High performance spray foam insulation for Grade 2 listed barn restoration

Old Mill Barn is a Grade 2 listed building in the conservation area of Standon, Hertfordshire

The barn, which is one of the oldest buildings in the village is thought to date back to the 17th Century

Contractors restoring and converting an architecturally significant barn complex in the Hertfordshire village of Standon were faced with a difficult challenge in bringing the 300 year-old structure up to modern thermal performance standards, without compromising the unique and highly original, internal timber frame and external boarded facades.

Old Mill Barn is a Grade 2 listed building, situated close to the River Rib in the conservation area of Standon Village. The owners of the building were granted permission to convert the L-shaped single and two-storey structure into a two- bed home and engaged Hertfordshire based conservation contractors, Datum Point Construction to undertake the work.

The barn, which is one of the oldest buildings in the village and thought to date back to the 17th Century, had up until recently, been used as a storage facility. Much of the original timber frame and external horizontal timber boarded exterior were still in place and in relatively good condition.

The visual appeal of the barn and its contribution to the village setting were influential in its listed status so bringing the building back into use, insulating it to modern standards and restoring its fabric in a sensitive and sustainable way, were priorities for Datum Point Construction.

The barn comprises a traditional internal frame of rough-hewn timbers with an external skin of dark painted weatherboard, set on a low brick plinth. Roofs are pitched, with clay plain tiles and half hips to all gables.

Paul Adams, Construction Director and Project Manager for Datum Point Construction takes up the story. “We’ve worked on a number of historic building restoration projects and know the challenges that old structures bring. Hardly


anything is square, there are gaps all over the place and most of the original timbers were hand cut and variable in dimension.”

Continuing, Paul said, “These factors took us down the route of a spray foam insulation solution rather than using conventional, rigid board material which would be difficult to fit and almost impossible to make the building anywhere near air tight.”

Because of the sensitive nature of the Old Mill Barn restoration, Datum Point Construction worked closely with Hertfordshire Building Control and Spray Foam Insulation specialists Icynene, to come up with the most appropriate material to insulate the building.

Clive Phillips, Building Control Officer in charge explains. “Working with Icynene’s technical team, it was quickly obvious that an open-cell foam insulation was best for the job, as it gave us outstanding thermal insulation but still allowed the building to breathe so there was no risk of internal condensation”.

Insulation sub-contractor, Foam Insulations Ltd, applied Icynene’s Foam Lite LDC 50 to a thickness of 100mm to all walls and 125mm to the pitched roof areas, achieving U values of 0.32 and 0.29 respectively.

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