12-12-2019, 10:19 PM
It is worth considering the science. Warm air holds more moisture than cool air but will have a lower relative humidity. Thus on an autumn day as the temperature drops the relative humidity rises until as the dew point temperature is reached condensation is formed. On a wet winters day the air between raindrops contains less water than the warm air in your kitchen when the spuds are boiling. This is why modern heat exchange systems drag air into buildings through heat exchangers whilst expelling the internal air. This keeps the temperature up and moisture down. Garages are not heated full time so it pays to insulate well to keep heat in. My own garage had single skin brick walls and a single skin tin roof. Every winter condensation would drip from the roof and the environment was poor. 18 months ago the roof was changed for a modern system of joists, plywood deck 100 mm insulation a second plywood sheet carrying a waterproof membrane. The change was staggering. No more condensation,Pleasant atmosphere and last winter the temperature did not drop below 5 degrees C at any time. When I was working a simple fan heater produced a pleasant temperature. Also the garage remains cool in the summer. What we need to achieve is to keep the air above dew point temperature at all times so condensation does not form. In doing this insulation is paramount. New houses have in excess of 200 mm in their roof, but any voids must be cross ventilated. Colin Ayre