Gary Millership, Technical Manager the Commercial Window Group, highlights key considerations for new build specifiers when selecting new build windows and doors
Highly regulated window and door specification can be full of pitfalls and contradictions. Part L (Conservation of fuel and power) and Part F (Ventilation), not to mention Part O (Overheating), sometimes appearing in direct opposition to one another. Then there’s wind loading to consider and, if it’s a floor to ceiling installation, containment and Part K.
Fortunately, there’s expert support on hand to help you negotiate the window and door specification minefield and help you get the most from your budget.
“It’s [window and door specification] very complex”, says Gary Millership, Technical Manager, the Commercial Window Group. He continues: “You normally end up with a few issues where regulations overlap and interfere with each other, and you’ve got to make sure that by solving one problem, you don’t create another one.”
What’s most commonly overlooked in window and door specification?
“One of the most common mistakes is when people are installing full height windows and glass and they haven’t done the appropriate barrier loads, because now that window that they’re installing is a barrier within the building and key to keeping people safe”, Garry explains.
“It’s important that the glass and also the frames installed holding the glass, can withstand human impact.
“It’s a very common mistake to overlook that at the early stage of specification and pricing – people get it wrong far too frequently.
“In past roles I’ve had people come to me after the event saying that they want me to prove that their windows that they installed to act as barriers are sufficient to do the job. And obviously, I can prove by calculation, unfortunately, that they aren’t and it will mean a complete re-fit of a window built with bigger sections and bigger pieces of steel.”
Part K sets out the requirement for provisions for containment in all doors and windows where there is a change in floor surface height of 600mm or more in residential applications and 380mm in commercial ones.
The assumption across both commercial and residential applications, however, is that the glass must be able to withstand loadings and impact up to 1100mm from the floor. This is a height equivalent to balustrading.
The actual loadings IGUs need to withstand are defined, as identified by application, but also square meterage. The larger glass area of over-sized IGUs, driving a specific set of requirements.
Gary continues: “It doesn’t by default, create a requirement for laminates, in IGUs. You get installers and builders specifying laminates as a ‘catch-all’. This is only a requirement under Document K in u-channel balustrading. It doesn’t apply to IGUs and windows.
“Over-specifying product artificially inflates cost. We’ve worked with a number of installers and builders to explain specifications to both.
“It’s because the regulation can be interpreted – and that by definition creates scope for misinterpretation, increasing costs – and more seriously, posing a risk to safety.”
How will Approved Document O (overheating) change window and door specification?
Approved Document O (Overheating) is another area that has big ramifications for window and door specification but which is, according to Garry, poorly understood.
Singularly focussed on preventing the over-heating of homes in summer through solar gain, like Part L and Part F of the building regs. it sits within the broader framework of the Future Homes and Building Standard. It sets limits for the allowable area of glazing dependant on orientation also dividing the UK into different areas of risk.
“House builders are pouring a lot of glass into buildings which is great and delivers a lot of natural light but it also creates a problem in the summer of overheating”, Gary continues.
“Developers particularly in built up urban centres face the key challenge of making homes more thermally efficient but also to prevent overheating.
“Against this context ventilation assumes critical importance. It’s also a careful balancing act which can be defined by a host of different factors including aspect.
“We can help anyone in new build design and develop the window aspects of the project in a far more cost-efficient way and to make sure that, those boxes are ticked.”
How can housebuilders save money on project delivery?
Gary argues understanding changes to regulation and how it impacts window and door specification is key. This he says allows housebuilders and social housing providers to avoid costly mistakes and to develop specifications which maximise budgets and lower delivery costs.
“Housebuilders are sometimes reluctant to engage until they’re actually at that point where it’s too late to affect the specification”, Gary says.
“There’s always someone prepared to go in with cheaper costs, but to get the cheaper costs, they may be cutting corners. And this is where the windows may fall short of building regulations or project requirements.
“We work differently. We work in partnership with housebuilders nationally and regionally to develop specifications that work for where they’re being fitted.”
How does the Commercial Window Group work with housebuilders and housing associations?
The Commercial Window Group offers a complete design, specification, manufacturing and installation service with extensive experience of partnering with social housing providers.
Product ranges are manufactured exclusively in the UK by the Emplas Group, one of the UK’s largest and leading window and door manufacturers.
At the same time, built around a regional model, partnership with the Commercial Window Group allows social rented housing providers and housebuilders to work with regional experts, nationwide.
The Commercial Window Group also has a 40-year partnership with Profile 22, one of the UK’s most widely specified window and door systems, and glass and building products leader, Saint-Gobain.
“We supply great products – and with 12-months fixed prices – we also offer a high degree of visibility on project costs to housebuilders”, Gary continues.
“It’s our technical expertise combined with the local knowledge that our regional delivery model gives us, which brings a unique insight to our approach, helping you to maximise your budget”, he concludes.
Q. Why do housebuilders choose Glevum as their newbuild window installation partner?
A. “We always do everything we can to do what we say we will do.
It’s not just about getting your frames onsite. It’s not just about getting the windows there. When the customer asks, it’s making sure that we follow through what we say we’re going to do.
You will get your windows installed today. They will all be working. We’ll try and foresee any problems. We want to turn up to site, we want to install the windows, and we want to move on to our next site.
We do that with a consistent presence on site and good communication.
We’re very process-driven. We invest a lot in our structure and our behind-the-scenes processes from an online call-off system through to visibility on our portal for our installers to see what they’re installing, to see house builders’ drawings.
“We do believe we’re cutting edge with that, and that does ensure that our customers reap the benefit of that.”
For more information on the Commercial Window Group’s next generation high performance window and door ranges and our regional delivery partners call 01234 567890 or email [email protected]
