Ceiling height

[bolst3r]

What is an acceptable ceiling height for a garden office? I know it largely depends who it's for but I don't want to make it ridiculously low just because i'm short (5'10")

My problem is the space lost from what i'm planning for the floor and roof:

FLOOR:
• 80mm Raised piles to give air flow to base and avoid damp ingress
• 95mm frame
• 18mm WPB
• 25mm batton and celotex
• 18mm chipboard
• 5mm carpet tiles

Floor total = 241mm

ROOF (WARM DECK):
• 12mm Plasterboard
• 95mm roof joists (2.5mm length)
• 12mm WPB
• 2mm vapour barrier
• 75mm celotex
• 5mm EPDM
• 50mm edge trim

Roof total = 251mm

Leaving a ceiling height of a little over 2m

I can change the roof to a cold deck but really didn't want to go down this route as it's not as efficient (so they say) and is more complicated to install...

What would you lot do?

 

[^woody^]

2m is not even the height of an external door frame

Why can't you do a more normal 2.3 ceiling height?

 

[bolst3r]

@Woody

Problem is permitted development only allows my office to be a total of 2.5m in height as it's within 2m of my boundary

Not sure how these companies selling these 'garden office' solutions get away with it. I expect they compromise slightly on the thermal efficiencies to get the necessary headroom although looking at the images included below they do seem to have lower than normal ceiling heights...

I guess a cold deck roof would save me 100mm so I could make the ceiling height just under 2.2m

Untitled

• bolst3r
• 19 Jun 2013
• 1

 

[tony1851]

because i'm short (5'10")

You think that's short?! I'm 5' 5 "15/16ths

 

[^woody^]

Put your insulation between the roof joists - the full depth of the joists. If you want to, and add 12mm to the underside before the plasterboard to avoid pattern staining

Put floor insulation between the floor joists and the deck on top with no battens and no need for two layers of 18mm ply and chipboard. Just the joists and then 1 deck on top of them

I'm not sure that the 80mm raised pile are to achieve? Reduce that

 

[bolst3r]

@tony

My wife would question my stated height...

@woody

Are you suggesting a closed roof with no space left for ventilation? Assume I would leave out soffit vents and seal the whole lot and this wouldn't cause an issue?

The 80mm piles are to raise the base frame off the floor so air can pass through and to avoid damp ingress. If I don't put the base on raised piles it will be sat in/on the ground. Not sure how to overcome these issues

Thanks for the info but not sure i understand what you're saying about the floor construction - being really dumb here I know, please bear with me... I was going to build a sturdy frame that sits on the piles, then wpb, then insulation/batons followed by chipboard then carpet. Are you saying stick the insulation in the frame voids? If so how do I stop it falling out, getting wet and vermin in?

 

[^woody^]

Yes no ventilation in the roof just insulation

You only need a minimum 25mm air gap beneath the floor for venting. But if you are worried, then just lower the ground beneath the floor to form a bigger void, and then keep the floor just above ground level

Or build the floor off paving slabs

Insulation can be held in with nails, battens, netting or expanding foam, and covered with polythene/membrane or 6mm ply

Untitled

• ^woody^
• 20 Jun 2013
• 1

From a design point of view, I would avoid building a cabin off timber posts in the ground, as these will rot

 

[Porque223]

2m is not even the height of an external door frame

Why can't you do a more normal 2.3 ceiling height?

Over here door heights are 80"/2 m and ceiling, 8'/2.4 m and I assume these dims accommodate 95% or 99% of the people who use them, at the time they were built.

 

[tony1851]

ceiling, 8'/2.4 m

Over here there is no statutory minimum for ceiling heights.
It's so that large Victorian houses can be converted with additional floors to cram in as many immigrant Eastern Europeans as possible.
They can then all be given all kinds of benefits for just sitting around begging while the landlords rake in the profits.

 

[bolst3r]

@Woody

Ok that makes sense and digging out the ground is a good suggestion, I can then cover it with a weed membrane and gravel just to keep things neat I guess as long as I have gravel or some sort of loose flooring round the perimeter then I don't have to worry about damp and water ingress?

It will feel slightly strange not leaving a ventilation gap behind the insulation in the roof, would rather stuff it full of insulation and of course would use a vapor barrier but what stops condensation building up and rotting the roof joists? Is it the fact that the insulation will stop the warm air getting through to the cold roof deck thus stopping condensation forming?

@Tony1851



Think i've covered every emotion...