Glazing your Garden Office or Summerhouse

If you are contemplating a garden office or summerhouse, you may be seduced by those designs which have a lot of floor to ceiling windows. They look very attractive but how practical are they?

Glazing is certainly another important consideration from a comfort and design perspective. Starting with the insulating side; glass is an appalling insulator. Comparing a good quality double glazed unit with a wide, argon filled gap between panes with a well insulated wall, the window will let through roughly 4x as much heat as the wall. So, from a thermal point of view it would seem to pay to reduce the glazed area to a minimum.

However, if you have ever been in a conservatory or glasshouse on a sunny day you will know how hot a fully glazed building can get so you can use glass to capture heat from the sun, known as ‘solar gain’. Glass also lets in light so getting the glazing right is a complex balance of many factors. By and large the optimal arrangement is:

- modest amount of south facing glass with plenty of shade from the Summer sun

- windows in East, West or North facing walls to give light.

North facing windows are ideal and are much favoured by artists because they give plenty of indirect light. East and West facing is good too but bear in mind in Winter the Sun will be low in the sky and may be very distracting if your work space faces in these directions.

There is absolutely no point installing single glazing but what about triple glazing? There is no doubt the insulation of this type of unit is far superior to double glazing and the premium is not as great as you might think but it is probably only worth considering in Northern parts of the country or particularly exposed situations.

As well as the glass there is the frame to consider. Good performing glazed units are fine but if the frame is leaky then much of the benefit from the glass is wasted so, if you can, ask suppliers to give you the whole frame u value rather than just the value for ‘centre pane’ (the glass alone).

As well as seals, ease of opening, security etc. you might want to consider maintenance. Softwood requires protection if it is not to rot and this protective coating or treatment often requires renewing every few years. Other things to look for are whether the beading which holds the glass in place is nailed in. If so, you may find the nails rusting over time which then lets in the rain and the rot sets in.

Hardwood windows are a much better option but are still likely to need repainting every 4-5 years. PVC and Aluminium are low maintenance alternatives as well as combinations such as timber frame with Aluminium sash (the opening bit). This has the huge advantage that the Aluminium, provided it is correctly treated in the first place, will never require repainting during its lifetime. It also means the sashes are very light.

Doors and windows are an obvious security risk so consider how the strength of the locks and how many locking points there are. Even if all opening windows or doors can be locked, consider installing a movement sensor linked to the home security system. A cable can be laid at the same time as the power and computer/phone cables and, for the extra peace of mind this is well worth doing.