Most entries are at the roof edge. A meaningful minority are not, and those are the ones that get missed — because everybody surveys the eaves and nobody looks at the top.
The ridge
The ridge is the horizontal line at the apex, capped with ridge tiles either bedded in mortar or fixed dry with a mechanical system. The ends of the ridge line, where it meets a gable, are the vulnerable points: mortar cracks and falls out, and dry-ridge end caps go missing in the same way verge caps do.
An open ridge end leads into the highest part of the roof space, which is warm, dry and as far from any disturbance as it is possible to get. It is a good address, and animals that find one tend to stay.
The tiles
Individual tiles are not usually a way in on their own, because the underlay below them is a second line of defence. What creates an opening is a tile problem combined with an underlay problem, and those go together more often than not:
- A slipped tile, from a failed nib or a corroded nail
- A cracked or broken tile, frequently from foot traffic or a fallen branch
- A lifted tile after a gale, particularly on an exposed slope
- Tiles disturbed around a previous repair, an aerial fixing or a solar installation
The underlay, which is the real issue
Traditional bitumen felt has a service life, and on roofs of a certain age it has reached the end of it. Perished felt is brittle, tears at the slightest disturbance, and sags away from the battens. Once it has failed, every displaced tile above it is a direct opening rather than an inconvenience.
Older buildings may have no underlay at all, which was normal construction for a long time. In that case a single displaced tile is a hole into the roof space.
This is why a roof can look sound and not be. The covering is the visible layer and the underlay is the one doing the work. A roof with perfect tiles and perished felt is a roof with a great many potential openings.
Thetford's housing
A great deal of the town's housing was built within a few concentrated periods, which means whole streets share a roof construction and a roof age. Where one property's underlay has reached the end of its life, its neighbours are usually at the same stage — which is worth knowing if a street starts having the same conversation.
What to look for from the ground
- Ridge tiles out of line, or a visible gap at either end of the ridge
- Mortar fragments in the gutter or on the ground below a gable
- A tile sitting proud, slipped down, or with a corner missing
- A dark line or shadow where a tile should be sitting flat
- Daylight visible in the roof space from the hatch, away from the eaves — which usually means high up
Questions
How long does roofing felt last?
Traditional bitumen felt has a finite life and many roofs of a certain age are past it. Modern breathable membranes last considerably longer.
Can one slipped tile really let a squirrel in?
Where the underlay has perished or was never there, yes. Over sound felt, usually not on its own.
Is a dry ridge better than mortar?
It avoids the cracking, and it depends on caps and fixings that can go missing. Both want checking after a gale.
Squirrel Control Thetford
Squirrel control in Thetford is £280 fixed cost. Proofing work, where it is needed afterwards, is £180. Call 01502 630 122 and tell us what you have heard or seen.
For squirrel control in Thetford, call 01502 630 122, or read the Thetford squirrel control page.