BUILDING FABRIC & EXTERIORS
Bi-fold door specification made clear
When it comes to buying bi-fold doors, there are various factors to bear in mind before laying out cash on such an important purchase. Solarlux breaks down the key areas to consider
I
t may not seem so to the casual observer, but bi-folding doors are not all built equal: the quality and finish can vary enormously and there is no substitute for seeing, operating and ‘feeling’ the product for yourself. The mechanism and ease of use can vary drastically between brands. A bi-folding door can be superb addition to your home, adding value and saleability for many years; however some brands use cheaper parts which could result in a shorter lifespan and demand more upkeep. For example, nylon runners are far less effective and not as long lasting in comparison to their more robust stainless steel counterparts.
WEATHER RESISTANCE
High quality manufacturers produce secure systems which don’t rattle in the wind and offer extensive noise reduction from both weather and traffic noise – an important factor for any door. With a good quality bi-fold door you can achieve a noise reduction of 44 dB and full protection from the elements during inclement weather, while still allowing natural light to flood through the property, bringing a homely warmth to relax and unwind in.
Sometimes people ask ‘how can I determine whether a bi-fold system meets my requirements?’ Michelle Spangehl, marketing manager at Solarlux, explains: “I have come across this question many times during exhibitions. My advice is to ask for certificates that indicate the system’s performance. For instance, DIN EN regulations for protection against driving rain, resistance to wind load
july/august 2017 and air permeability.
“As an example Solarlux always tests its systems to the highest standards so that we’re able to achieve protection against driving rain up to class 9A, wind load B4 and air permeability class 3 according to DIN EN regulations. Another tip is to ask for cross sections of the doors. The more sophisticatedly engineered the profiles and floor tracks the better the performance – be it weather resistance, security or thermal efficiency.”
THERMAL PERFORMANCE
Although bi-folding doors are all about creating open spaces, they also need to perform when closed. Many manufacturers now offer triple glazed doors and are pushing this product option. However, it’s not necessarily all about triple or double glazing – if the profiles are of high quality triple glazing won’t be necessary to reach the key Uw value for window thermal performance of 1.1. If the door’s frame is of poor quality triple glazing will not offset the difference.
It’s worth keeping in mind that the quality of a bi-fold door is also determined by what you cannot see. Generally, heat is lost via the profiles, so high quality manufacturers incorporate precisely engineered thermal breaks (air chambers) in order to reach a low U-value and prevent condensation. When comparing Uw values ask manufacturers if they have considered the profile and frame within their calculation – often they refer to the glass only.
Previously to achieve a Passivhaus standard you had to choose a system
All images © Solarlux
www.sbhonline.co.uk 37
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