Self-Build: Estimating Your Building Costs


Self-Build: Estimating Your Building CostsThe cost of your build is determined by numerous factors – size, specifications, number of storeys, your level of involvement in the project etc. and “Build Your Own House and Home Magazine” guide you through a thorough estimation of all your costs is essential to avoid any nasty surprises as your build progresses.

It is possible to outline a rough estimate of what a build might cost. There are many estimating tools and guides available on the market. But it is essential to remember that every self-build is a unique project and with it comes unique costs. Unforeseen ground conditions, over runs, or the loss of a subcontractor can all have a major detrimental effect on your budget. However if problems do arise it is possible to make allowances for them at an early stage.


Overall Costs
Figures published in July 2007 by the Society of Chartered Surveyors (SCS) for re-build insurance costs provide an important insight. It quotes a standard four-bed detached house in Dublin with an area of around 1,270 sq ft (118 sq m), costing €188 per sq ft to rebuild (or €2,023 per sq m). The price to build the same house in Galway is estimated at €130 per sq ft or €1,442 per sq m. Costs for Cork, Waterford and Limerick are estimated at figures between those for Dublin and Galway.

These figures are minimum base costs for a standard house type only and are not inclusive of houses with more than two storeys, out buildings, patios or boundary walls. They include calculations for basic professional fees for a building surveyor, architect or quantity surveyor. If you are building your own home it can be assumed that you will have unique features that most likely will not have been included here. The rule is to avoid miscalculating your budget, make sure to factor in everything downtown the plumbing, electrical work and joinery through to clean up costs and site maintenance. Finally these figures are based on research carried out during 2006-2007 so it is advisable to contact the SCS for any updates on this. The latest SCS lea6et outlining insurance rebuild costs can be downloaded from their website (


DIY vs. Contractor
If you are able to take a hands-on approach and carry out much of the work yourself there are considerable savings to be made. While there are certain jobs and elements where professionals are needed, much of the work can be carried out by the house owner, with possible savings from five to 30 per cent to be made. For instance, if the overall estimate puts the build cost at €150 per sq ft, it may be possible to reduce this cost to as little €97.5 to €105 per sq ft. In a self-build scenario the client opts to manage the build personally. This will of course mean taking on a project management role,  which puts more pressure on the homeowner but can provide greater satisfaction.

The three major non-financial advantages of self-build are:

  • Being up-to-date on all site activities
  • Personal satisfaction when job is completed
  • Any delays are simply lost time and do not incur a financial penalty


Hiring a Project Manager
If managing the build yourself is not possible then hiring a project manager can eradicate the time and hassle of engaging various trades and coordinating them. Instead, these fall to the contractor/project manager. They will also supply insurance in the event of defective workmanship. The main con of hiring a project manager is the higher cost to the project. This could also mean over-runs or delays will cost more as a financial penalty is usually involved. Disputes can and do arise, remember contractors and project managers will defend their positions. This can lead to delays, walkouts and in rare instances court action.


Cost Breakdown
It is good advice to first estimate your total costs and then add a further 20 per cent to this figure for unforeseen costs. Every house is unique. But there are a number of different matrices available to estimate your overall costs. The following is only a guide to help you work out an approximate cost of your project and do remember that every project is different in the type of construction, route of construction, the material used and the quality required. The figures below show the approximate percentage of the total cost of a new home through each stage of the build.

This is based on an average detached home on two floors.

  • Site Clearance 3%
  • Foundation 9%
  • External Walls 17%
  • Roof 9%
  • Windows and External Doors 7%
  • Upper Floor 2%
  • Stairs 1%
  • Internal Walls 2.5%
  • Internal Doors 2.5%
  • Floor Finishes 4%
  • Wall Finishes 5%
  • Ceiling Finishes 2%
  • Heating 6%
  • Electrical Installation 4%
  • Water Installation (Cold/Warm) 2%
  • Waste & Sanitary 7%
  • Kitchen 5%
  • Built In Cupboards 1%
  • Professional Fees 11%

With the need for greater energy efficiency, a little more of your budget attributed to the insulation and energy and heating sources of your house will pay major dividends in the years to come. A central aspect of achieving more energy efficient home is by looking at air-tightness and ventilation. One construction industry expert referred to air-tightness as the most important element of any future building design. Tom Barbour, Managing Director of Ecological Building Systems, estimates that installing an air-tightness membrane on  our house would cost as little as .47 per cent of the overall build but would be essential to the building’s energy performance. If you are considering this route you will also have to consider a controlled ventilation system for the house. Finally, it is important to remember that every project is unique and that managing the costs of building your home is like managing a small business because of the numerous different cost centres. Understanding your costs from an early stage and managing them prudently requires great skill and application. It is not easy but it can be rewarding.


Cost Savings
One very important factor on cost saving would be your initial design of the house. The following are just some guides:

  • If you want a lot of space at a lower cost, go for a two-storey house instead of a bungalow, as a bungalow has a much larger foundation area and roof coverage than a two-storey house. For example, in a two-storey house all the rooms upstairs share the same foundation and roof as the space downstairs, but if you were to gain the same space in a bungalow you would have to double the foundation and roof area.
  • When planning your walls, be aware that block layers charge much more for projects that have a lot of different levels and angles as this makes their job much harder and it takes more time, so if you can, keep it straight and simple.
  • When planning the roof, remember that more angles and gables means more material, more time and cost. If you can, keep it simple.
  • Think about the heating and waste system, many options are cheap at the beginning but will cost much more over the long term.


Useful Contacts:

  • Irish Association of Self Builders. Web:
  • RIAI, 8 Merrion Square, Dublin 2. Tel: 01 676 1703. Web:
  • Society of Chartered Surveyors, 5 Wilton Place, Dublin 2. Tel: 01 676 5500. Web:
  • If you are looking for a Surveyor or an Architect for your self-build project then check out the Services Directory on

Source: Build Your Own House & Home Magazine

There is 1 comment for this article
  1. Zequek Estrada at 9:39 pm

    It might be easier to meet with a building consultant to find the overall cost, especially if you’re doing it yourself. There are most likely fewer possibilities for mistakes to happen. In the long run, that would be really beneficial.

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