What dew-point margin should I use for coatings?

Many coating specifications ask for the surface to be at least 3 degrees above the dew point, which is the default here. Use the figure in your product data sheet or specification.

Does it show rain from the last few days as well?

Yes. The Record tab gives measured rainfall day by day from the nearest Environment Agency gauge, with the station named and its distance from the site.

Can I hide the limits that do not apply to roofing?

Yes. The roofing preset shows the limits roofing uses, and Settings has a switch for every limit on the first screen.

Weather Metric › Roofing weather forecast

When are wind, rain and dew point outside your roofing and coating limits?

Roof work and external coatings answer to three things at once: gusts on large sheets, rain on open work, and air that sits too close to its dew point. Weather Metric reads each against your own figure for the next 24 hours.

Sheets and gusts

Roofing sheets and membranes behave like sails. The roofing preset starts the careful-lift gust at 28 km/h (about 17 mph), a common planning figure for handling large sheets; set your own from the method statement. Where it is exceeded, the caution line suggests considering holding large or light loads and briefing the team.

Rain on open work

The rainfall threshold is set per hour, in millimetres. The roofing preset starts it at 0.5 mm an hour, because membranes, adhesives and open decks tolerate less than most external trades. The limits show the wettest hour and its window, and the Record tab keeps what actually fell at the nearest Environment Agency gauge.

Dew point and coatings

Coatings and many adhesives need the surface to sit a margin above the dew point, commonly 3 degrees. Weather Metric works out the dew point from the forecast temperature and humidity and reports how close the air comes to it during working hours. It is an air figure: the surface temperature measured on site is the reading that governs.

What it leaves to you

Weather Metric reports forecast and measured conditions against limits you set. It does not decide whether an activity goes ahead: the lift plan, the method statement, the manufacturer’s figures and the people responsible on site do that.

Questions people ask

What dew-point margin should I use for coatings?: Many coating specifications ask for the surface to be at least 3 degrees above the dew point, which is the default here. Use the figure in your product data sheet or specification.
Does it show rain from the last few days as well?: Yes. The Record tab gives measured rainfall day by day from the nearest Environment Agency gauge, with the station named and its distance from the site.
Can I hide the limits that do not apply to roofing?: Yes. The roofing preset shows the limits roofing uses, and Settings has a switch for every limit on the first screen.