When negotiating a building job with a single builder you can present your builder with an unpriced bill of quantities to price from, a take off, prelims, your own specifications and drawings. By having it priced independently you can then make a direct comparison between the builders rates and your own estimate enabling you to negotiate effectively. The bill will make sure the builder hasn’t missed anything and the prices supplied are “workable”, not excessive or too cheap, i.e. balanced. It serves no one to have a builder on site losing money. An alternative procurement method could be creating just a schedule of work, these tend not to have quantities, just specifications, but it will be more difficult to make price comparisons or negotiate, due to the different interpretations of the quantities made by the builder compared with the client.
A priced bill and breakdown will provide a lot of useful information to the builder, saving valuable time, the builder can use this information to estimate or plan the works and it will contain lists of materials and labour resources, which will need to be tuned to suit the builders personal preferences, which is much easier with the hard work having already been done. Most builders would write their own bill of quantities for every job, so providing one is a definite plus when asking a builder to quote.
Once the price negotiation is completed, the builder will then be reliant on the quantities you have provided, therefore, the builder should be paid for any variations or errors should any quantities be overstated, conversely omissions of work can be deducted. The bill will point to and refer to drawings in all descriptions, in the same way a schedule of works would, and only if a quantity is wrong should their be need to make adjustments to the original priced bill.
The benefit is that both yourself and the builder will be working with the exact same quantities for the work involved, saving any dispute at a later date. As an example, if you’ve estimated 120m2 of plaster skimming, the builder has now priced for that exact amount. If the builder had been given a schedule of works and asked to work out the quantities, the builder may over or underestimate the amount of work. This brings its own problems should the contract go ahead as undesirable attempts to recoup a loss or hide an excess quantity may come into play once the contract is signed. Either way someone loses out. Having loss making builders working for you is best avoided.
A bill of quantities is a far cleaner way of conducting business, with much more certainty, openness and clarity than simply leaving the builder to work out the quantities. The client tells the builder exactly whats needed to be done, by providing both quantities and specifications, rather than just specifications.
The client would have to accept all legitimate changes to the quantities, and the specifications, but the huge upside is the client will be getting no more or less than is being paid for. That is the beauty of providing a bill of quantities.
It is important to make sure the bills descriptions and quantities accurately reflect the work involved by accurately pointing to the items on the drawings. The objective to minimise misinterpretation, not miss any items and make the quantities accurate. That is the job of the quantity surveyor.