Eliminate Condensation In Loft With Roof Ventilation
Friday, 17th August 2018
You don’t have to be cooking up a storm or taking a hot shower to generate moisture in the home. Nor do you have to be running a tap or be anywhere near water for that matter. We release moisture into the air every time we talk, sleep, breath. It’s an unavoidable by-product of everyday living.
While it’s easy to see the visible effects of condensation in our bathroom or kitchen when warm moisture hits the cold surfaces of windows and radiators and forms drops of water, it’s harder to keep track of the final destination of all that other vapour we so regularly release.
As is its nature, moist air travels upwards, rising through our floors until it reaches the roof space, the part of the home where the effects of condensation can be most damaging, especially in cold roof constructions.
In some cases during the winter months, moisture build-up in unventilated lofts can have devastating consequences, from causing damp, mould and ice damming, to potentially rotting the timber that holds the roof together.
How Can Roof Ventilation Fight Condensation In The Loft?
All cold roofs should have some form of roof ventilation in place to prevent warm air condensing in the loft. The most popular roof ventilation solution is to have soffit vents providing cool, fresh air into the loft from a low level, and a tile vent or ridge vent at a high level for the warm stale air to exit the building.
This two-way ventilation removes the damp air and creates gentle movement of air in the loft, helping to prevent damage to possessions, mould forming on the ceiling and timbers from rotting.
Good ventilation systems will usually specify how much air they can circulate, but how much you need can depend on a number of factors, including location of the property in regards to wind exposure, if your loft has been converted into a living space, and, most tellingly, how much insulation is in place throughout the home.
However many air vents you require, the principle remains the same in that you need ventilation to ensure healthy movement of air.
While today’s building regulations normally ensure all new builds come fitted with sufficient ventilation and insulation from the outset, with older homes that were built around the regulations of the day, creating this healthy climate is not as straightforward.
Many homeowners have made smart, money-saving decisions to improve insulation in the home through filling wall cavities and upgrading to double glazed windows without appreciating the need for roof ventilation is equally, if not more, important.
Modifying homes in this manner means that there are less gaps in the home for the warm moist to escape out of, meaning the vapour gets trapped inside and eventually creeps up to the loft.
Older homes that have not had additional insulation fitted will generally not require ventilation if showing no signs of condensation- although this kind of home will naturally be a lot colder for it.
Be aware that if your cold roof space is unventilated, the existing loft insulation can soak up the water droplets from condensation above, resulting in the insulation not working as well as it should.
Having effective roof ventilation, such the Manthrope tile vent featured in the video above, in place will help solve these problems and mean less worry about what's happening in your loft.
As well as getting ventilation right, remember to get into the habit of opening up your windows and airing your home a few times a day to remove a lot of the moist air at source before it has the chance to rise through the home.
The enclosed void of a warm pitched roof with insulation fitted along the line of the rafters means ventilation is not normally required.
My Loft Is Too Hot. Help!
As if summer 2018 hasn't been hot enough, spare a thought for those people who have been feeling the heat even worse thanks to a roof space that is insulated, yet unventilated.
Not having proper roof ventilation fitted to combat the effects of solar gain is not a good idea. Solar gain occurs when the sun shines down on the roof, passing through into the loft space which, if unventilated, can cause a suffocating build-up of heat.
If your unventilated loft space has been converted into a habitable room, this could be very uncomfortable for those living and sleeping in it, although if roof windows are installed this will help massively in keeping the area cool.
If your loft is unoccupied and has little or no ventilation, all that heat from the sun will slowly make its way down into the upstairs. This can cause uncomfortable overheating in bedrooms and bathrooms.
The effects of having an unventilated roof is a lot harder to see in the summer than it is in winter, although you might be able to feel it and smell it too. The constant shine of the sun on the roof can cause black bitumen felt to begin smelling, a sure-fire sign that there is a lack of fresh air being circulated up above.
What Loft Ventilation Is Available?
As you can see, having the right roof ventilation installed is essential in both summer and winter to avoid the respective effects of solar gain and condensation.
How much ventilation you need will depend on how bad your condensation appears to be as and if you have recently added insulation to the home.
At Roofinglines, we sell roof ventilation for both pitchedand flat roofs. Soffit vents are available in push-in, circular and strips to provide that low level fresh air flow from a quick, low cost installation that is DIY friendly.
To ensure unwanted stale air exits out the top of your roof, plain title vents, slate vents and interlocking tile vents can be purchased for most roof covering designs and brands. Tile vents can be installed at low and high level without the need for soffit vents to help create the same gentle air flow effect. One or two high and low level vents each is a popular arrangement.
If you are unsure of the exact make of what you have on your roof, universal vents, like the one above from Ubbink, can be fitted with most tile and slate regardless of brand or design.
Over fascia vents are discreet clip together units that can be nailed over the top of a fascia board to provide a continuous 10mm flow of low level ventilation. Though the preferred option for many roofers, they are a harder DIY job compared to a soffit vent.
Dry ridge is a very good solution to providing top level ventilation at the apex of the roof and can be used in combination with low level fascia vents, soffit vents or tile vents. Ridge vents with mortar bedding are also an acceptable high-level option.