Should flat roofs be vented?
It’s almost always needed, except for houses that already have warm flat roofs. As for cold flat roofs, which are more common, they need this type of ventilation because they collect higher amounts of condensation during the winter.
Do you need to ventilate a warm flat roof?
A warm flat roof usually does not require ventilation. What space do I need to allow for the ventilation? To ensure sufficient ventilation, enough space must be provided to allow for the movement of air, preventing the risk of condensation forming within the roof.
How do you fix interstitial condensation?
Another few methods to stop interstitial condensation is through vapour controlled layers positioned on the warm side of insulation, replacing old materials with newer materials designed specifically to resist condensation forming, ventilated cavities, and installing thermostat controlled heating to create a constant …
Why do flat roofs sweat?
Condensation within a flat roof mainly occurs during cold weather when moisture vapour in the air which has been generated within the heated building, rises from the room below into the cold roof void above the ceiling.
Do I need a vapour barrier on a flat roof?
To use EPDM for a warm deck flat roof construction, solid (closed cell) roof insulation such as Kingspan or Celotex should be placed on top of the roof deck, rather than in between the rafters. A vapour barrier will then need to be installed to reduce condensation in the roof structure.
Should I insulate my flat roof?
If you have a flat roof over an unheated space like a garage, then there is no need to insulate this. A flat roof should have a layer of insulation built into the structure at some level. When an insulated roof is built from new, the insulation layer can be included at different levels within the structure.
What is the dew point for condensation?
Dew Point is the temperature at which moisture will condense out of the air. If the temperature of any surface is at or below the dew point temperature then dew (condensation) will form. Here are some examples of Dew Point conditions: 85°C and 85% RH, the Dew Point is 80.9°C.
How does interstitial condensation occur?
Interstitial condensation commonly occurs when moist air permeates through elements of the building fabric, across which there is a temperature difference, typically, but not always, when warm, moist, internal air moves towards the cooler outer parts of external walls or roofs, driven by a pressure difference.