How does my build system affect its design?

ABOVE: This former derelict cottage was completely renovated using a combination of blockwork and timber frame. Read more.

Q: I’ve just purchased a plot on which I hope to build a four bedroom home. I have yet to approach a designer as I wanted to gather my ideas together first. However, I am at a loss as to whether to choose blockwork or timber frame. How will each construction system impact on the design — both on the outside, and on the interiors?

Pete says: You have certainly started off with the right idea by way of gathering your initial thoughts.

Historically, blockwork was always considered the cheaper way to build but, personally, I never bought into this argument. Although based on pure component costs, it would appear that although a blockwork build could be done cheaper, there is much more work involved in sourcing, securing and installing these components and, furthermore, there are lots of them. With a timber frame build, around 40% of your cost and build process becomes the responsibility of the supplier. This immediately reduces your suppliers on the project and keeps a large part of the operations within the remit of a single-source supplier.

Timber frame is also constructed in factory-controlled conditions, allowing more of the build to be manufactured off site in line with current guidelines. If you intend to do some of the work yourself, such as electrics and plumbing etc, I often find it easier to work with a timber frame due to its skeletal nature, rather than chasing block walls out.

In terms of the design implications, I would generally consider both methods as structurally equal. Spans of beams and trusses can be achieved to pretty much any specification nowadays — whether it’s done in timber or steel. I often find that groundworks can be complex with blockwork builds as often there will be steels that require additional footings over and above the block walls. Whereas timber frame is typically engineered with a shared loading through the frame, unless you plan to build a post and beam-style home, which requires separate pad foundations.

Interior spaces can be very much affected by your choice of construction. Timber frame will allow you to potentially expose most of the engineered structure, which can be used as a feature in its own right. Blockwork construction, however, would typically utilise steel posts and beams which require fireproofing by way of board enclosure. Alternatively, you can leave beams exposed for Modernist contemporary interiors, but they will need to be treated with a fireproof (intumescent) paint to the building inspector’s satisfaction.

With regards to architecture, a good designer will be able to design your home as either traditional or contemporary, regardless of structure. And, to a certain extent, you do not have to choose your preferred build method before the planning stage. However, if you were after a traditional design with lots of timber, it would not make sense to choose blockwork with a view to then inserting lots of timber. So on this basis, it is likely that your architectural vision for the project will lead you naturally to one or the other.

In addition to designing homes for self-builders, designer Pete Tonks has recently created the Zone Studio range for Potton. He also runs his own architectural practice, PJT Design (pjtdesign.co.uk). Read his blog at homebuilding.co.uk/blogs.

Further reading:

• Timber Frame or Blockwork?
• The 12 Steps of Self-build: Construction Systems