This case study shows an example of joists being repaired without removing the roof covering. A low disturbance repair using Rotafix manufactured timber replacement units being bonded into place using Rotafix Structural Adhesive removes the need to take the roof covering off the castle.
Clyne Castle is a grade II listed building situated on a hill overlooking Swansea Bay, near Blackpill, Swansea. It was originally built in 1791 by Richard Phillips.
It is a two-storey castellated mansion, built of randomly laid local sandstone with Forest of Dean stone dressings situated on the outskirts of Swansea.
The Castle with its many annexes has a complex roof structure made from slate. These annex roof structures drain into the interconnected valley drainage system formed from lead sheeting.
The failure of the valley drainage system has resulted in a prolonged exposure of parts of the roof structure to sustained water ingress leading to wet rot in the underlying span beams, hip rafters and ceiling joists. The suspended ornate lath and plaster ceiling has suffered localised damage but is a period feature that must be retained.
Protectahome, approved Rotafix contractors, were subcontracted by RM Williams to undertake the specialist repairs required to restore this beautiful building to its original glory with minimal disruption to the integrity of the existing building features.
Protectahome, in conjunction with Rotafix and Ian Jones Associates, Structural Engineering Consultants, developed a series of low disturbance repairs to the roof timber members using Rotafix Structural Adhesive, (RSA), Glass Fibre Reinforced Plastic (GFRP) rods, and KERTO structural engineered timber sections to replace in situ the timbers that had been ravaged by the ingress of moisture over time.
The hip beams supporting the roof were badly damaged at the wall plate and bearing ends. Once the structure was supported it was possible to remove the damaged and decayed timber.
Measurements were then taken and an oversize KERTO replacement prepared off site. The Rotafix Timber Resin Splice (TRS) side slot design was chosen as the preferred method of joining the original and replacement timbers as access was limited.
Structural calculations showed that 6 number 16 mm diameter high tensile rebar connections would be required to meet the requirements of the design.
Once the Rotafix TRS section was on site the experienced craftsmen of Protectahome cut and fitted the new timber to the exact requirements. The slots in the KERTO and existing parent timber were then injection filled with the RSA.
The span beams were repaired by removing the damaged timber. Holes were then drilled up into the ends of the parent timbers to allow high tensile strength 20mm rebar rods to be bonded in place. New sections of KERTO were made to measure that featured 6 side slots to receive the protruding 20mm diameter rods. The slots in the timber were filled with RSA. KERTO engineered timber was used to give guaranteed strength consistency to the joist repair.
Bonded in rods were also used to repair joists in the ceiling. In this instance it was possible to achieve the design specification using 12mm GFRP rods and replacement grade C24 softwood timber .
Once the ceiling joists had been repaired the lath and plaster restoration work commenced in the knowledge that the roof structure was rigid and sound.
This project has demonstrated that with good retrofit disciplines coupled with materials specifically designed for the job in hand and experienced skilled craftsmen it is possible to repair in situ complex structures with minimal disruption, saving time and money as well as preserving the building heritage and original design
For further information about products used in this project or any queries with respect to structural adhesives and on-site bonding please contact us on +44 (0)1639 730481 where one of our technical team will be happy to assist.