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Whether you are building a simple residential extension or altering the layout of your office, there are several pitfalls to avoid when appointing building contractors.

Here is a brief guide to some of the typical problems faced in the world of construction and how to mitigate such risks. 

Ensure that building works are sufficiently written down, agreed and priced before entering into a contract.

The Schedule of Works

Also known as a ‘Specification of Works,’ this document lists the works that you will require and sets some ground rules regarding timing, quality and statutory obligations (of which there are a few). It is key to explaining what you require – as they say, “the devil is in the detail.”

Building project success is largely defined by this document and will be heavily influenced by how much time and effort you put into this essential ‘pre-build’ stage.   It really is important – as seasoned project managers, we devote as much time as we need to have our Schedules ‘fit for pricing,’ as we say.

Failure to provide enough written information for the contractor to fully understand your requirements, and price them correctly, will often lead to confusion and subsequently delays and increased costs during construction.

A copy of a typical Schedule of Works can be seen at the link here.

It is also very important to understand that if you simply specify ‘paint walls’, you will likely receive Dulux trade paint or other. Changing the paint type last minute will lead to increased costs and a potential reason for delay.

Choice of materials and their availability

We are still feeling the impact of Brexit and lockdowns in the construction industry, where the availability of materials can often be a key reason for delays.

In many instances, products have to be purchased way in advance of delivery to ensure that the build programme is not impacted.

Wherever possible, list the manufacturers and the exact products that you require in the Schedule of Works. Research delivery timescales for principal fittings, otherwise you may have to switch to something else.

A note about programmes

The contractor’s building programme should demonstrate the logical sequence of the works to be undertaken, in date form.  With this you should be able to identify the ‘critical path,’ which represent the works that interlink throughout the life of the project and determine the start and finish dates.

All other works will be undertaken around this inter-link and may or may not be reliant on the ‘critical path’ works being individually completed.

Below is a simple example of the ‘critical path.’ The arrowed lines between excavating, pouring foundation, framing, roof and exterior identify the essential works that determine the key project dates.

Simple ‘Critical Path’ chart, Courtesy of Smartsheet

By determining what the ‘critical path’ works are going to be, will you be able to see what risks each key work stage presents to the successful completion of the project. Reviewing a contractor’s programme will also allow you to check progress from time to time.

Choice of contract

Acceptance of a contractor’s quotation forms a binding contract, even verbally! If the quotation is light on content, you can already see the possibility of increased costs and delays before the works have even started!

There are formal building contract documents for residential and commercial properties and these should be entertained for works in excess of £30,000 or so. They set out the rules of engagement and what to do in the event of dispute – much easier and cheaper than litigation, should things go wrong.

Our favourite forms of contract are provided by the Joint Contracts Tribunal and are widely used. Click on the pictures below to find out more.


Obtaining at least one quote is always a good thing. We usually try to obtain at least three as prices can vary wildly, reflective of the differing costs charged by the various sub-contractors used by each builder. 

When looking at quotations, always ask “what is not included?”

To compare ‘apples with apples’ you can see that providing a well written Schedule of Works will enable each contractor to price for the same things and not wholly something different.

Health and Safety

If you are about to alter or extend your house or associated buildings, thinking of putting up a new one or demolishing an existing one, then the Construction (Design and Management) Regulations 2015 (CDM2015) apply to your project.

The new regulatory regime for the landmark Building Safety Act came into force in England on 1 October 2023 and now also applies to residential projects subject to Building Regulations, apart from some excluded minor works. 

The exclusions are for works which are so minor in nature that no building notice or deposit of full (building control) plans are required e.g. replacing a shower or replacing a damaged cable for a single circuit, and also excludes small detached buildings.

Where the project only involves one contractor, the Client duties specified in CDM2015 must be carried out by the Contractor. Ensure that they are aware of their duties under CDM2015, including the Client duties that they are responsible for undertaking, on your behalf. Ask for examples of how they manage their obligations.

Choice of contractor

Without being too obvious, it is essential that you check with each builder that they have:

  • References (enquire on at least one recent job they have completed).
  • Experience.
  • Insurances (employers and public liability, plus professional indemnity insurance if they provide advice or design parts of the build themselves).
  • Reasonable financial status. If in doubt, you may need to agree a guarantor.
  • Member of a trade association such as the Federation of Master Builders, Confederation of Roofing Contractors, etc. Vetting or listing websites may provide an indication of service but should not be wholly relied upon.
  • Payment requirements – many seem to ask for a deposit or money up front, which presents obvious risks. As project managers, we only pay monthly, for work completed to the standard expected.
  • Agree in advance what warranties or guarantees are to be provided, for both materials and workmanship. 

If the contractor is a Limited Company, all the better. You will be able to see their historical turnover at Companies House.

Managing the works

If the works are of a size and cost in excess of £30,000, it would be wise to employ the services of a building surveyor to manage and inspect the works. the role is known as ‘Contract Administration’. Fees can be scaled down to either frequent or periodic inspections, if that’s suitable.

Expect to pay at least 10% of the cost of the works to a Contract Administrator to prepare the schedule of works and manage the project to completion, thereby limiting the risks associated with construction. It will provide peace of mind, an experienced set of eyes and ears, limit cost increases and is, overall, money well spent.

Signature Surveyors Ltd, 12 January 2024