Jump to content

Builder Quote Mistake - Liable for excessive mistake?

Please note that this topic has not had any new posts for the last 391 days.

If you are trying to post a different story then you should start your own new thread. Posting on this thread is likely to mean that you won't get the help and advice that you need.

If you are trying to post information which is relevant to the story in this thread then please flag it up to the site team and they will allow you to post.

Thank you

Recommended Posts

Hi all,

I will try and make this as brief as possible.

I am currently getting a brick porch built it is 2/3 built. The price was agreed before building work commenced at £5,700. 

During the build i changed the plans for the roof before work on the roof had started, from a pitched roof to an hipped roof. I requested the extra cost for the roof on 6th August but did not receive the updated cost until work on the roof was close to completion.

After several requests for for the amended price, i finally received an updated price on the 31st August.

The final price of the build on the 31.08.19 is now £10,000. The additional cost of the hipped roof was £1,400 . However in the exchange of emails the builder has ACCEPTED liability that he miscalculated the size of the porch by adding the length and depth of the porch instead of multiplying.  Therefore, this means that the materials for the bricks, cement, footings and labour for all ground works and brick layering, have all been miscalculated by in the builders quote.

Subsequently, in the last 48 hours, i have now had 5 different quotes off him.

1 - 10,000
2 - 8,900
3 - 11,000
4 - 9,100
5 - 8,300

I have rejected all of these, as i do think i should be liable to pay for his incompetence regards to miscalculating the size of the build. 

I asked him the question if i had not changed the plan for the roof and the porch was built as planned with a pitched roof for £5,700, would you now be asking me for more money. His reply was yes due to miscalculating the size.

For a quick solution i offered £7,500 for the completed build which i believe is reasonable but he has rejected this but would accept £8,300.

Estimated build time was 2 weeks, we are now into the 9th week.

I believe i am in my right to stand firm as he as accepted liability.

Any feedback would be appreciated.


Link to post
Share on other sites

Have you paid anything already – and if so how much?

Link to post
Share on other sites

Thank you.

It's certainly going to get a little complicated. I had better warn you now that I have a little sympathy for the builder – I'm assuming that he is a small firm – not some massive building company.

I think that your offer of £7500 is very decent – but let's look at a little bit at the legalities as well.

You had a contract for a certain project and the agreed price was £5700. At some point, well into the project, you varied the contract and of course the builder was happy to go along with it – especially, I suppose, that it represented more money and therefore a greater level of profit. However – even if it was not your fault, you did not get an agreed price until the variation was well underway.

Section 15 of the Supply of Goods and Services Act 1982 says that where a price for services has not been agreed then a reasonable price will be implied. It seemed to me on that basis that the law would probably require you to imply a price which was reasonable for the variation just before the varied work was undertaken. The 1982 act is largely repealed but it still seems to me to be a good way of deciding the cost of services where a price has not been agreed. I expect a court would be quite happy to accept this

You are in a position where the work is not complete and so to a great extent you are at the builders mercy because I can imagine that if you have to bring someone else in to complete the work, not only will you then have to pay the new builder to take up an existing job – which he may not be happy with – and for which you may end up paying a premium, but also you may well find yourself in a dispute with your existing builder and which you might lose. If your existing builder came here then I would probably be suggesting that he looks at the maximum reasonable price rather than the minimum reasonable price – given that there is probably a range with a lower and upper limit.

Not only that, it will delay the completion of the work which apparently has gone on much longer than you expected anyway. You could easily be looking into October or even November before the work eventually gets finished and you still have the dispute on your hands.

You have indicated that the builder has already come up with a few different prices ranging from £11,000-£8300. £8300 is not far away from your £7500 and I hope you won't mind me asking you whether this really is a matter of economics or whether it has become a matter of principle for you.

Your legal position is to go get two independent quotations for a hipped roof to be built on to the structure at the point at which it had no roof whatsoever and then to compare those quotations with the figures that your own builder is giving you. I think that would then give you your legal position and what you should reasonably expect to be paying your builder and if it went to litigation what your builder could reasonably expect to win from you.

At the same time, in order to understand your level of risk if you decide to lock horns with your builder on this issue, I would  also get two independent quotations for finishing the work. I think this would put you in a position where you then understood fully what it would be reasonable to pay a builder and what you might expect if there was some litigation and you lost (don't forget to factor in the delay, the stress of the litigation et cetera).

If my suspicion is right that this has become a matter of principle for you then I would urge you to put it to one side, bite the bullet and settle for his lowest quote of £8300 because if you get independent quotes you might well find that you would normally have been expected to pay far more than this. On the other hand of course, you might find that your £7500 is within the reasonable range and in that case you could show your present builder the two independent quotes and persuade him to carry on on that basis.

However a final matter you need to factor in is that if you fall out with your builder but he reluctantly agrees to take up the work and to complete the job, you are then dealing with an Artisan who is carrying a grudge and this could have repercussions in the final quality of the work and also in dealing with any subsequent snagging list.

I think that you are between a rock and a hard place and given the difference between you of £800 – I think I know which way I would jump.

It's clearly a tough situation for both sides.

Link to post
Share on other sites

Is this a builder or a bingo caller?

His incompetence in calculating material is not your problem. 

I would give him the original £5700 and live with the pitched roof.

Or, as you're prepared to pay £7500, give him the £5700 and get someone else to do the roof to your liking for the remaining £1800.

I would build 3 porch roofs with £1800, fully insulated,no matter what sort.

Link to post
Share on other sites



The hipped roof is near completion stage, so it is too late for that option.


Good shout with regards to him being a bingo caller. I can not keep up with the amount of quotes.  I think a new calculator is required for this builder, although i have an email also saying that he pressed the wrong button on his calculator which 'may' have been one of the causes of his initial mistake.



Link to post
Share on other sites

Sorry if I sound a bit nosey, but how big is this porch?

You talk about near completion and projects similarly to the construction of a 6 metre extension. 

A standard porch would normally be completed in less than a week.

It takes me half a day to do a hipped porch roof.

Seriously,  it's normally such a small built that it's done and dusted in no time at all.

Unless you're writing from Texas and have a 20 yard porch...


Link to post
Share on other sites



The size has been an issue from that start.


When the builder came to measure up for the quote we asked him we would like a big porch but within planning regulations.  His reply was you can have any size porch you want as you do not need planning permission.  We said we would like a porch similar in size to others built in my road. These have also not applied for planning permission.


So we agreed 4mX1.4m.  However he has built the porch 4mx1.9m, therefore it is a large porch.  During the build, it has come to light that planning permission is required, as it exceeds 3m2.


In the 9 weeks construction to date, this included 9 days were the builder went on holiday, we did not know when the quote was agreed that the builder was planning on going on holiday. 



Link to post
Share on other sites

4x2 metre= max 2 weeks construction. 

Cost of the hipped roof would be max £300 extra.

This would include the extra labour, extra lead, tiles, gutter etc.

I don't understand how he doubled his quote.

Also, it's common knowledge that anything over 3m2 is subjected to planning permission. 

To be honest, if you build a 3.5m2 or even 4m2 is virtually impossible that anyone would ever say anything,  but almost 8m2 (?!?!)

Anyhow,  for that size, £8500 is a fair price if double brick cavity walls, insulated, plastered inside and including upvc door (non composite).

His initial £5700 quote is more likely for a well built standard 3m2 porch.

Link to post
Share on other sites



Thanks for your reply.


I have made a final improved offer of £7800 for the completed porch, which includes a composite front door, the door has been installed.


The completed porch includes plastering and electrics.


You seem to have some knowledge in this field, am i being unreasonable by offering £7800 when his final quote is £8300, albeit for his error with the calculations.  I also have to live with the risk regarding planning.



Link to post
Share on other sites

£8300 for a 8m2 porch double skin and insulated would've been my very lowest quote.

However he made the mistake, so i think he will accept the £7800 offer.

Anyway,  I assumed he's built a double skin cavity brick wall porch, insulated same as new built.

Am I wrong? Because a single skin breeze blocks would change the game completely.

Link to post
Share on other sites

The walls are exterior brick and the interior walls are breeze block. There is no cavity or insulation between the 2 brick layers. 


The interior walls will have a membrane on with insulation and then plastered.  So i assume this counts as a single skin?


What price are we talking?

Link to post
Share on other sites
2 hours ago, admos30 said:

There is no cavity or insulation between the 2 brick layers. 


For the sake of £50 rockwool insulation he left the cavity empty???

Worse than that, he didn't make a cavity???

The dirty bodger!

The porch will be cold my dear, sorry.


2 hours ago, admos30 said:

The interior walls will have a membrane on with insulation and then plastered


No membrane needed. Totally useless.


Price is as said before, it's a double skin cavity construction. 

He started well, but no cavity insulation makes me think... where else did he cut corners?

Edited by king12345
Looked better at previous post
Link to post
Share on other sites
  • Recently Browsing   0 Caggers

    No registered users viewing this page.

  • Have we helped you ...?

  • Create New...