Building costs

A recent purchase of a ‘Homes’ glossy magazine inspired me to write this post. An article within showed a series of elegant extensions with finely detailed designs under an ‘Extensions for every budget’ title. It also listed their building costs (varying with & without VAT). In my experience these were considerably lower than I would expect. On the assumption that the magazine/builders/architect/client were not lying about their expenditure, I have drawn the following conclusions:

  • The magazine refers to build cost. This may be the construction contract value, i.e. not including any client-supplied subcontractors (say a flooring company), the kitchen, bathrooms or sanitaryware, the landscaping, the furniture (fitted or otherwise), and possibly decorations & light fittings.
  • The date of completion for some of them may have been some time ago. Since the fall of the Pound against the Euro after announcing Brexit the cost of lots of building materials has risen accordingly. The Federation of Master Builders released an article stating the concern of rising material costs.

Every client I meet understandably has a budget in mind, and a maximum they feel comfortable spending. It is a rare project to be given full freedom without capping the cost. Estimating building costs is a specialist and experienced area. As a small practice, Tom Spriggs Architect Ltd, does not offer accurate cost estimating. At sketch stages to assist making broad decisions I advise clients that building work costs in the region of £2000/m2 (including VAT). On a typical small project to an existing building that includes knocking through internally, moving drainage, altering a bit of the original layout and building a new single storey extension, new kitchen, flooring, woodburning stove etc I apply this £2000/m2 over the whole affected area. On a few recently completed projects, this is working about correct or even a bit low in some cases. Internal fittings (kitchens and joinery), finishes or site constraints (builder access, sewers, foundations) can bump this cost up a bit by being a little unusual. One recent project extension and alteration worked out at over £3000/m2 as it was both complicated on-site and included high end fittings.

However, should a break-down budget be required at early stages (before detailed drawings are produced), then two options present themselves.

  1. Seek expert advice from a Quantity Surveyor or QS for short (for a relatively low fee). This is their job, they estimate construction costs based on drawn information. It goes without saying that if they are working only from outline drawings, they will be making a number of assumptions and the bottom line will be either a budget estimate, or a price range. Conversations between the architect and the QS will attempt to iron out as many of these assumptions as possible, but the only way to pin a figure on the construction is with detailed drawings. Even then there will have to be allowances, or provisional sums for certain items and areas of unknown findings.
  2. Ask a builder to provide the same sort of service, based on their own costing methods. Many builders will offer this for free, on the assumption that they will be in with a favourable chance of securing the work. It is a lot of work to ask a builder to do this for nothing, so should only be done when the design is pretty fixed, or cost advice is crucial to making a decision.

Criticisms of each option can include: “The QS will bump the price up to cover themselves”, and “the builder may knock the price down to secure the work”. As long as the parties involved know why they are being asked to price, and are reputable, local firms this shouldn’t really be the case.

This is not intended to scaremonger or put potential clients off, as each project is quite different, but more a word of warning against some of the magazine figures, that may raise aspirations above desired budgets.