Choose your build method
Duncan Hayes gives the lowdown on the main build methods
Brick and block
Masonry construction is the building method of
choice for the majority of the UK, and especially so in England. In fact, about
70 per cent of all new self-builds are built with this traditional technique.
Brick and block houses use a cavity wall construction with an inner skin made
of blocks and an outer of brick, with cavity ties linking the two walls and the
gap filled with insulation.
Key to the strength of the system are the
structural internal walls that help bear the weight of the upper floor. With
this method the external walls go up first, to first floor, then the internal
load-bearing walls followed by timber joists or a concrete floor, and then the
build continues.
On site construction Everything is built on site, which can mean a lengthy time to get the
superstructure up. Brick and block is a ‘wet’ construction and needs time to
dry out. In particular it can’t be laid in heavy rain or when it’s below
freezing
Labour It is
easy to find skilled workers familiar with the techniques and labour prices are
currently quite competitive
Finance Brick and block can be easier to finance with conventional lenders as
the stages mirror most self-build mortgage providers’ stage payments
Flexibility Bricks are very forgiving, easily dealing with any discrepancies in
foundations, levels or measurements. This also means that they will accommodate
any changes in the design as the build evolves
Mass The
mass of the materials gives the structure a high thermal mass, absorbing and
retaining heat in the building fabric that is radiated back into the house when
the temperature falls. However, there is limit to the size of the cavity of
around 100mm, after which it causes structural issues, and so U-values have a
threshold. New insulation materials and thin-joint systems will address this in
the future. Mass offers good sound proofing, too
Timber frame
Timber frame is extremely popular with
self-builders, with nearly 22 per cent of all new homes using this method,
although the figure is skewed regionally, with more in Scotland, where it has
long been a favourite.
In this method the timber frame acts as a
superstructure, supporting the entire building so there’s no need for internal
load-bearing walls. The frame is prefabricated off-site in a factory, and there
are several different methods of construction to choose from (see below).
Most manufacturers fabricate and erect the
frame, taking it to the water-tight stage, and most will be able to recommend
contractors for other work, such as foundations, or even take the house to
completion for a turn-key solution. Frames are not forgiving and foundations
that are not precisely measured will cause delays.
Speed One distinct advantage is the speed of on-site
construction, with many frames going up in a matter of days. The lead times are
long though, and once the frame is designed and ordered it can be difficult and
costly to change the layout, so you must be able to visualise what rooms you
want where early on. The off-site construction and speedy erection means that
bad weather on site is less of a problem
Labour Finding
labour that is comfortable working with timber frame is harder than with brick
and block, but most work is done by the supplier, with relatively little onsite
labour. However, you may need to shop around to find a supplier. Always look
for industry accreditation, such as TRADA or the UKTFA’s Q-mark. See the
directory for details
Design Timber
frame offers a myriad of design options, with many companies having stock
designs that can easily be tailored to your needs at the design stage. From
ultra-modern Huf Haus styles right through to classic oak frame houses there is
a wide range of styles and influences to choose from. This also includes the
finish of the exterior, including everything from green oak frames left on show
with infill panels, houses finished with wood cladding, tiles and a brick skin
or the whole house rendered
Sustainability Timber from FSC sources is very eco – it’s carbon neutral, renewable,
non-toxic and organic, with a low embodied energy, especially if harvested
locally
PACKAGES
A typical build route involves contracting in
professionals and trades to design and build your home, with a main contractor
responsible for the structure. The alternative for self-builders is package
companies, who will do some/all of the process for you.
You can choose the level of involvement you
want, and different companies work with different build systems and have
different designs: some will only build in green oak, while others offer a
range of systems, such as Potton, which includes SIPs (Kingspan TEK) in its
wider range of timber frames.
One plus of this system is that design fees are
usually included in the cost, helping to keep the up-front fees to a minimum,
and you don’t need to get bogged down in sourcing subcontractors if you don’t
want to.
Fees vary according to the design, system and
materials, and also the level of service you require. Many timber-frame
companies will take the house to water-tight, while others offer a more
complete package.
The advantage of building with package
companies is that they are used to small-scale projects, and will be able to
offer help and advice, as well as provide you with a detailed bill of
quantities early on, helping your budget stay on track. If you want to have an
active part in the build let them know early on to make sure that both sides of
the build are happy. Package builds are extremely popular with ‘time-poor’
self-builders, as they take a fair amount of the stress out of the process.
Although less common, there are a few brick and
block package companies such as CB Homes and Design and Materials.
To find out about alternative build systems read the full article in the
March 2010 issue of Build It
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