Sorting out snags

Old buildings expert Marianne Suhr checks renovation progress at Watts Barn to find out whether any problems have arisen and how they’ve been solved.

After a huge leap of faith and an arduous 13 months on site, Heather and Graham’s dream home was almost complete. What had once been a rather decrepit and ancient timber-framed barn was now on its way to becoming a 21st-century four-bedroom house. But of course complex and prototype projects always encounter problems, and Watts Barn was no exception.

ABOVE (left-right): The dreaded damp patches are noticed on screed on the sunken floor levels; Old-fashioned bitumen is applied to seal any gaps around the base of the house and to prevent damp from rising upwards.

Water works
The first ‘snag’ was noticed during the winter, towards the end of the plastering contract. In order to cope with the freezing temperatures, the windows had been shut and the builders had covered them with plastic sheets to stop them getting splattered and stained with lime plaster.

During a routine inspection, surveyor and project designer Richard Cain noticed the new honey coloured oak window frames were developing surface patches of grey and black. Huge quantities of water were being evaporated within the building as the lime plaster dried out; this caused humidity levels to be exceptionally high. The moisture-laden air had reacted with the oak and caused surface staining and blackening.

Immediately Richard asked the builders to open all the windows during the day to provide natural ventilation, and to use dehumidifiers during the night. The worst affected windows were sanded down to remove the staining before being treated with oil.

Next came the nightmare that every surveyor and homeowner dreads – low level damp. The builders reported patches of damp appearing on the concrete floor screed, and quickly realised that it was coming in from outside. The ground floor had been dug down – almost 2m below the level of the garden in some places – to create more headroom at either end of the barn. Despite installing a high-tech damp proofing system to keep water out, something had gone awry.

ABOVE (left-right): The new green oak ridge beam has been nibbled by a powderpost beetle; A close-up of the powderpost beetle ‘emergence’ holes in the ridge beam.

Plugging leaks
Surveyor Richard and foreman Mike Staples, aka Chico, decided to test where the leak was coming from by digging a trench around the outside of the building and filling it with water to effectively form a moat. It appeared that the seal between the floor slab and the bottom of the wall had failed, and water was trickling in under the floor.

After various investigations, Richard decided to remedy the problem with a good old-fashioned solution – bitumen. This was heated up and painted on to the outside of the wall at low level, sealing the gap. After the bitumen had dried, Chico tested its effectiveness by filling the trench with water again. He was relieved to report that the leak had been resolved. The drains were then relaid to take away rainwater and the trench was backfilled with gravel.

The last problem came when Graham noticed some small piles of fine sawdust on the stairs. Richard inspected the timbers above to find tiny holes in the surface from woodboring beetles, eating through the surface of the wood and dropping piles of ‘frass’ below.

The beetle was powderpost beetle, only present in newly felled or green oak due to the high starch content. This would have died out within a few months as the wood seasoned, but Graham decided to treat it with an eco-friendly chemical, just to prevent any further damage.

As Richard told me, every project is bound to have a few hiccups along the way; sometimes contracts turn sour and the team fall out. The important thing is to discuss problems calmly with everyone involved and work out a solution, rather than look for someone to blame.

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