Is my home suitable for a loft conversion?

This week I went out to see two local enquiries, both looking for loft rooms. Whenever I go out to look at an enquiry I have to look into the future to see how the design ideas will progress – what can we achieve, which will be the problems that I can solve and what can’t I fix? Making a loft room is a complex design problem and there is a lot to be resolved – the stairs, the joist plan, the roof structure, the steel. What I need to discover on my first visit is the problems that cannot be overcome – the foundation problems in the hierarchy.

On site, once I have talked to the client to see if they have a clear idea of what they want, they have a realistic budget and I think I can help them, I have two things that I know will make or break the project. Here they are so you can check them yourself if you would like to know.

1. The headroom

Go into the loft and measure the height from the top of the ceiling joist that you are carefully balancing on to the underside of the ridge board. This is the surprisingly thin board that form the apex of your roof and that the rafters are fixed to. You are looking for 2.7m. If you have this, you have the best chance for a good loft room. I have done loft rooms with much much less than this – right down to 2.1m and there is a way to do it, but it involves a lot of compromise and it is not always possible. Maybe you are looking at buying a house with the idea to have a loft room – check in the loft now. If you can stand up straight in the middle that is not enough. You want to be able to stand up and not be able to touch the ridge board. I went out to see an enquiry last year and the client was convinced that they had good potential for a loft room. They were already using the loft, which was very large, as a storage space and a den, which could be reached with a loft ladder. They had 2.2m to the ridge, which is very low and a loft room was not possible. Here is why. We need 2.0m headroom above the landing at the top of the stairs for building control. Some building control items can show some flex, not this. The insulation layer to the underside of the existing roof will be about 200mm thick, which will take us down to 2.0m, but the existing ceiling joists are only 75 or 100mm deep. They are not strong enough to take the normal loads of a habitable room – a bed, wardrobe, book case. The new floor joists will be about 200 thick with the floorboards on, leaving us only 1.9m if we can fit them in between the existing joists.  In a house with high ceilings in the first floor bedrooms we can put the new floor in at a lower level and steal some height from the bedrooms below. For this client the first floor ceilings were already very low, only 2.1m, so we had nowhere to go.

2. Means of escape

If your home is on fire, you need a safe route to escape. What a makes a safe route is set out in the building regulations and you can look it up for yourself right here. Firstly you will need smoke alarms to the current approved standard – not a design obstacle at all. The hard part is finding the escape route. This needs to be a protected route from the bedroom door to the outside that passes through no other room except a hallway. If you live in a 100 year old terraced house, you might not even have a hallway, going through one or even two rooms before you can can get from the stair to the street. That’s fine for a first floor bedroom – because the building regulations say you can jump out of the window – but for a loft room, it’s a big no. There is an alternative, which is very commonly used in the local typology, which is alternative direction of escape. If you have a house where the stairs come down between the kitchen and the dining room, you can get out through the kitchen or through the living rooms. The idea is that you turn your back on the fire and go the other way. If your home has the stairs running side to side across the house, so you enter the second living room to get to the stairs, you have a problem. You are coming down the stairs, in a fire and you don’t go into the hallway and out, you don’t have an alternative, but you have to go through living room 2, which might be on fire.

There are four solutions to this problem. The most beautiful is to have an escape window into the alleyway from the bottom of the stairs. My local authority building control won’t accept this – you can jump out of a bedroom window but not from 1 metre above ground level – but my independent building control service will, so I use them in this situation. It’s a good solution and in my opinion safer than going through the room. If you don’t have an alleyway on that side, you are stuck.

The next three solutions are not so sweet. You can use a mains fed domestic sprinkler system. This is also independent inspector only. You can take out your ground floor stairs and replace them with another pattern that give two directions of escape. I have done this and it worked – but it needed a client with a lot of determination! The third option is the double landing. It is hard to explain and hideous to conceive. It also comes from the local authority. What disturbs me most about this solution is that as soon as the building control officer has signed it off, the builder will be back to rip it out. Here’s the scheme: you form a flat landing on about stair five, break out door height openings in the wall on both sides and put an enclosed landing and four steps into each room, giving you two directions of escape. Don’t do this – move house.

So, back to my two enquiries. Mrs M has 3.0m of headroom and existing stairs with two directions of escape – we are go! Mr H has 2.2m of headroom and the project has been abandoned. There are a lot of other considerations for the design of a loft room such as where to put the stairs, whether to have a dormer, the planning permission, building regulations and of course, your party wall notices, but these two considerations should be at the top of your mind before you start on the project.