27 Nov 2019

A room with a view

Jonny Davis, Director of Cotswold Windows, explores the latest design staple – large-format glazing and advises on the practical considerations when opening up your home.

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The demand for an unimpeded view has been the collective cry of UK self-builders for several years. As a result, the trend for floor-to-ceiling glazing isn’t going anywhere. Instead, the products and capabilities are evolving, with architects and manufacturers pushing the envelope of performance and aesthetics.

While industrial, warehouse chic has long been a popular interior style, the look of commercial and retail buildings is influencing our residential exterior design choices.

The shapes remain traditional – square and rectangular, but the style is unashamedly modern. Windows and doors continue to grow in size while the frames, often in a dark tone, diminish, providing those unobstructed views. Modern windows and doors with clean lines are now firmly on-trend.

Yet, the desire for more glass, less frame and bigger and better windows and doors must be balanced with budget and feasibility. As a rough guide, the bigger the hole, the more costly it will be to fill it; not least because of the structural challenges that this presents.

Structural requirements

Large windows and doors require extra structural support. This is something that has to be factored in at the design stage and is vital for a precise fit and long-term performance. We would recommend that the project manager and architect get onboard with the supplier as early as possible to capitalise on their expertise. By working together, a viable and budget-conscious solution can be achieved, without compromising on structural integrity.

The supplier should be aware of everything. We often work with architects to assess the site before the specification is finalised. This allows us to head-off any potential issues early in the design process.

A typical site assessment would include the location, altitude, position in relation to the coast, wind speed, building height and frame/glazing size required. The wind load is also calculated, allowing the most appropriate profile and glass to be selected.

Practicalities of installing big windows

One of the challenges of large glazed units is the risk associated with handling and installation. For manual lifting, the Health & Safety Executive states: “The law does not identify a maximum weight limit. It places duties on employers to manage or control risk – measures to take to meet this duty will vary depending on the circumstances of the task. There is no universally safe maximum weight for any load; however, there are varying degrees of risk”.

Mechanical versus manual lifting is, therefore, determined by the size and weight of the glazed product, and at the discretion of the client, contractor or supplier/installer. For example, a Sky-Frame horizontal sliding window measures 3.2m x 4m (larger on request) and weighs over 500kg, so mechanical lifting equipment would be required by the fitting team. A nominal figure of £1000 should be budgeted for the hire of mechanical lifting equipment.

The weather is also a critical factor, especially wind speeds. A risk assessment would be advisable prior to the installation, to determine how and if the lift should go ahead.

Solar gain

When selecting glazing for large apertures, solar gain must be factored in. This is a particular consideration for glass on south-facing elevations. Most window and door companies control solar gain through high-performance glass, with manufacturers offering a variety of options, including coated and uncoated glass. Solar control glass, for example, can help prevent heat build-up on the hottest days.

When choosing solar control glass, look out for the g-value – the measure (in percentage terms) of how much solar heat is allowed in through a building material or product, e.g. a window. The g-value of standard double glazing is typically 71%, whereas certain types of solar control glass can reduce the solar gain down to 28%.

While specialist glass is one solution, consider the location and orientation of the building during the planning stage, especially the shading benefits of neighbouring buildings and trees. This can be a natural and cost-effective way to address solar gains.

The right information

For an efficient and positive build, relevant and accurate information should be shared early in the design process. Window manufacturers benefit from detailed and precise section drawings of what is to be constructed. This isn’t a requirement as this can be picked up later in a site survey, but good construction drawings certainly lead to the best finish and results on site.

Elevations or plans of the basic system or style required is essential for generating a detailed quotation. This is particularly important for those working to a budget. Many window companies will offer support at the design stage, often providing full technical drawings showing the product integrated into the building.

À la mode

We have mentioned both windows and doors in this article, and that too is an important decision. Self-builders should think about the purpose of the glazing – is it simply to admire the view or does it need be practical? Will it need to open? Will safety be a factor? Will it give access to the outside?

And, there are endless products to choose from; it is worth digging a little deeper to find the latest product innovations – a bi-folding door may have been high on the wishlist but would sliding doors be more suitable?

As ever, sticking to a budget (for most) is critical. The window and door market have so much to offer, so be prepared. Material is a good place to start – look for proven industrial materials if you wish to nail the trend; aluminium has long been an architectural favourite. Then think about the frame – square edges and crisp lines are important here. It’s then over to the finishing touches – colours and textures – inside and out, and furniture.

Further information....

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