MONEY - HOW MUCH WILL MY EXTENSION COST?

How much will my extension cost? It's probably the most important question for a client, and it's one of the most difficult to answer.  It's essential to know as early as possible in the process whether a project is affordable, but there are so many factors that affect the cost, it's simply impossible to be accurate about costs until the project is almost complete.  This is why so many projects - large and small - run 'over budget'.  Here are some of the issues...

Material costs

The cost of materials varies week by week, and within a construction project there are an awful lot of materials to buy - from the basics of bricks and mortar, to the less obvious, like wall cavity ties.  We live in an age of globalised supply chains, and when these work materials are cheap and plentiful.  Unfortunately they don't always work.  When a ship gets stuck in the Suez canal thousands of containers full of goods are stranded on the ocean, which artificially limits supply and drives up costs.  When there's a global pandemic Chinese factories close, and basic items aren't produced.  When factories in Germany can't get enough power to run, windows and doors don't get made.  These uncertainties and risks are unknowable - who would have guessed that all 3 of these scenarios would take place at the same time?!  The result has been significant inflation in the cost of construction materials through 2021 and 2022, driving up costs for builders and in turn for clients.  

Labour costs

These costs are surely under greater control than materials?  In some ways yes, but political decisions have an impact on the available pool of workers, and fewer workers means higher costs.  Many small scale construction companies don't have enough projects at any given time to be able to employ full-time electricians or plumbers.  This means that they have to sub-contract the more specialist aspects of a project, and of course that also means that the cost of that work is less certain.  Labour costs can be especially difficult to manage when projects are delayed - people still need to be paid, even if nothing is happening on site.

Other costs

Materials and labour are around 70% of the cost of any construction project, and so what's the rest?  Skips, tool hire, lifting equipment, scaffolding, 'sundries' (think sandpaper and paint brushes), overheads, and even a little profit if the builder gets lucky!  These add up alarmingly quickly.

Time

This is the most difficult aspect of cost prediction and control.  When a client starts the process of a house extension, there may be a year or more of design work, planning approvals, and finding a builder.  During that time the cost of materials and labour can spiral without warning.  The build itself also takes time, perhaps another 6months or more.  During that time you may find unexpected (and unwelcome) surprises on site that lead to additional costs.  Clients are also prone to adding more and more work in as the project goes along - 'scope creep'.

The result of all this uncertainty is that asking your architect (or anyone else) how much your extension will cost is like asking how long is a piece of string?  We can guess, but that's all it can ever be - a guess.  

Sorry!