Dry verge caps blown off

1What a dry verge cap is and what it protects

The verge is the sloping side of a gable-ended roof, where the last row of tiles stops above the wall. Traditionally this side was finished with a strip of mortar. A dry verge system replaces that mortar with a cap, usually clipped or screwed into place, that covers the end tile and seals the joint without wet trades.

The cap does two things. It keeps rain from running in under the end tiles, and it holds those tiles down against wind. Take it away and the end of the roof loses both protections at once.

You will often notice the failure first as a piece of plastic or tile in the garden, or as a flapping sound at night. The related page on dry verge noise explains the warning signs that tend to come before a cap goes.

2Why caps come off at the gable

The perimeter of a roof is where wind pressure is strongest. Marley's account of BS 5534 says tiles around the perimeter had to be fixed twice, which hints at how hard that side is worked. A cap that relies on a single fixing, or on clips that have gone brittle, is the first thing a gale finds.

Fixings can fail in several ways. Screws may have been driven into a soft batten end and pulled out. Clips can snap if they were bent during installation. Caps from one maker are sometimes mixed with clips from another, so they hold in calm weather and give way in a blow.

Movement at the edge adds to this. If the supporting undercloak or the end tiles themselves are loose, the cap has nothing firm to grip, however carefully it was fitted in the first place.

3What to do straight away

Stay on the lawn rather than going up a ladder. Photograph the gable side, noting how many caps are missing and whether the tile ends are still in line. Collect the fallen pieces and keep them dry; their shape and any markings help identify the system.

If rain is getting in, the exposed side is covered first. A temporary cover keeps water out of the wall head and the timbers until the proper parts are sourced, and a leaking roof is given priority.

Avoid filling the open edge with mortar or sealant as a stop-gap. It does not bond reliably to a dry system, and it makes it harder to remove cleanly when the right caps are fitted. Our page on verge repairs covers the wider job, including what happens when the damage goes beyond the caps themselves.

Keep an eye on the neighbouring gable if the houses are a pair or a terrace, since the same weather and the same age of fixings often affect both ends.

4Identifying and replacing the system

Dry verge, ridge and hip systems are tested to BS 8612:2018, which Marley describes as the test specification for such systems. Each maker publishes fixing instructions for its own parts, so a replacement should come from the same family or a clearly compatible system.

We identify the profile from the remaining caps, the pieces you have kept and the tile type. If the original product is no longer made, a full run may need replacing with a current system so the clips and caps match along the whole side. A clip that has been bent open once will not grip properly a second time, so old clips are renewed with the caps rather than reused. That is a bigger job than a few missing parts, but it avoids a mixed, weaker edge.

Hips on the same roof often use related components. The page on hip irons explains the bracket that supports the lowest hip tile at the eaves.

5What is checked underneath before the caps go back

Before new caps are fitted, the end tiles, the battens and the undercloak beneath them are checked. A soft batten end will not hold a screw, and a broken undercloak leaves the tile edge unsupported. Replacing caps over a failed base only restarts the same fault.

If the edge is sound, the new caps are fitted to the manufacturer's instructions with every fixing in place. If it is not, the repair widens to include the undercloak or the end tiles.

Your survey includes pictures of the gable itself, and the price is given in writing as one sum. Since the 2014 revision of BS 5534, mechanical fixings are expected on ridge and hip tiles, and the thinking at the verge is the same. You can read what the work covers under ridge tile repairs.