Build-It Magazine 2004: A guide to building with an oak frame.

For many first time self-builders the suggestion that timber-frame housing might be a good idea for their project is often met with a raised eyebrow. This is hardly a surprise when we’re so used to living in homes built from brick and block and the idea of a wooden house conjures up images of wobbly walls, draughty rooms and dark interiors. But before you make your decision throw scepticism to one side for a minute and consider these points.


Step one: understanding wood as a house building material.

Strength
The sturdiness and strength of a timber-frame structure starts to be achieved even before it has been erected on site. An engineer reviews the frame plans to ensure the structure will be technically sound and then they are made into a working drawing using Computer Aided Design (CAD) technology. This provides an accurate cutting list for the design and because the wood is made into the frame inside the factory there is opportunity for any flaws to be highlighted and corrected.

As a material, wood has a tendency to contract as it ages and this makes the joints pull tightly together and form stronger bonds, You only have to look around the country to see that timber-frame houses built hundreds of years ago still stand firm, and for countries that lie on the earthquake zone, timber-frame housing is often the number one choice. From a mortgage lender and insurer’s point of view, a timber-frame house is as good as brick and block and they don’t distinguish between the two.

Insulation
Wood is a natural insulating material and provides a certain measure of warmth even before added insulation is put in. Some experts might say that brick and block is warmer than timber-frame because it is made up of two that can be filled insulation. While this is true, it shouldn’t be forgotten that timber-frame insulation levels often exceed building regulation standards because high specification wall and floor panels can be fixed onto the frame in the factory or on site.

For example, Part L of the building regulations says that the U value for external walls must be no greater than 0.35W/m2K in England and Wales, and 0.30W/m2K or 0.27W/m2K (dependant on central heating system) in Scotland. When the U-values are compared (a low number means a higher level of insulation), it is possible to see a timber-frame built with a 140mm layer of rigid foam insulation material has a U-value of 0.19 while 140mm of most mineral wools only produces a U-value of around 0.30. It is these high levels of insulation that appeal to those living in colder climates. For example in Scandinavia, North America and Scotland the majority of new builds are timber-frame houses.

Soundproofing
Soundproofing is about density and air. For timber-frame housing the wall panel provides the density, and the air is created by the cavity between he panels that is filled with a sound absorbent material to break up the sound waves.

A higher level of soundproofing can be achieved in timber-frame houses by replacing plasterboard with a specialist acoustic wall panel. Some timber-frame companies have their preferred products but you can also talk to companies like Custom Audio Designs or Monarflex who specialise in acoustic floors and walls.

Safety
Like all construction methods, timber-frames have to meet with Part B of the building regulations on fire safety. Broadly, this is an assessment of the internal lining material, the structure and insulation. For example, if a fire were to break out on the outer frame cavity barriers between the frame and cladding have to be able to demonstrate they can restrict flames and hot gases. In a fire, a wood structure is likely to stay together longer because wood chars and burns slowly whereas steel and masonry can suddenly buckle or collapse.

The environment
At first glance, a timber-frame house sounds like it would do more damage to the environment than good. After all, we all know that we need to look after our forests so how can building in timber help? All mainstream timber-merchants who farm from sustainable managed forests and some even rotate where they get wood supplies and buy from merchants in the UK and overseas.

In the bigger picture, wood is a natural insulating material and constructed in the right way can help contribute to reducing your fuel bills. Even the manufacturing process of a timber-frame is thought to be energy efficient because some of the work is done by hand or small electric hand tools rather than by heavy machinery.

Speed
You’ll find that speed is often quoted as one of the biggest benefits to building in timber-frame and while it is true that getting to the weatherproof stage is usually quicker, it is not always the case with every house. It is difficult to put precise times against building a timber-frame house but as a rule of thumb, a kit house, where the frame and the wall panels are built in the factory, can be made weatherproof much quicker than a brick and block house, whereas a complex bespoke design such as a sold oak frame take as long, if not longer to build.

A spokesperson from the UK Timber-frame Association (UKTFA) says when a house is made using factory manufacture timber- frame panels it can be weather protected in three to five days and completed in as little as ten weeks: “This is significantly quicker than masonry relieving self builders’ frustration at having to pay mortgage costs on a semi-constructed property.”

However, if you were to choose a bespoke design with details such as exposed oak beams and a vaulted ceiling then it could take a month or more to be crafted in the workshop, a further month or more to erect and then even longer to complete. Other factors that speed along the process are the labelling of the frame components so that the wood can be stacked ready for assembly and the use of plasterboard rather than plaster so you can start painting and decorating without waiting for the walls to dry out. And don’t forget a timber-frame can still be erected in wet weather.

Step Two: timber-frame design
You need to decide if you want to build in timber-frame quite early on in your project and, ideally, hand-in-hand with the design. The reason for this is two-fold; first of all a timber-frame will influence the scope and style of your new home and your architect needs to know this could be an option when you brief him. Secondly if you considering an off the shelf design you’ll need to make sure that a timber-frame is viable.

Timber-frame construction is modular and distributes weight across the whole frame so it can withstand heavy load without the need for load bearing walls. This gives you plenty of flexibility with the design and opportunity to create unsupported wide-open spaces, ideal if you are keen on open-plan living or you want a high vaulted ceiling. The modular design also works well if you plan to build an extension later on or adapt the interior layout as your lifestyle changes.

It is important to note that if you build a timber-frame house this does not mean it will necessarily look like a wooden house. It is perfectly possible to use a timber-frame for the structure and then clad the frame in brick and it will look exactly like masonry house. However many self builders choose the timber-frame route because they like the look of interior exposed beams, timber cladding on the exterior and the detail that can be created around the eaves an windows with wood. Talk to your architect to find out how wood can enhance your house design.