RICS

01473 788186

Email: john@johnsparks-surveyor.co.uk

Fees not subject to VAT

Timber Frame

General Advice - Case Study 2Up until the advent of the canals and railways, buildings other than the grand houses and cathedrals were built using local materials. Transport costs for other materials would have been prohibitively high. This resulted in each local area developing its own style of vernacular architecture largely reflecting the local geology and materials to hand. East Anglia does not have any significant amounts of building stone but forests had grown up over the clay soils, making timber freely available. People would have built shelters using a timber framework with a clay/mud infill or cladding and a thatch roof covering, probably being straw inland and water reed in the river valleys. The vast majority of these buildings would have been low grade structures which have long since rotted away. It is generally only the grander houses and structures of the comparatively wealthy which have survived to the present day.

In Suffolk, compared with Kent & Sussex, relatively few examples of domestic timber frame architecture remain prior to about 1400 but with the expansion of cloth production (flax in the north of the county and wool in the south) wealth started to accumulate. This can be seen mainly in the towns such as Lavenham where exposed timber frames are on show. These frames were the equivalent of modern day “bling” and were designed to show the wealth and status of the owners.

General Advice - Case Study 2Despite much talk of medieval timber framed buildings, in Suffolk by far the largest group date from the 16th and 17th century (Tudor & Stuart) and were built with rendered elevations. These frames were never designed to be shown on the outside. This had the advantage stopping the draughts and rain blowing through the inevitable gaps between the frame members and the wattle and daub clay panels. A typical feature of the East Anglian landscape is the 17th century timber framed “lobby entrance” farmhouse (opposite). This has gables at each end of the steeply pitched roof. It has a large central brick chimney stack with rooms off to either side. Normally the entrance lobby and porch would be in front of the chimney and the staircase behind.

These old timber frame buildings were often recycled, not only from the point of view that frames were taken down and sometimes used elsewhere, but a more common scenario would be that from the 18th century onwards, when timber frame was no longer fashionable, the larger house would be divided up to provide workers' cottages. In the 20th century with timber frame coming back into fashion the pendulum swung the other way with cottages being converted back to a house for the wealthy and also former industrial buildings such as barns and warehouses being converted for residential use. The fact that these timber framed buildings were often made up of modular units meant that compared with brick structures they could be comparatively easily adapted and repaired which is possibly one of the reasons why so many have survived.

General Advice - Case Study 2General Advice - Case Study 2

In East Anglia and the south east nearly all the framed buildings were constructed using a technique known as box frame construction, an example of which is shown in one of my sketches (left). In all my Building Survey reports, be they on timber frame or brick, I will give a brief outline to the client as how the building works and how the various loads are transferred down to the ground. Unless a surveyor understands how the building works it will be impossible for them to advise as to whether the all too common structural alterations, such as cutting out frame members to provide a new door opening, will have adversely affected the structural integrity.

Most of these buildings have survived for hundreds of years although like the old trusted broom, which has had three heads and two shafts, it is inevitable that parts will have been replaced over the years, sometimes several times.

Although these old houses can be rewarding places to live, the last 150 years have not been kind to them. After about 1850 there was a radical change in building styles with the introduction of far less permeable building materials, such as cements together with barrier techniques to provide “damp proofing” and to keep the water out. Unfortunately all too often they do exactly the opposite, trapping moisture inside if they are applied retrospectively to old buildings. Old houses by contrast were built using relatively simple techniques and used permeable materials which allowed moisture vapour to pass in and out of the structure. In this way providing the building was maintained, high levels of moisture rarely built up. Even so low levels of rot and woodworm activity took place and at some point in their life most buildings have had parts of the base of the frame replaced. In the case of common furniture beetle and oak timber, the damage is often restricted to the sapwood as the photograph shows leaving the solid heartwood core intact.

General Advice - Case Study 2

Fungal decay and wood boring insect activity are two of the major agents of decay in old buildings. They are essentially symptoms of high moisture levels and the rate of decay will accelerate as the moisture content rises.

Unfortunately various industry bodies have been very effective in getting the general public to believe that unless you have the timbers sprayed with an insecticide or a damp course injected, the woodworm ‘will eat your house’. It is true that in some circumstances they can cause significant damage but the important issue to address is the level of moisture in the structure.

Due to the wide spread application of impervious materials such as cement renders, plastic masonry paint and bitumen roofing felt to the nation’s timber frame housing stock, it is vitally important that any surveyor advising on a timber frame house has an understanding of both moisture generation and movement paths within the structure. Only then will they be able to advise on the implications and impact of the materials which have been used in the construction or applied at a later date. I believe a pragmatic approach needs to be taken although wherever practical I would nearly always advocate replacement of impermeable material with permeable techniques.

Anyone considering buying one of these older houses will benefit greatly from having a general understanding as to how these buildings worked originally and how moisture levels and movements may impact upon the structure. My Building Survey reports are designed to provide you with this information as well as providing the information about defects and the repairs required.