Why we don't recommend patching a roof that's already failed

We get called to a lot of houses that have been patched. Usually multiple times, by multiple people, over multiple years. The patches have held, sort of, and the bills have been modest, sort of. And then one day the patches stop holding and the bills stop being modest.

This isn’t about criticising previous roofers. Sometimes patching is the right call. Sometimes it isn’t. The problem is when nobody tells the homeowner the difference.

When patching is fine

Patching makes sense when the surrounding roof is sound. A single slipped tile after a storm, on a roof that’s otherwise good for another ten years — patch it. A cracked slate on a 1990s roof that’s otherwise fine — replace the slate. These are sensible, targeted repairs.

A patch on a sound roof is cheap, fast, and effective.

When patching is throwing money away

The signs that the roof itself has failed:

• Multiple slipped tiles or cracked slates — usually means the fixings are failing throughout, not just in the spots you’ve noticed.
• Sagging in the roofline — structural movement, not just surface damage.
• Visible daylight in the loft — the felt and battens underneath have failed. Patches on top can’t fix that.
• Persistent leaks in different places — water is finding multiple paths in. Each patch fixes one path, but more paths open up as the roof continues to deteriorate.
• Mortared ridge tiles falling off — usually means the ridge mortar has failed throughout. Spot-fixing one section rarely holds because the rest follows.
• Tiles that crumble when touched — particularly older concrete tiles or delaminating slate. The material itself has reached end of life.
• Repeated patches over 5+ years — if you’ve had the same area patched three times, the underlying problem is not going to be solved by patching it a fourth time.

What we say when we see a failed roof

We write it up honestly. The report will say something like “this roof has reached end of serviceable life; further patching is not recommended; estimated remaining service life of current covering is X years; replacement quote enclosed.”

That sounds alarmist, but it’s not. A roof that’s been patched four times and is still leaking is costing more in patches than a re-roof would have. The math usually works out about three years in.

The thing nobody mentions: what patches hide

When you patch a roof, the patch fixes the visible problem. The patch doesn’t fix the bit you can’t see — the felt underneath that’s also degrading, the batten that’s also rotting, the fixings that are also failing. By the time the felt is failing visibly (stains on the ceiling, daylight in the loft), the patch is dealing with damage that’s been going on for years.

A re-roof strips the lot, lets us see what’s underneath, replaces what’s needed, and starts again. It’s the only way to genuinely reset the clock.

How to tell what you’ve got

Three questions:

1. How old is the roof? Concrete tiles typically last 40-60 years. Natural slate can last 80-150 years depending on the source. Felt underneath has a shorter life, often 20-30 years on older roofs.
2. How many patches has it had? One patch in 30 years, fine. Three patches in five years, the roof is telling you something.
3. What’s the rest of the roof look like? If you can see multiple failed areas from the ground, the ones you can’t see are usually not much better.

If the answer to any of those is “I don’t know” or “more than I’d like”, book a survey and we’ll tell you honestly what’s worth patching and what isn’t.