How do I fit continuous dry verge?

What does continuous dry verge replace?

The mortar fillet along the gable edge. Continuous dry verge is a screwed-down section that caps the edge course and closes the gap over the batten ends.

Nothing is bedded. It does the same three jobs mortar was doing: holding the edge slates or tiles down, keeping rain out of the roof void, and keeping birds and wasps out of the batten cavity. The Liteslate system uses a continuous section with connectors between lengths, rather than a separate cap over each tile, so there are fewer joints to fail.

Why does mortar keep cracking at the verge?

Because the roof moves and mortar does not. Timber swells and shrinks with moisture, the edge course lifts a fraction in wind, and mortar cannot follow either. It cracks along the joint, water runs in behind it, and the batten ends rot where nobody can see them. Freeze-thaw finishes the job. This is why BS 5534:2014 stopped mortar counting as a fixing at all. Every ridge, hip and verge unit now has to be mechanically fixed, whether or not there is mortar as well. A verge you repointed five years ago failing again is normal, not bad luck.

Is fitting dry verge a job I can do myself?

On a bungalow, a garage or an extension, yes, with a tower and a second pair of hands. Not above single storey without an edge-protected scaffold.

Settle the access question before you buy anything. A verge run is at the roof edge, on the rake, which is the worst place on a roof to be working. Ladders and roof edges are where roofers get hurt, and a fall from a two-storey gable is life-changing. The scaffold hire cost is small next to the alternative. This is a two-person job either way, and you stop when it starts gusting, because a verge length is a sail and so is a slate.

How is continuous dry verge fitted?

Strip the mortar, check the timber, then work eaves to ridge.

• Hack off the old fillet and clear the debris out of the gutter before you go any further.
• Check every batten end. Soft, dark or crumbling timber gets cut back to sound wood and replaced. Screwing new verge to rotten batten wastes the whole day.
• Set the first length at the eaves, lined up with the fascia, and fix it into the batten ends.
• Join lengths with a connector rather than butting them. The connector carries the joint and lets the run expand and contract.
• Work up the rake and close the top with a ridge end cap.

Screws need at least 25mm of penetration into sound timber. Fixing centres and screw length vary between systems, so follow the instructions on the product page rather than a rule of thumb. Verge detail also varies by house, particularly on a clipped gable or where the roof meets a parapet. If yours does not look like the diagram, ring us before you cut anything.

Does dry verge change roof ventilation?

No. A verge is not a vent, and capping it changes nothing, because ventilation happens at the eaves and the ridge. If the roof was short of air before, it still is afterwards. Low level air comes from circular or continuous soffit vents. High level air comes from a ridge vent, or from a tile vent where a ridge vent is not practical. Condensation dripping off the underside of the felt in January is a sign of missing eaves ventilation, not verge ventilation.

How many lengths and connectors do I need?

Measure the rake, not the width of the house. The rake is the sloping edge from eaves to ridge, and it is always longer than the horizontal span. A plain gabled house has two rakes per gable end, so four runs before you count dormers, porches or a bay. Length per unit varies, so divide the rake by the figure on the product page rather than guessing. The numbers that decide the order:

Item	Figure	Note
Fixing method	Mechanical, every unit	BS 5534:2014, mortar alone is not a fixing
Screw penetration	25mm minimum into sound timber	Cut back and replace rotten batten ends first
Batten size, rafters at 600mm centres	50 x 25mm	38 x 25mm where rafters are at 450mm
Eaves ventilation, pitch 15 degrees and over	10mm continuous equivalent, both sides	Soffit vents, continuous or circular
Eaves ventilation, pitch under 15 degrees	25mm continuous equivalent, both sides	Shallow pitches need more air
High level ventilation	5mm continuous equivalent	Where pitch exceeds 35 degrees or span exceeds 10m
Runs to measure	Rake length x 4	Two rakes per gable end on a plain gabled roof
Connectors per run	One fewer than the number of lengths	Add one spare per job
Wastage	5 per cent	Cuts at eaves and ridge