Dry rot ravages a historic priory


Castle Cary is a picturesque market town nestled in the tranquil South Somerset countryside and within its rural surroundings, lies St.Johns Priory. The Grade 2 listed property dates back to 1877 when it was originally designed by Charles Bell.

In World War II American Forces occupied the Priory before it became the convent home of the Sisters of Jesus Crucified who inhabited the building until 1997. Having since fallen into disrepair, Carlson Homes were granted permission to transform the property into luxurious apartments.

Before the extensive renovation to restore the building into its former glory could begin, Carlson Homes needed a commercial timber and damp report carried out by a PCA approved property preservation specialist to determine the presence, and extent, of problems associated with Dry rot.

Timberwise visited St.Johns Priory on two separate occasions in order to gain a better understanding of the site, the defects and the client’s expectations. It was this attention to detail that meant Timberwise were awarded the works, despite a further report being carried out by a third party.


Respectful of the building’s architectural integrity, an exploratory exposure survey was carried out. Having stood dormant and boarded up to avoid trespassers, there was no airflow within the property. It was confirmed that this, along with defective rainwater goods, had led to a confirmed Dry rot outbreak.

It was recommended that the remedial works be carried out over three phases:

Phase 1

Firstly before Timberwise Operatives could start work on the building the defective rainwater goods that were responsible for the water ingress were removed as were the boarded-up windows to allow for the free flow of air. Typical of its construction and period the St.Johns Priory had extensive internal timbers forming decorative architraves, covings and doorframes.

Timberwise Operatives were then able to remove all affected timbers within a distance of 1m from the last sign of from the Dry rot outbreak, this then ensured that all areas affected have been adequately ascertained. This was a collaborative effort alongside the client’s labourer team, a more cost-effective approach for the client rather than have two or three Dry rot experts undertaking the ‘labour only’ role.

As well as removing all affected timbers it was vital that all fruiting bodies and large fungal growths created by Dry rot, were removed. It was essential this was carried out with precision so as to not explode and give off millions of tiny brown spores looking to germinate on previously unaffected timbers.

Phase 2

The first course of high strength fungicidal spray treatment was applied to all affected and accessible areas, this was then left for a week to dry. Within the priory there were other major refurbishment works going on, Timberwise worked closely in conjunction with other contractors to highlight all of the necessary timbers that needed replacing.

The fungicidal spray is designed to penetrate deep into the masonry, the biocide then targets the fungus, kills it, and ultimately stops it from spreading. By leaving the spray to settle for a week, this allows sufficient time to revisit and  see if any regrowth of fruiting bodies or mycelium has occurred thereby ensuring that these could be adequately dealt with using environmentally friendly fungicidal treatments and ensuring that once the property was renovated there was no potential for a further Dry rot outbreak.

Phase 3

During the course of the extensive sterilisation works our trained Surveyor was on site regularly to check there was no evidence of regrowth, with no evidence present the second coat of spray treatment was applied.

Dry rot holds no prisoners, no matter how historical or beloved the property is, and this was a challenging exercise, however, our diligent work on site allowed St.Johns Priory to become lovingly restored and intertwine its historical architecture with modern-day living

Steve Kohler, Surveyor CSRT CSSW

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