Garden Office Guide: Glazing


Most garden offices come with double glazing as standard but you need to keep an eye on the specification lists as a few companies list single glazing as standard – this can be a way of keeping prices down, but single glazing does not really cut it in a garden office designed for year round use – double glazing is the way to go! Triple glazing is another option but in reality you will only find it on high end garden offices as it is expensive!

Floor to ceiling glazing is very fashionable in garden office design but does present a possible danger, to avoid harm the glass used in ‘critical locations’ in the garden office needs to be toughened so that if it breaks, it break safely.

Performance Double Glazing

Considerable amounts of heat can be lost through glazing this is obviously not good for the environment or your wallet! Double glazing is made from two sheets of glass with airspace in between, this space creates an insulating barrier, triple glazing has three panes of glass and two airspaces.

Many garden office suppliers state their glazing is Argon filled or Low E, but what does this mean? Well, double glazing can be made more efficient by coating the panes of glass with a special film or filling the airspace between the panes with a special gas, common examples are Low E glass and Argon filled glass:

Low E Glass

In Low E glazing the inner pane of glass is coated with an invisible to the eye film of metal oxide, this film lets heat and sunlight into the room but significantly reduces the amount of heat that can pass out of the window. Low E glass is also referred to as Pilkington K; this is the brand name of the Low E glass produced by Pilkington.

Argon Filled Glazing

With Argon filled windows (there are other gases which can be used such as Xenon and Krypton) the air in the void between the panes of glass is replaced with Argon gas. Argon is five times heavier than air meaning it has greater insulating properties. Argon is a clear gas so the glazing is as clear as normal air filled windows. Argon filled windows have less potential for condensation formation; they also are more acoustically efficient than standard air filled double glazing.

Toughened Glass

It is really important that the glass used in your garden office complies with Part N of the Building Regulations. Part N of the Building Regulations identifies ‘critical locations’ for glazing, these are locations at risk from human impact and in turn a potential human injury risk if the glass breaks.

Critical locations include doors, door side panels and any glazing that is within 800mm from the finished floor level. If part of a window falls within the critical location the whole pane must be toughened.

Toughened glass is also known as tempered glass and looks just like normal glass, the difference is that toughened glass is heat treated which makes it much stronger than normal glass. If toughened glass breaks after an impact it breaks into thousands of small granular pieces rather than sharp shards of glass.

In Example 1 the side window is more than 800mm from finished floor level therefore the  pane does not need to be toughened. The door needs to have toughened glazing as there is glass in the area 1500mm from finished floor level. The window on the front elevation does need to be toughened even though it is more than 800mm from finished floor level because part of it is within   300mm from a door zone.

With the second example the door has to have toughened glass because there is glass in the area 1500mm from finished floor level, in addition the sidelight needs to be toughened because there is glazing in the critical 1500mm from floor height zone and also the sidelight is in the critical 300mm from a door zone.

How do I Know My Glass Is Toughened?

You can easily check that the glass used in your garden office is toughened by looking for the British Standard kite mark; each pane of glass in a critical location of the garden office will bear the kite mark in one corner.

Self Cleaning Glass

Some suppliers specify self cleaning glass on their garden offices – this can save you hours of cleaning windows! Self cleaning glass has a special coating which interacts with sunlight to breakdown organic matter i.e. dirt and spreads out the rain droplets which then wash away the loosened dirt, it then dries quickly – streak free!

Garden office designers are becoming very clever with their use of glass and in the next part of this guide we will look at garden office windows.

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