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budgeting for home renovation

When undertaking a building project a key challenge is to manage to costs. All to often people start the process without fully understanding what is involved and how much it will cost, and are met with speed bumps and frustration along the way. 


Whilst a key principle in budgeting is that cost certainty comes with design certainty, it is possible to set yourself realistic expectations before undertaking a project.

budgeting for home extension

Work Out Your Construction Costs

The first step is to work out your construction costs based on the amount and type of work you’d like to do. Below are diagrams with ranges of the 'base costs' for the general works, following which further specialist items can be factored in as well. Each project has a unique set of circumstances and requirements, making it difficult to establish a precise figure before kicking off the design - however this guide will help you get a better understanding of what to expect, and roughly how to apportion your budget. 

Demolition Costs

ground floor construction costs

Full Demolition

£300 - £500/sqm

Breaking  up of load-bearing masonry walls, foundations, redundant drains.  Removal of structural timbers, joists etc.

Soft Strip

£30 - £50/sqm

Disconnection and removal of non structural and loose items including; partition walls, windows, ceilings, kitchen appliances, sanitary ware items, electrical cabling, plumbing pipework, radiators, lighting.

Base Construction Costs

Ground Floor

ground floor construction costs

First Floor

first floor construction costs


£2,000 - £2,500/sqm

The most expensive part of your project will be for the extension itself, which includes the 'hidden' elements such as structure, insulation, waterproofing and services, as well as the finishing of the new space. 

Full Refurbishment

£1,750 - £2,000/sqm

The areas immediately adjacent to your new extension, often the kitchen and dining spaces, will generally require full refurbishment and restructuring.  Given a limited reuse of existing part of your home, the costs will be marginally less than the extension itself.

Light Refurbishment

£1,000 - £1,250/sqm

For areas that you wish to upgrade with new finishes, services (such as lighting and heating) and general decoration, but that don't require any work on the hidden structure, insulation and waterproofing etc, the costs will be less again. These spaces will often be the sitting room at the front of your home, bedrooms and hallways.

Specialist Items Costs

£8,500 - £18,500


Varies depending on the size and shape, number of appliances, and level of specification. Kitchen design has become somewhat of a niche market in itself, and the prices can go well beyond these figures if you go for the top end.


£2,000 - £10,000

Again varies depending on the level of specification you choose for the fittings, and requirements such as underfloor heating. Rooms with showers and bath tubs will be at the upper end, whilst simple WCs on the ground floor will cost less.

Specialist Glazing

£1,200 - £2,000 /metre

The specialist glazing common in ground floor extensions, whether bi-fold, sliding or french, varies depending on the frame size, requirements for reducing solar glare, and level of security. Fortunately there are now many products on the market.

Work Out Consultant and Statutory Fee's


Measured building survey

£500 - £1,500

Drainage survey

£150 - £500

Architect & Structural Engineer

Up to planning application

3-6% construction cost

Planning application to project completion

4-8% construction cost

Planning Application

Householder planning application


Certificate of lawful development


Discharge of planning condition

£28 per condition

Additional Reports (that may be required for planning)

Tree report

Flood risk assessment

Ecology report

Archaeological report

£550 - upwards

£720 - upwards

£720 - upwards

£2,000 - upwards

Historic building report

£2,000 - upwards

Building Regulations

Varies depending on your local council. The use of an approved inspector will be more.

Building notice

£500 - £2,000

Full plans application;

plan fee

£500 - £2,000

Full plans application;

inspection fee

£600 - £2,500

Party Wall

If neighbors want their own surveyor

£700 - £1,000

/ neighbour

Add a Contingency

Having a sufficient contingency fund is vital to factor in to your budget from day one. Despite employing all the right professionals and commissioning the surveys required, there are things that cannot be fully known until the construction begins, and you need to be prepared for things that may go wrong. Without doing so may leave your project unable to proceed whilst you gather the necessary funds.


For home renovations and extensions the rule of thumb is 10% of the total for construction and fee’s. Once established, it’s important to resist dipping into this fund to add extra items to your project, otherwise you’ll be left empty handed if something goes wrong.

Got Any Questions?

budgeting for home renovation
budgeting for home renovation
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