Insulation for a shed?

[Haventgotascoobydo]

Hi all,

I’ve been reading the posts to get some help and advice but some of it is going over me head. If I give a bit of back story and then explain what I’m thinking of doing, would you let me know if this is ok, correct or something I shouldn’t do and advise another way.

I am new to this DIY stuff and have watched countless videos on how to do this so I apologise if I don’t understand the Jargon or write the wrong words lol.

We are getting a new 9x7 shed as my daughter (20yo) wanted somewhere she can have a base for her nail business (not to run from the shed) somewhere she can practise and have somewhere to go when her friends come over, rather than 4 of them all sitting on the edge of her bed. So I’ll have some plug sockets put in and some lights, (by a qualified electrician) I wouldn’t even attempt that but lol.

Im going to be doing a concrete base for the shed to sit on (the shed company have said to build the concrete 3” smaller than the shed) so the rain can run off and not bounce back up, and to not have it pooling at the base. So i’m going to do that.

regarding insulating the shed.

I was going to have it like this.

Shed wall/ceiling
Fill in between battens with Mineral Wool (no air gap between wall and insulation)
Then cover with 500 polythene membrain and staple to battens and seal any gaps
Then plasterboard on top?

does this sound ok?

also a question I wanted to ask about plasterbaording.

I’ve watched loads of videos and they all say to leave the gap and the bottom so it doesn’t get wet from any spillages. Which I understand, but what I don’t understand is, if we put down underlay and then wooden flooring, that would bring it up to near enough the plasterboard? Should I be putting an skirting board around all of the bottom of the shed before we put any flooring down? I’m just really confused about that bit.

I’ve attached a picture of the inside of the shed, if that helps?

Any help is much appreciated. Thank you in advance

 

[big-all]

general comments
is it 9x7 internal as in 10x8shed as a 9x7external will be perhaps 8x6 where a comfortable sitting area for 4 would be a bit cramped ??

if not to late plan and see if a bigger shed would work /be better ??

 

[mikeey84]

I wouldn't put plasterboard in a shed personally.

I would go for ply or OSB and paint it

 

[^woody^]

the shed company have said to build the concrete 3” smaller than the shed

What will the shed sit on then?

The detail between the shed walls and the floor is very important when you are using the shed for things other than a shed. Are you having a internal raised floor on top of the slab? If not how are you dealing with penetrating damp or blown rain between the bottom of the frame and bottom edge of the cladding? What about the cold floor and condensation or dampness?

Mineral wool is not that efficient in small thicknesses, so be sure on what your expectations are.

You don't need to membrane a timber shed as an internal vapour barrier, but you should be aware that timber shed cladding will saturate and that will in turn soak any mineral wool insulation.

The plasterboard should be above any solid concrete floor or similar, but does not need to be above any timber floor or floor covering. The gap is for preventing moisture creep from condensation not from spillages. Any gaps will need sealing regardless to stop draughts.

 

[Luckyphil]

We Insulate a lot of Sheds & Concrete sectional Garages , we use 50mm Kingspan ( if the Shed Framing Battens are deep enough ) or we batten out the Framing to enable the Kingspan to fit with an air gap behind it , we always use 6mm or 9mm Plywood glued & nail gun pinned , there’s always a chance of dampness in a Shed , Plasterboard will degrade quite quickly if it gets damp

you can paint or seal the Plywood , I’ve seen Sheds with feature Walls with a fancy Wallpaper on it

cheers
Phil

 

[big-all]

in my opinion 12mm ply on dry to damp sheds is by far the best cladding material on the inside walls you can hang virtually any weight you like from it without fear off damage and the surface in a workshop or garden room is smooth and generally without painting less industrial than osb/chipboard/or mdf
plasterboard only if up to internal standards with insulation no water or damp ingress and heating from daily at normal levels to at least minimum to drive off damp most off the time

 

[magicmushroom666]

You'll want a ventilated gap up against the back of that cladding, as it wont be completely water tight, I wouldn't just pack it full of insulation.

 

[Haventgotascoobydo]

What will the shed sit on then?

They said to build a concrete slab 3 inches smaller than the shed, is that not right?

The detail between the shed walls and the floor is very important when you are using the shed for things other than a shed. Are you having a internal raised floor on top of the slab?

There is also a wooden floor that comes with it and was thinking of putting insulation boards down, then putting laminate flooring?


If not how are you dealing with penetrating damp or blown rain between the bottom of the frame and bottom edge of the cladding? What about the cold floor and condensation or dampness?

The shed company said to build the concrete slab 3 inches smaller so that the shed over hangs and the rain won't bounce up onto the bottom wood of the shed and it will drain away?

Mineral wool is not that efficient in small thicknesses, so be sure on what your expectations are.

You don't need to membrane a timber shed as an internal vapour barrier, but you should be aware that timber shed cladding will saturate and that will in turn soak any mineral wool insulation.

so is it best do get the Kingspan Insulation boards instead but leave an air gap between the boards and the shed wall?

The plasterboard should be above any solid concrete floor or similar, but does not need to be above any timber floor or floor covering. The gap is for preventing moisture creep from condensation not from spillages. Any gaps will need sealing regardless to stop draughts.

Really want to thank you for you reply, I'm totally new to this ( as you can tell from my questions/answers lol) so this is really helping.

my answers are in bold, does that sound about right

 

[Haventgotascoobydo]

You'll want a ventilated gap up against the back of that cladding, as it wont be completely water tight, I wouldn't just pack it full of insulation.

I did think that I would have to get a vent somewhere, but wasn't sure if I was being dull and it wasn't a necessary thing.

 

[Haventgotascoobydo]

We Insulate a lot of Sheds & Concrete sectional Garages , we use 50mm Kingspan ( if the Shed Framing Battens are deep enough ) or we batten out the Framing to enable the Kingspan to fit with an air gap behind it , we always use 6mm or 9mm Plywood glued & nail gun pinned , there’s always a chance of dampness in a Shed , Plasterboard will degrade quite quickly if it gets damp

you can paint or seal the Plywood , I’ve seen Sheds with feature Walls with a fancy Wallpaper on it

cheers
Phil

I was a bit torn between plasterboard or ply, I was thinking, they both do the same but plasterboard was cheaper, but then thinking about it, it may cost me in the long run if the plasterboard gets ruined. I may go for the kingpin insulation but not sure what size the batten would be so ill wait for the shed to get here. I did see little plastic like spacers you glue to shed wall which would stop the insulation touching the wall and keeping the air gap?

 

[Haventgotascoobydo]

in my opinion 12mm ply on dry to damp sheds is by far the best cladding material on the inside walls you can hang virtually any weight you like from it without fear off damage and the surface in a workshop or garden room is smooth and generally without painting less industrial than osb/chipboard/or mdf
plasterboard only if up to internal standards with insulation no water or damp ingress and heating from daily at normal levels to at least minimum to drive off damp most off the time

Kinda now thinking of plywood

 

[Haventgotascoobydo]

general comments
is it 9x7 internal as in 10x8shed as a 9x7external will be perhaps 8x6 where a comfortable sitting area for 4 would be a bit cramped ??

if not to late plan and see if a bigger shed would work /be better ??

Ive taken your advise and gone up a size. Brilliant thank you

 

[Haventgotascoobydo]

I wouldn't put plasterboard in a shed personally.

I would go for ply or OSB and paint it

Brilliant thank you, Im now thinking of doing that even thought its a bit more expensive.

 

[^woody^]

You may not be able to match this exactly but here's a quick sketch to illustrate some principles.

Bottom of walls are high risk for damp ingress and splashes causing timber to rot prematurely. Ideally, timber cladding and frames should be at least 150mm above ground level, and it's best if the frame is built off two courses of bricks. But if the frame must sit on a slab, DPC should be used to keep water out.

If you are buying a pre-made shed panel, fitting a rain barrier behind the cladding may be difficult, so consider a gap instead

 

[Haventgotascoobydo]

You may not be able to match this exactly but here's a quick sketch to illustrate some principles.

Bottom of walls are high risk for damp ingress and splashes causing timber to rot prematurely. Ideally, timber cladding and frames should be at least 150mm above ground level, and it's best if the frame is built off two courses of bricks. But if the frame must sit on a slab, DPC should be used to keep water out.

If you are buying a pre-made shed panel, fitting a rain barrier behind the cladding may be difficult, so consider a gap instead


View attachment 256516 View attachment 256524

could I cover the back of the cladding inside the shed in the polythene, by staple gunning it to the cladding and then put the celotex?