Marianne Suhr: Transforming a timber framed house

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The project: Honey Cottage, a timber-framed 17th-century, Grade II listed, four-bedroom home in need of extensive repair and modernisation.
This month's challenge: To restore the front elevation with a traditional porch and casement window.

I’ve been watching with interest over the last couple of months as Honey Cottage has gone through some fairly radical repairs and alterations. When Harriet and Brian took it on, the historic front elevation had been blighted by a 1970s picture window and modern front porch. The ancient timber frame had been chopped about and was in a pretty poor state. Richard Cain, their surveyor, advised restoring the front to its original form by reinstating the frame, putting in an appropriate casement window and replacing the porch with a new green oak design.

The walls contain a mixture of original wattle and daub panels and 19th-century brickwork in between the oak timber frame. Wherever the frame has been repaired or reinstated, the infill panels have had to be removed in order to get access to the carpentry work. Having gone through a similar process on my own house last year, I suggested using ‘Hemcrete’, an infilll material, wherever they had to be reinstated.

It is one of my favourite modern products and is a sort of modern day wattle and daub, a mixture of chopped hemp and lime that has fantastic insulation properties. While it will look the same as wattle and daub once it has had a coat of lime plaster, and technically it will ‘breathe’ in the same way, it also leaves evidence for future generations about the work that has been carried out in 2009. Although the builders were initially sceptical, I think they are fully converted and are genuinely pleased with the end result.

The new porch is a triumph, and an emphatic improvement on the previous structure. Designed to just the right scale and built by skilled craftsmen, it completes the front elevation perfectly. The individual oak timbers were prepared on site using a chainsaw to form the delicately curved posts. The diamond set mullions in the window openings are a traditional feature, and were originally used to support the leaded glass panels.

A project like this is not for the faint hearted. Harriet and Brian are camping out in two rooms while the front wall is being propped, dismantled and then rebuilt. And if this sounds like your worst nightmare, add to the mix a broken ankle. Harriet is now on crutches dreaming of the day when she can have a soak in a dust-free bathroom.

Marianne's Checklist: Timber-framed houses
If you’re buying a period timber-framed house, it is critical that you employ a surveyor with specialist knowledge. Here are the key things to consider:

• Budget for the worst-case scenario If the walls have been rendered in cement, it is likely that there will be some degree of decay to the timber frame beneath and further investigation will be needed.
• Saving the frame I’m amazed at how a piece of timber that looks rotten on the outside is rock solid just a few millimetres below the surface, so don’t assume all is lost.
• Manage woodworm Any sign of woodworm on the outside is almost certainly superficial and nothing to fear, provided the timber is oak and not elm.
• Be prepared to discover rot The sole plate is the most likely section to rot – this is the horizontal beam carrying the bottom of the frame. It should be sitting on a masonry plinth wall, above ground level. If it has to be replaced the wall will need to be propped and partially dismantled. This is expensive.
• Employ an expert for repairs Always get a specialist carpenter, someone who is keen to repair rather than replace the timber elements.

Choosing new infill panels
Infill panels are often problematic. If they have shrunk they can cause draughts and water ingress. In many parts of the country it’s traditional to clad a timber frame with weatherboarding to overcome the problems. Here are the main choices:

WATTLE AND DAUB This is the most common material. It uses a mixture of hazel ‘withies’ taken from the hedgerows, woven around vertical oak ‘staves’. On to this a mixture of clay-based earth mixed with straw was applied. If replacing the odd panel, then this is often the best option.
BRICK Often wattle and daub panels were replaced with brick where they were available. These were commonly plastered over with lime, or sometimes applied in a herringbone pattern. Since they are so thin, just half a brick thick, they tend to be rather unstable, especially during repair works. They are also very poor insulators.
POLYURETHANE A common modern infill material is polyurethane foam board, often foil-backed to reflect the heat. A tape is fitted around the edge to form a seal with the timber. While these are thermally efficient, they look very flat and ugly.
HEMCRETE This is easy to mix using a cement mixer, and is cast between two boards while it sets. It can be shaped, sculpted and finished with lime plaster and limewash.

WORDS & PHOTOGRAPHS MARIANNE SUHR
Featured in the July 2009 issue of Period Living