We asked our Company Architect, Tom Somerville to look at the reasons why so many
individuals still prefer a solid structure. Tom holds a first class honours degree in Architecture and has been involved in
self-build for 25 years. He has carried out post graduate studies on both masonry and
timber framed construction.
The choice of construction has always been an issue large in the mind of all self-builders and has been a subject of debate in the industry, comparing the relative merits of traditional and timber frame construction, more so as the cost of energy continues to spiral upwards.
I felt those about to decide on a new home would welcome a knowledgeable overview of traditional construction. Let's look at why masonry build has endured the test of time and try to identify why it is the prime method of construction for your new home.
Traditional construction as we know it didn't really become the first choice for building until the Great Fire of London, up until which stone or clay bricks were used as an in-fill to oak frames. The oak frame was substantial and could be trusted to keep the weather at bay provided the spaces between were similarly weather resistant. This method worked well enough, with artisan labour erecting all manner of buildings but to standards, which are unacceptable today. That was until the Great Fire revealed the system's fundamental weakness - it burned. Good for eradicating the plague, but bad for buildings!
Where to best spend your money
Renewable energy features such as photovoltaic roof tiles and heat pumps have genuine ECO credentials and have naturally become popular with self-builders. However they have a high capital cost, require maintenance and it's easy to spend more than you need, sometimes for questionable benefits.
Renewable energy should not be dismissed but there is an alternative we believe you should seriously consider. It is simpler and friendlier on your pocket and means investing in the structural fabric of the building and quality of build.
Building Towards 2014
Reduced heat loss and increased air tightness
The standards of thermal efficiency laid down in the Building Regulations are due to change in 2014. Looking to the future we now provide our clients with a minimum 'U' value of 0.17 W/m²/°C for external walls. This is achieved by incorporating high performance interlocking cavity insulation giving an airtight wall. Other improvements include thermal plasterboard to first floor ceilings and the latest in window technology. The latter features a 'U' value for the double-glazing of 1.2 W/m²/°C and a unique 'Secure by Design' locking system approved by the Police.
Future Proof Your New Home
Passive House Principles
If you are looking to really cushion yourself against the ever-increasing cost and availability of energy then you may be interested in investing in the Principles of Passive House technology*.
External walls 'U' value 0.10 W/m²/°C
Triple glazed windows/patio doors 'U' value 0.80 W/m²/°C
Enhanced high performance ground floor system
Enhanced high performance roof insulation
High thermal mass
Insulated entrance doors
Mechanical ventilation and heat recovery system
This typically adds around 10% to your build costs but you may consider that a small premium to pay for minimal energy bills and increased comfort. If this is of interest we can calculate the exact figure for you and you can then make an informed decision.
N.B. This option is available regardless of size of dwelling, architectural style and orientation of your building plot. In other words you don't have to build an ultra-modern design with a south facing rear garden to benefit from Passive House Principles.
*Footnote: This option should not be confused with 'Passivhaus' which requires certification. Building to 'Passivhaus' standards will add significantly more to your build costs compared to building with Passive House Principles.
Long lead times for timber frame
If you have spoken to a timber frame salesman you will no doubt have been advised that it is quicker to build by this method than if you adopt a cavity wall construction. There is an element of truth in this, but it is by no means the whole story. The time to order your timber frame is when you have your planning approval, only a fool would do so before this.
You will then be quoted a delivery date by the timber frame manufacturers of between 8 and 12 weeks, sometimes even longer, leaving you to prepare the footings, a job that only takes a few days. The chances are the well-organised self-builder is left waiting weeks for the frame.
On the other hand, the masonry built home can carry on, giving it a head start. Any advantage that timber frame offers in speed of construction is generally lost, and both build methods tend to finish in about the same time.
A further point to remember with timber frame is that the footings must be built accurately to fit the factory built frame, if they are not then the panels may need some fairly major alterations. Again the masonry built home is at an advantage because of the flexibility inherent in the build method, allowing problems to be worked around.
Thin bed blocks: If time scale is important to you but you still want all the advantages of cavity wall construction you can consider large format blocks. Briefly, these are high quality, autoclaved and aerated concrete blocks that are significantly bigger than a standard block and laid on a thin bed of 2mm/3mm. It is possible to halve the build time for these compared to a normal block, making the construction of the cavity wall significantly quicker. The other good news is that you can still have solid floors as the walls can be designed to support them.
As Design & Materials company architect, it is important for me to understand the relative build costs between cavity wall construction and other popular methods, especially in the context of the particular needs and skills of each of my clients. Since I have built my last two homes in timber frame and cavity wall respectively, I believe my judgement to be reasonably accurate and unbiased. I have found cavity wall construction, compared like for like, to be cheaper than timber frame.
But to find the real facts on the different build methods don't rely on salesmen undertake your own research from independent sources.
Unless you have recently won the National Lottery it is unlikely that you have a pot of money to see you into your new home without considering finance. Stage payments to builders can also be a headache, arriving late from your lender after you have spent the money. Since package companies and manufacturers don't provide overdraft facilities you have to look at the build route to mitigate this problem. Don't blame the timber frame companies for charging so much money up front, they have cash flow problems too.
The most cost effective way is to drip feed the builder with materials, not only because this involves you in less expense as you build but it also means there are fewer costly materials left on site for the thief. Masonry construction is a perfect way to build in this respect. You are more able to limit expenditure during the project and heavy blocks and bricks are just not worth stealing in significant numbers. Just be sure you don't run out of materials unless you want to pay your builders for standing time.
No creaks or echoes
A traditional cavity wall house with solid floors and walls throughout has that quality that is so difficult to define. It simply feels solid, secure and permanent. I suspect it is about the factors mentioned earlier making the whole greater than in its parts. It is about the absence of echo when you tap the walls, or creaks when you walk over the floors, or the sounds from other rooms and even the warmth despite the heating being switched off hours before. These are sensory factors you tend not to keep at the front of your mind but do add up to comfort. Worse still, creaks, conversations and chill air can indeed force themselves into your conscious thought and that becomes an annoyance.
Timber frame forced to meet legislation
It is no surprise that the ever improving standards of legislation are catching up with the values enjoyed by our clients who appreciate the merits of modern brick and block construction. The NHBC have reported a significant number of complaints in the past from customers who have found the lack of sound insulation between rooms unacceptable. From 2003 Part E of the Building Regulations included more demanding standards of sound insulation within every home built. The focus is on partitions and floors between bedrooms and other habitable rooms, between bedrooms and bathrooms as well as between bedrooms themselves.
As ever, higher standards means higher costs. Not so for our clients, they have enjoyed levels of acoustic insulation comfortably meeting the new standards for years. Timber frame construction, on the other hand will require expensive modifications. Partitions will need to be lined with TWO layers of plasterboard on each side as well as the inclusion of mineral wool quilt between the studs. Whether this eliminates that unwelcome noise when you tap a timber partition remains to be seen. As far as timber floors are concerned mineral wool quilt will once again be called for. However, I can't help wondering how effective these measures will be.
As always the quality of workmanship is crucial to the success of a timber frame and the mineral wool will have to be carefully packed into the partitions and floors to avoid gaps. These measures will certainly increase the cost differential between timber frame and modern masonry construction, so why pay more for less.
Solid brick and block construction
I have spoken about the place of traditional cavity construction in today's housing industry but I have to conclude that it is time to change its name to modern masonry construction. The benefits of extremely high levels of thermal insulation and sound absorption and overall flexibility in particular make it a strong choice for any home, meeting as it does the demands of modern life where energy conservation and privacy are important to us all.
Let's all put an out of date notion to bed once and for all and embrace modern masonry construction in the new millennium.
For further information on modern masonry construction contact the Modern Masonry Alliance at http://www.modernmasonry.co.uk and the Concrete Centre http://www.concretecentre.co.uk
About U value: A 'U' value is a measurement of the rate at which heat passes through an element of a building expressed as watts per metre squared per degree centigrade. For example from the outside brick to the inside face of the plaster in a cavity wall. The lower the 'U' value figures the better.