Loft height - minimum regs require

[Lucasdemoley]

Hi,

I bought a house with a large extension. The extension part of the house is prepared for a loft conversion ( suitable floor joist, veulux window, dorm windows, plenty of hear height), however the only place I can make access to the attic space is from the existing house due to room layouts.

One bedroom has already been partitioned off to I assume allow a stairs to be installed (currently my wives shoe room). It is quite narrow though, only approx 1.2m wide, reducing to 0.9m due to a chimney breast so I assume I would probably have to use a spiral staircase.

Anyway, in the attic of the existing part of the house the head height is only 2m in the centre, which is about 30cm wide, after which the roof slopes quite steeply (I would say 45 degrees). It has already been boarded out, however I will need to upgrade the joists in this area as the previous owner simply cross-battended this area to better spread the weight, as opposed to doing a proper job.

So my question is would this ever be building regs compliant, or will I only ever be able to consider it as a store area? How much extra height would I need to be compliant?

Also, does anyone have knowledge of spiral staircases? I am guessing I would need to consider the point loadings on the joists if I was to install one?

Many thanks for help!

 

[freddiemercurystwin]

Strangely there's no minimum requirement for ceiling height except above a stair where it should be 2m or a bit less if the roof is sloping. So if you could live with less then that's fine but some future purchasers may well be put off. I don't follow the stair bit, need a couple of sketches of the plans to appreciate that probably. Supporting a spiral stair sounds like the least of your worries if you've only got 2m in the middle and have to beef up the floor and add a ton of insulation at roof level.

 

[Lucasdemoley]

Strangely there's no minimum requirement for ceiling height except above a stair where it should be 2m or a bit less if the roof is sloping. So if you could live with less then that's fine but some future purchasers may well be put off. I don't follow the stair bit, need a couple of sketches of the plans to appreciate that probably. Supporting a spiral stair sounds like the least of your worries if you've only got 2m in the middle and have to beef up the floor and add a ton of insulation at roof level.

Cheers for the reply. Is 2m at the centre point or does it have to be the whole width of the stairs?

The ceiling is already boarded and insulated (although I am not sure if its to the required level, any ideas what thickness insulation required?). Whilst the floor will need some work, I shouldn't loose any height as the cross boarding is about 3 inch thick onto of the existing ceiling timbers, so if I take this out and put back in proper timbers, I don't think their profile will be thicker than this.

Effectively I have a loft the full width of my existing house, about 9m or so, and 2m high in the middle. The new roof butts into the existing roof at 90 degrees. The ceilings are lower in the new part of the house, giving more attic space, so whilst the attic space in the existing part of the house isn't really usable (bar maybe putting a shower at one end), there is quite a bit of usable space in the extension, which is a much lower pitch.

I'll probably end up making another post about the spiral stairs, I am just trying to figure out the way the attic conversion will work as I am undertaking other works which need to consider what I will eventually do with that space.

Cheers.

 

[xr4x4]

http://www.kevinparsonsltd.co.uk/res/BR_PDF_ADK_1998.pdf

Page 8

 

[freddiemercurystwin]

I don't know what your floor set-up is? Has any strengthening been done to the floor? Was this done to any design, has Building Control been involved?

Anyway, typically you need about 100mm insulation between the rafters and a continuous 40mm layer beneath, then plasterboard, with a 25mm gap between the insulation and the underside of the roofing membrane assuming its breathable. That's assuming your rafters don't need strengthening and are deep enough.

 

[Lucasdemoley]

I don't know what your floor set-up is? Has any strengthening been done to the floor? Was this done to any design, has Building Control been involved?

Anyway, typically you need about 100mm insulation between the rafters and a continuous 40mm layer beneath, then plasterboard, with a 25mm gap between the insulation and the underside of the roofing membrane assuming its breathable. That's assuming your rafters don't need strengthening and are deep enough.

Hi, in the new part of the house the joists in the attic are the same depth as the ones in the first floor so I assume they are suitable, however I will ask someone in work to double check the dims.

Thanks for the info on the rafters, again in the new part of the house I have plenty of space, but I think the old part of the house I might struggle with the depth you mention - I'm pretty sure my rafters in the existing house are only 4inch deep but I will double check.

As far as floor boarding is concerned, should I go for the attic boards like you get in B&Q, or should I go for the large sheets, half width so they fit through the attic hatch?

Many thanks.