On Tuesday, 30 January 2018 21:44:05 UTC, Tony wrote:

Hi I have the same problem with my corrugated garage roof which has been cold
tar sealed on the outside and painted with Matt emulsion on the inside which
now explains all the condensation from the water based emulsion. I notice the
roofing sheets from the door to midway roughly dry out (no dripping) when I
have the garage door up for about 3-4 hours suggesting air circulation. Any
advice gratefully received Tony

You need to reduce RH. Your condensation has nothing to do with the roof's coatings. There are 3 ways to reduce RH:
1. Ventilation
2. Heat
3. Dehumidifier

Relying on ventilation alone is likely to result in dampness when outdoor conditions are damp. Heat costs. Dehumidifiers are cheap to run, but cost to buy of course.
If it's insulated, computer controlled heat just to limit RH to 80% is also an option. Ask Andrew Gabriel.


NT