The short answer
End caps are the small finishing pieces at the ends of a dry verge run. One closes the bottom of the verge at the eaves, and another finishes the run at the apex. They stop wind and rain entering the open end of the verge unit. A cap that is not fixed to the right point, or is the wrong shape for the tile, can blow off.
Caps are among the smallest pieces in a dry verge kit and among the first to go missing. Fitting them properly takes more care than their size suggests.
The parts of a dry verge run
On a gable-ended house the last row of tiles up each sloping side is the verge. A dry verge system finishes that edge without mortar, using a row of verge units that run from the eaves up to the ridge. Each unit is clipped or screwed to the tiles or to a batten, and the joints between units are closed with small connectors. The whole run is then capped at each end.
Which end caps does a verge need?
There are normally two. The lower cap, at the eaves, closes the open bottom of the first verge unit so that wind and birds cannot get inside it. The upper cap, at the ridge, ends the run neatly at the high point of the roof, or ties into the ridge system. Some kits provide left-hand and right-hand versions, since a verge on the left of a gable is the mirror of one on the right, and some provide a single cap that suits both sides. Check the data sheet to find which applies to your kit.
Without these caps the hollow inside the verge unit is open at both ends, and it behaves like a funnel for weather.
How end caps are fixed
The cap is held in two ways. It slides or clips onto the end of the verge unit, and it is secured with a screw or a pin into the batten or tile beneath. Some designs rely on the shape of the cap to lock it in; others need a fixing through a marked hole. The maker's instructions say which, and following them matters, because a cap is held by very little.
Can end caps be glued instead of fixed?
Adhesive can supplement a fixing but should not replace one. A bead of sealant on a damp or dusty cap may hold through a dry spell and let go with the first frost. Wind lifts a cap from beneath, so a mechanical fixing has to take the load. Marley says the 2014 revision of BS 5534 ended the assumption that bedding mortar alone could hold ridge and hip units, and the same lesson holds for a verge cap that is stuck on and nothing else.
Screw length counts. A screw must pass through the cap and reach sound timber, not merely bite the tile. Where a cap sits at the very end of a verge, the batten behind it is often shorter, so the fixing point needs checking on the day.
Why caps blow off
Verges are among the most exposed parts of a roof. Gusts that hit the end wall of a house rise and sweep across the edge tiles, and the suction is strongest at the corners, which is exactly where the caps sit. A cap that is a poor fit for the tile has a gap round it that lets the wind in. Once air gets underneath, it lifts the piece away, and the next gust takes the unit beside it.
What makes a cap the wrong fit?
Tile profiles differ. A cap made for a flat tile will not sit snugly on a pantile or a double Roman, and one meant for the right-hand end will not close the left. Cheap kits sometimes ship a generic cap that fits several profiles poorly. Plastic that has become brittle, or a clip that has been bent during fitting, is another cause. And caps are small enough to be forgotten: a verge fitted in a hurry may have no top cap at all.
If caps are missing, the unit behind them is exposed and can fill with dust, leaves and nesting material. Our page on dry verge fallen off deals with what happens when the run itself comes away.
Checking and replacing caps
You can check caps from the ground. Look at each end of the verge, at the eaves and just below the ridge, for a missing piece, a gap beside the cap or a cap sitting at an angle. After a gale, look again, and a pair of binoculars helps. If you hear tapping or rattling at the gable end in the wind, a loose cap is a likely cause.
Can I buy a replacement cap and fit it?
You can buy parts for many kits, but the cap has to match the make, the tile profile and the side of the gable. Fitting needs access at the very edge of the roof, which is a working-at-height job and best left to a roofer. When we survey, you see photos of each cap and the fixing behind it, then receive one written price.
A single replacement cap is a small repair. Where several are missing, we look at the fixings along the whole verge as well, because one loose piece rarely stands alone. The dry verge system page covers the kit in full, and dry ridge and verge sets the wider scene.
More on verge caps
Do end caps need to match the colour of my tiles?
They should sit close to it, since the caps are among the few parts visible from the road. Kits usually offer several colours, and some offer clay or concrete caps as well as plastic. Checking a sample against the roof in daylight before ordering avoids a visible mismatch on the day.
Can birds nest behind a missing verge cap?
Yes, an open verge end gives birds a sheltered hollow. If a nest is already in use, wait until the birds have left, because under the Wildlife and Countryside Act 1981 anyone who intentionally destroys a nest in use commits an offence. Once the nest is empty, a fitted cap shuts the gap for good.
The full picture: Dry ridge and verge repairs in Taunton ยท More short answers