House Extension Or Loft Conversion?

Lisa Raynes

by Lisa Raynes

21/03/2021, in Main Blog

Deciding whether to perform a house extension or a loft conversion can often be tricky. To help you with this, here’s our analysis of four key factors: requirements, costs, value and disruption.

Consider your Requirements

For a side or rear extension you will need space on your land, planning permission, and your neighbour’s agreement.

On the other hand, for a loft conversion you will need at least 2.5m headroom in the loft, which many 1930s semi detached houses lack. This can be achieved through raising your roof or lowering your ceiling which will affect your first floor.

Get an Idea of the Cost

An extension will typically cost around £50,000 for a single storey, (at around £1,000 to £1,500 per square metre), or £100,000 for a two storey extension. The costs depend on the scale of the extension, and whether you will be doing any internal reconfigurations.

A loft conversion, for a typical smaller house in Manchester, will usually cost around £35,000 plus VAT, but larger houses usually start between £40,000 and £45,000. The larger the loft is, the more space you will need to decorate.

Because of the high costs of projects, we are always looking for easy wins during consultations and workshops. For example, Magda always tries to understand why the client wants what they want so she can find the cheapest and easiest way to achieve that; a client who initially wanted a second storey extension actually just wanted an office with a view, so just moving her rooms around was enough to achieve her dream home!


Assessing how a project will change the value of the house is a key part of our process; we give you a month after the Concept Design Workshop to speak to builders to get an idea of costs, estate agents to get an idea of value, and neighbours to ensure there aren’t any showstoppers. After the month, you will have a one hour follow up consultation, included in the cost of the workshop, during which you will decide whether to proceed with the project and make any changes to the plans.

Both options will mean an opportunity to gain extra bedrooms which will increase the value of your home. An extension is more flexible, however, as it could allow you to create an open plan living kitchen dining space, which is often desired by many.

You need to be careful not to become too ‘top-heavy,’ as if you have a 4 or 5 bedroom house, people will have expectations about what the reception space will be like. Those who want to buy it could assume it has a kitchen, living, dining space and a reception room, which a loft conversion won’t provide.

Allow for some Disruption

The level of disruption varies depending on the design, but extensions can often be very disruptive because they can involve remodelling the house, removing access to the kitchen and bathroom. We often suggest moving out during extensions, but checking on the building works regularly.

Loft conversions, on the other hand, are minimally invasive as most of the works are from the outside, so they are only disruptive in that they require a staircase which might go through a small bedroom. You could easily live in your house during a loft conversion.

There’s a lot to consider, but our free one hour initial consultations and our Concept Design Workshops are ideal, friendly, low commitment spaces to really consider all your options.