090 GGP 0815

GGP August 2015

90 TOOLBOX Tackling trickle vents With condensation a hot topic for so many householders, this month The Window Company (Contracts) senior fitter, Garry Smith, tackles the issues of ventilation and I’ve been told that the GGF’s condensation guide is one of the most downloaded leaflets on its website and that doesn’t surprise me at all because condensation and how to avoid it is an issue for almost every resident and tenant I meet. The first thing I have to explain though, when I go in to fit their new windows, is that they won’t necessarily stop condensation. It’s just a matter of physics that normal living will always produce condensation in any home. It can obviously be reduced by double or triple glazing, but condensation will always find its way onto the coolest surface in any room and if that room isn’t heated for any reason, then it’s likely to be the window. Obviously, condensation inside a sealed unit is an indicator that the unit has failed, but condensation on the outside is actually a good sign because it means the window is effectively stopping heat from escaping and warming up the outer pane. The only way to tackle condensation inside, especially in modern, well insulated houses, is via effective ventilation – everything from regularly opening the window to installing extractor fans in kitchens and bathrooms. And, from a window fitter’s point of view, that means installing trickle vents. As everyone in the industry knows, they’ve become the default way to meet the requirement within the Building Regs for background ventilation and, even though they are only officially required where the window being removed already had trickle vents, it’s good practice to install them anyway. The rules state that the new vent should offer at least the same capacity as the old one but if this isn’t clear, then the minimum required is 5,000mm² EA for habitable rooms and 2,500mm² for wet rooms. Most vents are marked with the EA to make our lives easier! There are three types of trickle ventilation – through frame, over frame and glazed in. Over frame is only needed when you can’t fit the trickle vent through the frame and you need to route ventilation over the frame of the window, and glazed in is when the trickle vent is fitted on top of the IGU. 90% of the time though, we fit the most common through frame type. The main point to make here is always to check that the plaster line doesn’t obstruct the vent, because then it just won’t work. When we order in our frames they are pre-routed to accept the vent, but we always fit on site to avoid it being damaged or broken during installation. Obviously, we always carry extra vents on our vans in case of breakages. It’s expensive and time consuming to have to go back to a job just to fit or replace a trickle vent. One of the most important tips for installation is to always put a mastic line around the outer part of the vent to stop the ingress of water. I know this is sometimes forgotten but it’s one of the biggest reasons for callbacks from householders faced with a leaking window or an annoying whistling noise. The other important tip is always to take the time to talk the householder through the use of the vents. Obviously, they need to see how they operate so they don’t break them by trying to open them incorrectly, and then they need to understand that they have to leave them open for them to work effectively in tackling condensation and creating a healthier environment inside the house. It’s also worth explaining that using a trickle vent can improve their security because they don’t need to leave a window open to let fresh air in so they aren’t vulnerable to any opportunistic burglars. trickle vents. www.ggpmag.com August 2015 Garry Smith


GGP August 2015
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