When a roof starts giving trouble, the big question is whether a repair will do, or whether it's time for a new roof. Repair too often and you can spend more than a replacement would have cost; replace too early and you've spent money you didn't need to. This guide explains how roofers make that judgement, so you can have an informed conversation about your own home.
When a Repair Is the Right Answer
A repair usually makes sense when the problem is local and the rest of the roof is in good health. Typical examples:
- A few slipped or broken tiles after a storm
- A ridge or hip that needs re-bedding
- Failed lead flashing around a chimney or dormer
- A blocked or leaking valley
- A single damaged area from a fallen branch
If the tiles or slates elsewhere are firmly fixed, the felt or membrane underneath is intact and the timbers are dry, a well-done repair can give many more years of service.
When Replacement Makes More Sense
Replacement becomes the better value when the problems are widespread or keep coming back. Warning signs include:
- Tiles slipping all over the roof: on older roofs, this usually means the nails have corroded (nail fatigue). Fixing one area just moves the problem elsewhere.
- Torn, brittle or missing underfelt: on many older roofs the original felt has perished, so any tile movement lets water straight in.
- Rotten or undersized battens: the timbers holding the tiles have softened or broken.
- Repeated repairs: if you've had several call-outs in the last few years, the roof is telling you something.
- Porous or spalling tiles: clay and concrete tiles that are crumbling, flaking or soaking up water.
- A sagging roofline: this can mean structural issues that need investigating.
Our guide to the signs your roof needs repairs covers what to look for from the ground.
The Age of the Roof Matters
Different roofs last for very different lengths of time. A concrete tile roof might last 40 to 60 years, a clay tile roof longer, and a natural slate roof can last a century. If your roof is near the end of its expected life, a large repair is often money that would be better put towards a replacement. Our guide on how long a roof lasts has typical lifespans for each material.
Across Surrey, many 1930s homes in places like New Malden, Ewell and Long Ditton are now reaching this point, with original tiles, battens and nails that have done nearly a century of work.
A Simple Rule of Thumb
As a rough guide, if the cost of the repairs you're likely to need over the next few years is getting close to a significant part of the cost of a new roof, replacement usually wins. A new roof also comes with a fresh guarantee, modern breathable membrane, better ventilation and the chance to improve insulation.
The Middle Ground: Partial Re-Roofing
Sometimes only one slope or section of a roof has failed, perhaps the side that faces the prevailing wind, or a rear roof that's had more weathering. Re-roofing just that section can be a sensible compromise, as long as the new and old areas are joined properly and the replacement tiles match.
What About Planning and Building Regulations?
Like-for-like re-roofing rarely needs planning permission, but there are exceptions, and replacing a large part of a roof can mean the insulation must be brought up to current standards. Read our planning and building regulations guide before you decide.
Get an Honest Opinion
We'll inspect your roof, show you photos of what we find and tell you honestly whether a repair or a replacement is better value. If a repair will do the job, we'll say so. See our roof repairs and new roofs services, then call 07470 744247 for a free, no-obligation inspection. There's no call-out fee and no deposit.