The short answer
Sometimes, but not in heavy rain or high wind. A dry ridge is fixed with screws, clips and a ridge roll or batten rather than wet mortar, so it does not need dry weather to set. Safety still decides the day: wet tiles are slippery, wind makes long ridge units hard to handle, and an open ridge must never be left exposed to a shower.
Dry fix takes the mortar out of the weather question. It does not take the roofer's safety, or your loft, out of it.
Why dry fix and mortar differ in the wet
Along the very top of the house the two slopes meet, and ridge tiles cover that join. The older way is to bed those tiles in mortar. Mortar is a wet mix of sand and cement that must be laid, shaped and left to cure, and rain can wash the cement from a fresh joint or leave it weak.
Does dry fix really avoid that problem?
In large part, though not completely. A dry ridge holds its tiles with mechanical fixings, screws and clips into a batten or ridge board, and a vented roll or strip closes the gap beneath. Nothing there needs to cure. Marley points out that the 2014 revision of BS 5534 treats mortar on its own as too weak in tension to hold ridge and hip tiles, which is why mechanical fixings are part of any current ridge job.
That gives dry fix a real edge on a changeable Somerset day. Our page on dry ridge against mortar sets out how the two compare across the whole job, from the first fixing to the last.
What rain still stops
A wet roof is a hazard before it is a technical problem. Slates and clay tiles lose their grip when wet, moss turns a pitched slope slippery, and a roofer carrying long ridge tiles in a gust has little room for error. If the weather puts anyone at risk, the job waits for a better window.
Is wind a bigger problem than rain?
On a ridge, yes. The top of a roof is the most exposed part, and a stiff wind can catch a tile or a roll as it is lifted into place. A light shower can be worked through with care, provided the tiles are not so wet that nobody can stand on them. A strong blow cannot, and nobody should be asked to try.
Rain also matters once the old ridge comes off. For a short time the apex is open, with only underlay or bare timber below, and water that gets in can reach the loft insulation and ceiling. We strip and re-lay in sections so that no length of open ridge is left uncovered. If a shower arrives, tarpaulins go over what is exposed and the job pauses until it passes.
Wet timber and the fixings
The fixings bite into a batten, the timber strip that the tiles hang on, or into a ridge board. Timber that is soaked holds a screw perfectly well in the short term, but it also tells us something. A batten that stays wet or has gone soft is a fault, and screwing a new ridge into it only buries the problem for a winter.
Can a wet roof be inspected properly?
Yes, and often the best time to read it is just after rain. Staining on the underside of the tiles, damp felt and a wet batten line all show where water is getting in, and a wet day makes those marks easier to read. We photograph those before any fixing goes in, and the pictures come with the written price.
Where the existing battens are sound, the new ridge is screwed down to the maker's data sheet and the union with the verge, the point where ridge meets the gable edge, is checked. Our page on ventilated dry ridge explains how the roll lets the loft breathe once the roof is closed up again.
Planning a ridge job around Somerset weather
We watch the forecast for the specific days, not the week, and we look again on the morning itself. A dry ridge that goes on in a calm window of a few hours is a good outcome. A job split across showery days is usually phased, so that the roof is closed up each evening before we leave the site.
What happens if it rains partway through?
We stop, make the open section watertight and return when conditions are safe. Nothing is rushed to meet a date, and nothing is left half open overnight. The customer is told by message what happened that day and what is planned for the next, so you always know where the job stands.
If a leak is the reason for the call, the first step is to stop the water, then repair the ridge properly once conditions allow. Our overview of dry ridge and verge work explains the survey and fitting steps. Tell us when you book if you have a loft conversion or stored belongings under the ridge, and we plan the covering around them.
More on ridge work and weather
Will rain damage a dry ridge once it is fitted?
No. A dry ridge is built to shed rain from the day it goes on, with the roll or strip sealing the gap under the ridge tiles. Wet weather does not affect the fixings once they are tight, and a vented roll lets the loft breathe in damp conditions as well.
Can you re-bed a ridge with mortar in the rain?
It is a poor idea. Fresh mortar needs to cure and heavy rain can leave a weak joint. Given the BS 5534 position that mortar alone is not relied upon, we would rather fix the ridge mechanically and wait for a safer window, whatever the method.
The full picture: Dry ridge and verge repairs in Taunton ยท More short answers