A guide to extension costs - part 1, architects


In previous posts I have mentioned that the most common question that we get is "How much will my extension cost?"


I have tried to give a guide previously but it is really difficult to price anything without drawings from an architect. So on this series of price guides I will start at the architect - this is where most projects start.


Their costs depends on the size of the project so this is based on a single storey rear extension.


Firstly your architect will want to conduct a measured survey which will include measurement of the existing dwelling, including the site curtilage, boundary treatments, drains and other relevant features. From this you will get drawings of the existing property - you could expect a cost in the region of £650 - £700


From these drawings they will work with you to generate preliminary sketches for your project. This is an area that could mean multiple discussions and attempts to prepare drawings that satisfy your requirements. Prices are in the region of £750. If your brief is not clear, or you frequently change your mind, this could double so make sure you know what you need. (the architect will help with what it looks like).


Once you have final drawings agreed they need to be converted into detailed construction drawings, liaising with structural engineers (See part 3 for costs). These are prepared to and standard required for Building Regulations Application and the Building Control Department.


Getting to the planning approved stage (more about costs in part 2) is the next step. Home owners could do this themselves but it often makes sense for the architect to have the discussions and manage the process. If there is a glitch you will need to go back to them anyway! Costs for this stage are arounf £850 - £900. Add £400 - £450 if you want the architect to submit and negotiate through to a positive planning decision.


That brings a total figure for the architect in the region of £2,750