts again.
• A storm check — after every named storm, run of gales or heavy snow, once it is safe to be outside.

Newly repaired or re-slated roofs are worth watching a little more closely for the first year. Older roofs with heavy moss deserve the same routine, but with a lower tolerance for "I'll deal with it in spring".

A month-by-month routine

This is built around the British weather year, so you are checking for the right things at the right time rather than repeating the same survey twelve times.

• January and February. Walk the perimeter after gales and look for slate fragments on the ground or in borders. Their colour and thickness hint at which part of the roof they came from. From inside, check the loft for daylight between slates and fresh damp patches on rafters or around the chimney breast. If snow settles, leave it alone — scraping at a roof is how people break slates, and a frosty surface is not somewhere to be.
• March. Clear gutters, hoppers and downpipe outlets of winter debris. Blocked gutters are behind a surprising amount of "roof" damp, because water backs up under the eaves and into the wall instead of running away.
• April and May. Look hard at flashings and chimney stacks now the weather has settled. If birds are nesting under lifted slates or in the eaves, leave it — wild birds' nests are protected, so timing matters. Book any non-urgent work now; dry, calm weather suits roofers and gives you more choice of dates.
• June and July. The best month for a slow, thorough survey. Check valleys and the chimney stack for moss and seedlings, and look at the flashing around dormers and rooflights for lifted lead or cracked mortar.
• August and September. The pre-autumn clear-up. Cut back branches that overhang or scrape the roof, and deal with ivy before it works its way under slates and into the mortar.
• October and November. The pre-winter inspection. Check ridge tiles, the mortar along verges, and the flaunching around chimney pots. Anything loose will be looser after a freeze-thaw cycle.
• December. Watch the forecast and check again after the first hard frost or thaw, when new damp patches often appear inside.

What you can check from the ground

Stand back far enough to see the whole elevation, then work slowly along it. Binoculars help, and so does your phone camera zoom — a photo taken from the same spot each season makes changes obvious.

• Dark gaps in the slate courses, which usually mean a slate has slipped or gone.
• Slates that look cracked, flaking or lighter in colour than their neighbours.
• Ridge tiles sitting out of line, or mortar missing between them.
• Lead flashing lifting away from the chimney, or dark staining running down the wall beneath it.
• Heavy moss or plants growing in gutters, valleys or the chimney stack.
• Gutters sagging, overflowing or sprouting grass, and downpipes that no longer line up with the hopper.
• Any dip, hump or wave in the roofline that was not there last year.
• Damp staining on render, soffits or brickwork just below the eaves.

Inside, look for ceiling stains, peeling paint at the top of a wall, and a musty smell in the loft. Water rarely appears where it enters.

What to leave to a roofer

Slate is brittle and slick. Walking on it cracks tiles, and cracks let water in — so a well-meaning inspection can cost you more than the problem you were checking for. Stay off the roof, do not lean ladders against gutters, and do not prod at slates with a pole. Anything above gutter level is a job for someone with the right access equipment and insurance.

When to stop looking and pick up the phone

Book someone promptly if you spot any of the following:

• A slate missing, or clearly slipped out of position.
• Water coming in, or a stain that has grown since your last look.
• Daylight visible through the roof from inside the loft.
• Loose ridge or verge tiles, especially after wind.
• Flashing pulled away from a chimney or wall.
• A roofline that has visibly sagged.

After storm damage, photograph everything before anything is moved. If you plan to claim, check your buildings insurance policy wording — insurers usually expect you to prevent further damage, but the details vary, so read the policy or speak to your insurer before work starts.

Making the habit stick

Put two reminders in your calendar: the first dry weekend in April, and the first in September. Add a note to your phone each time you look, with the date and anything that has changed — it is far easier to describe a problem to a roofer when you can say when it appeared. If your roof has matching spares in the garage or loft, keep them; old slates are hard to match later. And do not let a handful of slipped slates convince you that you need a new roof. Most of the time, a small repair is all that is needed, provided you catch it early.

Photo: macayran / Pixabay