Are wood window frames insulated enough?
Monday, 23 August 2021
With so many old timber window frames being replaced by uPVC casement alternatives, perhaps you’ve made the assumption that wood is low performing. Actually this is not the case. Wood remains a very strong and functional material for use in window frames. To explore whether wood window frames are insulated enough though, we’ll look at the different properties and benefits of wood in your window frames.
Window Insulation
Which features of our windows make them well, or not so well, insulated? And in the search for ever higher performing materials and designs, where does wood sit?
How it works
The focus of both double and triple glazed windows is in the structure of the glazing. The gap between the panes of glass is filled with an inert gas such as argon, which is heavier than the surrounding air. This is the key to the high thermal performance of double and triple glazed windows. However, the frame itself can be key in the overall performance of the window. In standard casement windows, there are seals and a thermal break which protects against the loss of heat through the frame itself.
Energy Performance
Wood is a naturally low conductor of heat. In fact solid wood frames do not require a thermal break in the same way that other materials do, since they are so naturally well insulated. In fact, wood as a raw material provides a massive 400 times more insulation than steel, and over double that when compared to aluminium. Therefore it does not rely on the surrounding casement engineering to perform highly in the window’s energy performance.
Noise
The same goes for noise insulation. As wood is porous, there are tiny air pockets within the material that contribute to sound protection. When combined with double or triple glazing, this means that wood can perform better than any other material when it comes to noise penetration in the home.
Heat
While we all want heat to be retained in the winter in the UK, the same cannot be said of those hot summer moments! As wood carries low conductivity of heat, when used for window frames, it will not contribute to the transfer of summer heat into the home. The same goes for heat loss during the winter. Of course, heat transfer is chiefly down to the glazing. With UV coating on the glass in your windows, heat in the home can be far better regulated. This is why the evolution of glazing technology is so important, since it can now prevent too much heat from penetrating the glazing.
Wood Properties
Wood is fundamentally eco-friendly and has the lowest heat conductivity of any frame material. The manufacture of wooden frames produces less toxins and requires less energy. This is all great for sustainability. It’s a flexible material that is easily worked and formed and can be finished to any colour or texture. When looked after consistently, it’ll actually increase in durability with age. There’s a reason that it’s still used in building projects to such an extent.
Any Downsides?
If wood is such a naturally well performing material when it comes to insulation, then, why is it not more widely used?
Maintenance
The major downfall in wood as a window frame material comes from the maintenance requirement. It must be conscientiously and consistently maintained, treated and painted for the duration of its life, or it is prone to damage, rot and warping. If these issues take hold you’ll be looking at replacing the whole of your window system.
Pests
Another Achilles heel of wood is its vulnerability to insects and pests. Insects such as woodworm and termites can break down your windows to an irreparable state. They will be held off by regular treating and painting, but here we are again with high maintenance requirements!
Cost
There is a considerable price tag when it comes to wooden framed windows. Treated as an investment, they can last and last and look fantastic. This clearly can make the initial outlay cost worthwhile. It’s not without some additional work, though.
Wood compared to other materials
By comparing the performance of wood framed windows with those of other materials, we can clarify where wood scores highly. While there are are most certainly benefits to using wood for window frames, it’s important to understand the benefits of other popular window frame materials.
uPVC
This material is supremely high performing in all of the areas required by building regulations. UPVC frames are thermal and UV efficient, they have great soundproofing properties and are extremely secure. Alongside all this, there is no maintenance required.
Aluminium
This is lightweight but super strong. So it will support large areas of glass with no trouble. It’s great for bespoke projects as it’s such a workable material. Plus it needs minimal maintenance to keep performing, and looking, great for over 40 years. Then, it’s recyclable so scores for sustainability too.
Timber Effect
Timber effect window systems bring real authenticity to a home aesthetic without any of the hard work! The material is durable and high performing and can sit comfortably in any style of building. The energy efficiency of this window material really is up there, with a U-value of just 0.8.
Aesthetics
There are occasions that undeniably require wooden frames. For period properties, listed buildings, and character preservation, wooden window frames are generally the ideal choice. Older buildings are generally less regular in terms of size and shape, and this makes bespoke wooden window frames an ideal solution. Hand crafted to fit, with wood's natural look, you’ll achieve an authentic and seamless aesthetic. Similarly, building projects with a sustainability focus will benefit from wooden framed windows. The natural look that is brought to the building is supported by the sustainable credentials of this material.
Importance of glazing
Of course, the thermal performance of your windows is not all down to your choice of frame material. The structure of the window and glazing used is just as crucial. Multi glazed windows offer massively increased protection to your home, no matter what the frame material. This comes in the form of heat and sound insulation, security, privacy, and increased property value. You’ll have choices between double and triple glazing, tinted and obscured glass, and even smart or e-glass. Check out our other articles to learn more about these choices. Or just get in touch !