Bulletin 28: Heating System

Heating System Requirements

The heating system comprises the following seven aspects

  1. underfloor heating to the ground floor rooms
  2. radiator heating to the bedrooms and snug
  3. heating to the swimming pool and pool-hall
  4. heating to the games room air handling unit
  5. heating to the TV room air handling unit
  6. heating to the bathroom towel rails
  7. heating to the domestic hot-water calorifiers

Underfloor Heating

The entrance hall, kitchen and orangery will all be finished with a stone floor while the  drawing room, library and dining room will be finished with an engineered wood floor. In all these cases there will be no fitted carpets although in certain areas the floors to these rooms will be partially covered with rugs. Therefore in all these areas we consider that the most appropriate form of heating is “wet” underfloor heating. This form of heating uses a series of polythene pipe loops buried in the floor screed through which hot water from the domestic heating boilers is passed. The photographs below illustrate the installation of underfloor heating pipework prior to the floor being screeded

Underfloor heating pipes for the drawing room.

Underfloor heating pipes for the drawing room.

The underfloor heating pipes for the entrance hall.

The underfloor heating pipes for the dining room. The floor is prepared by placing 100mm thick rigid thermal insulating foam panels directly on to the base concrete to cover the whole floor. The insulating panels are then overlaid with the black polythene membrane that can be seen in the photo which is held in place by adhesive tape. The polythene heating pipes are then laid out as shown and held in place by plastic clips that penetrate into the insulating foam. Once all the heating pipes are in place the whole floor/heating assembly is covered with a concrete based screed that forms the floor ready for the final floor finishes.

 

The heating pipes from the various floor zones are connected to a manifold that controls the hot water from the

The heating pipes from the various floor zones are connected to a manifold that controls the hot water from the central heating boiler when heat is demanded by the room thermostat. There are two such manifolds on each of the three floors.

Radiator Heating

In areas where the floors are finished with fitted carpets we consider that a better form of heating is to use “wet” radiators that are heated by hot water from the heating system boilers. The reason for the difference in approach is that in my view fitted carpets act as a thermal insulator to the floor which significantly degrades the performance of any underfloor heating system. I have never been warm in a house that has underfloor heating with fitted carpets! As we intend to have fitted carpets in the snug and all the bedrooms we are  therefore installing radiators in all these rooms.

Where "wet" radiators are used these are installed in the panels beneath the windows as shown in the above photograph.

Where “wet” radiators are used these are installed in the panels beneath the windows as shown in the above photograph. The radiator element is the black unit beneath the window. and the hot water feed from the boilers is shown ready for connection to the right hand side of the radiator. This connection is made via a motorised valve to control the amount of heat depending upon the room thermostat demand. The radiator will eventually concealed behind a panel that incorporates a grill to permit the flow of warm air into the room.

 

Heating System Hot Water Delivery from the Boilers

 To accommodate the seven different heating requirements defined above the heating system employs three separate heating circuits which are illustrated by the photograph below and shown diagrammatically in the Plumbing Schematic drawing accessed at:

Plumbing Schematic

Heating system hot water delivery sub-system.

The heating system hot water delivery sub-system is shown here. Hot water from the boilers is delivered to the top of the low loss header which is the large diameter vertical pipe in orange to the left of the picture. From this low loss header three heating circuits are connected; these are the  three uppermost  horizontal pipes. Each of these three feeder or “flow” pipes has its own dual redundant pumps. The top feeder has the pair of very larger more powerful pumps since these pumps deliver water at high temperature (80degrees C) to the domestic hot water calorifiers, the swimming pool heating system, the games and TV room heaters and the bathroom and lavatory towel rails. The second and third horizontal pipes from the low loss header supply water, also via their independent dual redundant pumps, to the underfloor heating and radiators respectively. The three bottom most horizontal pipes connected to the low loss header are the returns from the three basic heating circuits. Note the various pressure and temperature gauges used to control the system and regulate the temperatures of the various segments. As in the case of the domestic hot water pumps the heating system dual redundant pumps operate on a weekly duty cycle (that is they automatically change over each week) to even out wear and to ensure that in the event of a failure the standby pump has not seized up through prolonged none-operation.

Close up of the pipes, pumps and gauges of the heating system.

Close up of the pipes, pumps and gauges of the heating system.

 

The Boilers

In common with all the other aspects of the heating system the boilers are also in a dual redundant configuration.  The chosen boilers are a pair of Worcester Bosch GB162 wall hung condensing gas boilers that deliver 100kW of heat each.  A data sheet for these boilers is available for download from the blog library:

Worcester Bosch Cascadable Boiler Data Sheet

Our original intention was that the boilers would be mounted in the plant room along with all the other apparatus associated with the domestic hot and cold water and heating system. However during the build process of the house it became apparent that the flues to take away the exhaust gases to the roof would inevitably be in sections because of the length of the flues extending from the basement to the roof level. It is a requirement that the joints of such flues are inspected on an annual basis to ensure their gas-tight integrity. A failure of a flue joint could result in leakage of flue gases and there is an associated risk of carbon monoxide poisoning to the inhabitants of the house. The space in the vertical void that was put in place to take the flues along with the other basement ventilation ducting was extremely limited. To allow safe access for inspection of the flues an access ladder would have had to have been permanently installed in the void also. Whilst not impossible, access would have been extremely tight and claustrophobic and without harnesses when using the ladder that would have restricted access even further it would have been potentially dangerous.  Accordingly we decided to install the boilers in the bay of the new garage that had already been designated for use by a standby generator.  Pipes with substantial thermal insulation buried in the ground conduct the flow and return hot water between the low loss header discussed above in the basement and the boilers. The heat loss from these extended delivery pipes is negligible. The advantage of installing the boilers in the garage apart from a vastly simplified flue arrangement is that the annual service can be carried out without having to enter the house. moreover there is ample room for access to make servicing as easy as possible.

Boiler in the process of being installed in the end bay of the garage dedicated to the standby generator which can be seen to the right of the picture.

Boilers in the process of being installed in the end bay of the garage dedicated to the standby generator which can be seen to the right of the picture. Note the hot water delivery pipes making their way around the rear door.

A closer look at the boilers being installed.

A closer look at the boilers being installed.

The drawings that define the heating system are as follows and can be viewed by down loading them from the blog library:

Lower Ground Floor Heating Services

Ground Floor Heating Services

First Floor Heating Services

Bulletin 27: Domestic Hot and Cold Water

Water pressure

As its name implies Ridge End sits on a ridge so that from time to time we have found that the pressure of the mains water supply to the property can be quite low. This is particularly so during hot spells in the summer when in the evenings it would seem that people come home from work and turn on their irrigation systems and take showers to freshen up after a hot sticky day. To ensure that the new house has a plentiful supply of water at an appropriate, constant pressure we have taken the decision to install a pair of water tanks in the basement plant-room that are filled from the incoming water main. From this local store booster pumps supply water all around the house at a good constant pressure.  Each tank has a foot print of roughly 1metre square and is 2metres high. Thus each tank has a capacity of 2 cubic metres so that they hold 2000 litres giving a total stored capacity of 4000 litres or 4 metric tonnes of water.

Water purity; avoiding legionella

One of the pitfalls of storing large volumes of water is that it must be kept sterile. To this end water from the tanks is constantly recirculated through an ultra violet steriliser. This works by passing the water from the tanks over an ultra violet (UV) lamp where the effect of its UV light is to kill any bacteria or algae that might form in the still water of the tanks. Once the water has passed through the UV lamp it is returned back to the tanks.

Cold water storage tanks. The cold water tanks are the tall rectangular structures to the left of the picture. The two cylindrical tanks to the right are the hot water heaters.

Cold water storage tanks. The cold water tanks are the tall rectangular structures to the left of the picture. The two cylindrical tanks to the right are the hot water heaters.

 

Dealing with “hard” water

 Another aspect of the mains water supply to Ridge End is that it contains calcium salts and so is quite “hard”. Hard water has the effect of furring up appliances such as washing machines, dishwashers, kettles etc with a hard lime-scale deposit. It also causes a nasty lime-scale deposit to build up on kitchen and bathroom sanitary ware. The way to avoid this is to use a water softener. Such a device is included in the Ridge End domestic water system design. This operates by transferring the calcium ions in the water for sodium ions through an ion exchange mechanism in a water softener. The resulting softened water containing sodium salts does not cause the furring associated with hard water since sodium salts are soluble. Unfortunately softened water is not good to drink as prolonged exposure to high levels of sodium in drinking water is liable to lead to human health problems such as high blood pressure. To get round this problem the ridge end water supply design supplies three types of water:

  • Boosted-pressure un-softened cold water to the two kitchen sinks and the boot room sink for drinking
  • Softened cold water to all sinks and bathrooms
  • Softened hot water to all sinks and bathrooms

Hot water supply

Hot water is supplied from a pair of water “calorifiers”.  A calorifier is an industry term for a storage vessel that has the capacity to generate heat within a mass of stored water. Essentially these are storage vessels that incorporate coiled pipes that sit in the body of stored water. By passing hot water from the house boilers through the pipe coils heat is transferred to the stored water to provide a supply of hot water to the house. These are shown in the photograph below.

The cold water storage tanks are shown on the left. The pumps that boost the cold water pressure to all parts of the house are shown in the middle of the picture. The two hot water calorifiers are the smaller, white vertical tanks to the right of the picture. The UV steriliser is the device mounted vertically on the wall.

The cold water storage tanks are shown on the left. The pumps that boost the cold water pressure to all parts of the house are shown in the middle of the picture. The two hot water calorifiers are the smaller, white vertical tanks to the right of the picture. The UV steriliser is the device mounted vertically on the wall.

Dual redundant resilience

It should be noted from the photograph above that all aspects are duplicated for redundancy. A single failure of any equipment will not deny hot or cold water from the house!  To this end the cold water storage tanks are duplicated and are filled from the incoming water main and connected to the system via independent connections. Similarly the hot water calorifiers are in a dual redundant, independent configuration.  The dual redundant pump configuration supplying the boosted pressure cold water operates with each pump on a weekly “duty cycle” so that the pump doing the work is changed over each week. The reason for this is to allow even wear on the pumps and to ensure that in the event that one of the pumps does fail and an automatic change-over is initiated the other pump is operational. If this weekly change over were not to be implemented it is likely that the standby pump would be dormant for a considerable time, perhaps years, before it was called to action. In this eventuality if it had never been actuated over such a prolonged time it is likely to be seized-up and so would fail also resulting in a catastrophic domestic water failure. Without this pumped water supply it will not even be possible to flush a lavatory or have any drinking water! This of course makes the house also vulnerable to an electrical power failure; but this will be dealt with in a subsequent blog bulletin.

Hot water supply

In a house of the size we are building here it would take a long time for the hot water to reach the bathroom taps or showers from the  hot water storage tanks/calorifiers in the basement. Furthermore it would be a waste of both water and energy. To overcome this problem the hot water is constantly circulated around the house via all the bathroom, kitchen and boot-room outlets in a “circulating hot-water main”. Accordingly it will only be necessary for the very short pipe from the main to the various faucets to be evacuated before hot water is delivered. The disadvantage of this of course is the complexity of having  “flow” and “return” pipework to and from the hot water tanks and the pumping mechanism to accomplish the hot water recirculation. This complication is more than adequately compensated for by the added convenience of fairly instant hot water and the reduced waste. The specification for the time delay to receive hot water at any of the hot-water taps is less than 5 seconds.

Domestic hot and cold water and central heating pipe runs passing from the main plant room along the ceiling of the games room in the basement.

Domestic hot and cold water and central heating pipe runs at the top left of the picture, passing from the main plant room along the ceiling of the games room in the basement.

Plumbing pipe runs in the ceiling void of the drawing room on the ground floor.

Plumbing pipe runs in the ceiling void of the drawing room on the ground floor. Note the hot and cold water tap-offs going through the concrete ceiling to one of the bathrooms above. The grey and white drainage pipe work taking foul water from the bathrooms above can also be seen.

 

All pipe-work is lagged. This picture show the same view as before with the pipe lagging installed.

All pipe-work is lagged. This picture show the same view as before with the pipe lagging installed.

More lagged pipe-work.

More lagged pipe-work.

The drawings that define the domestic hot and cold water supply are as follows and can be viewed by down loading them from the blog library:

Plumbing Schematic

Lower Ground Floor Domestic Water Services

Ground Floor Domestic Water Services

First Floor Domestic Water Services

Lower Ground Floor Drainage

Ground Floor Drainage

First Floor Drainage

 

 

Bulletin 26: The Mechanical and Electrical Systems

The Mechanical and Electrical Systems comprise the following aspects:

  • Domestic hot and cold water supply
  • Soil and waste water management
  • Heating services
  • Ventilation services
  • Electrical power
  • Lighting
  • Integrated Audio/Visual (AV) and Information Technology (IT) services including telephone access
  • Fire Alarm and Security system

Each of these aspects will be described and discussed more fully in subsequent Bulletins but for now I will confine this Bulletin 26 to some general comments about the design philosophy behind the design of the M&E systems. The watch-word for the house systems is resilience. That is to say that as far as possible the house should not be stopped from being able to provide the essential services and levels of comfort because of a single equipment failure in any of the house systems. It has to be accepted that at some time equipment on which we rely will fail at some point either from some inherent failure mechanism or through simple wear and tear. For example if the house heating system were to rely on a single boiler the house would be deprived of any heating or hot water in the event that the boiler failed. In the depth of winter with high demand for boiler repair services my experience has been that this could extend for several days until the boiler could be repaired.  In the case that the boiler needs total replacement this could be even longer.  Imagine how disastrous this scenario could be  at the Christmas festive season with a house full of guests! Therefore if we are not going to be inconvenienced by equipment failures some form back-up system needs to be considered. In the case of the Ridge End replacement house design most of the systems have been duplicated in a “dual-redundant ” configuration in some instances with an automatic “fail-over” to the standby equipment to ensure resilient operation of the  house systems. This philosophy of resilient design has been employed through out the house, extending for example to the kitchen where multiple ovens and duplicate hobs have been included for both increased capacity and resilience in the event of an equipment failure.

The drawing pack for the M&E services are included as a set of pdf files in separate pages of the blog. The M&E services have been divided into a page for water, heating, ventilation and drainage services and a separate page for the electrical power, lighting, IT and A/V services. For those interested in following the descriptions of the various M&E services it might helpful to cross refer to these drawings from time to time.

 

Bulletin 24: Roof Completion

Once the fundamental timber structure of the roof was completed it was covered in a roofing “felt” held in place by roofing batons nailed horizontally to the structure. These batons not only hold the roofing felt in place but eventually are also used to attach the roof slates. The type of roof that we have chosen to implement is a “cold roof” where the roof void is unheated and the thermal insulation installed to minimise heat loss through the roof is placed in between the roof joists, immediately above the room ceilings. Conventional roofing felt is impermeable therefore In a cold roof,  without ventilation of the roof space, condensation will form on the underside of roofing felt and so the roof void will be damp, particularly in winter. Tyvek is a modern, spun polyolefin, non-woven fabric membrane manufactured by DuPont. In its form as Tyvek® Supro it is a permeable membrane which is used  as a roofing underlay in pitched roof construction. It forms a secondary water shedding layer ( the roof slates or tiles being the primary layer of course) that also reduces the wind load acting on the slates and adequately resists wind blown snow and dust from entering the construction. Tyvek® membranes offer benefits over traditional impermeable roofing underlays by minimising the risk of interstitial condensation occurring within roof constructions Over the last 30 years or so, as we have become more aware of the need to conserve energy and so the required levels of insulation within roofs have become greater. This has had the effect of increasing the likelihood of condensation forming on the underside of the roofing felt. Prior to the introduction of modern vapour permeable membranes, the only way of reducing this risk was to introduce ventilation openings in the roof to effectively “change the air”.  Since Tyvek® is a vapour permeable material  as a roofing underlay it offers low resistance to the passage of vapour. A Tyvek® underlay permits water vapour within the roof space to permeate through to the batten space. Natural air movement through the roof subsequently allows any moisture-laden air to escape to atmosphere. Roofs with no provision for airflow beneath the underlay will be more energy efficient than conventional, ventilated roofs. The ability of Tyvek® membranes to provide the function of condensation control eliminates the need to ventilate between the underlay and the insulation. A non-ventilated Tyvek® system not only prevents excessive condensation but also offers substantial gains in energy efficiency.

Tyvek place over the roof rafters and held in place by the roofing batons.

Tyvek placed over the roof rafters and held in place by the roofing batons nailed place horizontally, ready to enable the slates to be attached.

Tyvek placed over the roof rafters and held in place by the roofing batons

Tyvek placed over the roof rafters and held in place by the roofing batons

 

 

 

 

 

 

 

At the centre of the roof hidden behind the four external ridges is a substantial flat roof. This part of the roof covers the central stair hall below which goes from the ground floor all the way up to the second floor ceiling so that a central galleried staircase is formed. A pair of polygonal roof-lights set into the flat roof provide natural day light to the stair hall. These roof lights are centred on the semi-circular walls at either side of the stair hall. From time to time debris from leaf fall will have to be cleared from the flat roof section and its associated gutters. To facilitate this a hatch has been constructed into the structure to allow access via a ceiling hatch in the main guest-suite bathroom ceiling, through the pitched roof above and onto the flat roof. The flat roof structure and its access hatch are shown in the photographs below.

The flat roof timber construction.

The flat roof timber construction. Note the Tyvek membrane and roofing batons fully installed on the ridged part of the roof in the background.

The timber flat roof access hatch structure is shown here.

The timber flat roof access hatch structure is shown here.

 

 

 

 

 

 

 

Three chimneys are incorporated into the flat part of the roof. Two of these chimneys are active as they act as flues for the decorative flame effect gas fires in the dinning room and drawing room. The third is there to provide symmetry but also serves a useful function for providing a “penetrator” through the roof for the cables from the antennas that will eventually be installed on the roof.  The photograph below shows the fixing the final stone into place of the last chimney to be built.

Fixing the last chimney stone in place.

Fixing the last chimney stone in place.

 

Here the construction of the roof-light upstands, the flat roof access hatch and two of the chimneys can clearly be seen.

Here the construction of the roof-light upstands, the flat roof access hatch and two of the chimneys can clearly be seen.

The water proofing of the flat roof was achieved by using Fatra fleece-backed PVC membrane adhered directly to the roof surface. The fixing method is quite simple. A polyurethane adhesive is applied to the roof and the Fatra membrane is then rolled out on to the wet adhesive by applying pressure using a roller or soft brush. The rolled out membrane is overlapped slightly at the edges. A water tight seal at the resulting seems is ensured  by using a hot air welding gun to melt the membrane slightly at the overlap so that it can be welded together by applying pressure with a Teflon coated roller. Fatra rainwater outlets are specifically designed to work with Fatra membrane. Each comes with a flange of Fatra membrane to enable the outlets to be welded to the roofing membrane and provide a jointless sealed system. At the corners of the roof Fatra preformed corners are used and at every change in direction of the membrane Fatra coated membrane trims are used for reinforcement at those points.

Spreading the polyurethane adhesive before laying out the fatra membrane.

Spreading the polyurethane adhesive before laying out the fatra membrane.

Detail of the fatra roof outlets welded in place.

Detail of the fatra roof water outlets welded in place. These outlets allow rainwater to drain out of the drainage gullies of the flat roof area. The outlets are connected to drain pipes which pass through the pitched roof void and to the outside of the house to the rainwater hoppers and drain pipes of the roof guttering.

 

 

 

 

 

 

 

The timber access hatch structure was completed by attaching a stainless steel  hatch lid mechanism. Owing to the weight of this hatch the opening is assisted by incorporating a pair of gas-struts into the deign. To water proof the access hatch timber structure it is entirely encased in lead sheeting.

The stainless steel access hatch with its supporting timber sub-structure encased in lead for water tightness.

The stainless steel access hatch with its supporting timber sub-structure encased in lead for water tightness.

A close up of one of the roof-lights showing how it is mounted on to its up-stand and how the fatra membrane provides water proof integrity.

A close up of one of the roof-lights showing how it is mounted on to its up-stand and how the fatra membrane provides water proof integrity.

The completed flat roof note the installation of the air-conditioning heat exchangers and the air extraction fan for the kitchen.

The almost completed flat roof. Note the installation of the air-conditioning heat exchangers and the air extraction fan for the kitchen.

Turning back to the main ridges of the roof once the Tyvek membrane and roof batons were in place the primary water shedding covering of slates was started. The slates we chose were from the Penrhyn Slate Quarry located near Bethesda in north Wales. Welsh slate is still deemed to be the finest available. Cheaper slate is obtainable from Spain and China but it often is plagued with iron pyrites within the slate rock formation. This eventually oxidises to iron oxide or rust owing to exposure to air and water which then results in nasty brown streaks staining the roof. Welsh Slate is exceptionally durable. It is unaffected by normal extremes of temperature and is highly resistant to acids, alkalis and other chemicals. It retains its colour, even in UV light and is impermeable to water. It is non combustible and is compatible with all other building materials. Welsh Slate roofing material is available in two colours that reflect the true nature of its beauty. These subtle and elegant colours are further complemented by the distinctive natural texture of slate, creating an added dimension to any roof. The Penrhyn Quarry slate we have chosen has natural Heather Blue tonal variations which combines with colour of the lead used to waterproof the ridges and valleys of the roof form which in my opinion makes for a beautiful overall finish.

The slates were fixed in place using copper nails. At the ridges of the roof as slate will not bend over the angle of the ridge waterproofing is achieved by a lead strip which conforms to the shape of the ridge and overlaps the slate on either side of the ridge. To help form the lead and maintain it in position "mop-sticks" are nailed over lead straps on to the apex of the ridge. These are clearly visible in this photograph.

The slates were fixed in place using copper nails. At the ridges of the roof as slate will not bend over the angle of the ridge waterproofing is achieved by a lead strip which conforms to the shape of the ridge and overlaps the slate on either side of the ridge. To help form the lead and maintain it in position “mop-sticks” are nailed over lead straps on to the apex of the ridge. These are clearly visible in this photograph.

This photograph shows the lead waterproofing of a ridge and how it is formed over theridge "mop-stick". The lead strip is held in place by bendin over the lead strps that are shown under the mop-sticks in the previous photo. Note the welded end piece over the mopstick at the bottom of the picture.

This photograph shows the lead waterproofing of a ridge and how it is formed over the ridge “mop-stick”. The lead flashing strip is held in place by bending over the lead straps that are shown under the mop-sticks in the previous photo. Note the welded end piece over the mop stick at the bottom centre of the picture.

Similarly at the valleys of the roof where the slate planes meet lead is placed in the valleys so that water is shed from the slate into the lead formed valley and then down the lead valley form into the gutter.

Similarly at the valleys of the roof where the slate planes meet lead is placed in the valleys so that water is shed from the slate into the lead formed valley and then down the valley form into the gutter. This photograph shows how that lead valley is formed.

An aerial view of the roof with slates in place awaiting the lead flashing to the ridges.

An aerial view of the roof with slates in place awaiting completion of the lead flashing to the ridges.

A view of the house with the roof completed after the scaffolding had been removed prior to re-erecting it to be suitable for the renderers.

A view of the house with the roof completed after the scaffolding had been removed prior to re-erecting it to be suitable for the renderers. Note that the guttering is not quite complete, requiring lengths of guttering to be cut to the exact length to fill in the gaps.

 

Bulletin 23: The roof structure

The modern, usual method of constructing a house roof is to use factory assembled roof trusses that have been designed using a computer aided design (CAD) modelling tool. This is generally quite economical  for simple roofs since the trusses can be fabricated from lightweight lengths of timber of small cross-section. Economy is achieved through minimising the amount of material and by achieving a commonality of truss so that the roof is implemented using a repeated  number of the same truss design. This repetition in the manufacture of trusses is ideally suited to low cost factory production techniques. The disadvantage of this method of construction is that generally a large number of cross braces are required in the truss design to achieve the required strength from the lightweight timber sections. This coupled with the frequency with which the trusses must be placed renders the enclosed roof volume fairly unusable because of the intervening trusses and their cross braces. To my mind a roof of this sort of construction resembles “knitting in match-wood”; cheap construction but the roof void becomes unusable for anything substantial.

In the case of the Ridge End roof, examination of the plans, elevation and sectional drawings in the “Architectural Style and Floor Plans” page of the blog shows that the roof is a complex structure. Firstly it comprises four main intersecting ridges that run with the perimeter of the building with a flat roof area in the centre of the building over the central staircase. Additionally there are two octagonal bay sections  to the front of the house along with an intersecting triangular gable over the central part of the front, necessitating yet another intersecting ridge.  To complicate things further, closer examination reveals that the roof ridges to the front and rear of the building are slightly lower than the ridges over its two side wings. This degree of complexity means that a large number of different truss deigns would be required and that there would consequently be few repeated trusses. If such a construction method had been adopted it would have still required skilled carpenters to assemble the roof and construct in-situ the parts of the roof not amenable to factory production. The resulting increased design cost and scope for cock-up seemed to outweigh the advantages of a factory produced truss design approach. We therefore decided to fabricate the entire roof as a “cut in -situ” traditional structure with ridge beams and rafters fashioned as necessary by skilled carpenters/joiners. The side advantage of this method of construction is that it produces a roof void space that is wide open. This openness makes the useable for installing the various mechanical and electrical items that will be the subjects of future bulletins, whilst allowing easy access for future maintenance and repair. Moreover the open roof space provides an attic space that allows a huge amount of storage should it be necessary in future.

We would have preferred to have had a slightly higher roof pitch. Unfortunately our planning permission restricted the overall height of the building to be no more than 1metre higher than the current house. With a ground floor ceiling height of 3.1metres and bedroom ceiling heights of 2.7metres this restricted the roof pitch to 28 degrees. This angle added to the complexity  of the build since a lot of trigonometric calculation was required to determine the various rafter forms. Thank goodness for CAD tools!  An unfortunate consequence of the 28 degree roof pitch is that the internal height of the roof space is quite low meaning that movement through the roof void will be at a “stooping walk”. Nevertheless a large useful space has been achieved.

 I believe that it is remarkable that just about the whole of this complex structure was accomplished by just two men; Niall, a highly skilled craftsman, aided by his apprentice, Lee. The really remarkable aspect is that Niall is just 24 years old and owing to his all-round capability has become the principal overall craftsman/carpenter on the project.

The ceiling joists are laid are placed onto the first floor wall structure and reinforcing steel beams. Here roof form over the octagonal bay window feature of the main bedroom suite emerges.

The ceiling joists are laid are placed onto the first floor wall structure and reinforcing steel beams. Here roof form over the octagonal bay window feature of the main bedroom suite emerges.

The first of the main ridge structures is constructed, building up from the horizontal first floor ceiling joists.

The first of the main ridge structures is constructed, building up from the horizontal first floor ceiling joists.

 

 

 

 

 

 

 

 

This image shows the large enclosed open space that is achieved by the decision to adopt a "cut roof" approach rather than factory produced trusses. The intersecting beams and the increased number of trusses that would have been required would render the roof space unusable.

This image shows the large enclosed open space that is achieved by the decision to adopt a “cut roof” approach rather than factory produced trusses. The intersecting beams and the increased number of trusses that would have been required would render the roof space unusable.

This is another photograph that illustrates the large loft/attic space that we have achieved.

This is another photograph that illustrates the large loft/attic space that we have achieved.

 

 

 

 

 

 

 

 

this photograph illustrates how the main ridges round the perimeter of the house intersect each other.

this photograph illustrates how the main ridges round the perimeter of the house intersect each other.

Photograph from inside the roof structure illustrating the amount of space under the roof.
Photograph from inside the roof structure illustrating the amount of space under the roof.
Another illustration from the other ridge show the roof void.

Another illustration from the other ridge show the roof void.

 

 

 

 

 

 

 

 

 

 

This photograph illustrates the complexity caused by the number of intersecting ridges and valleys of the roof design.

This photograph illustrates the complexity caused by the number of intersecting ridges and valleys of the roof design.

 

The complexity of intersecting ridges and hipped bays.

The complexity of intersecting ridges and hipped bays.

 

Aerial shot of the roof structure and how it fits on to the house.

Aerial shot of the roof structure and how it fits on to the house.

 

 

 

Bulletin 22: The first floor takes shape

Steadily, block by block, Charlie Viney and his team of brick-layers, Ollie, Ian and Kyle progressed to the first floor. The first floor structure was constructed in exactly the same way as the ground floor. The inner skin of the external walls and were built with the concrete blocks laid flat to give thick walls of high thermal capacity and good acoustic insulation. The internal room dividing walls and outer skin of the external cavity walls were constructed with blocks laid on edge for economy but with the external walls also incorporating 100mm of Kingspan “Cooltherm” insulation and a 50 mm air cavity for maximum thermal insulation. The central staircase walls were constructed from over 10,000 bricks so that the curves of the stair hall walls  could be achieved. When the first floor walls were at full height a crane was used to lift and place the large number of steel RSJ beams that are necessary to support the roof. The photographs below illustrate the construction of the first floor block-work structure.

The first floor from the front of the building.

The first floor from the front of the building.

The first floor from the side of the building with the Orangery in front. Note the wooden protection applied to the stone architraves of the Orangery doors.

The first floor from the side of the building with the Orangery in front. Note the wooden protection applied to the stone architraves of the Orangery doors.

Photograph showing the brick central stair hall of the house with its curved end walls.

Photograph showing the brick central stair hall of the house nearing completion with its curved end walls.

 

Crane lifting the steel RSJ beams into place to support the roof.

Crane lifting the steel RSJ beams into place to support the roof.

Photograph illustrating the complexity of the steel structure that supports the roof of the house.

Photograph illustrating the complexity of the steel structure that supports the roof of the house.

 

 

 

 

 

 

 

 

 

Photographs illustrating part of the internal first floor block work layout.. The octagonal structure will eventually be the vaulted lobby linking the rooms of the main bedroom suite, the bedroom, bathroom and dressing room. bedroom

Photographs illustrating part of the internal first floor block-work layout.. The octagonal structure shown will eventually be the vaulted lobby linking the rooms of the main bedroom suite, the bedroom, bathroom and dressing room.

Another photograph showing a different aspect of the first floor internal block work.

Another photograph showing a different aspect of the first floor internal block-work.

 

 

 

 

 

 

 

 

 

The complete first floor showing the roof structure also.

The complete first floor showing the roof structure also. Note the protection around the stone architraves of the windows and front door. Note also the clearing of the scaffolding in the vicinity of the front door so that the portico can be built to enable the venetian window  and pedimented gable end above the front door to be completed.

 

Bulletin 21: The Orangery Stone Entablature

Once the lead roof of the orangery was completed the finishing touch was to construct the stone entablature that forms a decorative finish round the top edge of the orangery and boot room walls. The stone is the same Oat Hill oolitic limestone used for the decorative plinth, window and door architraves.

The architrave stone blocks are secured in place with lime mortar and stainless steel brackets at the top of the Orangery outer skin walls.

The architrave stone blocks are secured in place with lime mortar and stainless steel brackets at the top of the Orangery outer skin walls.

Stone blocks are fitted in place to form an apparently seamless architrave.

Stone blocks are fitted in place to form an apparently seamless architrave.

After adding the frieze and coping the entablature is complete.

After adding the frieze and coping the entablature is complete.