Solid construction, undertaken with block or brick masonry, and timberframe construction are the two most popular construction methodologies for new houses in Scotland. Although south of the border timber frame accounts for only a small amount of new build homes in Scotland the picture is in contrast as more than half of new homes constructed incorporate a timber frame.

From the onset it is important to stress in general terms there is no best technology only more or less appropriate ones in the context of a specific bespoke project. Moreover in terms of cost both approaches tend to be more or less equal. However from a developer’s perspective if large pro-forma payments are required for a prefabricated timberframe kit, there are cash flow issues. There are however fundamental differences between the two approaches which will now be addressed.

As a general rule both solid and timberframe houses have inter and outer leaves or skins to form the external walls. These leaves are separated by a cavity which is generally filled with insulation with solid construction, and left open in the case of timberframe construction where the insulation is placed in the structural inner leaf.

Timberframe is generally prefabricated in factories with on site works limited to assembly. (Assembly being simply the erection of the timberframe kit.) Timberframe can however be manufactured on site. This is called ‘stick building’, and is often undertaken when a construction is complex. Other than for complex builds, prefabrication has a number of advantages including increased control over the manufacturing process. Moreover prefabrication allows concurrent engineering whereby the timberframe can be manufactured immediately following detailed design, while at the same time that sub-structure work packages are being undertaken on site. This can shorten the on-site construction process especially in Scotland where inclement weather can cause delays for works being undertaken outside. This potential time saving can however only be realised through tight project management, as it can easily be lost.

Timber structural framework is used in timber frame houses. This takes the form of studwork, with insulation between the studs which are enclosed by plywood and plasterboard that also act as bracing. With timberframe construction it is generally the timber inner leaf that is load bearing. If wood can be sourced from sustainable forests, this coupled with the fact that very little energy is expended in the manufacture of timber materials gives obvious environmental advantages.

With solidly constructed houses the inner leaf is masonry, such as block or brick, with insulation in the cavity. Another difference here is that with solidly constructed houses the load is generally shared between the inner and outer leaf.

The internal finish can be either dry-lining or wet plaster with both a timberframe and solid inner leaf. However the methodology for achieving the desired internal finish varies in accordance with the inner leaf construction. Generally dry ling is used in timber frame while masonry inner leaves tend to be ‘plastered on the hard’. With both solidly constructed block and brick, and timberframe, houses the outer leaf or skin of the external walls can rendered or faced with stone. It is worth noting that if wet plaster is used to finish the inner leaf then it is recommended to wait until this is thoroughly dried before applying wallpaper. This can take in excess of six months!

The difference between timberframe and solid construction is perhaps most evident in terms of insulation. There are two forms of insulation which must be considered namely thermal insulation and acoustic or sound insulation. The density of a material is a factor affecting the performance of a material in terms of acoustic insulation which is an obvious advantage for solid masonry construction in respect of airborne sounds. Nevertheless, at extra cost, timber framing can be filled with acoustic insulation of increase performance. Timber flooring has an advantage over solid concrete flooring in terms of impact sounds which are conducted to a higher degree with denser materials. In terms of thermal insulation, even with an inner leaf constructed from light weight insulation blocks, it is generally accepted that timberframe houses tend to perform better when considered on an equal cost basis. However thermal insulation in solidly constructed houses can be enhanced for an increased cost.

In conclusion we must revisit our initial position that there is no best approach only more appropriate ones relative to individual projects.