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Grade II Listed Thatched Barn in Bedforshire

Restoration of Grade II Listed Thatched Stone Barn in Bedfordshire

This project involved the Consolidation & Stablization of this Grade 2 Listed building in Bedfordshire. The barn was originally constructed in 16c using locally sourced stone & clay as building mortar. The barn had been repointed at some point with Lime Based Mortar.

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 eleavtion due to a large bulge, fill voids and lime grout stone walls & make opening in rear stone wall.

Structural Crack in Gable Wall of  Listed Building

The Gable Wall had previously had a power cable attached which has pulled the stonework and a large section of Gable Elevation. The stone gable was constructed from local staone & clay as a bedding mortar.

A access scaffold was erected to the gable wall. An internal 3 level bird cage scaffold was erected to provide access.

The thatched roof had been laid over the stone wall tops. As the gable wall has been constructed from clay the stonework dis-assambled without damaging the masonry.

The gable wall had moved around 14" off centre, we installed some addition supporst to prevent the gable wall from collasping during dismantling.

 

Solid Masonry Wall being taken down

As we dis-mantled the stone gable wall, we stored the stonework on the scaffolding. We seprated out the rubble fill from the centre of the solid wall for re-using.

As we removed the masonry addition 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.

The Lime Pointing on the exterior stonework had been left expose as the clay bedding mortar had weathered away. A large number of period building around Bedfordshire had been constructed using a clay mortar.

Solid Wall Construction on Grade 2 Listed Building

This shows the internal of the stone wall on the Listed Building. The centre of the wall is filled with small stones & clay 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.

Structural damage on Gable Wall

Here you can see the internal bird cage scaffolding. This scaffolding has cup brackets that aretaking the load of the thatched roof. These cups are adjustable so that once the scaffolding is erected the load of the perlins & rafters can be taken from the stone walls.

Due to the barn not having many windows in the stone walls or thatched roof we installed some tempory festoon lighting.

Restoration Contractors working on Grade II Listed Building in Bedfordshire

He we are dismantling the stone wall on the next scaffolding deck. We have removed the cracked and dis-lodged stonework first to prevent it from colasping.

All the internal stone rubble & clay mortar drops to ground level we pick out the stone rubble fill and store it in a pile for re-use when we rebuild the stone gable wall. We had to contact the conservation officer to work on this Grade II Listed building in Bedfordshire.

Restoration Contractors building stone wall using Lime Mortar

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 exsiting gable end wall was re-used int he re-construction. The rubble fill stone from the centre was tightly packed back into the wall centre.

The stones are very bedded very tight, this allowed us to build with the risk of collaspe. The lime mortar joints were raked out and so they could be lime pointed with the rest of the gable wall. The stone wall could not be built plumb as the existing stone wall is far from plumb.

Building Contarctors working on Grade 2 Listed Building building stone wall with Lime Mortar

This kind of solid stone walls can be very warm and dry when working correctley. 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 when lime pointing solid stone walls that all the voids are filled and packed using a lime mortar. The pointing mortar must not be to strong as this will affect the breathable of the solid stone walls. A good lime pointing for Bedfordshrie would be a NHL 2, if the building is Listed Gade II or Grade I lime pointing mortar must be used to staisfy the conservation officer.

For internal Lime Plaster it is always best to use a Lime Putty based plaster this allows maximum breathablility. If the solid stone walls are damp and wet with mould growth the chances are that a modern gypsum based plaster has been used at some point.

Constructing and Building Solid Stone Wall on Listed Building with Lime Mortar

Here you can see the rubble fill laid in the centre of the wall. Using a lime based mortar for the re-building work, the stone work was keyed into the exisiting stone on the gable elevation.

We used vertical and horizontal building lines to make sure the stone work was inline with the existing Listed Building.

We covered the stonework in the evenings with layers of hessian as there was still a ground frost. As the wall was not being lime pointed till later on in the year any frost damage could be removed.

Building Solid Wall Construction with Lime Mortar

We coursed the stone work to match the original courses of the Grade II Listed Building in Bedforshire. The original wall had through stone 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 used lime mortar for the rebuilding as this will have the same thermal movement as the existing structure.

Gable Wall re-built on listed building in Bedfordshire

Here the solid stone wall has been re-built with lime mortar. The Structural stability of the wall is now secure. We used a lime based mortar to consolidate the lower section of the stone wall, we also had areas of the stone wall were we used the Lime Grouting system.

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.

Taking down solid stone wall

We also installed a new doorway in the rear elevation. This door way is was needed to access what was a small building to the rear of the Grade II Listed in Bedfordshire. We started by carefully dismantled a 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.

 

Install doorway to listed building

We dismantled the solid stone wall to ground level and removed the foundation stones. As with the gable elevation we used Hydraulic Lime mortar of 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 condsolidate the masonry.

Building Solid Masonry Doorway
Here we are building the masonry returns of the doorway. Lime Mortar was used, the corner stones had to be pitched with a 90 deg angle.
Green Oak Beams to be installed over door opening

Two solid oak beams to be install over the newly created doorway opening. These two beams weigh over 500kg between them. We used lifting equipment to place the beam on the scaffolding deck. We adapted the scaffolding to accest in the installation of the oak beams.

The oak beams were sourced from a local timber yard & cut to size.

Green Oak Beams installed over doorway

Once the oak beams had been positions we pack under the oak beams with lime mortar and slate. As the stonework had be built with very tight joints the oak beams could be installed after completion of the wall construction.

You can see the scaffolding that had to be adapted to hold the oak beams at the correct height while we packed lime mortar under the oak beams.

Here the stone work has been lime pointed with a NHL2 lime mortar, finsihed with a stiff brush to blend to the stonework.

Oak Beams

Once the lime mortar had been packed under the oak beams bearing points the stone wall above the oak beam had to be built up to the wall plate with a lime pointing mortar.

The thatched roof line had to altered so the new slate roof on the rear building could be intergrated into the thatch.

When working in close proxciminty to green oak with lime mortar care must be taken so the lime does not come into contact with parts of the oak that will be left on show. The lime mortar reacts with the oak and stains the surface black.

Doorway installed on Listed Building using Lime Mortar

Here we have completed the new doorway. The returns have been built up with the corner stones dressed. The Hydraulic Lime building mortar & Pointing mortar with allow the newly constructed doorway to move with the rest of the grade II listed building.

In the village where this Listed Building is located in Bedfordshire there are a number of other Listed Building Grade 2.

Installing Helical tie bars on Listed Building

We drilled the corners of the Grade II listed building with a 1.5m drill bit. We then chased out the lime mortar joints of the masonry. The drill holes were flushed with water to remove all dust & debris. We chiseled out the cheses to a depth of 75mm.

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 flexiable cementious grout to fix the bars in place.

 

Grouting Helical Crack Stitching Bars

Crack stitching bars provide a permanent solution for masonry repairs and cracked wall reinforcement.  Crack repair rods are simply and effectively grouted across cracks in walls to reconnect and strengthen masonry.

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.

The structural repair system integrates the axial strength and elasticity of Thor Helical bars with the properties of WHO60® grout to enhance the tensile, shear and flexural capacity of masonry walls.

Anchored across fractures, the Thor Helical crack stitch ties progressively accumulate building loads and disperse them back into the structure to strengthen cracked walls.  This effective masonry stitching repair provides resilience against further cracking with minimal cost and little disruption

Restoration of stonework on Listed Building

We used a Hydraulic Lime Pointing mortar to consolidated and stablize the masonry work of the Grade II Listed Thatched Barn. After the prevoius lime pointing mortar was removed from the stone work we washed the walls with a high pressure jet wash.

Large areas of the masonry had to be filled and packed using lime mortar. We used grouting gun to inject the lime mortar deep into the masonry work.

Some of the stones needed to be replaced as they were cracked or delaminating. We also inserted pinning stones to reforcing the lime mortar.

Lime Grouting on Listed Building

We stablilized and consolidated all four elevation of the Listed building barn. With the addation of the Helical tie bars the property was now structurally stable.

After the stablilization all the elevations are to Lime Pointed using a Hydraulic Lime Pointing Mortar.

Restoration Contractors working on Grade II Listed Building
Void filling with Lime Mortar. Lime Grouting can be difficult as it is unknown where the Lime Grout follows to. The stabilization for the Masonry walls & restoration of the Grade 2 Listed barn in Befordshire took our specialist restoration to complete the works

 

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