A builder works on the parts that support the house. Masonry, concrete, foundations, slabs and openings in load-bearing walls fall within their remit. In refurbishments, they are usually the first trade on site after strip-out, thereby setting the geometry on which all subsequent trades build.
Builder's work includes masonry, concrete work, foundations, slabs, stairs, as well as openings and underpinning. In alteration projects, this also includes recesses for services, creating new openings and closing old ones. The builder also handles site set-up and often coordinates excavation and drainage works.
The most common alteration request is an open-plan living area, which means making an opening in a load-bearing wall. Whether and how this can be done is not decided by the builder alone, but by a structural engineer. They determine the lintel, bearing points and whether temporary propping is required during the work. Anyone who skips this step risks cracks in the upper storeys or worse.
Ask for quantities and unit rates rather than a lump sum, especially for cubic metres of concrete, square metres of masonry and linear metres of lintels. Check whether scaffolding, temporary supports, core drilling, recesses and disposal of demolished material are included. For older buildings, there should be an allowance for unforeseen items; without it, surprises turn into costly variations.
Alterations to the load-bearing structure, extensions and additional storeys require a permit; the requirements vary by canton and municipality. For work near the property boundary or on shared walls, neighbours should be informed at an early stage. A schedule of condition before construction starts protects both sides if cracks appear later.
The builder is usually followed by the first-fix electrical, plumbing and heating installations, after which the plasterer closes up the walls. Plan recesses and chases together with the building services contractors before concrete is poured or walls are built. Cutting chases afterwards is expensive and weakens the structural element.
The older the building, the less the plans reveal about what is actually built into it. You often find masonry from different periods, beams added later without documentation, voids, or foundations that are shallower than assumed. Allow for this rather than being surprised by it: an agreed contingency and a clearly defined process for variations, including written approval before the work is carried out, make such findings manageable. Without this arrangement, this is exactly where the cost overruns that everyone talks about in alteration projects arise.