Barn Conversion Overview
Build Overview
The original building consisted of a timber field barn built on flint footings with later lean-to additions both on the south-west and north-west sides. The pan-tiled roof was intact but unlined, whilst the timber frame and oak weatherboarding was intact but badly weather damaged in places. The whole Barn had been lined with galvanised sheeting internally about a metre high, and the south-east side a concrete wall poured against the weather boarding to about the same height. This had resulted in all the lower timbers rotting including the oak baseplate. There had been a later doorway cut into the north-west side, and one cut into the north-east aspect, currently the main doorway. A storm had pushed the Barn in a westerly direction, so it was laying against the lean-to’s as support. The south-west lean-to outer wall had subsided and was sliding towards the adjacent ditch with the roof collapsing as a result. The north-west lean-to structure walls were in place but severely damp in places as the roof was collapsing in one corner. Not being generally weatherproof the building as a whole was of little use, and without restorative treatment would eventually collapse.
Both lean-to additions were demolished and rebuilt with conventional footings, whilst the barn had a steel reinforced slab inserted under it, the barn walls supported on nibs projecting under the barn walls. Thickenings were added at structural points in the floor. This is effectively three separate buildings, only joined by the timber elements above ground, the lean-to aspects on solid footings, whilst the Barn floating on a concrete plinth. To allow for movement there are no solid joins between the buildings.
Structurally there was a base build requirement that met our structural engineer’s recommendations, this included additional roof bearers and oak beams with haunches giving internal support, as well as marine ply for stability. On top of this was the use of marine ply in all internal walls to create internal boxes to resist movement, and added to this was triangulation, such as in the Hall walls and lean-to roofs, providing additional support to the ‘lean’ of the main barn. The philosophy throughout the conversion was to over engineer everything.
The purpose in allowing old redundant Barns to be converted to dwellings is to preserve them. Unfortunately, virtually everybody converts them, and builders rebuild them as a new build using an existing frame. Look inside the majority of Barn interiors and you will see great expanses of white plaster where there was brickwork or timber. If internal timbers are left visible, then it is only a bare profile of timber faces. Look at the walls and they will all be vertical, look at the roof ridges and they will all be straight and level, look at the gutters and they will fit the facias perfectly. These are Barns that have been rebuilt and altered, builders can only work with vertical surfaces and straight lines, and financial constraints dictate that the quickest conventional building methods are employed. Attention to detail is lost.
I was determined to preserve our Barn. The twisted shape has remained. All the internal timbers are on view. The rebuilt extensions have reused old timbers. It has been a nightmare that no builder could possibly estimate. Fitting square windows into trapezoidal openings, cutting odd shaped doors, trying to use spirit levels and squares in a building that is both undulating and leaning on both planes. I made the roof ridge board from battens in order to preserve the twist and undulations. The gutters have no fall and twist with the facia board to accommodate the lay of the roof. Every part is bespoke from the hand cut green oak beams to the light fittings that were made from five different components sourced from different suppliers. All fixings are screwed and not nailed. I spent a day fitting one vertical infill timber, then decided a week later it wasn’t right and spent another day replacing it. It has been a rewarding challenging nightmare.
Walls
The design intent at the outset was to leave the timber frame of the barn exposed on the inside, without any infill’s, instead covering it with a 215mm layer of timber frame and insulation. Once the frame of the barn was stripped and repaired it was covered in pre-painted 12mm plasterboard, then 12mm marine ply to give it structural stability. After the main Barn was completed the lean-to elements were constructed using timber frame internal walls covered in marine ply for structural stability, with a brick outer. The whole structure was then wrapped in a multifoil layer of TLX Silver, externally over the barn and internally over the lean-to elements. This has a 25mm sealed air gap to both sides and provides a totally sealed envelope over the entire building.
The barn was then covered in a 4” * 2” timber frame fixed through into the original timber frame, both to provide an additional structural frame and to encompass 100mm of Celotex style insulation. This theme was followed through the roof and internal outer walls of the lean-to construction. The roofs were pantiled over cross battening, to provide an open path for rain and debris. Cavities on the new walls were insulated with insulation batts, the external being finished in cottage style brick over a flint finished block.
Internal walls were a 50mm timber frame, insulated with Knauf insulation, covered in marine ply on both sides, finished with plasterboard.
Flooring
The solid floor construction of the barn was a 150mm steel reinforced slab with 300mm thickenings under structural supports, over 50mm of aggregate. This was covered with a DPC membrane and 100mm Celotex style insulation, then an OSB sub-floor. Over this followed a 38mm services void then another OSB sub-floor. Over this is a layer of SFTV Superfoil, followed by a foil backed 25mm polystyrene layer preformed for underfloor heating pipes. This is finished with an 18mm layer of chipboard flooring, under painted in matt black to aid heat absorption.
The suspended floor construction of the lean-to floors consisted of a 100mm DPM concrete sandwich over aggregate, with a ventilated air space over. Floor joists over sleeper walls were in filled with 100mm Celotex style insulation. In the Bedroom the remaining joist space was topped up with 25mm Celotex, SFTV Superfoil, then a foil backed 25mm polystyrene layer preformed for underfloor heating pipes, before final flooring as the barn.
The Kitchen / Hall / Bathroom was a similar construction to the bedroom floor, except that it had a further 50mm void to provide a route for the services that it had to accommodate. This also allowed the underfloor heating to be laid over the joists, covering the whole of the Hall and the central areas of the Kitchen and Bathroom.
The upstairs bedroom floor was conventional joists, filled with Knauf insulation, with an OSB sub-floor within the joist supporting SFTV Superfoil, then a foil backed 25mm polystyrene layer preformed for underfloor heating pipes, before final flooring as the barn.
Windows & Doors
Our aluminium windows are manufactured from Smart Systems ‘Alitherm’ profiles and the bi-fold patio doors from ‘Visofold’ profiles and all finished in a polyester powder coating in dark grey metallic SEN014 Vulcan Black. More information can be seen on the manufacturer’s website at www.smartsystems.co.uk.
All frames include a ‘polyamide’ thermal barrier. Windows have multi-point & shoot-bolt locking, with push button lockable handles and lockable night-vents and doors have multi-point and dead-bolt locking. All glass is ‘energy-saver’ double-glazing, incorporating soft-coat ‘Low E’ glass, argon filled cavities and warm-edge spacer bars.
Controliss electric roller blinds are fitted in the lounge, in textura golden fabric, with wireless control.
The front door was an engineered oak in an oak frame fitted with draught sealing strips, fitted with a double-glazed vision panel. This was finished in four coats of polyurethane varnish. However, the exposed position proved too extreme and it required much fettling to accommodate swelling in wet weather.
Hence this has now been replaced with a black composite door and frame, again with a double-glazed vision panel. This has proved effective, although there is still some slight swelling in winter.
Heating Systems
The primary heating system is underfloor water pipes heated by an external oil-fired boiler. All forms were evaluated, including heat pumps and solar.
In order to minimise the slow response and latent heat dissipation experienced with a conventional concrete slab system, an over floor system was used, but built into the floor build. This comprises 16mm plastic pipe, arranged in 7 loops totalling 515 metres with an output of 12,875 BTU. This is laid at 150mm centres in preformed insulated channels directly under the chipboard flooring, itself painted matt black on the underside to aid heat absorption. Whilst the pipework is laid on reflective foil, the underside of the pipework carrier is itself laid over SFTV Superfoil to minimise downwards heat loss. The loop feed pipes are accommodated in the floor services void and are fully insulated.
The 7 heating loops are arranged in 5 zones, the lounge having 3 loops, including one perimeter loop having a higher output under the glazed window panels. The 5 zones are individually controlled via a UH8 Controller and utilise Heatmiser Neostats in each zone for local heat and time control. Whilst hard wired for reliability, the whole includes mesh interoperability with an internet interface offering off-site control, including geolocation, via a Smartphone. Integrated into the operation sequence is an external frost stat, actually operating at a higher, but variable, temperature, to limit heating when the outside temperature rises in the day.
Floor coverings are designed to permit heat transfer, the carpeting falling within 2.5 Tog.
There is a further zone comprising 3 heated towel rails, each with individual thermostatic control valves, all operated via a seperate thermostat. This is designed to provide some initial chill heating during spring and autumn outside of full underfloor operation, as well as auxiliary heating in winter.
The pump and control valve manifold are housed in the airing cupboard, utilising any heat loss for beneficial use.
The heating source is a Warmflow KC90HE combi condensing boiler rated at 21/26 Kw, with an ‘A’ Sedbuk rating, and an output of 24 litres minute DHW. This has proved the least reliable aspect of the build, with various problems, so I cannot recommend Warmflow.
Overall the system is designed to provide a fast response invisible highly efficient heating system especially suitable to the high ceilings found in the lounge area.
A conventional Multifuel wood / coal stove is fitted in the lounge as an alternative should this be preferred or required, but is not a part of the calculated heat requirement.
The master bedroom is fitted with an Electriq ELQ-9WMINV split unit air conditioning unit. This has an output of 9000 Btu/h and an air source heat pump output of up to 3.4 Kw. It is rated at A++ cooling and A+ heating. Again, it has not been taken as a part of the calculated heat requirement.
Lighting, Electrics & Automation.
The wiring has been unconventional. All lighting points are wired back to switches, except for the outside and lounge lighting which has been wired back to a central point. All light switches are single gang to avoid confusion, with the exception of the Lounge switches which are not required for normal use. This central point is known as Node Zero and is housed within a high-level Hall cupboard. All external and Lounge control points are also wired back to this central point. Control points include daylight sensors to control outside lighting, movement sensors inside and outside, switches and Lightwave interfaces. This is then multiplexed as inputs and outputs to allow hard wired programming of lighting, as well as easily accommodating future changes.
The base operation is hard wiring that is not dependant on wi-fi, radio or infra-red signals to operate, enabling failsafe operation of all systems in any event. The lighting has Lightwave integration over this to allow for push button wireless control. The Heating has wireless operation over wi-fi over this to allow for Smartphone control. The audio-visual entertainment is controlled by conventional infra-red remote controls, but over this is a Logitech wi-fi system with a single controller operating local infra-red blasters. This gives unidirectional control of all equipment via pre-programmable sequences operating multiple commands.
In overall control there is a final layer of two Alexa units giving voice control of all Lounge functions regarding entertainment and lighting, and all Barn heating.
All lighting is provided by standard low energy led lamps. External security and garden lighting are incorporated in the above systems. There is a night lighting function that provides backlighting to the lounge, kitchen and bathroom, operated by movement. This means sufficient lighting is provided automatically to use the kitchen or bathroom in the evening or night times.
All forms and makes of home automation were evaluated. This is a fast-changing environment without any clear standards. The bottom line was that everything must continue to work in the event of catastrophe, i.e. it must be fail-safe. As far as possible it should also be future proof, and it must be inexpensive. Some systems such as Philips Hue and Nest were prohibitively expensive – 22 light bulbs in the Lounge and 6 heating thermostats would be horrendously expensive.
A CCTV system is in hand but is yet to be fitted and commissioned.
Cat 45 wiring has been a part of the initial conversion. There is a standard wi-fi router in the barn, and a Vodafone Fem to Cell unit for mobile phone signal. The problem with encasing the Barn in multifoil is that it becomes impervious to signals, effectively a Faradays cage. Hence a second router is sited externally to provide wi-fi outside. Ethernet cabling goes to two buildings outside, six camera positions, and five points within the Barn.
Wiring has been based on the principle that everything should be mains powered where possible, not battery, and prime communication should be over wiring, not wireless.
Conclusions
Overall the design has fulfilled the requirements 99%, with very little in the way of regrets. The build has exceeded expectations, with the seasoning of timber beforehand almost eliminating any shrinkage, and the over engineering providing a build with an infinite lifespan. Areas where the design could be improved were constrained by the limitations imposed by the Barn itself – i.e. unable to incorporate a utility room.
Very little would be done differently a second time. The wood burning stove proved unnecessary – it produces convection air movements and dust, both unwanted in a timber barn, and the extra heat is not required. It is very rarely lit. The underfloor heating is much more successful in that it is a gentle heat without cold spots or convection. But even this is drastically over engineered, given the level of insulation. In fact, the bedrooms are never turned on, the barn mainly heated by the towel rails and lounge underfloor. The decision to greatly exceed current building regulations requirements on insulation was a wise one.
The only troublesome areas have been the front door proving inadequate weather wise, the boiler unreliability, and infestations of mice in the outer fabric – the last point I should have paid more attention to during the build, it is amazing how small a gap they can get through!
The original building consisted of a timber field barn built on flint footings with later lean-to additions both on the south-west and north-west sides. The pan-tiled roof was intact but unlined, whilst the timber frame and oak weatherboarding was intact but badly weather damaged in places. The whole Barn had been lined with galvanised sheeting internally about a metre high, and the south-east side a concrete wall poured against the weather boarding to about the same height. This had resulted in all the lower timbers rotting including the oak baseplate. There had been a later doorway cut into the north-west side, and one cut into the north-east aspect, currently the main doorway. A storm had pushed the Barn in a westerly direction, so it was laying against the lean-to’s as support. The south-west lean-to outer wall had subsided and was sliding towards the adjacent ditch with the roof collapsing as a result. The north-west lean-to structure walls were in place but severely damp in places as the roof was collapsing in one corner. Not being generally weatherproof the building as a whole was of little use, and without restorative treatment would eventually collapse.
Both lean-to additions were demolished and rebuilt with conventional footings, whilst the barn had a steel reinforced slab inserted under it, the barn walls supported on nibs projecting under the barn walls. Thickenings were added at structural points in the floor. This is effectively three separate buildings, only joined by the timber elements above ground, the lean-to aspects on solid footings, whilst the Barn floating on a concrete plinth. To allow for movement there are no solid joins between the buildings.
Structurally there was a base build requirement that met our structural engineer’s recommendations, this included additional roof bearers and oak beams with haunches giving internal support, as well as marine ply for stability. On top of this was the use of marine ply in all internal walls to create internal boxes to resist movement, and added to this was triangulation, such as in the Hall walls and lean-to roofs, providing additional support to the ‘lean’ of the main barn. The philosophy throughout the conversion was to over engineer everything.
The purpose in allowing old redundant Barns to be converted to dwellings is to preserve them. Unfortunately, virtually everybody converts them, and builders rebuild them as a new build using an existing frame. Look inside the majority of Barn interiors and you will see great expanses of white plaster where there was brickwork or timber. If internal timbers are left visible, then it is only a bare profile of timber faces. Look at the walls and they will all be vertical, look at the roof ridges and they will all be straight and level, look at the gutters and they will fit the facias perfectly. These are Barns that have been rebuilt and altered, builders can only work with vertical surfaces and straight lines, and financial constraints dictate that the quickest conventional building methods are employed. Attention to detail is lost.
I was determined to preserve our Barn. The twisted shape has remained. All the internal timbers are on view. The rebuilt extensions have reused old timbers. It has been a nightmare that no builder could possibly estimate. Fitting square windows into trapezoidal openings, cutting odd shaped doors, trying to use spirit levels and squares in a building that is both undulating and leaning on both planes. I made the roof ridge board from battens in order to preserve the twist and undulations. The gutters have no fall and twist with the facia board to accommodate the lay of the roof. Every part is bespoke from the hand cut green oak beams to the light fittings that were made from five different components sourced from different suppliers. All fixings are screwed and not nailed. I spent a day fitting one vertical infill timber, then decided a week later it wasn’t right and spent another day replacing it. It has been a rewarding challenging nightmare.
Walls
The design intent at the outset was to leave the timber frame of the barn exposed on the inside, without any infill’s, instead covering it with a 215mm layer of timber frame and insulation. Once the frame of the barn was stripped and repaired it was covered in pre-painted 12mm plasterboard, then 12mm marine ply to give it structural stability. After the main Barn was completed the lean-to elements were constructed using timber frame internal walls covered in marine ply for structural stability, with a brick outer. The whole structure was then wrapped in a multifoil layer of TLX Silver, externally over the barn and internally over the lean-to elements. This has a 25mm sealed air gap to both sides and provides a totally sealed envelope over the entire building.
The barn was then covered in a 4” * 2” timber frame fixed through into the original timber frame, both to provide an additional structural frame and to encompass 100mm of Celotex style insulation. This theme was followed through the roof and internal outer walls of the lean-to construction. The roofs were pantiled over cross battening, to provide an open path for rain and debris. Cavities on the new walls were insulated with insulation batts, the external being finished in cottage style brick over a flint finished block.
Internal walls were a 50mm timber frame, insulated with Knauf insulation, covered in marine ply on both sides, finished with plasterboard.
Flooring
The solid floor construction of the barn was a 150mm steel reinforced slab with 300mm thickenings under structural supports, over 50mm of aggregate. This was covered with a DPC membrane and 100mm Celotex style insulation, then an OSB sub-floor. Over this followed a 38mm services void then another OSB sub-floor. Over this is a layer of SFTV Superfoil, followed by a foil backed 25mm polystyrene layer preformed for underfloor heating pipes. This is finished with an 18mm layer of chipboard flooring, under painted in matt black to aid heat absorption.
The suspended floor construction of the lean-to floors consisted of a 100mm DPM concrete sandwich over aggregate, with a ventilated air space over. Floor joists over sleeper walls were in filled with 100mm Celotex style insulation. In the Bedroom the remaining joist space was topped up with 25mm Celotex, SFTV Superfoil, then a foil backed 25mm polystyrene layer preformed for underfloor heating pipes, before final flooring as the barn.
The Kitchen / Hall / Bathroom was a similar construction to the bedroom floor, except that it had a further 50mm void to provide a route for the services that it had to accommodate. This also allowed the underfloor heating to be laid over the joists, covering the whole of the Hall and the central areas of the Kitchen and Bathroom.
The upstairs bedroom floor was conventional joists, filled with Knauf insulation, with an OSB sub-floor within the joist supporting SFTV Superfoil, then a foil backed 25mm polystyrene layer preformed for underfloor heating pipes, before final flooring as the barn.
Windows & Doors
Our aluminium windows are manufactured from Smart Systems ‘Alitherm’ profiles and the bi-fold patio doors from ‘Visofold’ profiles and all finished in a polyester powder coating in dark grey metallic SEN014 Vulcan Black. More information can be seen on the manufacturer’s website at www.smartsystems.co.uk.
All frames include a ‘polyamide’ thermal barrier. Windows have multi-point & shoot-bolt locking, with push button lockable handles and lockable night-vents and doors have multi-point and dead-bolt locking. All glass is ‘energy-saver’ double-glazing, incorporating soft-coat ‘Low E’ glass, argon filled cavities and warm-edge spacer bars.
Controliss electric roller blinds are fitted in the lounge, in textura golden fabric, with wireless control.
The front door was an engineered oak in an oak frame fitted with draught sealing strips, fitted with a double-glazed vision panel. This was finished in four coats of polyurethane varnish. However, the exposed position proved too extreme and it required much fettling to accommodate swelling in wet weather.
Hence this has now been replaced with a black composite door and frame, again with a double-glazed vision panel. This has proved effective, although there is still some slight swelling in winter.
Heating Systems
The primary heating system is underfloor water pipes heated by an external oil-fired boiler. All forms were evaluated, including heat pumps and solar.
In order to minimise the slow response and latent heat dissipation experienced with a conventional concrete slab system, an over floor system was used, but built into the floor build. This comprises 16mm plastic pipe, arranged in 7 loops totalling 515 metres with an output of 12,875 BTU. This is laid at 150mm centres in preformed insulated channels directly under the chipboard flooring, itself painted matt black on the underside to aid heat absorption. Whilst the pipework is laid on reflective foil, the underside of the pipework carrier is itself laid over SFTV Superfoil to minimise downwards heat loss. The loop feed pipes are accommodated in the floor services void and are fully insulated.
The 7 heating loops are arranged in 5 zones, the lounge having 3 loops, including one perimeter loop having a higher output under the glazed window panels. The 5 zones are individually controlled via a UH8 Controller and utilise Heatmiser Neostats in each zone for local heat and time control. Whilst hard wired for reliability, the whole includes mesh interoperability with an internet interface offering off-site control, including geolocation, via a Smartphone. Integrated into the operation sequence is an external frost stat, actually operating at a higher, but variable, temperature, to limit heating when the outside temperature rises in the day.
Floor coverings are designed to permit heat transfer, the carpeting falling within 2.5 Tog.
There is a further zone comprising 3 heated towel rails, each with individual thermostatic control valves, all operated via a seperate thermostat. This is designed to provide some initial chill heating during spring and autumn outside of full underfloor operation, as well as auxiliary heating in winter.
The pump and control valve manifold are housed in the airing cupboard, utilising any heat loss for beneficial use.
The heating source is a Warmflow KC90HE combi condensing boiler rated at 21/26 Kw, with an ‘A’ Sedbuk rating, and an output of 24 litres minute DHW. This has proved the least reliable aspect of the build, with various problems, so I cannot recommend Warmflow.
Overall the system is designed to provide a fast response invisible highly efficient heating system especially suitable to the high ceilings found in the lounge area.
A conventional Multifuel wood / coal stove is fitted in the lounge as an alternative should this be preferred or required, but is not a part of the calculated heat requirement.
The master bedroom is fitted with an Electriq ELQ-9WMINV split unit air conditioning unit. This has an output of 9000 Btu/h and an air source heat pump output of up to 3.4 Kw. It is rated at A++ cooling and A+ heating. Again, it has not been taken as a part of the calculated heat requirement.
Lighting, Electrics & Automation.
The wiring has been unconventional. All lighting points are wired back to switches, except for the outside and lounge lighting which has been wired back to a central point. All light switches are single gang to avoid confusion, with the exception of the Lounge switches which are not required for normal use. This central point is known as Node Zero and is housed within a high-level Hall cupboard. All external and Lounge control points are also wired back to this central point. Control points include daylight sensors to control outside lighting, movement sensors inside and outside, switches and Lightwave interfaces. This is then multiplexed as inputs and outputs to allow hard wired programming of lighting, as well as easily accommodating future changes.
The base operation is hard wiring that is not dependant on wi-fi, radio or infra-red signals to operate, enabling failsafe operation of all systems in any event. The lighting has Lightwave integration over this to allow for push button wireless control. The Heating has wireless operation over wi-fi over this to allow for Smartphone control. The audio-visual entertainment is controlled by conventional infra-red remote controls, but over this is a Logitech wi-fi system with a single controller operating local infra-red blasters. This gives unidirectional control of all equipment via pre-programmable sequences operating multiple commands.
In overall control there is a final layer of two Alexa units giving voice control of all Lounge functions regarding entertainment and lighting, and all Barn heating.
All lighting is provided by standard low energy led lamps. External security and garden lighting are incorporated in the above systems. There is a night lighting function that provides backlighting to the lounge, kitchen and bathroom, operated by movement. This means sufficient lighting is provided automatically to use the kitchen or bathroom in the evening or night times.
All forms and makes of home automation were evaluated. This is a fast-changing environment without any clear standards. The bottom line was that everything must continue to work in the event of catastrophe, i.e. it must be fail-safe. As far as possible it should also be future proof, and it must be inexpensive. Some systems such as Philips Hue and Nest were prohibitively expensive – 22 light bulbs in the Lounge and 6 heating thermostats would be horrendously expensive.
A CCTV system is in hand but is yet to be fitted and commissioned.
Cat 45 wiring has been a part of the initial conversion. There is a standard wi-fi router in the barn, and a Vodafone Fem to Cell unit for mobile phone signal. The problem with encasing the Barn in multifoil is that it becomes impervious to signals, effectively a Faradays cage. Hence a second router is sited externally to provide wi-fi outside. Ethernet cabling goes to two buildings outside, six camera positions, and five points within the Barn.
Wiring has been based on the principle that everything should be mains powered where possible, not battery, and prime communication should be over wiring, not wireless.
Conclusions
Overall the design has fulfilled the requirements 99%, with very little in the way of regrets. The build has exceeded expectations, with the seasoning of timber beforehand almost eliminating any shrinkage, and the over engineering providing a build with an infinite lifespan. Areas where the design could be improved were constrained by the limitations imposed by the Barn itself – i.e. unable to incorporate a utility room.
Very little would be done differently a second time. The wood burning stove proved unnecessary – it produces convection air movements and dust, both unwanted in a timber barn, and the extra heat is not required. It is very rarely lit. The underfloor heating is much more successful in that it is a gentle heat without cold spots or convection. But even this is drastically over engineered, given the level of insulation. In fact, the bedrooms are never turned on, the barn mainly heated by the towel rails and lounge underfloor. The decision to greatly exceed current building regulations requirements on insulation was a wise one.
The only troublesome areas have been the front door proving inadequate weather wise, the boiler unreliability, and infestations of mice in the outer fabric – the last point I should have paid more attention to during the build, it is amazing how small a gap they can get through!