Extension and Refurbishment in Great Shelford

The early stages

This job in Great Shelford started at the end of July 2026 — a house extension with a full internal refurbishment and landscaping to follow. What is on this page is a working record of the early stages rather than a finished result: it runs from the survey and strip-out through the groundworks to the start of the superstructure, with the first lift of blockwork up on the engineering-brick plinth and the external drainage going in.

We publish these stages on purpose. Almost everything a builder actually does is buried or plastered over by the time a project is finished, and the stages below are the ones that decide whether the finished house stands straight and stays dry.

Survey and strip-out

The house was photographed room by room before anything was touched, inside and out. That record earns its keep later: once a wall is down or a floor is up, the photograph taken on the first morning is the only evidence of what was there before.

Internally this was a soft strip rather than a demolition. Ceilings came down to expose the joists, partitions were removed and openings cut through internal walls, with adjustable steel props set under the joists before any load-bearing element was touched. Propping is the part a homeowner never sees in a finished photograph, and it is the part that decides whether the floor above stays where it is.

Demolition and clearance

A flat-roofed outbuilding was taken down to clear the extension footprint. Its roof was a reinforced concrete slab, which has to be broken out rather than lifted off, and comes apart leaving the reinforcement mesh hanging in the opening. Some of the rendered blockwork walls were kept and still stand. A chimney breast was also removed from the flank wall.

Groundworks and foundations

The footprint was set out in chalk before a spade went into the ground. Trenches were then excavated across it to around 1.4 metres, with the depth recorded against a tape and the existing footings exposed alongside so the new foundations could be related to what is already there. Concrete was poured and starter bars set into a pad within timber formwork.

Substructure and the ground floor

Blockwork foundation walls were built up to damp-proof course, which sets out the room layout of the extension in outline before anything above ground exists. A block retaining wall was built along the boundary at the same time.

The ground floor is beam and block: precast concrete beams laid onto the blockwork, a geotextile membrane over the oversite, then infill blocks laid and levelled between the beams. It is checked for level as it goes down, because everything above it — walls, door frames, kitchen units — inherits whatever error is left in it.

Plinth, damp-proof course and the first lift

The superstructure started in the first week of September. A plinth of blue engineering bricks was laid off the substructure walls, the damp-proof course bedded on top of it, and the first lift of blockwork raised as a cavity wall from there, with wall ties across the cavity and weep vents set into the plinth course so that any water reaching the cavity has somewhere to drain. The photographs show the corner and a pier at this stage, and the cavity itself at floor level before it disappears behind the next lift.

Drainage

The external drainage went in alongside. A trench was opened to the rear of the house, the existing services exposed and protected, and a new 110 mm foul run laid to falls on a pea-shingle bed, with the branch connection and rest bend set up to level beside the new plinth. Surface water goes to a modular soakaway crate wrapped in geotextile and bedded on shingle, with the two surface-water runs connected in before the trench is backfilled.

What follows

The rest of the superstructure, the roof, glazing, internal finishes and the landscaping follow on from the stages shown here.

More on house extensions and home refurbishment, or see what we do as builders in Great Shelford.