How Much Will Your Project Cost? Part Three

This definitive guide will help you come up with a self-build budget, as well as showing the effect your choices will have on what you spend.

Having an understanding of build costs is essential for any self-builder. It will help you to work out what you can afford to build, whether a contractor’s price is over-inflated or hopelessly optimistic, and the cost implications of each decision you make. A detailed budget plan will also help you to assess the overall financial feasibility of your project, comparing total costs with your home’s end value — something many lenders, especially the banks, will want to see before they will release any funds.

There are many factors that determine the cost of building your own home, from how much work you do yourself, to the level of professional involvement from an architect or project manager; from the shape, size and height of your design, to the quality of the fixtures and fittings you choose. Even the region you live in affects build costs because labour prices vary across the UK. This guide will equip you with an understanding of all of the factors, enabling you to plan your self-build project and weigh up your options to get the very best out of your available budget.

Design Details

Stairs

The staircase is an opportunity to make an architectural statement, and if this is your intention then you need to make an additional allowance for this above the sum included in the average build costs. The standard specification solution is a softwood staircase consisting of two straight flights linked by a half-landing, with a softwood balustrade, painted or stained, at a cost of around £1,250. The good specification includes a single straight flight in painted softwood at around £1,500, whilst the excellent specification allows for a straight flight in hardwood, with hardwood balustrading at around £2,150. If you build additional storeys, e.g. attic level or basement, you need to allow for additional staircases.

Chimneys

Many modern houses – especially those built by speculative developers – do not include a chimney, largely because of the cost, which starts at £6,100. Many ecological houses also forgo a traditional open flue chimney in favour of a wood burning stove and stainless steel flue, at an installed cost of around £1,650-2,500. Self-builders tend to like to spend on feature fireplaces, and if this is your intention then you will need to make an addition to your budget calculations to account for this. The standard specification has an allowance of £6,100 per fireplace and flue; the good specification has an allowance of £7,600 and the excellent £10,300.

Kitchen Cost Guide*

The excellent quality specification price includes an allowance for a quality kitchen from a mid-market brand name supplier with timber worktops. The good quality specification includes top-of-the-range units from a contract supplier such as Howdens or Magnet with timber worktops. The standard specification includes basic white MDF units with a laminate worktop. You can adjust the cost per square metre figure relevant to your project to suit your choice of kitchen. If you are going for a top-of-the-range designer kitchen then get a price from your supplier, including fitting, and substitute this for the kitchen allowance per square metre.

*(allowance £/m²)

Wall Finishes

Concrete blockwork walls can either be given a traditional two- or three-coat hard plaster finish, or dry-lined using plaster board glued to the walls and then skimmed with a finishing coat of fine plaster, or the joints covered with tape and filler. Timber frame walls are usually finished with plasterboard, with the joints taped and filled, although sometimes a skim coat is applied to even out the walls. Many developers prefer dry-lining on both masonry and timber walls, as it is quicker than hard plastering, which requires time to dry out, and is less prone to cracking from shrinkage or movement. On more expensive schemes, they tend to use traditional hard plaster as it gives a more solid feel. Costs are similar for both wall finish options. If you upgrade to fibrereinforced plasterboard it will add to costs.

The standard specification assumes emulsion paint throughout, with minimal tiling to kitchen and bathrooms at £40- 55/m². The good specification includes more tiling in the kitchen and bathrooms and wallpaper in the living rooms at £50- 65/m². The excellent specification also includes wallpaper to the living room and bedrooms at £60-80/m².

Ceiling Finishes

Ceilings are usually covered with plasterboard and finished with a two-coat skim of fine gypsum plaster and emulsion paint at £21-23/m². If you decide to add decorative coving, ceiling roses or other decorative plasterwork you will need to make an allowance for this.

Alternative Floor Finishes*

(*Includes labour and wastage)

Built-in Cupboards

Most houses include some built-in storage areas. These are already allowed for within the costs at between £20-40/m².

Internal Partitions

In masonry houses the standard specification is 100mm concrete blockwork and steel or concrete lintels for the partition walls on the ground floor and 38mm x 89mm timber stud walls on the first floor. For timber frame construction all internal walls will be timber frame. High-quality masonry houses with a beam and block first floor structure may have all internal partition walls built in 100mm concrete blockwork.

Internal Doors

The standard specification includes hardboard-faced hollow-cored flush doors in softwood frames, hung and decorated at around £325 each including ironmongery. The good specification includes better hollow-cored flush doors in softwood frames (around £360 each). The excellent specification includes hard woodveneered solid-cored doors in softwood frames, at around £450 each. If you plan to fit superior quality doors you will need to allow for this in your budget.

Garages for Houses*

Integral and semi-integral garages should be included with the gross floor area of the house gives costs for rebuilding a range of garages.

(*measurements are for gross external floor area)

Key Elements

Windows and Doors

External joinery is another feature that selfbuilders place a great deal of value on and consequently tend to invest in quite heavily. The standard specification house has offthe- shelf painted softwood casement windows and doors, with double-glazed units and factory-fitted aluminium ironmongery at a cost of £50-60/m². The good specification includes high-performance, off-the-shelf, painted softwood casement windows and doors at £55-65/m². The excellent specification includes double-glazed alum - inium frames in hardwood surrounds and a hardwood panelled front door and good quality ironmongery is £85-95/m².

If you want to go for bespoke windows and external doors, substitute their total price for the allowance (joinery cost for your chosen specification multiplied by your gross internal floor area).

Two storey bay (3.0m² floor area)

*Costs per facing m²

Heating

The standard heating solution is a wet radiator system with a wall-mounted gas condensing boiler, two-channel programmable thermo stat, and thermostatic radiator valves. Smaller houses will have a combination boiler providing instant hot water, whilst larger houses will have stored hot water in a cylinder. A standard central heating system will cost £18-23/m² and this is the allowance in the average build costs. If you decide to install underfloor heating, this works out to be around 15% more expensive, so allow £20-25/m². If you plan to install ecological features, get a full quote and add this in to your budget.

Bathrooms and Cloakrooms

Hot and cold plumbing costs for bathrooms and kitchens etc. are much the same regardless of the specification you choose, but the cost of sanitaryware and brassware varies enormously from £2-300 for a full bathroom suite (bath, basin, WC, taps and wastes) up to several £1,000s. The quality and area of tiling on floor and walls varies from £23/m² upwards, and then you can add showers and enclosures, heated towel rails, underfloor heating, luxury baths, steam rooms, and more. The costs in the tables allow for two bathrooms and one cloakroom at the relevant cost (see below). If you plan to fit more bathroom facilities, or better quality facilities, then use the typical cost allowances below to allow for this.

Conservatories

If you plan to add a conservatory to your new home this needs to be priced separately. For rough budget purposes you can use the figures below but once your plans develop you should get a price for design and build and add this to your budget calculations.

*Gross external

Services

If your plot is not connected to mains services you should get quotes for connection from you local utility suppliers before purchasing the site. If there is the option of a mains gas connection, take it. As a budget figure allow £6,000 for connection to water, sewers, electricity, telephone and gas. If the site does not have mains gas you will need to budget an additional £2,000- 2,500 for installation of an oil or LPG tank. If there is no mains sewer you will need to budget for an off-mains alternative such as a septic tank or mini sewage treatment plant — you should find out what the local authority will accept and get a price from suppliers. Allow £3,000-4,000 for a three-four person household and £4-6,000 for a larger household.

Electrics Cost Guide

Standard electrical installation costs do not vary much from house to house other than by scale, as all houses use the same cabling, smoke alarms, extract fans and in most cases, standard pendant light fittings. Generally, the better quality the house, the more power sockets, phone and TV points there are and so the average cost per square metre for electrics increases.

If you decide to fit low-voltage downlighters, decorative light fittings, anything other than standard white plastic sockets and switches, automated lighting controls, a whole-house structured cabling network (Cat 5e), multi-room hi-fi, amp circuits for table lamps, or outdoor garden lighting you will need to make an allowance for these upgrades.

Originally published November 2008