Plumbing & Heating: Cost Guide

As with the electrician, it is quite likely that the plumbing and central heating engineer will work on a supply-and-fix basis, either wholly or in part. Most self-builders will not want to be involved in the purchase of minor items, but may wish to provide major items such as the boiler and underfloor heating for the plumbers to fit on a labour-only basis.

The trade is divided into two stages, first fix (carcassing) and second fix, and payment is often made as each stage is completed.

The first arrival of the plumber on site may be to fix the standpipe for the building water supply. Part of this may be used for the eventual outside tap, but the require ment for non-return and shut-off valves and the need to box in the standpipe itself means that around an extra £100 may have to be allocated.

The next time the plumber comes on site will be just before the roof is tiled in order to set up the soil vent pipes (SVPs). If they are to be responsible for the lead flashing instead of the roofer, they will then stay to attend to that. If they are fitting the guttering and downpipes then they may well fix the guttering from the scaffold before it comes down but leave the downpipes until later.

The plumber will work closely with the electrician in the wiring up of the boiler and control systems, and their testing and firing.

Safety First

Self-builders should only use qualified and registered plumbers who are certified by either ‘Gas Safe’, OFTEC (Oil Firing Technical Association Ltd, oftec.org), NAPIT Certification Ltd (napit.org.uk), or BESCA (Building Engineering Services Competence Accreditation Ltd, besca.org.uk). In practice, most competent plumbers are registered with most or all of these bodies.

The Costs

Heating: (1)The figures assume a complete underfloor heating system to ground and first floor (supplied by Robbens Underfloor Heating Systems Ltd, underfloorheating.co.uk), to include: electronic controllers; loop actuators; room thermostats; remote sensor thermostats; setback control thermostats; manifolds, highperformance multi-layer pipe; and fixings. This costing assumes that the choice of a solid beam and block first floor has been made. If the alternatives of either a timber joist or an engineered timber floor were taken, then the price for the underfloor heating system would rise by £320 due to the need for heat spreader plates and pipe fixings. These costings also assume a Trianco oil-fired condensing boiler. The boiler is a system boiler providing mains pressure hot water to the central heating and the domestic hot water, without the need for expansion tanks in the loft.

First Fix Plumbing: (2)These costs assume the use of copper piping, which, in truth, most plumbers are more familiar with. The use of plastic plumbing would not necessarily save a great deal, although a plumber who was experienced in using it might be slightly quicker.

Second Fix Plumbing & Sanitaryware: (3)It’s possible to spend much more than these figures on sanitaryware, but it’s as well to remember that flair and imagination can add more value than simply buying expensive fittings. Buying very much cheaper, on the other hand, could detract from the value.

Guttering & Downpipes: This usually falls within the remit of the plumber but in some cases will be taken on by another of the trades such as the carpenter or the roofer. It’s always best to fix the gutting from the scaffolding before it comes down as it’s much easier to set up the right falls from that vantage point.

How to reduce these costs:

• If a conventional radiator system with 16 basic radiators with TRVs (thermostatic radiator valves) was employed instead of under floor heating, then the savings could amount to £2,096.19.

• The first article in this series assumed the supply of gas onto the site and if that were the case then that would probably be most people’s first choice of fuel, and there would also be savings. A gas-fired condensing system boiler from Worcester Bosch (worcester-bosch.co.uk) would cost £722.75 — when you add up the cost of the oil-fired boiler together with the tank and all its accoutrements, that represents a saving of £1,748.97. But you would have to pay for the connection and supply of gas to site and that would reduce the saving to £498.97.

• You could fit the underfloor heating pipes to the floor yourself. It’s a long job but, given the plans of where and how things go, it’s not technically difficult. And it could save up to ten man days at £1,760.

Special thanks to Estimators Limited (estimators-online.com 0161 286 8601) and Design & Materials Limited (designandmaterials.uk.com 0845 404 0400) for their help in the preparation of this series of articles.

More Build Costs:

• Buying a Plot
• Building Foundations
• Floor Structure
• Superstructure
• Roofing
• Drainage
• Electrics
• Heating & Plumbing
• Plastering
• Internal Carpentry & Joinery
• Finishing Trades

Further reading:

• A Guide to Heating & Plumbing
• The Trades Explained: The Plumber
• How to Build a No-heat Home