There are several different Tricks involved in this particular project, which may relate to walling materials other than flint. Similarly, although this is a free standing wall, certain features may also be utilised in respect of retaining walls.
The wall shown is eleven metres in length, with two straight panels of three metres and one curved section of five metres. The height if the wall is nominally one metre, although the ground rises from right to left.
The foundations were 60cm x 45cm deep, stepped to rise with the ground, hence there are steps in the block walling to compensate, each step being 10cm to match either a part block or single brick plus generous mortar beds. The foundations were cast in one operation using 1.6 cement/sandy ballast wet mix concrete with three number 13mm steel rods set into the concrete to provide additional lateral strength.
Due to the fairly short run, and the fact that the wall is only one metre high, and strengthened by the curve, it was not deemed necessary to build vertical steel rods into the foundations and into the centre of the piers, although if the wall had been taller or in an exposed situation, these would have been added. The hollow piers were however, filled with wet mix concrete.
The photographs show how the piers are constructed in relation to the internal ‘hearting’ of the concrete blocks. The blocks are mortared into place with stainless steel ties through the bed of the blocks to extrude to both sides of the wall.
The flints are ‘Field’ flints, as dug i.e. not knapped or broken to expose the internal face of the stone, although some have been knapped by their transport and handling – this is not considered a defect, and add to the natural character of the material. The style is that chosen by the client, from around a dozen or so styles I can offer. This particular style is random, not coursed, but ensuring a mix of larger and smaller stones, some round, some broken or knapped, with no one type of stone being prevalent in one area i.e. as random as possible.
The mortar used is one part ordinary Portland cement to three parts 3.5 Hydraulic Lime to six parts of a slightly sharp or gritty sand, known locally as Rock Common. The mortar is very carefully batched using a number of buckets, each new mix being a precise match to the last to ensure a uniform colour match. The consistency of the mortar is vital – not too wet or too dry, but quite ‘sticky’ as a lot of the work is done by gloved hand. There is no trowel work at all, the pointing being achieved by gloved hands and a stiff brush when ready.
The timber structures are fixed to provide the builder with an accurate flat face, with a ‘reveal’ or shadow line of 50mm between the brick piers and the recessed flint face. As works progress, the batten across the face is raised in approx. 30cm increments, and fixed to the side uprights with screws. The battens are secured with short stubs fixed hard against the block walling on both sides, and the upper laterals are fixed precisely 33cm to the centre of the wall to ensure the finished build is accurate for both width and level.
The wall will be finished with a single row of slate to provide an accurate straight line on which to fix the brick coping (one and a half bricks laid soldier course, alternating as the work progresses.) The slate also helps to prevent water from seeping into the wall and causing possible frost damage.
The duration of work was six working days from foundation excavation to the amount shown, with myself building and one labourer doing the hard work. Total estimated to completion is another four days. Notice the shelter – if and when the weather prevent working ‘outside’, I move under the cover and continue building.
An additional plus on this project is that being a front garden feature, it is worth twenty rear gardens when it comes to promoting your services!
