Oak Frame Building Restoration – Carden Estate

Scaffolding and external tent erected

This award winning project involved Restoration & Repair work to a 400 year old oak Frame Building. The project took 14 months to complete and was awarded RICS Building Conservation Project of the Year 2014.

The Building was in a very poor state and required major ground & structural work before restoration could begin. The Oak Frame Building has subsided due to a collapsed drain and the structural timbers had decayed at the bottom, causing the building to drop. The existing stone foundations had also subsided due to the drainage problem.

The first stage of the project was to install internal props & supports to the main timbers in the Oak Frame. Acro props were used to lift the building by 25mm. We then installed tension straps internally to pull the Oak Frame together.

The whole Oak Frame was propped and supported as we didn’t believe that the building could stand as we began to strip it out. We had to also tie the Oak Frame building back to the Georgian section of the house to prevent it from leaning. The wooden frame was already 400mm off centre.

A full tent scaffold was erected over the Oak Frame building, this was due to the time of year & also the delicate nature of the building. The Covered Scaffold also allowed works to continue in all weather conditions. The repair of the oak frame building started once the scaffold had been completed. Restoration works started in January 2011.

The Slate roof, internal Floors & ceilings have been removed exposing the oak timber joists and supports

Our roofing team started to dismantle the old slate roof, carefully removing the original slate tiles, whilst restoration team set on remove the old fixtures & fittings. All the original wooden doors & door furniture were carefully taken down on stored on site, to be restored at a later date by our in-house joinery team. We salvaged as many of the original fixings as possible for reuse. The clay floor tiles in the study were carefully taken up and stored on site for re-use.  The Old Cast Iron Stove was very badly damaged internally and unfortunately could not be reused.

The ceilings & ceiling joists had become unstable due to water ingress from the roof.  All the Lath & Lime Plaster ceilings were removed and the ceiling joists de-nailed. Our skilled team of Restoration Contractors also started to remove the Brick Infill Panels from the Oak Frame. These brick infill panels were probably installed by a local Builder around 100 years ago, these brick panels are not the original.  All the bricks taken out of the infill panels were stored on site for reuse in other parts of the Restoration works.

The Oak Frame Building had to be monitored as the brick infill panels were remove. We had concerns with movement in the building as the weight was removed. We install additional straps & supported to the walls and Oak Frame.

Once all the brick infill panels had been removed. We used our Mini Micro Digger / Excavator to excavate the foundations of the oak frame building. The scaffolding had been erected with this in mind, so the standards were placed around 1m from the building, allowing us to use the excavator next to the Oak Frame Building.

New foundations dug out ready to be concreted. Notice the unsupported rotted external timbers.

We excavated material to a depth of 1.4m as we also need to excate the internal floor level.  The exiting foundation stones were removed, these stones were later used to make the stone dwarf walls. All the excavated material was stored on site and later used for landscaping works.

At this point the external timber walls and joists were not supported. Most of the external structural timbers were badly decayed at ground level. These would later be replaced on top of the new foundations & stone dwarf walls. The new foundations were cast with reinforcing bars and the stone dwarf walls constructed before the internal excavation started.

Internally we started excavating the internal floor levels using a micro excavator and mini loading shovel. Our Mini digger can fit through a doorway just 750mm wide. We reduced the floor level to allow for the 100mm of floor insulation and under floor heating design. The original floor tiles were only bedded on Lime Mortar straight onto the earth.

We also had to dismantle the large fireplace in the kitchen as part of the internal excavation. We installed Structural supports to the floor joists & Oak Beams as we removed the fireplace.

Once all the spoil had been excavated from the internal floor, we installed a 1200dpi plastic membrane to prevent damp penetrating the concrete floor slab. We used a local crushed Limestone as a base at a depth of 150mm. The Limestone sub-base was then compacted using a vibrating plate. The reduce floor level dig was a quick process and took around 1 week to complete the new internal concrete floor. The Excavated material was stored on site and later used for landscaping.

A new concrete slab was cast and then topped with an insulation layer. The under floor heating pipes were then pinned to the top of the insulation before a 75mm screed was applied. The Final internal floor was then laid on top of the screed. The boiler and equipment for the underfloor heating was housed in a newly constructed garage behind the building.

All the electrical & plumbing works were sub-contracted to local contractors.

New block work and external timbers being installed to support the remaining oak structure

Our team then proceed to complete block work to support the timber frame structure and build up the external walls of the property. New infill panels on the external walls were erected. Our joinery team removed old and decaying timber and replaced it with new treated oak timber to secure the structure. Internal floor and ceiling joists were also replaced and new ceiling lathes installed before being lime plastered.

Our roofing team replaced a number of Rotten Timber Rafters, however the majority of the roof timber was in good condition. We only replaced the timber in the roof  that was structurally required. The Oak Perlins in the building had suffered from a attack of Woodworm in the past but did not require replacing. We treated all the Timber with a multi treatment Woodworm, Dry-Rot & Wet-Rot for future preservation.

We found some Roman numerals on the Oak Roof Rafter, there was around 6 of the Oak Rafters that had these markings. We recorded and photographed the marking for future reference.

The roof was re slated with Welsh Blue Tonne Slates. We used around 80% of the original Tonne Slates, the remaining slates were sources from local reclamation yards. All the lead work for the roof was conducted on site by our roofing team.

The house was finished to an extremely high standard using top quality materials and craftsmanship.



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