Dry-fix vs mortar-bedded ridges
Cracked mortar along the ridge is one of the most common defects we photograph. The question is whether to re-bed it or convert to a dry-fix system.
Why mortar fails
Mortar is rigid and the roof moves. Thermal cycling and building movement crack the bedding, water gets in behind, frost widens the crack, and eventually a ridge tile lifts in high wind.
How dry fix works
A ventilated roll or union under the ridge, with each ridge tile mechanically screwed to a batten. No mortar to crack, ventilation at the ridge, and tiles that stay put in wind.
When mortar is still right
On listed buildings and some conservation-area properties where the appearance of a dry-ridge is not acceptable, correctly mixed and executed mortar bedding remains the appropriate repair.
Half-measures to avoid
Smearing fresh mortar over cracked bedding without raking it out is the classic short-lived repair. It looks fixed for a season and fails at the same joints.
Doing hips at the same time
Hips fail the same way and share the same access. If the ridge is being converted, doing the hips together is a fraction of the cost of a second visit.
FAQs
Slightly — the tiles sit on a ventilated roll rather than a mortar bed, which is visible on close inspection but not obtrusive from the ground.
The materials cost more than sand and cement, but the job is faster and doesn't need repeating in a decade.
It adds high-level ventilation, which helps, but it isn't a substitute for correct eaves ventilation.
Related reading
More on comparisons and the jobs that usually come with it.
- Flat roof systems compared and how long each lastsComparisons
- Roofer or general builder: who should do the workComparisons
- Warm roof vs cold roof constructionComparisons
- Roof replacement cost by roof type and property sizeCosts & budgeting
Looking for something specific? See our roofing services, cost guides, common roof problems or the areas we cover.
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