Stabilisation Consolidation Listed Barn

This project involved the Consolidation & Stabilisation of this Grade 2 Listed building in Bedfordshire. The barn was originally constructed in 16 century using locally sourced stone & clay as building mortar. The conservation officer had to approve all the works we under took on the Grade II Listed Building. All works on listed buildings in Bedfordshire will require Listed Building consent. When repairing old period properties any stonework or brickwork should be done with a lime mortar for lime pointing, lime rendering or lime plastering.

The Listed barn is to be converted into a residential property. We were employed to install Helical Crack Stitching Bars, re-construct the top section of the gable elevation due to a large bulging, fill voids and lime grout stone walls & make opening in rear stone wall.

The Gable Wall had previously had a power cable attached which has pulled the stonework out of place. The stone gable was constructed from local stone & clay as a bedding mortar. An access scaffold was erected to the gable wall. An internal 3 level bird cage scaffold was erected to provide access.

As the gable wall has been constructed from clay the stonework dis-assembled easily without damaging the masonry. The gable wall had moved around 14″ off centre, we installed some addition supports to prevent the gable wall from collapsing during dismantling. As we dismantled the stone gable wall, we stored the stonework on the scaffolding. We separated out the rubble fill from the centre of the solid wall for re-using.

As we removed the masonry additional props were installed to support the Thatched roof rafters & perlins. We use the internal & external scaffold to fix braces. The internal stone wall had not moved. The walls had pulled apart opening up the centre.

We used a Hydraulic NHL 2 lime mortar for rebuilding the stone work on Listed Barn in Bedfordshire. All the stone taken down from the existing gable end wall was re-used in the re-construction. The rubble fill stone from the centre was tightly packed back into the wall centre. We used vertical and horizontal building lines to make sure the stone work was inline with the existing Listed Building.

This kind of solid stone walls can be very warm and dry when working correctly. The lime pointing & lime plastering allowed the stone walls to breathe. In exposed areas of Bedfordshire the old stone walls have kept the rural people warm and dry for hundreds of years.

It is important that all voids are filled between the stonework is packed and filled using a lime mortar, prior to applying the exterior lime pointing.

We coursed the stone work to match the original courses of the Grade II Listed Building in Bedforshire. The original wall had “through stones” built in to tie the internal and external leafs together. Through stones were used for solid wall construction before wall ties. These through stones are usually large in size with two pitched faces.

We built the wall up and under the Grade 2 listed thatched roof, we had to lift the thatching in places to allow us to install the stonework.

We also installed a new doorway in the rear elevation. We started by carefully dismantling the original stonework. The stone was stored on site, as it was used to rebuild the doorway returns . The construction of the wall is the same as the Gable Wall solid stone with rubble fill. We install acro props internally to support the internal thatched roof structure.

We dismantled the solid stone wall to ground level and removed the foundation stones. As with the gable elevation we used Hydraulic Lime mortar for building the stone wall, a lime pointing mortar was also used. The centre of the solid stone wall was fill with the off cuts of rubble. These were tightly packed into the centre of the wall using lime mortar. Lime grouting around the doorway was necessary to consolidate the masonry.

Two solid oak beams were then installed over the newly created doorway opening. These two beams weighed over 500kg between them. We used lifting equipment to place the beam on the scaffolding deck. We adapted the scaffolding to access in the installation of the oak beams. The oak beams were sourced from a local timber yard & cut to size.

Once the oak beams had been positioned, we pack under the oak beams with lime mortar and slate. Then proceeded to reconstruct the wall above the oak beams up to the roof-line. The thatched roof line had to be altered so the new slate roof on the rear building could be integrated into the thatch.

When working with green oak and lime mortar, extra care  needs to be taken as lime mortar is highly acidic and will stain the surface of the wood black.

We used a 7mm Stainless Steel Helical Structural bar to re-enforce the corners of the Listed Building. The Helical bars are made from Stainless Steel this makes them resistant to corrosion. These Helifix bar were 2m in lenght. We used a flexible grout to fix the bars in place. Stainless steel brick stitching ties have a tensile strength within the 1050-1200N/mm² band and a spiral twist that permits a degree of torsional yield within elastic limits

Crack stitching bars provide a permanent solution for masonry repairs and cracked wall reinforcement. Crack repair rods are simple and effective when grouted across cracks in walls to reconnect and strengthen masonry. This effective masonry stitching repair provides resilience against further cracking with minimal cost and little disruption

Once all the core structural work had been completed and the building had been consolidated and stabilised our team  set to removing all the existing lime pointing mortar from the stone walls. The walls were then washed and flushed to remove any dirt, dust and debris, before any large areas of the masonry were filled and packed using lime mortar. We used a grouting gun to inject the lime mortar deep into the masonry work. We also inserted pinning stones to reinforce the lime mortar.

The building was then pointed  with a NHL2 lime mortar and finished with a stiff brush to blend to the stonework.

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