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Why Is Roof Ventilation Important?

Rooflight letting in sun

Providing your roof with adequate ventilation is vital to prolonging the life of your building, and saving money in the long term by avoiding costly structural repairs due to mould, rot, or damp that will occur throughout your building in the absence of proper roof ventilation.

Roof ventilation is important to maintaining the structural integrity of your home, as well as reducing energy costs, and creating a safe environment to live in. 

View our guide to roof ventilation below, and browse our range of opening rooflights to aid ventilation in your home.

Why does mould grow on walls?

Warm air contains moisture particles. As the warm air rises and hits the colder roof, the difference in temperature causes the moisture to cool and release water onto the surface, which can form a damp spot over time; particularly on materials such as wood, fabric, and brick – all of which can absorb water. Once a damp patch has formed, it can capture mould spores that are present throughout the atmosphere and encourage them to grow into colonies.

Mould occurs throughout most environments, providing a vital role in nature as a means of breaking down dead organic matter like trees and fallen leaves. It is likely that your house will already contain mould particles in the air, which is completely normal for most homes, so you should ensure the rooms of your house are properly ventilated to not encourage mould growth on damp surfaces.

Sources of moisture on roofs

Your average household routine of washing, cooking, drying clothes, and even breathing, releases moisture into the atmosphere, which can produce up to 14 litres of water vapour in a 24 hour period. If your house is not properly ventilated then this will cause major growth of mould in a relatively short period of time. This is particularly important for the top floor and roof of your house as hot air rises, causing more condensation to form.

Below we have included some of the most common reasons that condensation and moisture will form in your house.

General use

Most household activities will produce some form of moisture in the atmosphere. Anything from washing dishes, breathing, or taking a shower will produce moisture in the air, but these issues can be alleviated by providing adequate ventilation in your rooms by opening windows or turning on extractor fans.

Building materials

If you are in a new build property, there will be a considerable amount of moisture used in the building materials that could take up to 2 years to fully evaporate. A typical housing block will require around 8000 litres of water to build, which is used for things like cement. The evaporation of this water will usually be noticed in the form of minor cracks forming on your walls.


Weather events such as rain and high temperatures will create excess moisture in the air. You may notice condensation on your windows in the winter months when you are cooking, and this type of moisture must be properly ventilated to avoid accumulation on absorbent materials such as brickwork, plaster walls, and furniture fabrics.

Increase energy efficiency with proper ventilation

Providing your home with proper roof ventilation will allow you to reduce the cost of cooling down your home by letting hot air escape through window openings. This can potentially save you thousands over the course of your occupancy, and taking steps to invest in proper ventilation for your home will help offset any extra energy costs.

Learn more about energy efficiency with our blog ‘Are Rooflights Energy Efficient?’.

Increase your roof’s lifespan

Providing proper ventilation in your roof space will prevent the accumulation of mould, which if left untreated could be costly to fix, as mould can ultimately damage the overall structural integrity of your roof. In addition to this, if your roof space is allowed to accumulate excess heat, this can damage wood and PVC fittings by causing them to warp over time.

How can I ventilate my roof?

There are a number of ways to provide proper ventilation for your roof, with one of the best methods being to install a rooflight or skylight with either automatic or manual opening options. Some rooflight types are multifunctional, and can provide access to your roof space as well as ventilation.

The COXDOME Access Hatch Roof Dome can be fitted on standard builders upstands, and will fully open to provide access to your roof with manual opening options available.

You can also view our range of smoke vents and access hatch rooflights, which provide both ventilation options, and emergency opening functions in the case of fires or excess smoke.

What opening rooflights do we sell?

We sell a range of opening rooflights, including:

BS 5250-2021 British standards on moisture accumulation 

In 2021, the British building regulations were updated, which included guidance on the accumulation of moisture in residential buildings. These regulations are taken into consideration during the design and construction phase of building development, and they state that the building designer should consider the following:

  • Water incorporated during the construction process (including precipitation)
  • Precipitation after construction
  • Water vapour arising from the occupants and their activities
  • Temporary condensation occurring when cold weather conditions are followed by warm, humid weather

The regulations also state that the building fabric should provide a weathertight envelope to minimise or prevent the ingress of moisture from external sources, and BS 5534 deals with the construction of pitched roofs. The 2018 amendment to BS 5534 and the introduction of BS 8612 have sought to improve the product quality and standard of installation of dry-fix roofing systems.

Internally, moisture is generated by building occupants and their activities. Perspiration, respiration, cooking, cleaning and washing can all generate significant quantities of moisture that needs to be removed from the building, usually by ventilation.

BS 5250 acknowledges that occupants rarely use a building in the manner intended by the designer. It recommends adopting “fail-safe” solutions to account for the likely difference between theory and reality.

More helpful blogs

What rooflights do we sell?

We sell an impressive range of rooflights and skylights, including:

Based on 210 reviews
Bob toploft
Bob toploft
I am the owner of Top loft company ltd, after reviewing reviews from various companies I ordered 2 juliet balconies from tgs arrived within 3 weeks, comunications and help was brilliant. Thanks for all your help.
Jim H
Jim H
Great service from the team. Easy to order, good buying guidance and clear install instructions for my builder. Rooflights look absolutely great! The team at TGS couldn't have been more helpful in organising a smaller delivery vehicle to help with restricted access. Highly recommend TGS.
Jack Smith
Jack Smith
Great service from a very knowledgeable company. Thanks team Toughened Glass Systems.
Paul Smith
Paul Smith
I was spending a lot of money on several rooflights so I wanted to make sure I got it right and I did. The professionalism, expertise and the quality of the roof lanterns really set Toughened Glass Systems apart.
Tyrone Eldridge
Tyrone Eldridge
There are no complaints about the experience with TGS. The entire process of ordering, supplying and delivering was flawless. I would really recommend you order your flat roof sky lanterns from these guys.
Robert Childers
Robert Childers
Best place for rooflights, they supply many different types and options. Thanks for all your support Toughened Glass Systems!
John Smith
John Smith
The glass balustrade gives us an amazing view onto the lake outside. So happy we ended up going for the frameless glass balcony from Toughened Glass Systems instead of one with posts
Louise Newsome
Louise Newsome
My job is to design the interiors for a lot of houses and a lot of times the hardest part was when the client wanted some really inexpensive rooflights that should look like some contemporary ones as well. That until I found Toughened Glass Systems and started working with them more and more. They have a lot of this kind of stuff at a very decent price, a price for anyone I can say. If you’re looking for cheap skylights for flat roofs or any types of roof lights, they probably have something for you.
Krystina Taylor
Krystina Taylor
Always kept us up to date with our order even when delayed by a few days. Great service from the start and good quality glass balcony delivered.