Innovative timber repairs to a ‘Vic Hallam – Derwent System’ modular building in Manchester

15 October 2010

When Manchester City Council spotted a problem with timber decay they called out the team at Timberwise Manchester, experts in timber decay, to a school in Didsbury, Manchester for advice. Initially the survey was to investigate the 1st floor of the school that had deflected significantly.

Vic Hallam “Derwent System” modular buildings

The school in question was erected in the late 1950’s by ‘Vic Hallam’, a company who specialised in modular, timber-framed buildings. In this instance the property was created using the Vic Hallam  “Derwent System”. The “Derwent System” comprises of permanent buildings that are one or two storeys high and are based on a timber post and plywood box beam framing construction model.

The cause of the decayed timber

Emergency propping works were undertaken immediately to make safe the 1st floor whilst a further investigation of the timbers was carried out. Our investigations revealed extensive decay and failure within the majority of the timber columns / posts which connected the main structure to the walls taking the load to ground.  The decay had affected the posts between ground and first floor and extended into the horizontal beams.

The cause of this attack was due to the original timber window and door frames being replaced with UPVC frames. The replacement frames had no structural strength and the seals failed allowing rainwater to penetrate the main original structural posts and beams.

The innovative solution to replace the decayed timbers

Timberwise, working in conjunction with the Structural Engineers, Atkinson Peck of Stockport, designed a radical repair solution including a combination of bespoke steel strengthening plates and Timber-Resin splice elements along with specialist treatments to arrest any further decay in the timbers.

This innovative system allowed the building to be brought back to its original strength without the need for costly removal of all the windows and with the minimum of disruption. Indeed, the whole repair to a full elevation was carried out within the Summer holidays preventing the need to schedule additional closure to the school.

Timberwise also organised all the redecorations and making good. The children are now back at school safe in the knowledge that their school will stay standing for many more years to come.

The pictures below show the works carried out by the Manchester team.

Exterior of School

The exterior of the school. The school is a 1950’s Vic Hallam “Derwent System” modular building.

Delamination of timbers

The delamination of the timbers prior to work starting.

Timber repair

The rotton end of the timber is removed and replaced with a timber resin splice. The steel shoe that makes the joint between the beam and the post can also be seen.

Timber repair2

The new timbers in position. The steel shoe can also be seen.

Timber repair - the new posts in situ

Timber repairs from the timber repair specialists

Timberwise are experts in Timber repair and have a variety of solutions to replace rotten timber.

The picture to the left shows the finished job with all new posts fitted to along with new metal fixings  to fix the windows to the posts.

For more information on Timber repair systems from Timberwise call 0800 288 8660 or request a timber survey by completing our timber survey request form.