Is it wood, is it bricks or is it lego?

Time to practice your French with this post. One of the big new things coming over from continental Europe is "massive wood construction". This is an extension of the idea of a traditional log cabin - in which the walls are solid wood - but updated with modern hi-tech manufacturing methods. So instead of irregular round logs you have nice regular building blocks.

This provides very good insulation keeping the heat in and the noise from outside out. It's also greener than conventional fired clay bricks - which require more energy to make and produce more carbon dioxide in the process.

Obviously it requires an awful lot of wood, but the good thing is that cheaper, low quality, wood can be used. As there is so much of it, the force is shared over a bigger area, meaning it doesn't have to be nearly as strong or as stiff as the wood used in a timber frame building.

You might see this type of construction more often in the next few years for buildings like schools and hotels.

The first video is an explanation (in French) of one particular system of massive wood construction (there are others). Notice the computer controlled robotic cutting and drilling machines. Wood manufacturing really is like this in the 21st century.

The second video, which has no sound, shows the same system being used to actually construct a building. Notice how accurately the pieces fit together thanks to the precision manufacturing.

Careers in the timber industry

The UK's multipurpose forests provide environmentally friendly materials for all sorts of things and there are a vast array of different types of job out there.

For more information on jobs visit The Doorway and A Job In.

Wood colour and chemistry

Here's a fun little video from the WoodWhisperer talking about how the colour of wood can change over time. This is all down to chemistry and something called oxidation. That's the same process that turns a sliced apple brown.

Sapwood is the outer part of the tree trunk - the wood that the tree is using to transport sap. The heartwood is the inner part of the tree trunk - the part of the wood that the tree uses to store waste chemicals...the extractives mentioned in this video.

As a tree ages the inner part of the sapwood slowly turns into heartwood. Heartwood provides structural support to the tree, but not much else and with very old trees it is common for the heartwood to be decayed away.

Different species of tree produce different extractive chemicals which explains why they can have such different colours.

Traditional timber frame 2

Here is a nice contrast to the "traditional timber frame 1" video. Again it's a class of students in the USA, but this time they are using modern machine tools for their carpentry. The most interesting bit is towards the end where you can briefly see some computer controlled robotic saws in action.

Traditional timber frame 1

This video shows a group of students at a workshop in the USA building a traditional timber frame "post and beam" house using hand tools. Buildings like this are still being made (check out Carpenter Oak in the UK), but only for special projects. They require skilled craftspeople and large pieces of timber so are not practical for everyday houses... but can be very beautiful.

In contrast, a modern timber framed house is usually made from pieces about twenty times smaller in size! ....but that doesn't necessarily mean that a modern house won't last as long. The timber is used in a different way that allows for the forces to be carried by a larger number of smaller pieces. The wood is almost always a softwood like spruce, pine or fir which is dried in a kiln before it's used for building.

In this video it looks like the wood is a softwood, but post and beam houses are also often made from hardwoods like oak. In both cases, the timbers tend to be too big to be dried before use, so the connections must all be made to allow for the timber to shrink as it dries out as the building ages.

Check out "Traditional timber frame 2" to see the same sort of thing, but with modern power tools.

Japanese fighting walls

OK...we admit we don't know an awful lot about what is going on here because these videos are in Japanese.

What we think is happening is that people (engineering students?) are competing to create the strongest timber wall made with traditional carpentry joints. The walls are made to "fight" each other in pairs by putting a hydraulic jack between them that pulls them together (like tug of war in reverse).

The first video shows the construction of the walls and the second video shows the walls in action (perhaps the best video of the three). The third video shows the final stages of the competition.

The forces must be huge to cause these walls to break ...but you could stage your own miniature competition by making walls out of wooden lolly sticks or coffee stirrers.