Home extensions and renovations Converting a loft: planning what you want

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This article, Home extensions and renovations, was last updated on 10 July 2008 and is now out of date and held in our online archive for reference. Explore our latest Home & garden articles.

 Loft conversions can be very successful but they are a big job and not cheap! For up-to-date information about how much a loft conversion will cost, visit Which? Local, or you can ask a question on the Which? Local forum panel on the right-hand side of this page.

When you have a loft conversion, builders have to walk through your home every day. And when you have no roof, everything is exposed to the elements.

It’s essential to employ experts who do these types of extensions every day of the week. 

Loft conversions can be a big success but they are not cheap

Loft conversions can be a big success but they are not cheap.

Key questions to ask when planning a loft conversion

How easy will it be to convert your loft?

Certain types of roof structures are much easier to alter than others, and this affects the cost of the conversion. They can, in fact, be so costly that you might want to consider building a one- or two-storey extension instead, to achieve your objectives. However, in a terrace property, a loft conversion may be the only cost-effective way of gaining extra space.

There are simple ways of working out if you can convert your loft easily: firstly go up in the loft and see if you can stand up! Then consult a structural engineer or someone recommended by a loft conversion company, who should have their own surveyor. Make sure that he or she is a fully qualified, paid-up member of the Royal Institution of Chartered Surveyors (RICS).

How cost-effective will it be?

Check with local estate agents or surveyors on just how cost-effective it would be to convert your loft. This is especially important if you are not planning to stay for more than five years, as you may not get an instant payback from your conversion.

In some cases it may detract from the value if the loft conversion puts the property out of the maximum price that anyone would pay to live on your street. You should also consider the potential loss of storage space.

Stairs: loft conversion

It's important to work out where the stairs to your loft conversion will go.

Where will the stairs go?

Removing, replacing or installing a staircase is subject to stringent building regulations, as this is often the only route of escape from a loft conversion in case of fire. 

Depending on the layout of your home, you may be able to go straight up from the stairs that you have now, or take space away from another room. This will add cost to your loft conversion and you need to make sure it doesn’t alter the usability of the current room if you are keen to add value.

You can reduce the amount of room required by investigating ‘space saver’ stairs. These have a step on each side of alternative treads, reducing the room and height required. The staircase will need to have a wall on one side, which you might have to add as a partition wall from other rooms.

What type of windows do you want?

See if you can incorporate windows into the loft conversion. The more light you have, the more expensive your conversion will be, but this is one occasion when it should be a major consideration rather than an afterthought.

Mansard roof: This is where additional space is created by part of the new roofline protruding from the existing roof in an ‘A’ shape. Mansards are popular on inner-city terraces, where going up is one of the few ways of extending.

Dormer: A dormer is often seen on chalet properties, or bungalows when there isn’t enough height across the whole of the loft area, or you need extra height for a shower. A dormer can also help create the height required to put in a staircase and the balustrades that help to ensure the stairwell is protected if someone were to fall.

Roof lights: If you have enough space, then windows flush to the existing roof may be all that is required. They are ideal as they are easy to fit and you often see them on new barn conversions. Velux is a well-known brand.

Window requirements

  • You must be able to open windows for cleaning.
  • The glass needs to be heat reflective so that the conversion doesn’t get too hot on a sunny day.
  • You may need to make a window suitable for escape in a fire – check the building regulations with building control.
  • If the windows are very high up, you must be able to open and close them remotely.

More on this...

  • Looking to put in new windows when you upgrade? Visit our guide on how to buy double glazing
  • Thinking of extending your house instead? See our advice on extending your home
  • Problem with a builder or decorator? Find out how to deal with dodgy builders and decorators