I'm planning on building a new large shed, hopefully with low heating
requirements and a steady temperature all year round to enable me to
use it for woodworking projects.

To keep the heat loss down to a minimum I'm going to use a high level
of insulation in the walls floor and ceiling but even after reading a
load of literature. I can't work out if what I'm doing is going to be
ok.

With regard to the walls, the studs will probably be 89 x 38 CLS on a
600mm spacing with 12mm ply on the inner wall. The insulation will be
75mm foil covered celotex, with a tyvek outer breather layer and fibre
cement weatherboard on the outside to try and make it meet fire regs
(class 0)

Do I need a vapour barrier behind the inner ply?

Do I leave the gap caused by the difference in wall stud depth and
insulation depth on the hot side next to the ply or on the cold side
towards the tyvek or doesn't it matter?

The shed will be around 0.5m from a shared boundary fence and at least
5m from any existing structures. Will a mainly timber frame structure
covered in fibre cement weatherboarding (with a green roof of sedums)
meet class 0 standards or will I need plasterboard on all the inner
surfaces?


--

On 30 Oct, 13:14, Mike wrote:

With regard to the walls, *the studs will probably be 89 x 38 CLS on a
600mm spacing with 12mm ply on the inner wall. The insulation will be
75mm foil covered celotex, with a tyvek outer breather layer and fibre
cement weatherboard on the outside to try and make it meet fire regs
(class 0)

Do I need a vapour barrier behind the inner ply?

Do I leave the gap caused by the difference in wall stud depth and
insulation depth on the hot side next to the ply or on the cold side
towards the tyvek or doesn't it matter?


Pretty much what I did except I used ship lap for the cladding mounted
on 2x1 batten nailed to the studs with the building paper held to the
studs by the battens. This gives ventilation behind the ship lap.

I had the gap due to the wall insulation nearest the outside with the
foil side out (only one side of mine is foil covered). Then a poly
membrane which I am told is not strictly necessary but I did it anyway
and the 12mm ply. It worked really well.

I also have a warm deck roof constructed with 105 mm tissue faced
kingspan and a three layer built up felt roof on top. Saves having to
ventilate the roof space.

I have no idea about the class 0 fire regs I am afraid but wait for
others comments with interest.


Andy

Mike wrote:
I'm planning on building a new large shed, hopefully with low heating
requirements and a steady temperature all year round to enable me to
use it for woodworking projects.

The shed will be around 0.5m from a shared boundary fence and at least
5m from any existing structures. Will a mainly timber frame structure
covered in fibre cement weatherboarding (with a green roof of sedums)
meet class 0 standards or will I need plasterboard on all the inner
surfaces?

When you say 'large', anything with a floor area more than 15m^2 that
close to the boundary will require a Building Regulations application.
Also check about Planning. If it were more than 1m from a boundary, it
could be up to 30m^2 and still be exempt from Building Regulations.

Building Control will be concerned about structure, external fire
spread, resistance to moisture, and ventilation (amongst other things).

Roofs within 6m of a boundary must be class AA rating, ie,
non-combustible. Vegetation can dry up and represent a risk of fire
spread. External walls must be of 30 minutes fire resistance within 1m
of the boundary, which means in your case that you will need
plasterboard on the inside, as well as the non-combustible cladding.

The thermal insulation requirements do not apply to a free-standing
building of less than 50m^2.

A timber framed building should have a vapour barrier on the warm side
of the insulation. The plywood or other sheathing should be on the
outside of the studs, with breather membrane to the outside of that, and
a ventilated and drained cavity inside of the cladding.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed"?

Hugo Nebula coughed up some electrons that declared:

Mike wrote:
I'm planning on building a new large shed, hopefully with low heating
requirements and a steady temperature all year round to enable me to
use it for woodworking projects.

The shed will be around 0.5m from a shared boundary fence and at least
5m from any existing structures. Will a mainly timber frame structure
covered in fibre cement weatherboarding (with a green roof of sedums)
meet class 0 standards or will I need plasterboard on all the inner
surfaces?

When you say 'large', anything with a floor area more than 15m^2 that
close to the boundary will require a Building Regulations application.
Also check about Planning. If it were more than 1m from a boundary, it
could be up to 30m^2 and still be exempt from Building Regulations.

From my research, 5m (as mentioned by the OP) from the existing house
avoids the building being deducted from permitted development, weird stuff
like conservation areas notwithstanding.

Thanks for the heads up on the 1m rule. I've had a b***er of a job trying to
find a site for my proposed shed/workshop that get's by on a "no
permission" basis.

Although I've not seen many sheds that aren't against a boundary (or
certainly withing 0.5m) - have you ever known anyone be busted for such an
offence?

snip

A timber framed building should have a vapour barrier on the warm side
of the insulation. The plywood or other sheathing should be on the
outside of the studs, with breather membrane to the outside of that, and
a ventilated and drained cavity inside of the cladding.

That's useful to know.

Cheers

Tim

coughed up some electrons that declared:

On 10 Nov,
Tim S wrote:

From my research, 5m (as mentioned by the OP) from the existing house
avoids the building being deducted from permitted development, weird
stuff like conservation areas notwithstanding.

The regulations have recently changed (from October?). My first reading
seems to indicate that the permitted development limit (of a percentage of
the original size) was no longer there. Can anyone clarify on this?


I think permitted development is still there in general - it had better be
because I've got 40m3 of PD left and I plan to use it. The scope of
buildings in the garden changed a bit - I did notice that. You can stick
solar and ground source heat pumps in now as a permitted activity but you
may need permission for certain types of driveways (water runoff).


Cheers

Tim

Tim S coughed up some electrons that declared:

coughed up some electrons that declared:

On 10 Nov,
Tim S wrote:

From my research, 5m (as mentioned by the OP) from the existing house
avoids the building being deducted from permitted development, weird
stuff like conservation areas notwithstanding.

The regulations have recently changed (from October?). My first reading
seems to indicate that the permitted development limit (of a percentage
of the original size) was no longer there. Can anyone clarify on this?


I think permitted development is still there in general - it had better be
because I've got 40m3 of PD left and I plan to use it. The scope of
buildings in the garden changed a bit - I did notice that. You can stick
solar and ground source heat pumps in now as a permitted activity but you
may need permission for certain types of driveways (water runoff).


Cheers

Tim

BTW - have a look at this:

http://www.planningportal.gov.uk/upl...ouseguide.html

Cheers

Tim

PS

From the planning portal, the section on sheds:

"
Under new regulations that came into effect on 1 October 2008 outbuildings
are considered to be permitted development, not needing planning
permission, subject to the following limits and conditions:

*
No outbuilding forward of the principal elevation fronting a highway.
*
Outbuildings and garages to be single storey with maximum eaves height
of 2.5 metres and maximum overall height of four metres with a dual pitched
roof or three metres for any other roof.
*
Maximum height 2.5 metres within two metres of a boundary.
*
No verandas, balconies or raised platforms.
*
No more than half the area of land around the "original house"* would
be covered by additions or other buildings.
*
In National Parks, the Broads, Areas of Outstanding Natural Beauty and
World Heritage Sites the maximum area to be covered by buildings,
enclosures, containers and pools more than 20 metres from house to be
limited to 10 square metres.
*
On designated land* buildings, enclosures, containers and pools at the
side of properties will require planning permission.
*
Within the curtilage of listed buildings any outbuilding will require
planning permission.

*The term "original house" means the house as it was first built or as it
stood on 1 July 1948 (if it was built before that date). Although you may
not have built an extension to the house, a previous owner may have done
so."

On Sun, 09 Nov 2008 23:50:26 +0000, Hugo Nebula abuse@localhost
wrote:

Mike wrote:
I'm planning on building a new large shed, hopefully with low heating
requirements and a steady temperature all year round to enable me to
use it for woodworking projects.

The shed will be around 0.5m from a shared boundary fence and at least
5m from any existing structures. Will a mainly timber frame structure
covered in fibre cement weatherboarding (with a green roof of sedums)
meet class 0 standards or will I need plasterboard on all the inner
surfaces?

When you say 'large', anything with a floor area more than 15m^2 that
close to the boundary will require a Building Regulations application.

I'd deliberately planned it to be a smidgen under the 15m2 floor area

Also check about Planning. If it were more than 1m from a boundary, it
could be up to 30m^2 and still be exempt from Building Regulations.

1m from the boundary would place it too close to an existing garage to
use the path (it's a very narrow site)

Building Control will be concerned about structure, external fire
spread, resistance to moisture, and ventilation (amongst other things).

I really don't want to involve building control at all, the nearest
approach to any existing property besides the brick built detached
garage is over 5m

Roofs within 6m of a boundary must be class AA rating, ie,
non-combustible. Vegetation can dry up and represent a risk of fire
spread.

A green roof soaked with rainwater water and covered in soil and
sedum's will be just about non combustible - that it will sit on a
flammable fibreglass laminate over OSB ought to be irrelevant - surely
normal roofing felt will easily burn?

External walls must be of 30 minutes fire resistance within 1m
of the boundary, which means in your case that you will need
plasterboard on the inside, as well as the non-combustible cladding.

Plasterboard on the inside is completely unacceptable, I want to use
it for a shed/workshop not a living space!

The thermal insulation requirements do not apply to a free-standing
building of less than 50m^2.

They might not, but I'm reluctant to pay a fortune to heat or cool
this space when a few inches of celotex will keep it snug in winter
and cool in summer.

A timber framed building should have a vapour barrier on the warm side
of the insulation.

That *normally* being the plasterboard (foil backed?)

I'll not be using that, 12mm ply as a minimum so I can hang things on
the wall.
..
The plywood or other sheathing should be on the
outside of the studs,

Well I'd not planned for anything to be on the outside except the
fibre cement weatherboarding

with breather membrane to the outside of that, and

The breather membrane surely goes under the outside layer?

a ventilated and drained cavity inside of the cladding.

If the moisture barrier is on the inside, using foil backed
plasterboard or in this case probably plastic sheet, then surely any
moisture in the cavity on the outside of the celotex permeates through
the breather layer into the atmosphere. Venting the cavity to the
inside is surely the last thing to do, it permits moisture from
activity in the shed into the cavity which may then condense on cold
insulation.


--

On Mon, 10 Nov 2008 13:42:19 +0000, Tim S wrote:

BTW - have a look at this:

http://www.planningportal.gov.uk/upl...ouseguide.html

From the planning portal, the section on sheds:

"
Under new regulations that came into effect on 1 October 2008 outbuildings
are considered to be permitted development, not needing planning
permission, subject to the following limits and conditions:

*
No outbuilding forward of the principal elevation fronting a highway.

Good, it's in the back garden

Outbuildings and garages to be single storey with maximum eaves height
of 2.5 metres and maximum overall height of four metres with a dual pitched
roof or three metres for any other roof.

I'm aiming for minimum 2.1m clear height inside so with a few inches
of insulation in the rood I'll be way less than 2.5m

Maximum height 2.5 metres within two metres of a boundary.
*
No verandas, balconies or raised platforms.

It's a shed

No more than half the area of land around the "original house"* would
be covered by additions or other buildings.

No problem there

In National Parks, the Broads, Areas of Outstanding Natural Beauty and
World Heritage Sites the maximum area to be covered by buildings,
enclosures, containers and pools more than 20 metres from house to be
limited to 10 square metres.

None of which apply

On designated land* buildings, enclosures, containers and pools at the
side of properties will require planning permission.
*
Within the curtilage of listed buildings any outbuilding will require
planning permission.

*The term "original house" means the house as it was first built or as it
stood on 1 July 1948 (if it was built before that date). Although you may
not have built an extension to the house, a previous owner may have done
so."

None of which apply


Just concerned that the some overriding building regs legislation will
interfere with my plans on proximity to the boundary.


--

Mike wrote:
On Sun, 09 Nov 2008 23:50:26 +0000, Hugo Nebula abuse@localhost
wrote:

When you say 'large', anything with a floor area more than 15m^2 that
close to the boundary will require a Building Regulations application.

I'd deliberately planned it to be a smidgen under the 15m2 floor area

Then everything else is moot.

A timber framed building should have a vapour barrier on the warm side
of the insulation.

That *normally* being the plasterboard (foil backed?)

I'll not be using that, 12mm ply as a minimum so I can hang things on
the wall.
..
The plywood or other sheathing should be on the
outside of the studs,

Well I'd not planned for anything to be on the outside except the
fibre cement weatherboarding

with breather membrane to the outside of that, and

The breather membrane surely goes under the outside layer?

a ventilated and drained cavity inside of the cladding.

If the moisture barrier is on the inside, using foil backed
plasterboard or in this case probably plastic sheet, then surely any
moisture in the cavity on the outside of the celotex permeates through
the breather layer into the atmosphere. Venting the cavity to the
inside is surely the last thing to do, it permits moisture from
activity in the shed into the cavity which may then condense on cold
insulation.

I think you may have misunderstood.

Firstly condensation is greater on the inside of a building than the
open air, so you want a vapour barrier to prevent it migrating through
to the structure. Whether plywood would suffice for this purpose I'm not
sure; it's not something that's normally done, because...

Secondly, sheathing is usually provided to the outside of the studwork
for structural reasons; where it's not structural, it's better to have a
more permeable material. The sheathing is also something to fix the
breather membrane against.

A breather membrane forms a water-resistant layer to the outside of the
'inner leaf' structure, that can still allow vapour from the inside through.

There should always be a cavity between the membrane and the outer
cladding (which in your case is the fibre cement boards). If not you run
the risk of any water getting in, and any vapour getting out, not being
able to drain away.

But, hey! Building Regulations don't apply, so feel free to build it how
you like.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed"?

I looked into green roofs last year, you should be aware that it will
weigh in at 45 kilos a square metre.
Chris