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How Much Will My Home Extension & Remodel Cost?

If I got a pound for every time I was asked this question …

This is no doubt one of the most common questions that are on my clients minds.

My answer is always the same... it depends on what you want. I can give you rules of thumb but ultimately doing construction work can be so unpredictable. Nevertheless, in this article I have tried my best to give you an idea of what you may spend on your project.


How much will your home extension remodel cost?

Well, it depends on a few things…

  • The size and type of extension - A single storey lean to rear extension for example is less expensive than a wrap around or double storey extension.

  • The internal finishes - If you fit out your lean to with the newest appliances and interior decor then your costs could end up adding up to the cost of a basic wrap around extension.

  • Your builder - If they are expensive or reasonable.

  • Decision making - It depends if you keep changing your mind and making alterations to your plan.

  • Location - It depends on if you are building up north or down south.

  • Procurement - Will you be managing the build yourself or will you hire a design build firm to manage all the work?

Identify Your Budget

For this reason when it comes to budgeting we would offer this advice:

It may be more helpful to identify how much you are looking to spend (your budget) or alternatively you may want to think about the end product you are looking for and prepare a budget in accordance to your aspirations.

Costs, finish quality and the speed at which you desire the work to be completed, will all have a role to play in the final cost of your project. If you identify which is most important to you then you will be better equipped to know where you can personally make a compromise.

Rules Of Thumb For Extension Prices

  • Basic - Standard - 20-30K

  • Moderate -30-45K

  • Bespoke - 60K+

  • High End / Luxury - 100-250K+

You could for example have a moderate budget of £40K but not know where to start.

I have noted below what that could buy. Based on a semi detached property and raw building costs (straightforward masonry construction) not including professional fees (Architect, Structural Engineer etc). These are basic expectations but for more a bespoke product you should expect higher prices.

These prices are based on estimates within the North-West (subject to change) and visitors are to note that prices can vary tremendously particularly in London where it is generally more expensive to build due to increased costs.

I would also add 20% of the budget to your final costs in order to get you total expenditure.


£10,000 - £35,000

Internal Remodel

  • In this range you could do a basic internal remodel for your home.

  • With the right design advice you could make your money go further and create a totally different feel for your property.

Loft Conversion

  • A basic loft conversion could be achieved within this price-range, however, the level of work required to your property will impact costs, for example the condition of your roof may mean that it may be sensible to replace all of the slates as part of the works which could significantly add to the cost of your project.

  • With all loft conversions I would advise that you get a building professional to examine your property to first determine if a loft extension is possible and then identify the level of works required to make it a habitat space.


£25,000 - £50,000

You could for example have a budget of £40K but not know where to start.

I have noted below what that could buy...

Single Storey Rear Extension

  • Definitely a single story extension shell towards the rear (at the lower end - 2m/ at mid range -3m).

  • Between 40-50K decent rear extension and moderate internal fit out including basic kitchen.

  • With the right builder you could also get some decent interior fixtures and fitting.

  • You may need to add to the budget depending on the type of kitchen you want to install and appliances or additional features like underfloor heating.

  • Designing finishes like exposed concrete floors and exposing beams within your construction can often add a dynamic contemporary feel to your project.

Basic wrap around extension

  • Towards the upper end of this figure you may be able to achieve a basic wrap around extension shell with modest internal fittings.

What slightly increasing your budget could do

  • Add an extra 10-20K and you could likely get a decent two- storey extension shell to your home increasing space both upstairs and downstairs.


£50,000 - £100,000

This budget is beginning to enter the realms of :

  • contemporary rear extensions

  • double storey extensions

  • part single - part double storey extensions

  • More contemporary fixtures and fittings with features.

  • This may also include a level of interior architectural design for your home including fixtures, fittings and furnishings.

Conversions including Basement remodels

  • This may also include remodels with basement conversions that can quite quickly increase costs.


£100,000 - £250,000 +

  • This budget would begin to be in the realm of adding full scale additions to properties, incorporating:

  • Bespoke Design

  • Glass features

  • Cantilevers

  • Smart technology

At this level you may want to consider integrating smart technology solutions within the functionality of your home to assist with management and include bespoke features.

Other costs to consider

The above takes into consideration costs of construction, however, when calculating your total budget it is important to factor in associated costs that you may not have thought about.

  • Cost of living should you need to move out during the build

  • 10% contingency for the unexpected costs and for disbursements -Planning permission / Building regulations / Consultants etc

We wish you every success with your build and should you wish to seek assistance with your work we are happy to assist you in your project.

For help on your project call us today to book a free consultation or email


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