Monument

Lincoln Castle

Lincoln Castle was built almost 1,000 years ago by William the Conqueror. After his victory at the Battle of Hastings in 1066, William the Conqueror faced ongoing resistance and ordered the construction of a Castle in Lincoln as part of his strategy supress rebellious activity in the North of the Kingdom. The castle’s strategic location on top of the hill acted as a reminder to the local population that the Normans were in control.

The Normans constructed their motte and bailey castle by re-using the remains of stone walls that were part of the Roman city, Lindum Colonia. We also know that centuries earlier, Roman invaders built their legionary fortress on the same hilltop. The castle walls were built in stone in the late 11th century, replace a temporary wooden palisade.

Lincoln Castle Revealed
From 2010 – 2015 Lincoln Castle underwent a major £22m restoration project funded by various bodies including the National Lottery Heritage Fund. The project undertook a variety of works but a large proportion of the restoration works took place on the Castle’s curtain wall resulting in a creation of a new 360-degree Medieval Wall Walk along the Castle’s ancient ramparts.

Skills used at Lincoln Castle

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Roof

Good restoration and building work will last for years with appropriate maintenance.

The roof of the prison building was stripped, repaired and re slated in the early nineties. As it remained in good repair it wasn’t looked at as part of the 2010-2015 restoration and conservation works.

photo of lincoln castle prison roof and view to the cathedral

The Lincolnshire vernacular roofing material is pan tile and can be found on many historic buildings around the county. As a prominent public building however the Prison roof was covered in slate. Not only was this a display of status, slates depending on how they are laid would also be more air and weather tight.

Traditionally Slaters would have their own measures of slate that they were using. This would be kept on a marking stick which would then be unique to each slater. By marking and sizing the slates to their own measures no one else was able to steal and reuse their materials.

Slates can be attached to a roof in a variety of ways:

Centre fix Head fix Shoulder fix

Centre fix

Perhaps the most common is the centre fix, it generally dates from industrialisation. A centre fixing involves to pegs/nails being used on either side of the slate, about two thirds of the way down from the top and somewhere between 19-25mm in from the edge.

Head fix

Shoulder fix

A shoulder fix is a rare found way of attaching slates but is a good one. The nails like the centre fix go in one on each side but the holes are at the top of the slate rather than the middle. This means they are well covered by the other slates on the roof as they overlap each other. The bottom slate will be covered by the next row of slates and as slating appears to work in thirds by the row above that too; meaning it is covered by slate two and three. This is what waterproofs the roof. A good slater will also understand the slate surface and lay the correct slate to help direct the water flow off the roof without getting caught or puddling somewhere it shouldn’t.

If you look at the prison roof now what you will see is random diminishing (this means it gets smaller as it goes up towards the roof ridge from the wall) county grade slate. Where possible slates that had been removed from the roof were reused meaning that as much original material was kept as possible. Welsh slate from Penrhyn quarry, Bethesda North Wales was used to make up the short fall replacing slates which had broken or were no longer good to go back on the roof.

The slates were attached with a centre fix involving two copper nails to the rafters they range in size from 48 inches at the bottom to 20 inches at the top. They also have some lime mortar applied to help bed them in place too, but you can only see this from inside the roof space.

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Stonework conservation

A large part of resent restoration works at Lincoln Castle involved the Castle's stone curtain wall. The use of minimal intervention as a conservation principle allowed for high proportions of the existing wall fabric to be retained. Keeping in mind conservation principles some key actions during the works are highlighted below.

Sections of the walls were overgrown with vegetation some of which were rooted within the wall fabric, adding excess moisture to the stonework, damaging it. Careful excavation was essential to remove the vegetation and hopefully conserve as much of the original fabric as possible.
Repairing stone rather than replacing where possible. During the first phase of the works the team were able to retain a significant portion of the original fabric using approximately 260 tonnes of new stone.
Hiring experienced local craftspeople with specialist stone conservation knowledge, including knowledge of local geology and local building/construction methods meant that care had been taken to find people who would be able to do the repairs to the existing stone fabric as well as integrate new stones where needed.
The new stone fabric was sourced from the local Lincoln Cathedral Quarry and then hand prepared for the castle walls by 23 stonemasons. It took them approximately 2 hours to prepare each stone before it is set in place on the walls.
Creating a lime mortar to match and integrate the new fabric with the old was an important part of the works. Achieving the right mortar mix in terms of texture, appearance, colour and consistency means that the repairs would blend into the original fabric. 8 test frames of different mortar mixes were created by the team before approval. In the end sand from Norton Disney, 11 miles from site was used to create a more accurate match, so that when the new stones weather and blend in with the original ones the restoration work should appear to be minimally invasive.

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Lime mortar

Mortar is a workable paste which hardens, and it binds building blocks including stones, bricks and masonry units, allowing to fill and seal irregular gaps between them. It has been made in the same way for over 1000 years, it first appeared in Britain during the 4th century. The word ‘mortar’ is derived from the old French word mortier which means builder’s mortar, plaster or bowl for mixing.

The mortar was traditionally made of slaked lime, sand and an additive or binder. Many kilns were used to create limestone along the coast of Britain.

Process of creating lime mortar:

Firstly, the limestone would be smashed into small chunks allowing it to be heated when it was added to the kiln. The base of the kiln would be filled with coal, and then filled using layered coal and the small broken pieces of limestone.
After the kiln was layered adequately, a fire would be started at the base of the kiln. The burning process could last for up to 2 days depending on how big the kiln was. The coal would reduce in size, more coal was added allowing a longer burning process rather than doing individual burns which would be more time consuming.
Eventually the coal would turn into ash and fall out of the bottom of the kiln, along with the pieces of limestone. A rake tool would then be used to pull out the hot chunks of limestone as they fell out of the bottom of the kiln.
If the limestone was cooled naturally it created quicklime, if water was added to the hot pieces of lime it turned in slaked lime. Using water to cool the hot pieces of lime whilst they were still hot enabled it to become more brittle making it easier to smash it into powder.
The powdered slaked lime would then be used on construction sites where an equal amount of sand would be mixed with the slaked lime powder then water was added to create the right consistency. Many castles and homes were built using this method.

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aerial view of lincoln cathedral castle and high street

Designation

Designation aims to highlight the significance of a heritage asset and to help make sure that any future change to that asset does not result in the loss of its significance.

Heritage Assets of all type can be designated and the terminology for each asset type is different and carries different weight in legislation. Some designations are straightforward, and others are slightly more complex with different levels of grading.

Listed Buildings Scheduled Monuments Registered Parks & Gardens Registered Battlefields Protected Wreck Sites

Listed Buildings

Listing is a national designation covering buildings. A listing is a record of the special architectural, or historic interest of that building.

There are estimated to be over 500,000 Listed Buildings on the NHLE.

Listed Buildings are graded in line with their level of special architectural, or historic interest. The decision to include a building on the NHLE rests with the Secretary of State for Department for Culture, Media & Sport (DCMS), the Secretary of State is advised in this process by Historic England and their Listings Teams based around the country.

Grade I Buildings are of exceptional interest with only 2.5% of all Listed Buildings in this category.
Grade II* Buildings are particularly important buildings of more than special interest, only 5.8% of all Listed Buildings fall in this category.
Grade II Buildings are of special interest and is the most common grading with 91.7% of all Listed Buildings covered by this grading.

The requirement for Listing buildings currently comes from the Planning (Listed Buildings & Conservation Areas) Act 1990 – Section 1 & 2.

The Listing of a building affords it statutory protection meaning that in most cases, works to that building that affect the special architectural, or historic interest will require Listed Building Consent. In some instances, Planning Permission may also be needed. It is best to check with your Local Planning Authority which consents will be required when looking to make changes to a Listed Building.

Undertaking unauthorised works to a Listed Building is a criminal offence.

Scheduled Monuments

A Scheduled Monument is a designation of nationally important archaeological sites, these can be both above and below ground. There are over two hundred types of monuments covered by this type of designation.

There are far fewer Scheduled Monuments than Listed Buildings, with nearly 20,000 sites having been scheduled. Sites selected undergo very careful consideration are a representative sample of important sites from different periods from Prehistory through to the modern era. This is not to say that sites not covered by scheduling are potentially not nationally important.

The current power for protection of Ancient Monuments comes from the Ancient Monuments and Archaeological Areas Act 1979.

The Act provides protection to these sites through the requirement to apply for Scheduled Monument Consent from the Secretary of State for DCMS to undertake works to scheduled sites, works are defined as `demolishing, destroying, removing, repairing, altering, adding to, flooding, or tipping material onto the monument`.

Undertaking unauthorised works to a Scheduled Monument is a criminal offence.

Registered Parks & Gardens

A Register of Parks & Gardens of Special Historic Interest in England is kept by Historic England through the National Heritage List for England. There are over 1,600 sites on this register.

Registration does not have a consent system like Listed Buildings, or Scheduled Monuments, however the designation makes these sites a material consideration for local authorities when making decisions within the planning process. This means authorities must take the historic interest of these sites into account when making decisions on applications affecting them.

Organisations such as The Gardens Trust are a statutory consultee on applications affecting all Registered sites, in some areas this may also include the County Gardens Trust if one exists in that area. Like Listed Buildings, Parks & Gardens are Grade I, II* and II. Applications affecting Grade I and II* Parks and Gardens will require consultation with Historic England.

The provision for the Register of Parks & Gardens of Special Historic Interest in England derives from the Historic Buildings and Ancient Monuments Act 1953.

Registered Battlefields

Like Parks & Gardens, a Register of Battlefield sites is kept by Historic England through the National Heritage List for England. There are 47 battlefield sites on the register.

They are a material consideration in the planning process for local authorities when making decisions as part of the planning process that will affect these sites.

The provision for the Register of Parks & Gardens of Special Historic Interest in England derives from the Historic Buildings and Ancient Monuments Act 1953.

Protected Wreck Sites

A Protected Wreck Site is designated by the Secretary of State to provide a restricted area around wrecks to prevent uncontrolled interference.

Those wishing to visit, salvage or deposit anything at a wreck site is required to obtain a license from Historic England on behalf of the Secretary of State. To do so without license is a criminal offence.

The requirement for protection of historically significant wrecks comes from the Protection of Wrecks Act 1973.

Designation is not a top-down process, and anybody is able to nominate a site for designation to Historic England.

Nationally designated heritage assets have been recorded and available to view online via the National Heritage List for England:

historicengland.org.uk/listing/the-list

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