1.1 Case study
This report is a comparative study of masonry. The case study that I chose to further study on is the Beverley Minster, a substantial and assertive Gothic church located in the East Riding of Yorkshire. Architecture played a very important role for the church in Medieval England. The more splendid the architecture, the more the church believed it was praising God. The church in medieval England poured vast sums of money into the creation of grandiose architectural projects that peaked in the cathedrals at Canterbury and York. Beverley minster is widely regarded as one of the most beautiful gothic buildings in Europe.
fig.01 Beverley Minster West front
Beverley Minster
1.2
The church is composed of three parts, choir and transepts (c. 1225-1260), nave (c.1308-c. 1370), and west façade (c.1380-1420). It contains components of three gothic styles – early English, decorated and perpendicular all combined into a harmonious conclusion. A magnificent example, is the continuous vaulting from end to end.
fig.2 Beverley Minster
The minster owes its origin and much of its subsequent importance to Saint John of Beverley, who founded a monastery locally around 700 AD and whose bones still lie beneath a plaque in the nave. The institution grew after his death and underwent several rebuilds. The church is an impressive 102 metres in length, larger than a number of English cathedrals.
fig.3 Beverley Minster
1.3
On the approach to Beverley, the slender twin west towers of the Minster stand high above the flat surrounding countryside. Special points of interest on the exterior are the west front and the Highgate door, both considered to be exceptional examples of the Perpendicular style. These formed the inspiration for the present west towers of Westminster Abbey, designed by Nicholas Hawksmoor.
1.4
The layout of the Minster conforms to that of most medieval cathedrals and large churches. Starting at the west end and proceeding east there is the nave, transept, choir, sanctuary and retro quire. Two features of the Minster are unusual: there is a second transept near the east end and the main transept has aisles on both the east and west sides.
Fig. 4 ground plan of Beverley minster
1.5
The Minster was built in the period 1190-1420. The east end up to and including the main transept is largely Early English, typified by pointed arches, lancet windows, stiff-leaf decoration, dog-tooth moulding and Purbeck ‘marble’.
Construction
2.1
The stone used throughout is limestone, mostly from Tadcaster near York. It is light in colour, giving the Minster a bright, luminous aspect not often found in medieval buildings. Especially at the east end there is considerable use of black Purbeck ‘marble’ (actually not marble but a hard limestone from Dorset) in shafts and columns.
2.2
The limestone blocks were extracted at Tadcaster and transported 41 miles on cart to Beverley. The quarries at Tadcaster were also used to provide the blocks for York Minster nearby. As with all constructions the quality of the workmanship, and particularly the mortar affects the durability and life of the building. Though there are several other factors to be considered as to why construct Beverley Minster with limestone block.
2.3
The roof structure on the Minster is highly complex and has changed several times over the years. Attached at Appendix A is a drawing of a typical roof joint used at the time of construction.
fig.3 roof workshop of Beverley minster featuring the large
treadmill.
Masonry
Advantages of Limestone Block Masonry Construction
3.1
Through the ages but particularly medieval times religious buildings of such magnitude were often built with masonry such as limestone block. The desire to use this particular limestone was undoubtedly economic and the ready availability of raw materials. Many of the world’s most famous buildings have been built of sedimentary stone, from Durham Cathedral to St Peter’s in Rome. There are two main types of sedimentary stone used in masonry work, limestones and sandstones. Limestone is still quarried in nearby Lincolnshire to repair buildings such as the Houses of Parliament.
3.2
Limestone is the choice of the stonemason to utilize their carvery skills. Whilst durable and used for sustainability, Church designs often changed when under construction. Limestone offered the stone mason opportunity to carve new designs through the process.
3.3
Limestone construction provided solidity and a substantial degree of permanence. Whilst the East Riding of Yorkshire does not have a history of seismic events, the huge foundations will have been laid on the Holderness Clay alluvial deposits. Sustained durability given a probable restricted budget would be prerequisite.
3.4
Building with Limestone block offers a substantial protection against fire. It is none combustible and a solid construction. The mass of the building also offers substantial protection from storm damage.
3.5
The design process for religious constructions undoubtedly would have a requirement for acoustic effectiveness and the use of masonry blocks would have re-emphasized religious control over the population by the use of imposing material. The use of the blocks enabled the build of such a huge construction, clearly offering a huge degree of structural strength but maintaining an aesthetically appealing concept.
3.6
Whilst there is a debate on quarrying and the impact it has on the environment in today’s society, the Limestone was an effective economically readily available material and quite clearly made good business sense to utilize these assets in the locality.
Disadvantages of Limestone Block Masonry Construction
4.1
Extreme weather can cause degradation of masonry. Particularly the expansion and contraction of the freeze thaw cycle which shatters the surface. Beverley Minster has been damaged on numerous occasions by storms over the centuries. Though main structures remained intact. The color of the limestone will be affected over time by weathering and pollution. Though sandblasting and careful cleaning is available to resolve this issue.
4.2
Masonry construction does not lend itself well to mechanization, and requires skilled labor. Time served skilled stone masons are still the obvious choice for maintenance and repair.
4.3
Sedimentary rock by its very complex structure (compression of shale like substances) is not particularly cohesive and does not react well to oscillation and movement. Immense foundations would have been excavated and completed to support the structure.
4.4
Limestone would have been expensive both to quarry, transport and designed as opposed to other potential building construction materials for such a project. Limestone is a porous rock over time and will absorb moisture. Though modern technology is available to coat and weatherproof.
4.5
Repointing is the process of renewing the pointing, which is the external part of mortar joints, in masonry construction. Over time, weathering and decay cause voids in the joints between masonry units, usually in bricks, allowing the undesirable entrance of water. Water entering through these voids can cause significant damage through frost weathering and from salt dissolution and deposition.
Timber
Advantages of using a timber construction
5.1
Timber is a natural, ecological and sustainable product if reasonably sourced. A material used through the ages for a range of buildings. It does of cause compliment masonry structures in terms of certain wall structures, roof systems and joints. People have been building with timber for thousands of years. Timber is continually being grown in our forests and plantations.
5.2
Using Timber has lots of advantages. It is none toxic, safe to handle and weathers naturally. Life cycles of buildings are taken into account when using timber and costed accordingly.
5.3
Timber is very low in production energy, it takes very little energy to convert the wood in trees to the timber used in building. This means that the embodied energy in timber is very low, the lowest of almost all common building materials.
5.4
Timber has stored carbon from the atmosphere and will not be released unless used.
5.5
Timber is a very good insulator. It reduces the amount of energy used to heat and operate a building. Timber is a natural insulator and can reduce energy needs especially when it is used in windows, doors and floors. It is easy to work with using fairly simple equipment.
5.6
Locally available or can be transported easily. Clearly wood is versatile and can be milled to desirable working lengths and size.
5.7
Project times will be less as Timber is quicker to work with and reduces labor costs.
Disadvantages of using timber construction
6.1
The exercise of building in timber requires more precision and planning than a masonry property. Timber also needs a procurement process which takes time.
6.2
External timber elements, such as cladding and fascia boards are prone to rot if not well maintained.
6.3
Timber is highly combustible and history shows that fire is a real concern for all Timber constructions.
6.4
Timber will rot and decay when exposed to excessive moisture and will follow its natural urge to degrade if not protected.
Concrete
Advantages of using concrete construction
7.1
Concrete is versatile and modern. It can be molded and formed into just about anything. Its durable and also a very effective thermal mass.as it absorbs and retains heat well, keeping concrete buildings cool in the summer and warm in the winter.
7.2
Concrete is economical, has a long life and relatively low maintenance requirements. It is not likely to rot, corrode or decay. Concrete is a non-combustible material which makes it fire-safe and able to withstand high temperatures. It is also resistant to wind, water rodents and insects.
Disadvantages of using concrete construction
8.1
Concrete has a relatively low tensile strength, ductility and strength to weight ratio. It has low thermal conductivity.
8.2
Concrete is susceptible to cracking and may contain soluble salts. This may cause efflorescence and affect the general appearance.
Steel
Advantages of steel construction
9.1
Structural steel components are lighter and stronger than weight-bearing wood or concrete products. A typical weight-bearing steel fabrication is 30% to 50% lighter than a wooden equivalent. This makes steel frame construction far stronger and more durable than traditional wood framed alternatives.
9.2
Steel studs are available in a variety of sizes and can be fabricated order. This means they can be customized to bear specific loads in buildings of all different types and sizes.
9.3
Steel frame construction reduces the fire risk to a building and retarding the spread of a fire should one occur. Special flame retardant coatings act to increase this property of structural steel. However, it will burn after reached a certain level of heat.
9.4
Structural steel components are immune to the degrading effects of burrowing insects and mammals, which can cause a problem for wooden framework unless adequately treated.
9.5
Steel can be reused and recycled repeatedly without ever losing its qualities as a building material. This unique characteristic gives all steel a high economic value at all stages of its life cycle which, unlike some other construction materials, ensures that it is routinely recovered and reused.
Disadvantages of steel construction
10.1
Steel is not known for its warmth, due to its high efficiency in conducting heat. The insulation value of walls can be reduced by as much as half when heat is transferred away through steel studs, which is not great for energy retention.
10.2
One of the benefits of using wooden structural components is the ability to adjust them on site. A component can be cut down to size, nails hammered in to strengthen the join and so on. This obviously can’t happen with steel.
10.3
Steel frame constructions rarely work on their own. They usually require drywall, sheathing, insulation and supplementary wooden components to bring a building together. Maintenance cost of a steel structure is very high due to action of rust in steel and expensive paints are required to renew time to time.
Conclusion
The overall purpose to build Beverly Minster was to achieve an imposing religious building that was to serve God and ensure the people were aware of the power of the church.
To build an immense Church the size of Beverley Minster given the available resources at the times of construction could only be Limestone block offering longevity, durability and value for money. The stone mason could readily carve and design each block on site.
After researching the potential alternatives, steel and concrete were not readily available at the time of construction and even today, would not achieve the distinct imposing effect and colourisation of blocked limestone. Timber construction inside the roof compliments the Limestone block, however Timber could play no part in the structure of the walls.
A timber frame of that size would not be able to fix to the foundations and offer support and permanence. Fire risk and storm damage are also clear risk factors for such a construction and emphasizes the requirements for such a build bearing in mind the objectives for durability and cost, the only build consideration could be Limestone block.