Essential Checklist for a Successful Loft Conversion

Increase the chances of a smooth and happy loft conversion with our rundown of factors to consider when planning your project.

By Larry Bohan on 14 Sep 2019

completed loft conversion pre furnishing

Converting an unused or underutilized loft into a new room for the home is often the most cost-effective and least disruptive way of adding space.

What's more, the value a loft conversion adds to a property makes it the smartest, most profitable way of renovating.

This though does not mean loft conversions cannot go wrong or flatter to deceive. Our checklist aims to reduce the chances of disappointment by outlining the possibilities, costs and regulations involved in converting your loft.

Can I Convert my Loft?

Most lofts can be converted in some form depending on the existing roof space.

unused loft space pre conversion

Do You Have Enough Headroom? For a standard loft conversion with pitched roof windows, around 2.2-2.4m of space will be required between the floor hoists and the underside of the ridge beam to ensure adequate room for walking around once ceiling and floor are complete.

If you don’t have enough room to work with, a dormer extension or a whole new roof will probably need constructing.

How Is Your Roof Structured? Most properties built before 1960, which is the vast majority of homes in England and Wales, are built with thicker and fewer timbers with a large open void that lends itself to an easier conversion.

Homes built after this date tend to have trusses occupying the majority of the roof space. Though trussed roofs are harder to convert, there are plenty of ways around it. With the above in mind, pop up to the loft for a better idea of the work that might be involved.

Do You Know Your Roof Pitch angle? As a rule, the steeper the pitch the easier the loft conversion will be as there will be more usable space available. For advice on measuring, read our article 'How Do I Work Out My Roof Pitch'.

How Much Will My Loft Conversion Cost? Typically roof window conversions that require little structural alterations can cost below £20,000 and add around 20-25% to the value of your home.

Larger projects that require changes to the roof structure can cost anywhere between £30,000 and £50,000, but again will add serious value to a property especially in the more lucrative areas of the country, such as London and the South East.

What Restrictions Might I Have?

Not many as long as all building regs are met. Your builder should be aware of them all, but it’s worth factoring them into your planning.

floorplans for home improvements

Will I Need Planning Permission? Planning Permission is not required for most roof window conversions as they fall under Permitted Development (PD). You may need to apply for Planning Permission If you’re making significant changes to the roof’s external appearance and you certainly will if your home is located in a conservation area.

Do I Need A Party Wall Agreement? You will not need a Party Wall Agreement if the works are not going to involve a wall that is shared with an adjoining property. If your converting an attached or semi-detached loft, you must have a party wall agreement in place with your neighbours to inform them of the work you intend on carrying out. 

Stairs: A fixed staircase must be in place to provide safe access to and from the loft. Any stairwell requires a minimum headroom of at least 1.9m in the centre of the stairs and 1.8m at the side.

Fire Safety: Most lofts will need fire-resisting doors and sometimes partitions to protect the stairway and there must be a mains-powered smoke detector on every storey, including the loft.

Every loft conversion also requires a window through which a person can escape if the stairway cannot provide a safe exit from the house. The window must be able to open to at least 450mm.

Floor: The floor of your loft is guaranteed to need reinforcing to support the new room and staircase. It will also likely require upgrading to meet the minimum building regulations for noise insulation and fire safety.

Utilities: Do any chimneys, tanks or pipes need moving to create space for the new room?

Finding The Right Builder

Choosing the right tradesman for the job is essential to a successful loft conversion. Never be too hasty.

Loft during conversion

Ask For Recommendations: Talk to friends and family who have had similar work done for recommendations on builders and architects. Take a look around the local area for converted properties similar to yours. Do not be afraid to knock and ask neighbours who they used.

Consider a Loft Conversion Specialist: There are plenty of firms out there who specialise in loft conversions on both design and build elements.

Get several quotes: Using your measurements, get at least three quotes for a fairer estimation of costs. Once you have agreed on a price, make sure you are happy with the payment plan in place.

Is Everything Covered? It's good to make sure everything you need is included in your quote and to get written agreement detailing who is responsible for what. Do not be afraid to ask about VAT, insurance and for references of similar work they've completed.

Go Online: The web has become a hotbed for loft conversion design ideas of all shapes and sizes. Pinterest is one of the most popular avenues for this. If you like the look of a loft conversion you find, talk through it with your builder or architect to see if it's realistic.

Forward Planning: Find a tradesman who is happy to return to your home to follow up on their work and make it right if anything has gone wrong post completion.

Check Accreditation: Sift out the reliable builders from the cowboys by hiring firms who belong to a recognised trading association.

Contact Your Insurance Provider

Be sure to inform your insurer that you are undertaking building works to guarantee your cover will not be affected. Your home is subject to a range of extra risks during renovation, especially larger loft conversions.

How Many Roof Windows Do I Need?

Natural light is an integral part of completing the transformation of a loft.

white paint velux roof windows in loft

Quantity: Ideally, the glazing area in the room should equate to at least 15-20% of the overall floor space. Pitched roof windows that are installed in plane with the roof are able to transmit three times more light than vertical windows.

Type: The type of roof windows will depend on what your room is being used for. Moisture resistant PU and PVC windows are recommended for bathroom areas, centre pivot roof windows for higher pitches, for example above furniture, and top hung windows for creating a room with a view.

Glazing: Roof windows are available with special glass technology to to suit your needs. Options include noise reduction, privacy (opaque) and triple glazed. Read our Pitched Roof Window Buying Guide for further guidance.