Attic dormer head height

walkingshadow

Hi
I'm going to put a dormer extension onto my attic (bedroom and ensuite). The attic at its highest point is 2.1m and I cant raise the dormer higher than the exisitng ridge line. Is it ok to have my ceiling height at 2.1m? I simply dont have the height to raise it higher, and I've never seen it written that 2.4 is the absolute minimum.

Gumbo

walkingshadow wrote: »

Hi
I'm going to put a dormer extension onto my attic (bedroom and ensuite). The attic at its highest point is 2.1m and I cant raise the dormer higher than the exisitng ridge line. Is it ok to have my ceiling height at 2.1m? I simply dont have the height to raise it higher, and I've never seen it written that 2.4 is the absolute minimum.

Are you currently in a 2 storey house or a single storey bungalow?

walkingshadow

2 storey

BryanF

Kceire what's your take on retrofitting fire seals to standard solid doors in the stairwell to achieve 30mins? Would they require specific certification? And if the floor to ceiling wasn't 2.4 what additional ventilation methods would you accept, assuming an openable suitable escape window was installed. And where the 2.4m ceiling was less than twice the width of the room width would a dormer of say calculated m2 to balance this shortfall, achieve the requirement to get a habitable space ?

Gumbo

walkingshadow wrote: »

2 storey

Then you are now entering the regulations required for a 3 storey dwelling.
Technical Guidance Document Part B is the daddy here, and must be complied with.

2.1m head height is the least of your worries as there are much more requirements to be achieved.

I don't get too hung up on head height as whats comfortable for me may be too low for someone that's 6 foot 7 for instance. You will however have to comply with the other technical requirements such as the smoke detection, second means of escape, beefing up attic floor joists etc etc

BryanF wrote: »

Kceire what's your take on retrofitting fire seals to standard solid doors in the stairwell to achieve 30mins? Would they require specific certification?

No problem with this. The Regulation requires a simple self closer device on existing doors when converting the attic (assuming you are talking about an attic conversion rather than a 3 storey dwelling built from scratch?).

The whole point of the fire door is to protect the escape rout vertically down through the building, so I would rather a retrofitted self closer over a retrofitted fire seal as most doors will give the occupant sufficient time to escape should the need arise. The biggest problem here is making that occupant aware of the fire in the first place, and its my main reason why I plead with builders to install smoke detection in all habitable rooms.

I wouldn't request specific certification as long as I can see the retrofitted items.

BryanF wrote: »

And if the floor to ceiling wasn't 2.4 what additional ventilation methods would you accept, assuming an openable suitable escape window was installed. And where the 2.4m ceiling was less than twice the width of the room width would a dormer of say calculated m2 to balance this shortfall, achieve the requirement to get a habitable space ?

Ventilation requirements again, on a conversion, I am happy with the normal 100mm vent, as if its good enough for a full height room, I'm sure its good enough for the smaller room. I don't check if its habitable to be honest, it could be a study, a games room or a roller disco for all I care, if there's a permanent staircase in place and the attic is floored and insulated and liveable then it needs to comply.

If its a 3 storey from the ground up and a new build, then the rooms must meet the tri-angle calculation from the off set, there's no excuse for incorrect design in a new build in my opinion.

Dormers count as floor space, so I see no reason why they cannot be included in the area calculations. You may need to use an average calculation depending on the layout but I have no issues with that, but as I said above, I don't check if its habitable, if you can get it to meet the Part B standards, then fire away (excuse the pun) and use it as a bedroom as its as safe as its ever going to be in my opinion.

lawred2

@kceire; are you a building standards inspector?

Gumbo

lawred2 wrote: »

@kceire; are you a building standards inspector?

I can neither confirm nor deny those alegations.

lawred2

kceire wrote: »

I can neither confirm nor deny those alegations.

lol

Only asking because I'll be doing a loft conversion soon to add a new bedroom. I'd like to have all the work certified at the end

Gumbo

lawred2 wrote: »

lol

Only asking because I'll be doing a loft conversion soon to add a new bedroom. I'd like to have all the work certified at the end

Will it require Planning Permission?
Are you putting a dormer window in or just velux to the rear?

lawred2

kceire wrote: »

Will it require Planning Permission?
Are you putting a dormer window in or just velux to the rear?

single bedroom and we plan on putting two velux windows to the rear

no dormer and won't be touching the roof line

Gumbo

lawred2 wrote: »

single bedroom and we plan on putting two velux windows to the rear

no dormer and won't be touching the roof line

My plan of action would be :

Get a drawing done showing the proposed layout so you know what you will get (give or take).
Appoint an engineer to design the structure.
get minimum of 3 quotes.
Get same engineer to supervise the construction and certify at completion.

Where are you based?

lawred2

kceire wrote: »

My plan of action would be :

Get a drawing done showing the proposed layout so you know what you will get (give or take).
Appoint an engineer to design the structure.
get minimum of 3 quotes.
Get same engineer to supervise the construction and certify at completion.

Where are you based?

North County Dublin.. Near Malahide