Non habitable attic conversion.

[RetroSaint]

Hi all,

I am thinking of doing a non habitable attic conversion just to provide more accessible storage and also a playroom for the kids. So essentially it's a case of strengthening the floor in places where there is a very large span and insulating / plasterboarding the rafters. The attic itself is an old style perlin construction, so the entire attic space is open bar a strengthening cross piece 2/3 the way down the house which I'm not going to touch.

Heating would just be when it's in use (ie. an electric convection), so my main concern is the health of the timbers, the job itself is just making the attic space more pleasant to be in!

My initial thought is something like 100mm of insulation below the rafters and plasterboard on top. Or perhaps less insulation given the time the space would be in use.

Does anyone have any knowledge of issues with damp when converting a cold attic in this way? Would additional batons across the rafters between the rafters and insulation / plasterboard be of any use in increasing ventilation around the timbers?

Thanks!

 

[OwainDIYer]

I am thinking of doing a non habitable attic conversion just to provide more accessible storage and also a playroom for the kids.

Then it will be a conversion to habitable space and must be done to full building regulations.

Presumably you do not want your children descending through the ceiling or being trapped up there in a fire.

Building Control interpretation may vary slightly but generally as soon as you have any two of floor, boarded walls or ceiling, stairs, window or rooflight, it's regarded as habitable.

Even if you already have (as some older houses do) stairs to a floored attic, new thermal elements and new fixed heating will be subject to Building Regulations and may be notifiable.

 

[tony1851]

Under the Building Regs, there is no such thing as a 'non-habitable loft conversion' which will also be used as a 'playroom for the kids'.

What you are proposing is a habitable room which will require a Building Regs application.

 

[RetroSaint]

To be fair I do intend to follow regs in terms of floor strengthening (as already mentioned) and using what is suitable insulation. A 50mm in rafter and 50mm under rafter or 100mm below should I believe meet regs with suitable insulation last time I looked.

What I am interested in knowing is what I asked. This room is not intended to be heated and used on a regular basis, it's more like a nice shed which happens to be located on the top of my house.

So in the same way I don't consider my shed a habitable space, I don't consider this space a habitable space either.

My question is that of any potential problems of condensation damaging the roof timbers in a non heated and insulated attic room. I'd appreciate answers to the question posed.

 

[tony1851]

What sort of access are you considering? eg fixed ladder or pull-down, or alternating-tread stairs etc?
Sorry to be pedantic but access has a bearing on how the room is classed. There is little point in keeping to some of the regs if you are not using it as a habitable space.

 

[freddiemercurystwin]

If you intend to fit any kind of permanent access then you may not consider it habitable, Building Control will see it as otherwise. Most importantly is that the next owner will probably see it as habitable and as such you may well will be unwittingly providing them with a death trap. I for one shall not have anything more to do with this thread. I'm all for turning a blind eye when some crappy bit of bureaucracy that gets in the way but this is an altogether different beast.

 

[RetroSaint]

Just to reiterate this is largely to create additional 'nice' storage space. There is not going to be a fixed access to the space, there is likely to be a pull down ladder. At the moment there is just a hatch which isn't really very useful for regular access, and the misses won't venture up there as its full of cobwebs.

The issue, as with many, is a lack of storage with a couple of kids growing up. The intention is to be able to get access to all of the many things most of us store up in the attic like toys, clothes, etc, while making it pleasant.

The additional floor space for the kids to arse about in is just an added bonus.

I used to play up in the garage attic as a kid. This in my mind is a similar thing. Likewise I would have never considered the garage attic habitable.

Again my concern is over the integrity of my roof...

 

[RetroSaint]

Man alive some people get uppity. At no point have I said I am not following building regs, quite the opposite I have said they have been read and I am looking at appropriate measures. This is largely to give me peace of mind I might add, as I always tend to over engineer things.

I'll rephrase this to help those who have an issue here.

I am intending to follow all building regs to convert an attic space with regards to floor strengthening and insulation however I don't intend to heat this space and merely use it for infrequent access for storage.

Is the lack of heating going to case an issue with damp in the rafters given this situation?

 

[tony1851]

There are no building regs which deal specifically with loft floors for storage. If you want to upgrade the floor 'to building regs', it has to be done to carry normal domestic loading of 1.5 kN/sq.m.

This means one of two things;

either (1) you put in new floor joists, following the published size/span tables;
or (2) you try and strengthen the existing ceiling joists.

If you go for option 1, you will need main beams to support the new joists. These main beams will need structural calculations to prove adequacy - they are usually steel beams but large timber beams can be used if the spans are not great.

If you go for option 2, you will need to know how to strengthen the existing ceiling joists to bring them up to standard, which is not easy.

And this is not even considering factors such as insulation and electrics etc which again many people get wrong as shown by posts on this forum.

This is why there is no easy answer to your original questions because some things can't be done by half measures. You can't pick and choose which regs to comply with and which not to. Ultimately if things went pear-shaped, you would be liable.

 

[RetroSaint]

Thanks Tony,

I've read into the flooring side of things and a side by install of thicker joists. What is there at the moment doesn't fill me with confidence for storage in the area with large span -- you can feel the floor flex under you in the middle. Needless to say things are stored near the supporting ends of the span.

But I am happy with all of this, I can find suitable specs and understand how to handle these situations.

What I can't find any information on is if there are any ventilation considerations for a non heated space. Everything assumes heated, which is fair enough, but this isn't my goal.

As far as I can tell as well, if there is no fixed access or windows, etc, this isn't classed as habitable and regs do not apply. Even so I like to stick to them as a guide for what is safe and sensible.

The main reason for all of this is to create a more accessible and more pleasant storage area so others are happy to use it and I don't have to hunt around in bloody boxes all the time for things.

I wouldn't think it would cause damp issues given the loft space is not heated as you have no warm air to condensate other than residual heat from the house. But I will obviously be reducing airflow by boarding... hence my caution.

In that sense a vapour barrier and plasterboard may well be enough for my needs.

Assuming a non fixed access to this space and no windows, would building control asses this as non habitable?

I just want an easily accessible 'nice' storage space!

 

[RetroSaint]

Ok, from what I've read how you use the space and access to it determine its status. So this will be non habitable from bc perspective due to a ladder and complete lack of anything to allow habitation.

So if anyone could comment on my original question in my quest to make a 'posh loft' that'd be grand.

 

[OwainDIYer]

Access by ladder does not preclude it being considered habitable space. (Access by ladder may not be compliant with Building Regs, but that does not stop it being considered habitable space. A room without a window might not meet Building or other Regs, but that wouldn't stop it being a habitable room.)

It seems clear that, in law, you are creating habitable space, and the law requires you to follow Building Regulations in their entirety. This includes notifying the local authority.

If you're boarding out the floors and walls then it's becoming a 'room' and even though you might consider it a 'storage room' that's still considered to be habitable accommodation under Building Regs.

You can board the floor ONLY, and have a movable ladder, and it will remain an attic. Board the walls, or insulate, or fit a fixed ladder, and the work is more likely to be viewed as creating habitable space.

In any event any floor 'strengthening' is structural work and notifiable even if you aren't creating habitable space.

Sheds are exempt from Building Regs if certain criteria are met.

You really need to talk over what you actually want to do with your local Building Control Officer.

 

[tony1851]

Under Building Regs a habitable room requires purge ventilation (see Approved Document F).
This requires an opening to the external air of - IIRC - 1/20th of the floor area. That would imply some sort of openable window.
Besides this, there will almost certainly be other legislation (eg the Housing Acts?) requiring natural daylighting to habitable rooms, even if it didn't come directly under Building Regs.
It would be inconceivable in this day and age that the law would allow habitable rooms with no natural lighting.

 

[freddiemercurystwin]

That's an interesting point that's been covered before tony but you know apart from the purge ventilation issue I'll be damned if I can find any legislation that says a habitable room must have a source of daylight. I have seen such suggested regulations banded around but have never been able to find it.

 

[hansPulesh]

Hi all,

I am thinking of doing a non habitable attic conversion just to provide more accessible storage and also a playroom for the kids. So essentially it's a case of strengthening the floor in places where there is a very large span and insulating / plasterboarding the rafters. The attic itself is an old style perlin construction, so the entire attic space is open bar a strengthening cross piece 2/3 the way down the house which I'm not going to touch.

Heating would just be when it's in use (ie. an electric convection), so my main concern is the health of the timbers, the job itself is just making the attic space more pleasant to be in!

My initial thought is something like 100mm of insulation below the rafters and plasterboard on top. Or perhaps less insulation given the time the space would be in use.

Does anyone have any knowledge of issues with damp when converting a cold attic in this way? Would additional batons across the rafters between the rafters and insulation / plasterboard be of any use in increasing ventilation around the timbers?

Thanks!

If you have the space, have you considered an outbuilding in the garden or something along those lines? It'd be a lot easier and the regulations are a lot easier to work with. It also means that you won't need to mess with the structure of your house?