what is variations in construction
Quantity Surveyors are involved in dealing with variations that may arise within contracts with regards to,
1. Identification of required variations
2. Immediate measurement and valuation of any variations / additional works
3. Advising on the cost implications of variations
4. Agreeing contract variation
A variation is generally defined as the alteration or modification of the design, quality or quantity of the contract works. This includes the addition, omission or substitution of any work, including the alteration of the kind or standard of the materials.
The architect may issue instructions from time to time requiring variations which the contractor is required under the terms of the contract to comply with. Any modification to the works must be the subject of variation orders which constitute an instruction from the architect to the contractor.
The issue of variation orders ensures that as Quantity Surveyors we are kept informed of any changes to the contract works and have the opportunity to value the required variations in order to determine their monetary effect. When requested by the architect we would generally ascertain and advise of the likely cost effect of any proposed variation before he issues the variation order. This provides the architect and client with the opportunity to make an informed decision to proceed or to make an alternative proposal. Advance knowledge of proposed changes enables a full evaluation in terms of cost, quality and programming implications to be carried out in advance of their issue.
We value all variations which involves the omission of work as originally included in the bill of quantities and the addition of work as executed in its place. We would consider each valuation separately and their net values are then carried forward to a general summary. The total value of all omissions and the total value of all the additions are computed to arrive at a net balance which will then be added to or deducted from the interim valuation / payment which then becomes due to the contractor.
Under most standard forms of contract in the construction industry where Bills of Quantities are adopted the valuation of variations are generally made by Quantity Surveyors in accordance with four main valuation rules. The measured quantities of the variation may be valued in accordance with any of the following methods;
1. Rates contained in the Bills of Quantities or Schedule of Rates, whichever is applicable
2. On the basis of rates analogous to those above
3. On the basis of a fair valuation, at fair rates or prices
4. At Daywork rates at the prices ruling at the date the work is actually carried out
The summary of variations account will be submitted by the quantity surveyor to the contractor for comments. Following the settlement of any disputes or differences in quantities or prices between the contractor’s quantity surveyors and the clients quantity surveyor the variation account can then be finalised and signed by the contractor as evidence of his agreement to it.