Loft conversions: your questions answered

Planning a loft conversion project? Follow this advice from industry experts as they share their knowledge on popular design questions; a must-read before starting your project

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Q: Will my loft be suitable for conversion?

A: ‘First, make sure you have enough space – as a general rule, your loft needs to be at least 2.2 metres at the highest point, usually in the centre. If you do not have this head-height, do not be put off, as there may be alternative solutions, one being to lower the existing first-floor ceilings. Where head-height is at a premium, ensure that the loft company will commit to lowering the new suspended loft floor structure as much as possible (in between the existing floor joists) to capitalise on every extra inch of space. In a property with ample head-height, the possibilities are endless, and you could gain at least two extra rooms.

‘A property’s age does not pose a real issue. If the weight of the new loft-floor steel structure is designed to be distributed on the outside fabric of the existing building, then the added weight of the conversion is simply lost via these external walls. If the loft is designed to use some of the internal walls, then the structural engineers could ask the loft company to expose the foundations to make sure the internal load-bearing walls are adequate to take the additional loads. Always ask for a new steel structure design to bear onto the external/party walls of the property.

‘When designing a loft conversion, deciding to change your existing roof shape to either a dormer or mansard is often the most important decision to make. Due to planning restrictions, no alterations (apart from adding rooflights) can be made to the front elevation or any side of your property that directly overlooks a public highway. However, if you can extend within permitted development rules, a dormer window to the rear will allow you to maximise floor space, as well as be creative with the amount of glazing you incorporate into your dormer – French doors with a Juliette balcony, in particular, will maximise the light coming into a new loft room.’ Stuart Wyeth, company director at Skylofts

Q: What should I include?

A: ‘Try to ensure that the newly created space has a bath/shower room on the same level and will be an adequately-sized double bedroom with a good ceiling height, daylight and views. Converting a roof space for a single bedroom or one with a restricted outlook is unlikely to be cost-effective, and there is little point if value is lost on the first floor by compromising the size of existing bedrooms to accommodate a staircase.’ Jeremy Leaf, chartered surveyor, estate agent and RICS spokesperson

Q: What should a specialist loft company offer?

A: ‘When choosing a specialist loft company, you will benefit from an integrated project team who all work together to ensure the journey from initial concept to final build is as simple and stress-free as possible. The loft company will provide professional architectural designers, qualified Royal Institution of Chartered Surveyors (RICS) structural engineers, surveyors, loft estimators, project managers and specialist tradespeople and loft teams. This structure means that the company is able to see the project as a whole from the outset, giving it the ability to foresee potential problems

Q: How do i choose the right company to do the work?

A: ‘When choosing a loft conversion company, do not be persuaded to simply opt for the cheapest. Find a company or person that makes you feel comfortable, and always ask to speak with a previous customer and whether you can pop over to have a look at the work done. Admire the basics, such as how a hinge has been chipped into a new door, or the quality of the new roof and appearance of the new dormer. Find out if their chosen company went the extra mile by asking questions. Were they punctual, clean and tidy throughout the build? Did they start and finish the loft conversion within an agreed build schedule? Did they ask for any extra money along the way or was it a fixed price? You will find a lot of loft companies happy to commit to a fully fixed price and to sign documents to reflect this. As they are the professionals, it is their duty to capture all the costs, not yours.’ Stuart Wyeth, company director at Skylofts

Q: How much disruption will a loft extension cause?

A: ‘The house is scaffolded at the start of the job – and this is how the trades will access the new room until the staircase goes in and the hole in the roof is closed up. Skips will arrive to clear the loft of debris before the real work begins, then materials will be carried in and rubbish taken out (the loft company should organise the skip licences, but do check). About halfway through the process, the hole will be cut into the hallway ceiling for the staircase to go in, which can be messy, with plumbers, electricians, carpenters and decorators going up and down the stairs throughout each day afterwards. Our loft company was very respectful of our home, with the project manager vacuuming our hallway each evening. The biggest mess, however, was caused by leaking rainwater through the roof tarpaulins. One of the builders also put his foot through two bedroom ceilings, so these needed patching and re-painting when the loft was finished – which the company took care of without quibbling.’ David Houlton, who had his loft extended in 2013

Q; How can I tell if the head-height will be sufficient?

A ‘The most common design challenge with a loft conversion is head-height. Not only can you make uncomfortable spaces if you get it wrong, but you can also fall foul of building regulations (with the staircase in particular), and too often I have seen loft shower rooms where you would have to be a contortionist to get under the showerhead because headroom was not thought about early enough in the design process. The first thing to do is to fully understand the heights and slopes of the ceilings that are proposed. If you have a good set of drawings, cross-reference the plan and section of the proposed loft room to work this out. Even so, it can be difficult for people to really imagine how high a sloping ceiling will feel. I often suggest visiting a house where a loft conversion has been done, and bringing a tape measure to work out how the sloping ceilings in the proposed loft compare. ‘Alternatively, rigging up a sheet of MDF at the right height to slope at the right angle will give a real sense of if it will be comfortable, for example, to stand at a washbasin.’ Hugo Tugman, founder of Architect Your Home

Q: What should I consider when planning and buying new windows?

A: ‘Adequate and appropriate natural daylighting represents one of the principle challenges and key considerations for loft conversions, and a combination of windows and rooflights will provide a good level of daylight. The balance of windows should be considered with the property as a whole, lining up new openings with existing ones below, where possible, resulting in a more pleasant, architectural extension from outside. Provisions need to be considered throughout the full extent of the escape route, too; building regulations demand that you have fire safety windows that can open in case of fire.’ James Corris, architect at Riach Architects

Q: How long will a loft conversion take to complete?

A: ‘Assuming all consents are in place, a rooflight conversion could take three to four weeks, a dormer conversion four to five weeks, and a hip- to-gable conversion five to six weeks. If the whole roof is being replaced, for instance with a mansard conversion, allow six to seven weeks. If the conversion is prefabricated and delivered by crane, time can be condensed, which is an advantage where site access for scaffold is restricted.’ Michael Holmes, experienced renovator

Q: How should I heat my loft room?

A: ‘Most people choose to extend their existing system to heat their loft conversion – in most cases with radiators. A heating engineer will be able to calculate the heat requirement of the additional space and establish whether the existing boiler has sufficient capacity or needs to be replaced. An existing radiator circuit could be extended and thermostatic radiator valves (TRVs) added for control. Or, a large loft conversion could be set up as a separate zone with a programmable thermostat. Electric heating is another option, but, as it’s more expensive to run, is used more often for underfloor heating.’ Michael Holmes, experienced renovator and self-builder

Q: How can I ensure my loft isn’t too hot or cold?

A: ‘Installing the correct insulation is crucial to keep your room warm in winter, cool in summer, and to help keep down noise levels and your bills. It is also important to have the correct glass and the appropriate window blinds. Anti-reflective glass, or glass with different levels of glazing, will help – Velux has an online service to help advise.’ Becke Livesey, director at Econoloft

Q: How can I soundproof between the loft and the room below?

A: ‘As a minimum, you will have to fill the voids between the floor joists with acoustic insulation (usually dense mineral wool batts) and follow robust details at all junctions around the loft floor, using sealants to reduce airborne sound transfer. Double layers of ceiling plasterboard – required for 30-minute fire protection – will also help. Acoustic separation is the only way to make a big difference, which means introducing a floating floor in the loft, separated from the structural floor by acoustic matting and sound-deadening materials, such as cement-impregnated chipboard.’ Michael Holmes, experienced renovator and self-builder


See information on planning advice and costs