How to cost a house renovation – The London Economic

How to cost a house renovation

Home renovations are expensive.  If you speak to any experienced builder, the general rule of thumb is to take your budget and double it.

Trust me, I’ve done a few of them and my estimates have always been wildly optimistic. Roof off, floors dug up, rewired, re-plumbed, re-plastered, etc, etc…  isn’t where the money is spent.  Apart from the mega bucks spent on the finish, the cash drain usually happens in the areas you can’t see; insulation, groundworks, underpinning, replacing rotten timber, the list goes on.

So, before you take the plunge and assume that rennovating a property is the easy route to house beautiful, here’s a basic guide to costing up your home renovation. Make sure you leave no stone unturned in order to keep within budget and enjoy a beautiful home once the work is done…


First, ask a professional.

If you’re thinking about renovating, start by spending a small amount of money wisely. Enlist the help of a Chartered Surveyor to carry out a full survey of the property. Renovations might be purely cosmetic, but if you’re doing up an old property you need to check that major jobs don’t need your attention first: structural issues, subsidence, damp, collapsing ceilings, cracks, roofs, re-wiring, central heating, rainwater systems, rot and woodworm can catch out unsuspecting renovators.

It’s also worth paying for the opinion of a reliable builder and architect. This upfront cost might be hard to swallow, but it’s a wise spend; they’re likely to be able to spot particular problems and suggest cost-effective designs for your renovation.


Then, calculate what your budget is.

Do you have savings to use, or a loan? How about extending your mortgage? The bottom lie is that you need a precise figure to play with. While it’s impossible to tell you what you can expect to pay, as a rule of thumb:

  • builders charge a minimum of £1,000 per square metre when they’re constructing extensions
  • re-wiring a small three-bedroom terrace will cost at least £3,000
  • installing gas central heating in a three-bedroom terrace could cost up to £5,000
  • replacing a roof on a three-bedroom terrace will cost at least £3,000
  • re-plastering a three-bedroom terrace could cost at least £3,000

If you plan on doing the majority of the work yourself, your budget can be on the smaller side. However, this requires lots of labour, excellent DIY skills and buckets of confidence. You should also consider if your time is better spent earning money and paying the professionals, rather than labouring yourself – it could be a false economy.

If nothing else, be sure to allow at least 10% of your estimated costs as a contingency. Renovations rarely run to budget and you don’t want to end up in financial difficulty.


Apportion your budget to the rooms that need renovating.

Bear in mind that you don’t have to spend equal amounts in each room (and in fact, most properties won’t warrant this – typically, kitchens cost the most to renovate whereas bedrooms can be relatively inexpensive). Finally, decide how high spec you want the finishes to be as this will dictate how some of your budget is spent.

There can be a gulf in price between basic finishes and top spec finishes, so do some research on the type of finish you would like before you start the project.  In some circumstances it’s a shame to do all the hard work only to apply a cheap finish at the end because your budget didn’t account for the cost of better materials and fittings.


Call on the experts for particular jobs

Most importantly of all, hire professionals to perform renovation work that endangers your personal safety. For instance, electrical work and gas work must be undertaken by a registered professional. Plumbing is best left to an expert unless you’re skilled enough to tackle it yourself, and even fitting beautiful fixtures like Velux windows to let light into a dark space should be done by a registered installer to achieve a high-quality finish.

Ask your friends, neighbours and anyone you spot who has recently undertaken quality work for recommendations to skilled tradesmen.  Quite often the best people are very busy, so it’s worth booking them in early and expecting a bit of a wait.

If you’re strapped for cash or feeling overwhelmed about the potential scale of your renovation work, check out the Sainsbury’s Bank Money Matter’s Renovations Calculator; it will give you some ideas and help you to consider your options!



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