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What are the first steps I should take to convert my loft?

Johannes van Graan Johannes van Graan
Modern style bedroom by homify Modern
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Decided to try out a loft conversion to gain an extra room and up the value of your home? Hold on a minute before you start picking out paint colours – you need to find out exactly what this conversion will involve and how it will affect the design of your home. 

After all, any project that involves renovating an existing building and adding extra space to a home needs to be thought through carefully, don’t you agree?

Thus, to ensure you don’t wind up with a hastily completed job that is unsafe and illegal (yes, the law also comes into play here), scroll ahead first to see what you should be considering in your loft-conversion project.

1. Ensure your home can take the extra weight

​mansard loft conversion wandsworth Modern style bedroom by homify Modern

​mansard loft conversion wandsworth


Of course that conversion will add weight to your house, and although it may only be a modest increase, you’ll need to make sure that the existing structure can take it. Expose the foundations and check them, together with any beams or lintels that will need to carry more weight.

Your Building Control officer will also want to check all these elements, so dig a small hole to expose the foundations first. If it turns out that your house needs underpinning to support the extra weight, your budget might double before you even start on the actual conversion project.

2. Find out if there’s enough head height

With a professional designer by your side, illustrate clearly how much headroom will be available in your loft once it’s converted. Some architectural house plans aren’t too clear on this aspect. 

Remember that you’ll have to accommodate a staircase leading up into the loft – to make the best use of space, the new staircase should rise above the old one and not from within an existing bedroom. Besides, what is the point of converting a loft space if it means you are losing an entire room on the first-floor? 

homify hint: Without adequate roof space for water tanks and plumbing, the heating- and hot water system may have to be replaced with a sealed system. Although it is better to have an unvented hot water cylinder than a combination boiler, it will take up a cupboard-size room and you’ll need to find somewhere to put it.

3. What to know with Building Regulations and Party Walls

Converting a loft means you’ll require approval under Building Regulations (irrespective of whether they need planning permission), so it is much better to adopt the full plans application approach and have a detailed scheme approved before you find a builder

This is also where having an approved design from the start is worth it, as it takes much of the risk out of the work and also means the builder has a chance to give you a fixed quotation, rather than a vague estimate.

If your house is semi-detached or terraced, you must notify your neighbour of your proposals, which will usually fall under the Party Wall Act 1996. Your Building Control officer will inspect the work at various stages and, on a final inspection, should issue you with a completion certificate. 

Never settle any final accounts until you’ve received this certificate.

4. What if you want to alter the roof structure?

A guest bedroom for a star! Modern style bedroom by The Market Design & Build Modern
The Market Design & Build

A guest bedroom for a star!

The Market Design & Build

Most roofs are constructed with internal supports in the loft which will have to be removed to make way for the new room and be replaced with new supports that don’t impose on the space. Although there are a number of ways to alter roof structures for loft conversions, they all have one thing in common: the ceiling joists will almost certainly be inadequate as floor joists. This means that new floor joists are fitted alongside them (often 200 mm or 225 mm in depth), slightly raised above the ceiling plasterboard to avoid contact with it. 

When it comes to smaller lofts, it often occurs that the floor joists themselves will be used to support the sloping rafters. This is possible by constructing a dwarf timber stud wall 1 m to 1.5 m high (known as an ashlering) between the two. 

Thanks to the supporting ashlering in place, the internal struts and braces can now be removed safely.

5. Think logically about stairs

modern  by homify, Modern

Sitting Room


Stairs are always a tricky design, as space is tight. Narrow winding flights are acceptable, but may prove impractical in terms of moving furniture. Purpose-built staircases are around 10 times the cost of standard (off-the-shelf) designs, which is definitely something to remember when you’re planning your loft conversion.

Should you require a purpose-built staircase, it pays to have the design approved by your Building Control officer before you actually commission them. Ask your joiner or builder to send Building Control a copy of the design. 

As part of the fire safety upgrade for your loft (which we’ll get to in a minute), your stairways should lead to a hall and an external door. Should you have an open-plan arrangement where the stairs rise from a room, you will probably have to alter it, fitting a new partition wall or choice of escape routes.

6. Get the windows and light right

Suburban Family Home - Ealing Broadway, London Classic style windows & doors by Hugo Carter - SILENT WINDOWS Classic

Suburban Family Home—Ealing Broadway, London


Skylight windows are a blessing in this regard, for they don’t require a lot of structural alterations. Typically the rafters on either side of the skylight are doubled-up and trimmed across the top of the opening. 

Dormer windows, however, are structures in themselves, as they have walls and a roof as well as the actual window. At the rear of many homes, dormer windows can fall into the permitted development quota, which may lead to them not requiring planning permission. But you will need planning permission to place them at the front, which is why you often see skylights instead.

7. Upgrade for fire safety

Beyond ensuring that the new windows are large enough for escaping, loft conversions on bungalows have little effect on the fire safety of your home. But in a house where two-storeys become three, there are implications. 

The new floor will need at least 30 minutes of fire-protection, which could mean re-plastering the ceilings below it. Also, the loft room will have to be separated by a fire door, either at the top or bottom of the new stairs. Bear in mind that you will also need one escape-sized window per room – certain skylight windows are made specifically with this in mind.

Door self-closing devices are no longer required in homes, as they have proven to be a risk to children’s safety (trapping tiny fingers). Therefore, existing doors on the stairway (ground and first-floor) should be replaced with fire-resistant doors or upgraded. Plans submitted prior to this date fall under the previous guidance, which required self-closing devices on all the lower doors, but you should be able to apply to adopt the new approach.

When it comes to the electrical installation, mains-powered smoke alarms should be installed on each floor of your home. Make sure that these are interlinked so that they all sound when one is activated. Most have a re-chargeable battery as a back-up that allows the supply to be extended from a lighting circuit if need be.

8. Consider insulation for heat

Design and build of a 2 storey rear extension, outbuilding and loft conversion to a 3 bed semidetached property in the outskirts of London Modern houses by Progressive Design London Modern
Progressive Design London

Design and build of a 2 storey rear extension, outbuilding and loft conversion to a 3 bed semidetached property in the outskirts of London

Progressive Design London

As standards have increased, loft conversions have become quite awkward to insulate. The sloping ceiling will need insulation cut and fitted between (as well as on top of) the rafters. 

As the plasterboard will have to be fixed to the rafters through the bottom layer of insulation, you will want to opt for an insulation that’s as thin as possible. We therefore recommend using some high-performance insulation (like a foam board) for all of these areas. 

Remember that the ashlering walls and dormers will also need insulating with similar products before they are plasterboarded.

9. Consider insulation for sound

Loft Conversion In Nisantasi Modern houses by FLAT C/ ARCHITECTURE Modern

Loft Conversion In Nisantasi


The new floor also requires soundproofing, although this is easily achieved by laying a mineral fibre quilt between the joists. We advise to go with the heavier, denser sound insulation quilt instead of the lighter thermal insulation material. The same goes for any internal stud partitions between bedrooms or bathrooms. 

You might want to consider insulating any party walls, both against heat loss and noise. A lining framework of timber stud will allow you to achieve both and you can cover it with sound-rated plasterboard.

10. Remember storage

Sliding Wardrobe in the Loft : modern  by Bravo London Ltd, Modern
Bravo London Ltd

Sliding Wardrobe in the Loft

Bravo London Ltd

Converting a loft means losing storage space. Thus, make the most of what you have by using the eaves behind the ashlering – fit access hatches and have roll-out storage bins made to fit. 

Remember that if you insulate down the rafter line to the eaves, you’ll create a warm store for your belongings. Built-in wardrobes are also a great feature in loft bedrooms, where standard units won’t fit.

Take all the necessary steps and you will soon end up with the loft of your dreams. Good luck!

Let’s check out: homify's Loft Conversions of The Year.

Planning a loft conversion? Tell us how you’ll use it...
Whitton Drive by GK Architects Ltd Modern

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