Minimum door width into non habitable room?

[ProDave]

simple version of question: What is the minimum door width into a non habitable room (plant room) under Scottish building regs?

 

Longer version.

 

The plant room is the attic space above the attached garage. It is accessed through a door from the master bedroom. Next to this door was going to be the twin wall flue from the wood burning stove in the room below making it's way up to the roof.

 

But SWMBO has just changed the room layout around, and suddenly this wall needs more space, so the flue has to move.  The flue position is dictated partly by joists positions, so to move the flue over, it would have to jump into the gap between the joists "one joist over" if you see what I mean. That would put the flue in front of the door opening.

 

Here's a picture trying to explain it:

 

The wall is a supporting gable end wall, there is a lintel over the door opening supporting the ridge beam, so moving the door opening over is not an option. the only option is to make the door narrower.

 

I then have to make some assumptions as I have not yet chosen the flue.  It seems from the searching I have done the minimum flue size recommended is 5" which in the twin wall version has an outside diameter of about 280mm. (I don't know why but nobody recommends a 4" flue which I would have thought was plenty for my little 3Kw stove) A further assumption is what distance has to be left between the flue and a combustible material (i.e. the joist) Building regs leave it entirely up to what the manufacturer of the flue specifies. As I have not yet chosen which one I am using, I have taken a "typical" 3" clearance and allowed 80mm between the flue and the joist.

 

As the drawings shows that would allow me a door opening of 700mm wide which translates to an imperial 2ft 3" door.

 

My question, is would this be acceptable (it would be acceptable to me)

 

 

All I can find in building regs is the section on accessibility within a building which typically talks of door widths of 850mm but says a door may be reduced to 775mm if it is approached straight on (which this one is)

 

But this is NOT a habitable room, it is the plant room so does that width still apply?  The room in all probabilty will resemble a "loft" space with only part of it being floored for the mvhr to sit on and access to it.

 

 

[Guest Alphonsox]

23 minutes ago, ProDave said:

But this is NOT a habitable room, it is the plant room so does that width still apply?  The room in all probabilty will resemble a "loft" space with only part of it being floored for the mvhr to sit on and access to it.

 

What makes this a plant room ? Just the MVHR ? From your description it sounds like you are providing a generously sized, vertical loft hatch.

[ProDave]

It's a "plant room" because that is what is says on the plans. Originally it was going to contain the mvhr, heat pump (GSHP) and hot water tank(s). however we have changed to a monoblock ASHP and the hot water tank is going to go in a cupboard off the small bedroom so it is a lot closer to the kitchen. So now it is just the mvhr and some storage space. (with our vaulted ceilings there is very little conventional "loft" space)

 

But you have touched on an other potential issue, that is of the council tax valuer trying to include it as "habitable space" hence why (at least to start with) very little will be boarded.

 

I guess a "solution" to both problems is just install a small trap door that you have to undo a few screws to get in there? The door can then come later. But I would rather know the answer now and just fit a door.

 

 

[joe90]

I would have said it was a Cupboard !

[ProDave]

3 minutes ago, joe90 said:

I would have said it was a Cupboard !

Yes, but  what width of door does a "cupboard" require?
 

[joe90]

That's my point, cupboard doors in kitchens for example go down to 300mm. I cannot see how a minimum door width can be specified ?.

[Guest Alphonsox]

I've just fitted a new 6ft 6" x 24" wide door to our built-in wardrobe. Standard size at B&Q and easily big/small enough for your requirements. So it's not a plant room it's a walk-in cupboard.

[Simplysimon]

well, as your min. width of stairs is 600mm, i'd go with 600mm as specified as a cupboard. don't know if you've seen these -

http://www.nhbc.co.uk/Builders/ProductsandServices/BuildingControl/documents/filedownload,52832,en.pdf

http://www.nhbc.co.uk/Builders/ProductsandServices/TechZone/nhbcstandards/

 

simon

[ProDave]

The nhbc documents make it clear that it is only habitable rooms that need to meet the minimum door widths. Unfortunately that is not made clear in the Scottish building regs.  I feel a phone call to the "duty building control officer" will be due on Wednesday.

 

I could of course fit a standard width door, but then I would expect someone to complain the flue pipe is partly blocking the door, hence my idea to reduce the door with to remove that argument.