If the water table is high (for instance if the gravel is submerged), the bearing capacity will be halved, so it’s important to keep the foundations as high as possible. A shallow, reinforced, wide strip foundation may be suitable. The process of making stone walls using styrofoam is very similar, but there is no need for plaster, nor to scribe any joints; the pressure from the mechanical pencil on the soft foam while marking the courses will achieve the same result. As such, the Styrofoam rubble walls on the diorama (the ruined barn shown here, and the retaining walls) don't require further explanation, but the construction of the ashlar arch certainly does…

This can be a cost-effective way of building on sloping ground too, as the steel piles can be left above ground and linked together with tension wires or rods, and topped with a steel ringbeam or grillage to build from. Factors to Consider What Might Affect my Choice of Foundation System?Diagrams of strip foundations (left) and trenchfill foundations (Image credit: Homebuilding & Renovating)

Where it is not possible to construct conventional strip footings because the new building is hard up against an existing structure, or access to the adjoining land is not available, it may be possible to use an offset strip foundation rather than a more expensive piled foundation or a reinforced raft foundation. Typically 750mm wide and 450mm deep with a layer of A193 mesh placed in the bottom of the concrete with at least 50mm cover to the steel. The solution is generally suitable for single-storey structures.Now use a flat needle file to create chamfered edges along the archway. With the styrofoam walls complete, apply a layer of gesso to everything. Gesso is an acrylic paste made from chalk, binder, and white pigment. It’s used as a primer to prepare surfaces for painting, but it also provides a little more strength and texture. Simply apply it with a brush, and leave it overnight to dry. If the chalk is soft it will need to be excavated until firm chalk is reached. Chalk soils can be prone to erosion, so be wary of the possible presence of hollows or caves. These are a relatively new foundation solution consisting of slender, hollow steel shafts with a small number of steel helices (or screw threads) welded to them. The piles are screwed into the ground until they achieve sufficient friction to support the required load. Michael has presented over 150 property shows for BBC, ITV1, Channel 5, UK TV Style, and Discovery RealTime, including I Own Britain's Best Home; Don't Move Improve; Trading Up; Good Bid, Good Buy; Build, Buy or Restore?; How to Build A House; and Hard Sell. Short bore piles are typically 2–3m long and can be reinforced with steel (Image credit: Homebuilding & Renovating)

If sewage pipes leaving the building have to be deeper than the top of the foundation concrete then they should also be ducted; they cannot be trapped within the concrete and must be able to move freely. To keep the stones in our wall as horizontal as possible, multiple level trenches are dug on the steep sections of the hill. The first layer of stones can then be laid flat, working your way up the hill. Slowly build up the layers, but do try to copy the prototype where stone size and placement are concerned; larger stones are less common than smaller stones. Water pipes must enter the building at a depth of at least 750mm but no more than 1.35m below ground. If that means that they pass through a concrete foundation then they must either be laid prior to pouring or, better still, a duct installed for them to be pushed through later. The rear of the arch differs in three ways. Firstly, the crenellations are only half-depth except at the outer ends; which wrap around the sides. Secondly, a slope joins the bottom of the crenellations to roughly the same level as the top of the cornice on the front. Thirdly, the entire archway has a rebate where the gates once sat. These all require careful trimming with a sharp blade.

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There are three types of clay in the UK, classified by their plasticity, which is how much their volume can change due to their water content.

The capping stones feature a slope either side of a raised and rounded middle point. On a length of styrofoam 7mm wide, mark two parallel lines in the centre 1mm apart. Using a flat file, form slopes on either side.The raised section that’s left canbe rounded off with more light filing. Cut to the lengths required, then glue them onto the parapet using PVA. Where the soil is soft or of a low loadbearing capacity, wide strip foundations can be used to spread the load over a larger area, reinforced with steel so that the loading per square metre is reduced. Sand holds together reasonably well when damp, compacted and uniform, but trenches may collapse and so sheet piling is often used to retain the ground in trenches until the concrete is poured. The painting technique for the dry stone wall is slightly different from the rest. To ensure the paint reaches the crevices, spray a fine mist of water, then apply a very weak dark grey wash. Next, apply a slightly watery colour that matches the prototype stone in its un-weathered freshly-cut state. Finally, add additional dark grey washes as necessary, along with dry-brushed yellowy-green ‘lichen’ spots. Electricity and gas don’t usually need to be ducted or installed at this point as they are normally surface mounted. Finally, the building and warranty inspectors will have to approve the excavated foundations prior to any concrete being poured.

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Providing the chalk is not too soft, foundation widths of 450mm for low-rise buildings are generally acceptable. The depth of the foundation must be below any frost action, a minimum of 700mm. Medium plasticity clays are found in the rest of the South East, across the Midlands and up beyond the Humber Estuary towards the North East. They also turn up in some isolated areas in the North West of England near the coast To cover the entire quay, I use household filler/plaster as it’s cheap, available in large quantities, and you can make it to the viscosity desired by varying the amount of water in the mix. Apply a thin layer of PVA to the quay walls, followed by a generous coating of plaster. Once left to harden (which can be up to 48 hours), sand the plaster until the required smoothness is achieved. Tiny stones are glued along the top to reduce its ‘stepped’ nature; ahead of adding the capstones. The inset photograph shows one of three large clay ‘stones’ being roughened with a craft knife. Two of these are end stones (one visible on the bottom right of the main photograph), and the one left of the pliers would be used by people to hold onto while climbing over the stile.