What is a roof ridge?
The roof ridge (or simply ridge) is the top horizontal line of a gable roof, where the two sloping roof surfaces meet. It is the highest point of the roof. The ridge must be finished watertight, as water, wind, and snow can reach it from both sides.
How is the roof ridge finished?
The ridge is a vulnerable point on the roof: two roof surfaces come together and, without finishing, leave an open seam. There are several ways to make the ridge watertight:
Ridge with roof tiles (ridge tiles)
The most traditional method. Half-round or angular tiles are placed on the ridge and secured with:
- Mortar — The classic method. Ridge tiles are bedded in mortar.
- Dry ridge system (mechanical) — A more modern method using clips and a ridge batten. No mortar needed, more resistant to shrinkage and settlement.
Ridge with metal flashing
For metal roofing or lighter structures, a metal ridge profile is used. This is screwed over the seam and sealed with a rubber strip.
Ridge on a flat roof
A flat roof has no ridge — the water flows to a drainage point (gutter or internal drain). A mono-pitch roof also has no ridge, as there is only one sloping surface.
Roof ridge on a shed, garden house, or garage
When building a shed, garden house, or garage with a gable roof, you need to finish the ridge properly:
- With roof tiles: always use ridge tiles or a dry ridge system
- With bitumen shingles: the top layer of shingles is folded over the ridge, or special ridge shingles are used
- With corrugated sheets: use a ridge cap (metal or plastic) that covers both roof surfaces
A poorly finished ridge is one of the most common causes of leaks in self-build projects.
Ventilation via the ridge
The roof ridge also plays a role in roof ventilation. Warm, moist air rises and must be able to escape through the top of the roof. This prevents condensation and wood rot.
On well-ventilated roofs, ventilation ridge tiles or a ridge ventilation profile are used. The airflow works as follows:
- Air enters via the bottom (at the gutter)
- Flows upward along the underside of the roofing material
- Exits through the ventilation opening in the ridge
Common mistakes
- Mortar directly on roof tiles without a ridge batten — cracks with temperature fluctuations
- No ventilation on an insulated roof — leads to condensation problems
- Not checking the ridge after a storm — ridge tiles can shift in strong wind
Related terms
- Gable roof
- Mono-pitch roof
- Roof tiles
- Ridge purlin
- Fascia board
- Gutter