We’re about to go about a fairly major renovation (subject to planning of course …).

We will get a few quotes from different recommended builders but would you independently get a quantity surveyor to give you some idea of material costs as well as the quotes.

I estimate the build costs will be about 50K but that could be way off the mark.

Cheers.

For that amount, no. I would be very certain of what I want though before seeking estimates. It’s changes of mind that cost money…

We will get a few quotes from different recommended builders but would you independently get a quantity surveyor to give you some idea of material costs as well as the quotes.

You may get a few quotes…, asking and getting are two different things. We got a 50% response on our Tender, which I thought might be £50-60k and came in at £120-140k (inc VAT).

A QS will produce a bill of materials, which the Builders would quote against – so at least it’ll be like-for-like to compare against. But you would really need to employ the QS to review/agree those quotes.

Really depends on the cost of a QS vs likely savings and/or no overruns etc.

The value of the QS I would say depends on how good the drawings an information are. Alternative to that is that the QS will sit down and go through the project with you. I would say its unusual to employ a QS on that scale of project. However, there would be no harm in asking a local QS or two what service they offer for your sort of project and what it may cost. I agree with b r that at least your builder quotes will be ‘like for like’ if you use a QS.

We got a 50% response on our Tender, which I thought might be £50-60k and came in at £120-140k (inc VAT)

Ouch.

Estimate of approx 50k would just be for the structural side of things (building above garage and extending the entire back of the house which is a 60’s chalet style bungalow). I’m guessing windows / kitchen / bathroom / electrics / flooring etc is going to add another 50k.

Much more than this though and I suspect it may not be worth it but will also need to speak to estate agent first.

For that amount, no. I would be very certain of what I want though before seeking estimates. It’s changes of mind that cost money…

Absolutely this. If your going to spend your hard earned cash to buy some professional expertise for this kind of project then it’ll be much better spent on drawings and spec rather than QS fees.
I am a QS and the reality is that unless your drawings / specifications are detailed then the QS will be using a series of tools and techniques to guess at the value of the works.
If you get decent info to give to contractors for quotes, you’ll have a much better chance of getting accurate / like for like quotes to allow you get best value from the market place.
As a contractors QS there is nothing worse than getting a job to price with no info. The general response to this is to price a load of design risk or bang in a load of qualifications to the price.
In summary – Get the best info you can up front and market forces will price the job for you. Then stick to what you’ve agreed. Variations are how contractors make money.