Pick of the Best Garden Room Extensions - Project 1

As the summer break bursts into full swing, we take a look at some of the very clever and innovative sunroom extensions which have been created to make the most of the long summer days, and short wintry nights. We begin with those which are the most contemporary and minimal, providing the full inside-outside experience, and where better to start than with the fundamental 'Glass box' additions.

Apart from the obvious challenges of glass-cleaning and maybe an unfortunate number of wildlife/bird collisions, this double-glazed, frameless, glass-box extension to a characterful stone gable in no way compromises the beauty of the existing stonework, and provides maximum daylight and full surrounding views.

So starting with heat loss and gain, a building such as this alone cannot comply with current building regulations. The double glazing, even if reflective and with in-built glazed insulation, (energy efficient glass) loses too much heat in cold weather, and gets too hot when the sun shines directly through it. The way to overcome this is to treat the room as a 'conservatory', this is an unheated space, which is separated from the house with insulated (outside) doors. These can be kept closed for most of the time which retains the thermal efficiency of the main house and in the picture above this is easily achievable with a pair of doors in the position of the stone arch (clearly not visible here!).

As soon as this space is heated, or there is no separation from the house, it becomes part of the thermal envelope of the house and has to comply with current building regulations which can be a significant challenge. The image below show how this might work, but in order for this to comply with current regulations it is likely that a whole-house calculation was required to offset the heat-loss and solar gain against the remainder of the house structure. A limited amount of existing windows in the remainder of the house really assists in this calculation.

The other details to note are that you cannot have a double-glazed frameless door in a frameless facade as there is no way of draught-proofing or weather-proofing this, and so in a domestic situation there will always be a visible frame around any doors in these structures, something to consider in the design process. Also, what is evident in the image above is that in this extension there is a solid roof, which makes the addition visually a little heavier, but actually this is a great insulation-zone and provides valuable shading on sunny days and so is a much more practical addition than the fully glazed-roof version.

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