After the lengthy battle through planning we’re finally about to get our large extension project under way however all the quotes we’re receiving back from builders are coming in way over the build cost we gave to our architect originally.

We’re planning a 2 story side/rear extension in ICF. We’d budgeted for a build cost of £100k (with an additional contingency if needed). The quotes we’ve received back are coming in at almost double or triple that and we’re at a loss as to how to move forward to start work on our project.

We don’t really want to go back to the architect to amend design to go through planning again (as first time was a struggle) but we’re not sure how the quotes are so much higher than we though.
Any advise on how to move forward would be much appreciated.

  • Kevin Meaning

    I cannot give you an answer but I can empathise with you as I am in the same boat. I asked the architect what it would cost and cannot get a quotation within 180K of of his original estimate. (he has since slowly edged near to my estimate, but I cannot get a quote within 80k of my estimate either. All the builders seem to be busy at present so there is little incentive to sharpen the pencil. We’ve considered employing all the trades individually rather than have the builder employ them and add a bit of profit on top no doubt. We thought about doing some of the work ourselves even though I am not that great at DIY. Cutting back on the nice things we wanted but there seems little point in doing it without having nice things we intend to live with for the rest of our lives. Even thought about knocking the whole house down and building to exactly the same deign from scratch.Just keep trying other builders.

  • Peter Eade

    It is quite difficult for an architect or designer to come up with a scheme which not only incorporates their clients design ideas but is also within their budget. Generally if the project designer gives a guide price it would be based only upon a simple square metre measurement; this can often be way off the mark particularly with extensions and alterations. The reason builders quotes can be so diverse is because they are not being given enough information for them to provide a fixed price quote. The more detail there is shown on the plans the more competitive the price. Before going out to tender it’s worth ringing each builder to check that they are interested in quoting, this avoids receiving silly high prices from builders who don’t want the job. Typically the tender documents would be made up of the Building Regulation approved plans, structural engineers calculations (if required) , specification and a Form of Tender. The specification would show all PC and Provisional Sums and would clearly describe the proposed work. The Form of Tender is also quite important because when it is returned it will show the price of the project, the duration of the contract and how long the tender is open for consideration. If all else fails there are professional builders estimators around who could be employed to give a very realistic idea of what the project is going to cost. In NO circumstances ever ask builders for a quote based only upon the planning approved drawings, it is not possible for anyone to give a realistic price from the very limited information shown on the planning plan which is nothing more than a scaled illustration of the scheme.

  • Tara Florence

    I am a Quantity Surveyor with over 18 years experience in the industry, early in my career I spent several years at a senior level with Barratt Developments, before working freelance for other large firms. I have spent the last 5 or so years mainly pricing up tenders on behalf of builders tendering for work through architectural firms. I always price up using first principles labour, plant and materials as apposed to obtaining sub-contract quotations, because I am aware of the problems associated therewith.

    In my experience, inflated tenders are mainly the result of 3 contributing factors as follows:-

    (1) A lack of suitably experienced estimators in the industry, which has forced salaries up resulting in SME contractors unable to afford competent estimating staff.

    (2) The lack of competent estimating staff ‘in house’ has resulted in many SME main contractors using sub-contractors as estimating departments, however as many sub-contractors also suffer the same resource problems as main contractors, many sub-contractors pricing up enquiries simply ‘guestimate’ when time is against them, inserting large uplifts to cover associated pricing risk.

    (3) Architects also often use ‘schedules of work’ documents to obtain competitive quotations, some of these schedules are however very complicated to price, and require weeks of time breaking down labour, plant and material quotations obtained from suppliers into the appropriate lump sums required of the pricing document. Most main contractors simply don’t have time to do this properly, and so ‘guestimates’ are the result on many sums. I have known many contractors to simply pluck rates out from thin air, in order to submit a price within timescales dictated by the enquiry.

    Ok, so what’s the solution?

    You need to locate a main contractor in your area that delivers the vast majority of the works direct, therefore eliminating middle man overhead and profit margins on all but specialist sub-contract trades. If a tender price is built using sub-contract prices, the main contractor then needs to add his own OHP on, which only inflates the price further up and over the level which could be achieved, assuming the contractor delivered the majority of the work himself.

    Once you have found a main contractor that delivers most of the work himself, you know he’ll be pricing up himself because he doesn’t have the benefit of numerous sub-contractor estimating departments.

    CMS provide nationwide Quantity Surveying support to contractors and self builders, and do not base their fee’s on ‘% of project value’ payment structures. Visit: for more info, they also price estimates up from first principles labour, plant and materials on all but specialist trades. Their estimate can then be used as a benchmark to evaluate competitive quotations, and flush out those who intend to deliver the project using mainly sub-contractors..

    They also operate a cloud based commercial management system designed and built specifically for SME’s and individual developers. Their ‘in house’ team of QS, support members of the system 9-5, 5 days per week, and membership fee’s are a drop in the ocean compared to what a QS would normally charge..

    I appreciate some self build’s are simply a labour of love, however for developers who need to ensure their building projects yield profit, or deliver equity returns for the owner / occupier, check out They are currently upgrading their software into a cloud based operating system however they basically enable users to manage construction costs & income themselves, (with support when needed), using the same tools previously only available to large contractors with deep pockets.

    For self builder’s who can’t afford a full time QS or where % based fee’s render the project unfeasible, they really do offer an alternative worth considering..

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