I Want to Convert My Loft
In an old house, there are some important things to think about before deciding to convert your loft. This can be a good way to increase space without building an extension, but it will affect the interior of the house, the roof structure and the outside of the roof.
If your house is listed you will probably need consent to alter the roof space and timbers, the floor below, and the outside of the roof. You may also need planning permission or building regulations approval. You should seek advice before carrying out these changes.
Your existing roof
Find out about the existing roof space, and the features within it. There are three aspects to this: the history and significance of the roof timbers; the loft space and other roof features; and how the loft relates to the rest of the house and its layout. Finally you should check the condition of the roof in case you need to repair it as part of the conversion work.
In many old houses, the roof is an important part of why the house is interesting, even if it’s not seen (see I Want to Renew My Roof). If roofs are well built they last a long time and tend not to be affected by changing fashions, unlike room decoration and windows.
It’s not unusual for houses that look Georgian on the outside to still have medieval roofs. Old timber roofs were hand-made in oak or elm and often have interesting carved details and carpenter’s marks. The way roofs are constructed can show how old the house is because carpentry methods changed in particular ways over time.
In some old houses, the loft was used by servants. Look for clues such as blocked windows or traces of lost staircases. Although you may still need to make some major alterations, this type of attic space is usually easier to convert than a loft that was never meant to be accessible. If your roof has been altered fairly recently or turns out to have little historic significance, a loft conversion will also be more straightforward to agree.
Adding a staircase
If the loft is not already connected to the floor below, you will need a new staircase that complies with building regulations. In deciding the best place for the staircase, think about the layout on the floor below. Converting the loft will have knock-on effects elsewhere. If you can build the new stairs off a landing, this avoids cutting into a room. Part of the loft floor structure and the ceiling below will need to be taken out, so find out whether they are important. Also bear in mind the layout or plan of the house and keep the main rooms and staircase in their existing positions; they are part of its history.
Light, ventilation and insulation
If the loft has no windows, you will need to provide light and ventilation. A well-designed dormer window can work on some roofs, but on others, it may be better to use small rooflights. Some rooflights are available that are designed specifically for sensitive locations and sit flush with the roof. To decide what is best, assess the shape of the roof, the style and character of the whole house and how visible the roof is. Rooflights and new dormers are best avoided on the front roof slope.
Improving insulation is a major part of converting a loft, but you need to maintain roof ventilation at the same time, which may require additional roofing battens. The aim should be to keep alterations to the outside of the roof to a minimum.
Energy Efficiency and Historic Buildings: Insulating pitched roofs at rafter levelPublished 30 November 2015
This guidance note provides advice on the principles, risks, materials and methods for insulating pitched roofs at rafter level. When insulation is placed at this position the roof is often referred to as a 'warm roof'.
Inserting a new bathroom in a loft needs particular care as the new pipework, ventilation and other services can be difficult to fit in without damaging the roof structure or the loft floor. Site a new bathroom directly above a bathroom on the floor below, to reduce pipe runs and the risk of water damage.
In listed buildings you will usually be expected to keep old walls, all the roof timbers, old floors and plaster ceilings, though some of these will most probably need some additional strengthening work. For loft conversions in listed houses, we recommend you use a structural engineer as well as an architect or surveyor who will understand any repair issues as well as the historic importance of the house.