Loft room or bedroom: what actually decides it

I converted the loft of a bungalow about five years ago. Velux windows, an ensuite, two months of work, seventeen thousand pounds. It became a bedroom with its own bathroom and it has stayed that way ever since.

If I did it again I would put a dormer in. Not because anything went wrong, and not because I regret the money. A dormer would have made it feel more like a proper room, and there is a real distinction hiding in that sentence which is worth pulling apart before you spend anything.

The difference between a loft room and a bedroom

A conversion with a dormer or a mansard, reached through a proper entrance door into the room, reads as a bedroom. Somebody standing on the landing sees a door like every other door in the house.

A Velux conversion where you climb the stairs and walk straight into the space, with no door at the top, tends to be counted as a loft rather than a bedroom. That is how it gets described when the house is sold, and it is how buyers read it too.

Now, before this sounds like a warning: a loft room still adds value. It is usable floor area you did not have before, and done well it is worth having. Plenty of people are perfectly happy with one.

But the two things are not the same thing, they do not cost the same, and almost nobody explains the difference before the money is committed. A dormer and a door are what separate them.

The headroom rule that is not a rule

You will read everywhere that you need 2.2 metres. Worth knowing that this is not a legal requirement. The building regulations set no minimum room height for a loft conversion at all. What they govern is headroom over the staircase.

The 2.2 metres is a rule of thumb, and it is a good one, for a reason that has nothing to do with regulations. Measure from the floor to the centre of the roof before any work starts, and then subtract about twenty centimetres, because that is what the conversion itself takes: a new floor structure and strengthening, insulation between and under the joists, plasterboard and skim on the ceiling.

So a loft measuring 2.2 metres today is a room of roughly two metres when it is finished. My own view is that below 2.2 to start with, it is not worth doing, because the finished room will not be comfortable to be in.

That number is also why so many people are disappointed at a stage when it is too late to change anything. You decide while looking at an empty loft, which feels enormous. Then the layers go on, the walls come in, and the room you are standing in feels considerably smaller than the space you agreed to buy.

Where the stairs land, before headroom

The staircase is the first thing I look at, ahead of the roof.

A loft staircase takes somewhere between two and four square metres of the floor below, depending how wide you make it. If it goes above an existing landing, that is a cheap trade and you give up very little. If the only place it fits is inside a bedroom, you are about to convert a loft by destroying a bedroom, and the house may finish with no more usable rooms than it started with.

That, in my experience, is the thing that genuinely kills a loft conversion. Not the roof.

Trussed roofs, which are not the obstacle people think

Modern British houses, meaning roughly 1960s onward, tend to have trussed roofs, and there is a widespread belief that these cannot be converted.

They can. The work is re-engineering the roof so it remains structurally sound once the trusses are altered or removed. That takes thorough calculation and proper structural work, so it is not a small job and it is not a cheap one. It is a long way from impossible.

I have never seen a loft ruled out as unconvertible. I have seen plenty where the answer was that it would cost more than the owner wanted to spend, which is a different sentence and a much more useful one.

What the quote does and does not cover

Three things belong in the budget from the start, and only one of them is reliably in the price you are first quoted.

Fire safety is part of the conversion. Adding a habitable room at the top of a two-storey house brings requirements for a protected stairway, fire doors and linked alarms, and some of that work lands on the floors below rather than in the loft. This should be treated as part of the job and written into the quote, never presented to you later as an optional extra.

Party wall, if the house is not detached. For a terrace or a semi this goes in the budget on day one. A straightforward notice can be a few hundred pounds. Where there are several neighbours, or the situation is complicated, or somebody disputes it, it can reach five thousand.

The water tank. If there is a tank in the loft it has to go somewhere, and one answer is to switch the house to an unvented cylinder so no tank is needed at all. That is an extra plumbing job on top of the conversion and can add up to two thousand pounds.

The chimney breast, by contrast, is usually the easy one. It gets boxed in and becomes part of the design.

And then there is the category nobody can price in advance, which is whatever the job turns up once it is open. The single most common complaint I hear about loft conversions is not about the finished room. It is that the quote did not cover everything that later turned out to be necessary, and the price moved.

The rain

One thing that gets left out of every guide I have read.

There is a period in the middle of a loft conversion when your roof is open. This is Britain. If it rains during that window, and it will, you can have real problems, and they are problems inside your house rather than on top of it.

Ask how that stage will be managed before the work starts, rather than discovering the answer when water comes through a bedroom ceiling.

What a buyer will want to see

The same pattern as any other structural work: the paperwork is what survives, and the paperwork is what a surveyor and a solicitor will ask for.

They will want the Building Regulations completion certificate. They will want a window certificate, which means FENSA or Certass. Certass is the more common one for Velux roof windows and FENSA for uPVC dormer windows, and both are accepted when you come to sell. They will want the other certificates for whatever notifiable work was done. And where the house is not detached, they will want the Party Wall Award or agreement.

Keep them somewhere you will find them, because you are going to be asked for them years after you have forgotten which drawer they went into.

What it does to the house

A loft conversion generally increases value, and how much depends on the kind of conversion and the floor area you gain.

It does not much change who wants to buy the house, with one exception worth thinking about if you are near retirement or expect to sell to somebody who is. A loft bedroom means climbing two flights several times a day, and that makes it less attractive to older buyers.

When it is the wrong answer

Four situations, and if you are in one of them, think hard.

You do not have the headroom to start with. The staircase would destroy a good bedroom. The house is terraced or semi-detached and has already been extended, so this would simply be too much for it. Or you could get the same amount of extra space more cheaply by extending somewhere else, or by moving.

If any of those apply, an extension or a garage conversion is usually the better route to the same room. There is nothing special about a loft except that it is already there, and being already there is not the same as being cheap.