Estimating & Quantity Surveying

Estimating and Quantity Surveying (and Contractor selection)


As the word states this is the preparation of a detailed cost plan for the “works”, and this is based on the approved Building Regulations drawings. It is important, that these drawings are approved as this limits the opportunity for contractors to start trying to charge for “extras”, “changes” or “variations”.

The type of cost plan I provide is what is called a “Bill of Quantities”, an example of this is shown in (BofQ fig 1).

I do promote customers for whom I have prepared drawings to have a bill of quantities produced for their project for several reasons, typically;

  • It ensures that the customer is satisfied that they have a funding of a sufficient level that will pay for the design that they would like to achieve. (Many times I have undertaken design works, the customer is quite excited they are nearly ready to undertake their project, having handed copies of the drawings to several builders, when the quotes are in they can’t afford any of them.)
  • Once the client is happy that we have a design with a suitable funding level, we can hand “un-priced” Bill of Quantities out to builders, (BofQ fig 2.). I always suggest a minimum of four, (reason, you need three quotes to compare, four or more will allow for any builder that declines to tender.) Tendering by provision of a bill of quantities has the following advantages;
    • All builders are pricing exactly the same document so all quotes are directly comparable.
    • Because the quantities are provided, the builders can prepare their tender quicker as they do not have to “take-off” the quantities from the drawings themselves.


Selection of a suitable contractor is a very important decision to be made. Using a contractor that has been recommended is always a good start. If you are uncertain about contractor that might be suitable for your project, your building control officers may be able to give you a list of contractors. Assuming the client has undertaken a little homework and has four contractors from whom they are prepared to accept a price for the project, and the tenders have been returned. At this point the client should be prepared to, and is advised to visit at least one site in progress, and one completed site for each of at least three of the contractors. This will enable the client to assess how the contractor works on site (clean site – safe site) , and also to assess the quality of the contractors completed work. After all, there is no point in accepting the lowest quote if you are not happy with the quality of the contractors work. Also, seeing a completed project of an acceptable standard is a good yardstick by which the work can be judged and what you might expect of the quality on your project.


A building contract should always be used when having building works undertaken for the protection of both client and contractor. This sets out, amongst other things;

  • The agreed price for the contract.
  • The program for the contract.
  • Terms of payment for the contract.
  • The means of resolution of any dispute. (Hopefully this will not be required).

Quantity Surveying. (QS)

The quantity surveyor comes into play once the builder has been selected, price agreed and the work starts. He/she will visit the site assess the value of the works done to date, agree the value of additional items or even any items to be removed from the project. Again the bill of quantities clearly values the items in detail so any items to be removed can be deducted at bill rates.

Generally, most building extensions or individual house builds do not take too long and often a Quantity Surveyor would not be used. It may be that payments for works would be when agreed stages of work are completed. As an alternative, I am able to provide a further option for the bill of quantities with an additional column (see BofQ fig 3.), this enables the percentage of each item to be input on the valuation date to establish the value of works done, enabling the client to easily control the payment system themselves. (see testimonial of how this worked for one of my customers)

I always recommend a retention be held on the contractor, normally 5% throughout the contract, reduced to 2½% on substantial completion (when the builder has completed the works and leaves the site), and the remaining 2½% is released at the end of the agreed snagging period, (usually 6 months) once any snagging works have been completed. Any reputable contractor would find these terms normal and acceptable, and is usually a standard part of any contract.

My own personal experience as a quantity surveyor has involved me working for major construction companies, private clients, housing developers and commercial businesses on various projects throughout the UK and includes the following project types

  • Motorway construction
  • Motorway service area
  • River realignment and culverts
  • Sewerage pumping station
  • Bridges
  • Major drainage schemes
  • Bespoke high quality housing
  • Speculative housing development
  • Private client housing
  • Traditional building
  • Gas pipelines
  • Box reservoir
  • Industrial building
  • Tunnelling
  • Refurbishment works
  • Commercial developments and offices

Estimating for Building Contractors.

This is undertaken by production of bill of quantities in standard format but with many print options of supporting documentation including;

  • Full dimension take off report.
  • Fully analysed BofQ (Lab, plant, materials, sub-contract, PC & Provisional Sums with or without profit addition).
  • Analysed rate build-up (Lab, plant, materials, sub-contract, PC & Provisional Sums with or without profit addition).
  • Profit can be added as a single percentage or different percentages to each Lab, plant, materials, sub-contract, PC & Provisional Sums.
  • Separate lists for
    • Labour
    • Plant
    • Materials
    • Sub-contractors

I do recommend that the Bill of Quantities be fully prepared and the contractors actual labour, plant, material and sub-contract buy prices be fed back into the estimate to give as accurate price as possible giving the contractor the best chance of success. The Bill of Quantities method provides more accurate estimating resulting in higher chance of success and also enables contractors to identify relevant trades in which they can obtain competitive subcontract prices again knowing that all subcontractors have tendered on the same basis.

See sample print options. (hyperlink Builder typical print options fig 3)