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  • House extension – budget planner-template
  • ourmaninthenorth
    Full Member

    Assuming that we obtain planning permission, this year we’re due to embark on an extension (kitchen + dining room) and loft conversion to our house.

    We have a total budget + contingency plan in place. However, I want to be able track and lock down all planned and actual costs. Mrs North, being a university type, thinks money grows on trees; I work in the private sector and know it doesn’t!

    Searching online hasn’t thrown up anything obvious we can use – can anyone point me to a useful resource for me to collate all the line items necessary or share a template you’ve used before?


    Free Member

    The one I use is think of your budget, double it then add another £20k.
    Seems to be how it’s working for us at the moment.
    Keep telling yourself it’ll be worth it in the end.

    Full Member

    Few things:
    1 have you got 3 quotes?
    2 have you got the quotes of off proper detailed drawings? If not go to 1
    3 is the quote a fixed price lump sum or re-measurable/budget a builder will leave stuff out of the latter.
    4 do you have a builder booked? We got told 8 months waiting list for a couple of outfits here in brighton.

    Are you going for an all in one builder or project managing individual trades yourself? If latter you need quotes from all trades off of detailed drawings prior to starting.

    3 allow 20% contingencies.
    4 instruct builder.

    We had a book we wrote all the weeks expenditure in to keep track trotted up at end of week. We were being charged weekly (long story) it worked for us. We could have done a spreadsheet but we felt it was more hastle than it was worth. I’m a chartered civil engineer.

    Free Member

    tbh I just put together a spreadsheet of all the costs I could think of, with a different sheet for each area (groundwork, walls etc) and with a final totalling sheet.

    Came in at £50k, without VAT.

    Got 3 quotations, which averaged £140k inc VAT.

    My conclusion was that it’s very hard to estimate labour costs without been in the industry, and a 10% contingency was right – just that it grows…

    Also very difficult to get the quotations, as it’s a lot of work for them. And YOU need to fine-toothcombe the quotations as there were anomalies in all three quotes we received and quite hard to compare exactly (we didn’t use a QS so no ‘bill of materials’).

    Free Member

    For a simple extension (no major ground works, easy access)allow £1000 m2. For the loft you would be looking at around £600 m2 depending on where you are in the country.

    Full Member

    Google bill of quantities excel template – like this

    That will be a good starting point.

    Any decent quote should have this level of detail in it.

    Good luck!

    Full Member

    Van H says good stuff, planning drawings first, so depending who is drawing these and who you are employing and for what level. Do you have any consultants, architects, plan drawers assisting you, if so check what service they are offering, is it just first set of plans, what about changes?
    Planning dwgs for what it looks like (make sure it can be built, is structural engineer involved yet?)
    Any party wall issues with neighbours?
    Building regulations next = more detailed drawings, but not necessarily enough to price against, e.g. have you details how many sockets in the kitchen, at what height and where, what type and spec, etc? same for door handles, light switches, floor finishes, etc, etc you get the picture?
    Once ALL details are put on drawing, builders can price and even give breakdowns, but as said many have enough work so don’t need to price jobs!
    But mostly find people/builders who you can work with, price against a drawing and/or schedule, then stick to it, ANY variation or change will (mostly) mean cost increase.
    Oh and add insulation, insulation and more insulation!
    One last aspect your main contractor has to plan for health and safety in homes now under the latest CDM regs, so make sure they include this and get a written plan. Assuming you are going with a principal contractor who helps plan and coordinate everything, good ones worth their weight, but it all costs money;)
    Good luck and enjoy it.

    Full Member

    The one I use is think of your budget, double it then add another £20k.
    Seems to be how it’s working for us at the moment.
    Keep telling yourself it’ll be worth it in the end.

    ^ there’s lots of good advice posted on this thread but this sums it up for us (currently mid build) 🙁

    Full Member

    Beware of the unknown. MIL’s renovation + extension went way over budget as it turned out the house was basically built on a crater. Hubby was most unimpressed as he was the one picking up the tab, plus he received regular requests along the lines of “… and that’ll be another £10k/£20k/£30k.”

    Full Member

    We’ve recently finished a moderate sized house renovation/loft conversion.

    We chatted to a fairly pricey architect, and opted not to go with him in the end. However, his guess as to the costs was spot on..
    My guess was out but 100%.

    Ergo…Think of a figure, and double it!!

    Things to think about when getting quotes:
    A finished BUILD is not a habitable place – carpets, paint, fittings etc cost too
    Get good, friendly builders on board. Only once had they made an error (slight misplaement of velux windows). They were completely at ease about altering it (it was v early on, and I felt comfortable highlighting it to them). I, however, was often on site having discussions about ‘changing this/moving that’. It was good to have them open to discussion about stuff that wasn’t a delay, just a minor alteration to plan (internal non load bearing wall placement etc)

    I just set up a spreadsheet of costs. using Excel. Get used to typing large numbers..


    Full Member

    Just wrapping ours up, rear full width extension and new bathroom, only had one quote as we know the builder and his work. Was brilliant. I worked out a rough budget inc contingency and set-up a spreadsheet to keep track. Amended with quotes, then amended and actual. Worked out bang on, other than extras we added on and the new boiler that couldn’t be foreseen. Only thing that I wasn’t fully comfortable with was day rates for bathroom/ plumbing/ tiling (we had a lot of tiling) and electrics (plus materials – but I knew those roughly anyway). A fixed price would have been better but given how long the jobs took they wouldn’t have agreed or we would have got a rush job. Good luck. We’re mad enough to start a bedroom extension in the summer.

    And I would echo what DrP said about being able to talk to them and say when you’re not 100%. Our electricians made some cock-ups and that was awkward but got it done. I also spent far more time working from home and being ‘on-site’ than I ever thought I would but it paid dividends.

    Free Member

    post up the plans here and we’ll all have a guess.
    single storey extensions budget @ £1500 M/sq

    Free Member

    Thinking of doing some work…this thread is scaring the life out of me!

    I can live with £1k to £1.5k per sq mtr but something thinking £50k/£60k and quotes coming in at £140k is crazy.

    I can only assume they live in the South East!

    Just renewed my building insurance, they reckoned the cost of rebuilding my whole house would be £120k!!!

    Full Member

    I’ve been a construction estimator for nearly 30 years. I’m still to get it right – good luck!

    Seriously though – excel for budgeting and tracking costs. That template linked above is a reasonable format, just a bit Americanised. Press your builder for a fully detailed quote with all materials and labour costs scheduled which will make agreeing the cost of any changes much easier.

    And 20% contingency but don’t tell the builder this!

    Free Member

    Our builder opened up a trade account at a local merchants and we pay him a day rate for labour. We get itemised invoices for the materials used direct from the merchant and keep a record of how much we pay in labour on a piece of paper shoved behind the bread bin ! Works for me.

    Full Member

    Hi everyone.

    First, thanks for the enthusiastic input..!

    Second, a BOQ templates what I’m after – something where I can see each of the lines against which I’ll need to allocate money!

    Where we’re up to: we’re using an architect (I’m familiar with the +ve and -ve of this route). His initial drawings went past a builder and came back with a big number. So we sent him away to cut the design back to something that would be better VFM on our house. I mean, we could have kept the solid gold lavatories but something had to give…,

    He’s done initial drawings, which are currently with the planning dept for their pre-planning stage. Should get the headline feedback in early Jan. Assuming it’s ok at that point, then obviously we’re into the detailed work.

    My day job is not construction related, but I do lead the commercial side of various large projects. Hence wanting to start with the ability to both lock down costs and to track spend against them. I’m on the middle of a major IT programme and I’m getting to the point where I can’t negotiate price reductions fast enough to keep up with the “oh but we need that function we should have considerd 12 months ago and can’t launch without it”. I want my private life NOT to be like this..!

    My preference will be a single (principal?) contractor – I want fixed price, an agreed price book for any changes and one throat to choke. Oh, and the moon ins stick please.

    If anyone has any spreadsheets they’ve used/created for this type of thing, it would be great if you could share a (blank) copy so I can make sure I’m not missing anything.

    Thanks all.

    Free Member

    Advice above is spot on. Get a good builder you can trust and don’t be afraid to ask questions.
    Oh and try to enjoy it but tell the missus/partner it will take twice as long as you think and be twice as messy. My other half is used to me saying this….

    Free Member

    All the advise on here is all well and good but must get proper details drawings.

    Any builder or QS Worth there salt will only give a very rough budget price, as it’s too risky to price without proper drawing and structural engineers drawings.

    Also be advised that many builders are very busy at the moment and you will need to give them time to price the works. As are so busy at the moment they may not price with out proper drawings

    Free Member

    Only thing that I wasn’t fully comfortable with was day rates for bathroom/ plumbing/ tiling (we had a lot of tiling) and electrics (plus materials – but I knew those roughly anyway). A fixed price would have been better but given how long the jobs took they wouldn’t have agreed or we would have got a rush job

    Not sure why you couldn’t have got a fixed quote for this, I’d never tile on a day work basis, most tilers work on a meterage basis and know how much per mtr to charge. The only exception to this for me is large format flooring work where the adhesive/floor levelling is charged as used as it’s sometimes an unknown qty.

    Anyway, My Father was a QS for 40 years and all the advice above is spot on. As detailed a drawing as possible, price everything and then try not to be the customer that changes mind/makes it up as they go along as this quickly gets very expensive.

    Free Member

    Bought our house about 6 yrs ago and completely renovated + had a cellar converted.

    Ours was a builder to do the cellar conversion and is getting plumbers & electrician etc.

    Cellar conversion wasn’t the cheapest but certainly not the most expensive. He used some software to do the quote which was fantastic. We thought it was ott, but it broke the build down in to stages and itmomised everything to absolute detail, do both parties knew where they stood.

    I just knocked up a spreadsheet to track all costs and came in on budget, but that was with lots of careful planning.

    Make a point of getting written quotes for everything! Although most trades will try and avoid it….

    The only cock up was with the electrician. We went off the recommendation of someone. He came out to estimate. I had to chase him for quotation, which I only ever got verbally on the phone. His work was fine, but when the bill eventually came it was £5k + VAT which had never been the case in discussions. Basically I told him to do one and only paid the £5k but was very stressful for a while as we didn’t immediately get the sign off paperwork.

    So my advice would be spend a month or two getting estimates and sorting your costs in advance (once the project starts its too late) make sure people quoting do not decide to add VAT later !

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