Traditional building construction for a house extension
This is often referred to as brick / block cavity wall
construction and has been the main stay of most new homes and house extensions over the last 60 years.
Whether the external skin be stone, brick or block work provided it incorporates a cavity (insulated or not) and
it has a masonry inner skin then this will be referred to as traditional building construction in most
This type of traditional building method is now under pressure for change due to the ever increasing U Value
requirements of the Building Regulations that now requires a fairly substantial fully filled cavity if it is
to meet the thermal requirements. Once an external wall becomes over 300mm thick, it could be argued
that it now has an adverse impact upon the room sizes for the ever decreasing scale of our new properties
coming onto the market.
However, this traditional building method for the house extension walls will still be common place simply
due to its ease of installation by house extension builders who can obtain all the materials & trades they need
locally in most cases.
Even a timber framed brick clad property that has an extension will probably use this traditional building
method for the house extension as the timber frame inner skin component has added complications for the majority of
home extension builders without additional expertise.
Block manufacturers have responded to the demand for more thermally efficient materials for traditional building
methods by creating thermal blocks but at the cost of strength where many of these blocks can be broken or split by
applying just hand pressure. I refuse to use the highest thermally efficient blocks for this reason.
Nearly 50% of all home extensions will suffer from some form of internal skin block work cracks during the first
two years. Manufacturers blame lack of movement joints or poor installation methods but when you see
many of the blocks arrive on site still steaming fresh out of the furnace and still curing on the lorry,
I personally have my doubts.
Traditional building methods for a home extension also refers to the roof construction. Traditionally cut
roofs are what I consider to be traditional. This is where structural timber is supplied to site and the
carpenter (or chippy) cuts & installs the roof timber bespoke for the job to the house extension designers
The final roof covering can then be either tiles or slates over breathable felt.
Another form of roof construction that could also be considered as traditional building methods for a home
extension is the use of pre-formed roof trusses where fully formed rafters & ceiling joists with intermediate
struts and ties are brought onto site fully formed ready for manhandling into position.
Lazy home extension designers or architects often specify trussed roofs to avoid detailing and specifying a
traditionally carcassed roof structure that takes a bit more thought. Most home extensions are actually
totally unsuitable for a trussed roof design of roof structure due to the amount of cutting and adaptation required
when abutting the existing roof for example. Dimensional tolerances and inaccuracies often assist making a
trussed roof unviable for a home extension.
Most house extensions require a high degree of flexibility for the roof structure and only a good carpenter
can complete all the little tweaks and adjustments to marry through the new roof onto the existing that looks
correct when finished.