Chepstow is a beautiful town and community in Monmouthshire, Wales.  Located on the tidal River Wye, roughly 2 miles before the confluence of the River Severn.  Steeped in history, Chepstow’s Great Tower keep was commissioned by William the Conqueror following the Battle of Hastings.

With high ceilings and spaces which feel luxurious there is simply something that draws us towards the vast expanse of space and the warmth offered by listing buildings such as converted barns and farmhouses, often because of their idyllic rural locations.

Delta Registered Installers, Tywi Damp Proofing were commissioned with the sympathetic conversion of an old farmhouse located in Chepstow.  The project scope was to convert 1 listed farmhouse into 5 separate dwellings.

Original features, such as 5ft thick walls were embraced in this conversion project.

During initial inspections, penetrating damp was found. Penetrating damp is often referred to as lateral damp, which is the development of moisture through walls, roofs or any ground area of a structure.  If left untreated this penetrating damp will cause problems for the structure envelope and can lead to significant damage to the fabric.  Penetrating damp can be caused by a combination of problems such as the structure’s age, construction and exposed location.


After consultations with the developers, Tywi Damp Proofing suggested using a Delta System.  The air gap technology is favoured by English Heritage and Cadw as a reversible system suitable for listed buildings which maintains the structural integrity whilst being sympathetic in application.

Addressing issues of damp rising through the solid concrete floor, Delta MS 20 was applied with a channel system, in this ‘belt and braces’ approach.

Incorporating Delta PT using the “dot & dab” method, allowed for plasterboard fixings to the walls and finishes of a plaster skim.

All floors and drainage elements were fully tested to ensure these would drain to design requirements and is a fully maintainable solution, which complies with the requirements of BS8102:2009.

Case Study Results

A key advantage of using a Delta Membrane System was that the dwellings were ready for finishings as soon as Tywi Damp Proofing had finished their work as it was only necessary to wait for the plaster skim coat to dry.  The client was extremely pleased with the result.

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