Bricks and Building Forms
All openings in brick walls need some way of keeping up the bricks above the openings. This may be an arch or a flat lintel of some kind.
Examples of Flat Lintels
These sets of bricks brick lintels were made at the brickyard and arrived in wooden boxes packed with straw. By this time the Fire of London Regulations forbidding projecting eaves were not being obeyed rigidly in the suburbs, so these eaves needed some support.
The wooden window frame is fully exposed instead of being hidden behind a layer of brick. These heavy keystones are typical of the Edwardian Period, just before the First World War.
The stucco work includes dentil work (like teeth) inside the triangular pediment and below the canopy; a central mask with swags of flowers and fruit on either side; two elaborate Gibb’s brackets supporting the canopy, and an egg and dart moulding round the door. A drawing of this door appears in Dan Cruikshank’s splendid book, ‘The Art of Georgian Building’. Behind all this elaborate stucco is a simple lintel built into the brick wall.
The bracket design under this canopy goes back to the timber joists in early wooden Greek temple. The Greeks copied these wooden shapes into their stone buildings and the Church Street builder copied them in stuco. The design is over 2000 years old.
The lintels are made of ferro-concretebeams with a row of brick soldiers above. The latter are purely for decoration, not strength.
Here the windows have ferro-concrete lintels but the soldiers have been dismissed. The result is just as strong, but plainer.
In this block of modern flats the concrete floor above acts as a lintel so there is no need for an extra one. The grey bricks are laid as stretchers, showing that theses are cavity walls.
The weight is diverted round the arch and down to the ground. This means that there is almost no weight pressing down on the window head or door opening.
These diagrams show several types of arch and some of the formers used to build the arches.
Arches instead of lintels
Arches act as lintels, carrying he weight safely to the ground, and can be of many shapes.
Examples of Segmental Arches
The abutments and keystone are probably all in Sandstone, which was very popular and relatively cheap at this period.
These unusual lintel blocks are in red brick. At first they might be taken for terracotta, which is a hard pottery, but the surface of these blocks has begun to wear. Terracotta has a harder surface which resists the acid London rain better than this. The liver coloured terracotta fronts of the 1900 London tube stations are very well known and are still in splendid condition.
The old Tram Depot has now been converted into flats.
A stone archway under construction in Brittany with three layers of stone, with larger ‘keystones’ at random intervals. The supporting former on which the stones were laid, has just been removed.
The inner wall is in thermal concrete blocks, so that this building which will soon look like the old stone buildings nearby, will be constructed in the latest heat retaining manner.
Sometimes segmental and flat lintels are used together.
Flat Lintels inside arches
The relieving arches carry the weight of the wall round the windows and down to the ground. This allows the brick work within the arches to be half a brick thinner than the outer wall. The cut bricks of these particular lintels and of the arch, are very thin, hardly thicker than tiles.
This form of construction gives an elegant appearance to the building with contrasting brick colours and interesting shadows, far more attractive than a plain brick wall.
Two arched lintels windows with cut brick lintels inside relieving arches,
The round brick arch and the lower wall of the house have been covered with stucco and lined to give the appearance of stone. Some early builders used to colour and grain their stucco walls to make them look even more like stone blocks.
These windows have triple arches, allowing the window to be wider. The arches themselves have then been decorated with stucco.
Here the same shape has been enclosed in a much larger stucco framework, with a top canopy supported on brackets.
The gable wall of this house is angled, giving this unusual arrangement of curves. As usual, these quadrant windows are hinge vertically at the centre. The semicircular window allows far more light into this attic room than any rectangular one could have done. The use of contrasting bricks has much improved what could have been a awkward gable end.
A Corbelled Lintel
A most unusual corbelled lintel in Grasmere, Cunbria
Detail showing the lengths of the stone courses and a keystone apparently suspended on nothing. This last is a mystery, held up by magic. Can there be a bolt through it?
Instead of a normal arch, with the different stones pressing against each other sideways, the stones here have been corbelled. Each stone presses downwards but, because they are long and only a small part of each one projects, they cannot fall. Corbels are often used to support beams, some castles have corbelled passages, but corbelled window heads are very rare.
from Lintels final 23.6.07.doc
Revised: December 24, 2008 10:04 AM