Maintenance advice
Repair or replace? How to tell what your roof actually needs
Two contractors, two different answers, and a five-figure gap between them. Here is what actually determines whether a roof needs replacing.
Maintain Property South · · 2 min read
If you have had two quotes for a roof and they disagree about whether it needs replacing, the disagreement is usually about what nobody has looked at.
A roof covering — the tiles or slates you can see from the ground — is only one part of the system. Underneath it sit the battens the covering is fixed to, the felt or membrane that catches anything getting past, and the rafters holding the whole thing up. A roof can look tired and be structurally fine, or look presentable and be close to failure.
What points towards a repair
Isolated damage on an otherwise sound roof is a repair, and anyone telling you otherwise should be asked why.
- A handful of slipped or cracked tiles, with the rest of the covering in good order
- Failed mortar on the ridge or verge, where the covering itself is sound
- A leak that traces to a specific flashing, valley or penetration
- Damage from a single storm event on a roof that was fine beforehand
What points towards a replacement
Replacement becomes the sensible answer when the problem is systemic rather than local — when you would be paying repeatedly for repairs that address symptoms.
- Widespread delamination or crumbling across the covering, not just in patches
- Battens that are rotten or splitting, so new tiles have nothing sound to fix to
- A failed or absent underlay, meaning any water past the covering reaches the timbers
- Sagging between rafters, which suggests a structural problem rather than a covering one
- Repeated leaks in different places, which is usually a roof telling you it is finished
The loft tells you more than the roof does
The most informative ten minutes of a roof inspection are usually spent inside the loft with a torch, not outside on a ladder. Daylight through the covering, staining on the rafters, damp or crumbling felt and water marks on the joists say far more about the condition of a roof than the view from the pavement.
Getting a straight answer
Ask any contractor quoting for a re-roof what they inspected, whether they went into the loft, and what condition the battens and underlay are in. A contractor who has genuinely surveyed the roof will answer immediately. One who priced it from the drive will not.
