Dyffryn stoneworks project

Dyffryn house covered in scaffolding

Dyffryn is undergoing a substantial revival project to restore the house and gardens to their former glory. This year we are undertaking a huge project to repair and restore the stone facade of the house.

Dyffryn house gets a facelift

Over the autumn the house will be entirely covered in scaffolding meaning that the house will not be visible. We ask for your understanding in carrying out this vital work.

Dyffryn House will be undergoing a substantial stone restoration project this year costing just under £250,000. 

A previous survey carried out in 2011 determined that all elevations to the Grade II* listed mansion had suffered from decay. The stonework was gently Doff cleaned with steam to determine the extent of this deterioration.

As a result of this, 2017 saw urgent stabilisation works completed to the North elevation which was suffering from falling debris and water ingress. The Porte Cochere, a Victorian addition by John Cory allowing his guests to depart from their carriages protected from the elements, was particularly prone to falling stone.

The north and east sides of the mansion have suffered the most, likely due to the fact they get less direct sunlight enabling the growth of algae and are prone to damp.

Historic inappropriate cement repairs to the stonework had failed and was causing water to become trapped within the limestone and in turn causing freeze–thaw action. This triggered further damage to the stone.


Historical corner cutting?

The surveying of the stonework has certainly enhanced our understanding of Dyffryn House. Although John Cory, who extensively remodelled the mansion from an original Georgian mansion, was a very wealthy industrialist, it appears there are some questionable areas of workmanship throughout the structure.

The Bath stone is only a façade, hiding brick and river pebble back-fil in coal slag. Water ingress in the join where these opposing material meet has caused weaknesses.


Dyffryn House was re modelled by John Cory in around 18 months, not long for a 50 roomed mansion with a new Great Hall to be constructed. Could this explain the short cuts in construction? Cory was in his 60s when he took over the Dyffryn estate- perhaps he wanted his new home built quickly in order to enjoy it in his old age.

What stone will be used?

Oolitic limestone makes up most of the stonework, most likely from a quarry in Bath, it is also a soft limestone, another reason for its decay.


The plinth of the Mansion is made from grey pennant sandstone, likely from the Forrest of Dean. The error in the way the stone has been cut in the quarry means that it is susceptible to delamination.

This year’s stoneworks project will see the completion of the North elevations baluster and urn repairs, missed off the original project due to financial restraints. 

The east elevation, which has been roped off due to hazardous stonewall, will be included in this year’s works as well as all the chimneys, and sash windows, some of which have suffered from rot over the years.

The mansion stucco will also be re-painted and a shelter coat (similar to lime wash) will be used to protect the stonework from future erosion by wind, rain and pollutants.