With more and more homeowners opting to replace their old timber window frames with modern uPVC alternatives, it might be easy to assume that wood is a low-performing material. However, nothing could be further from the truth. When it comes to window frames, wood is still one of the most durable and functional materials. But to determine whether wooden window frames are adequately insulated, you have to assess the various properties and benefits of wood as a window frame construction material. Please check out Bill Butters Windows for all of your needs regarding windows and doors.

Window Insulation

First, we need to take a look at what features make windows well insulated and not so well insulated. And determining where wood lies in the list of high-performing materials and designs will greatly help in our assessment.

How it works

The effectiveness of double and triple glazed windows lies in the structure of the glazing. Both double and triple glazed windows are known to have a high thermal performance. The reason behind this is that the gap between the glass panes is filled with inert gas, for example, argon, which is heavier than the surrounding air. But did you know that the window frame itself can also affect the overall performance of the window? Standard casement windows have seals and thermal breaks that help prevent heat loss through the frame.

Energy Performance

Wood is a poor conductor of heat. Actually, unlike other materials, wood is so naturally well insulated that solid wood frames don’t require a thermal break. As a matter of fact, wood has 400 times the thermal insulating ability of steel and over 1700 times the thermal insulation ability of aluminium. And as such, wood doesn’t require surrounding casement engineering to achieve a high rating in terms of energy performance.


Same as with heat conduction, wood is also a poor conductor of sound. It is porous and contains tiny air pockets that make it a great material for noise insulation. This property, combined with double/triple glazing, means that wood outperforms all other materials when it comes to noise protection within your home.


During the winter months, we all aim to retain as much heat as possible within our homes. However, when the summer season comes along, we want to keep out as much external heat as possible. Given that wood is a poor conductor of heat, when used as the raw material for window frames, it minimizes the transfer of summer heat into your home through the frames. This also applies to heat loss during the winter season. Obviously, the structure of the glazing plays the biggest role in the amount of heat transfer. Solid wooden frames, combined with UV coating on the glass panes, ensure improved heat regulation within your home. Advancements in glazing technology have played a big role in minimizing the amount of heat that penetrates the glazing.

Wood Properties

Timber is an environmentally friendly construction material and has the lowest heat conductivity of all materials used in making window frames. What’s more, the manufacture of wooden frames doesn’t involve the production of toxins and requires less power. All these factors contribute to the sustainability of wood. In addition, wood is a flexible material, making it easy to work with. It can also be finished to your desired colour and texture. Through proper maintenance, wood actually increases in durability with time. This is one of the main reasons it is still used to this extent in building projects.

What are the Downsides of Wood?

Given all these properties of wood that make it an excellent material for insulation, you might be wondering why it isn’t being used more widely.
Perhaps the biggest con associated with wooden window frames is their maintenance requirement. Wood should be maintained conscientiously and regularly and it has to be treated and painted throughout its service life, otherwise, it will be susceptible to damage, rot and warping. If you allow these issues to set in, you might need to replace your entire window system.

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