The Importance of Ventilation in Roofs

By Sophie Mace 17 Mar 2023 09:25


Ventilation is critical in roof spaces, as excess moisture and condensation can have detrimental effects on a building, causing dampness, mildew, mould, and even structural damage.

Since warm air rises and carries moisture with it, it is only natural for it to end up within a roof space. When the warm air hits a cooler surface, such as a cold roof, it turns into condensation, which can sit on the surface or drip back down into the building. The solution is to ensure effective roof ventilation, so the moisture can easily pass out of the building envelope before condensation has a chance to occur.

Source of moisture in roofs

Moisture in the roof space can come from different sources, and the average household generates around 15 litres of moisture every day. Understanding where excess moisture is coming from is often the first step in dealing with the issue and ensuring adequate roof ventilation.

  • Weather – rainwater and humidity can cause excess moisture. While a well-constructed roof should keep out rainwater, occasional droplets may get through. This isn’t typically a problem, but if your roof is leaking, this is a much bigger problem that will need to be repaired to keep moisture out.
  • Occupant activities – Typical activities such as taking showers and baths, cooking food, and drying clothing all generate a large amount of moisture. The best way to deal with these sources of moisture is through a combination of extraction fans, opening windows, and ensuring adequate roof ventilation.
  • Building materials – in new build constructions, there may be residual moisture in the building materials, which can take two years to fully dry out, and during that time, moisture needs to be allowed to escape.

A key consideration when thinking about roof ventilation is how modern building regulations can affect moisture retention in buildings. Recently, an increased amount of insulation and efforts towards creating air-tight homes has been happening, but whilst that is great for keeping homes warm in the winter, without the correct roof ventilation, it can lead to problems such as dampness, mould, and poor indoor air quality.

Types of roof ventilation

Roof ventilation comes in a wide range of types and designs, and the right choice will depend on whether the roof is pitched or flat, cold or warm, and how complicated the roof structure is. For example, roofs with loft conversions and dormers will likely require additional ventilation to ensure all areas have enough ventilation.

  • Ridge Vents
  • Off Ridge Vents
  • Box Vents
  • Roof Turbines
  • Hard-Wired and Solar-Powered Attic Vents
  • Soffit Vents
  • Fascia Vents and Drip Edge Vents
  • Gable Vents

If you are in need of a roofing service or any advice regarding your roof. Get in touch today.


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