How to insulate and vapour barrier a metal shed?

[lindyw]

I've read all the threads I could find on insulating a metal shed and I still have a few questions. ( well- quite a lot actually!)

I have a basic 6x6 m metal shed- no vapour barrier under roof and no lining so I know I'll get condensation problems in winter.

I plan to use it as an art studio so need it to be  moisture proof as I'll have lot's of paper etc around.

Q1. Can I retrofit a vapour barrier without removing the roof?

Q2. If I use foil insulation panels with the silver side facing in do I need an additional vapour barrier or will the insulation panel act as a vapour barrier? I'm down the south of Tasmania so don't have humidity problems but cold winters cause condensation.

Q3. If I use batts in the walls I only have a 8cm deep gap between the wall and face of studs so I can only use a 1.5R batt. Is it worth using such a low Rvalue or should I go for the panels at R2?

Q4. Given that I should have a gap between the metal wall and the insulation how do I keep batts away from the outside wall? I know I can use spacers for the panels - do I do the same for the batts?

Q5. There are lots of comments about making sure there are no gaps in insulation but what about the metal studs which won't be insulated and form a direct link from outside walls to inner lining? Does this mean the insulation will not be very effective overall?

Q6. Can I insulate the 2 roller doors in some way?

Q7. Should I be adding more studs before lining with non structural 12mm ply or are the existing studs sufficient?roofSide wall with only three horizontal studs andSide wall

Thanks anyone for your advice.

[Jewelleryrescue]

Hi @lindyw 

Answers 1.

You may try and have the vapour barrier attach to the inside  shed frame. In the roof have strapping across it minimising sagging.  Probably stiff  foil board will work better here sealed at shed fram with silver  tape. But there is a risk trapping moister and the frame together might encourage corrosion of the frame.

2.The foil barrier will stop moister dripping for the most part. But many  try to rust frame work I might spray metal frame with extra paint as a extra rust barrier if you expect lots of condensation. Think  raining indoors.

3. I do not recommend batts if you cant get an air gap between the outer wall and batts as they will wick water and may harbour  mold. And as you said they have to be thinner to fit on walls too.  Thinner insulation R factor on  walls is not the issue

4 .Spacers yes I havent thought of a good solution here . in houses they use plastic strapping like wrapped around shipping cartons.

5  Spot on  @lindyw  both  sound and hot cold will use the frames and transmit right through if it is  possible stick a  stripe of foil board over the top of the inside shed frame too.  The amount of heat  lose through frame might be 15% as  aguide.

6.  There is a flexable blanket like aluminium foil sandwiching a foam thermal break. I havnt tried it on a  rooler door maybe too thick as the doors roll up and swells roller door roll dimentions?  Or 

Ametalin 1350mm x 60m SilverSark XHD Reflective Roof and Wall Insulation - 1350x60  I/N: 0810107   $162.75

7  For  fixing  ply you  might want stubs under the ply for 3 fixing  points on a full sheet of  ply.  as a  minimum especially on  roof incline.

If your  ply linng the shed you  can put  the  above insulation on the back of the  ply before fixing it and that will also give you an air gap to help dry out any condensation dripping in shed. the  insulation its self  will repel water so it runs to floor.   Ply  is  insulationg too, so is air gap, as is foil.  So a  good solution.

[MitchellMc]

Welcome to the Bunnings Workshop community @lindyw. It's marvellous to have you join us, and many thanks for your question about insulating a shed.

The first thing to note is that no matter how well you insulate a shed, it's still a shed, not a room in a house. So, keeping paper and artwork bone dry in there will likely be a difficult prospect. You can certainly use Foilboard, and by taping the seams, it will not only provide insulation but act as a vapour barrier. Don't forget about your floors as well. Moisture will be coming up through the concrete slab, and it would be best to coat it with an epoxy concrete paint as a minimum. You might even like to follow these guides: How to install a shed floor and How to waterproof a shed floor. A vast amount of water and moisture in a shed is due to it creeping under walls.

If you were to consider adding a floor, I'd be inclined to go the whole hog and create a room inside the shed with framed-out walls, insulation and plaster sheeting for lining. A door can also be added to the room. By doing this, you'll avoid having to insulate the roller doors. You'd be surprised how quickly, with a few helping hands, you'll be able to create a room inside a shed.

Please let me know if you have any questions.

Mitchell
 

A note for our New Zealand members: The use of foil insulation products in buildings is prohibited.

[lindyw]

Thanks for your helpful advice @Jewelleryrescue . I appreciate your detailed response.

I've been looking at the Ametalin Silver sark and thinking about fixing to the back of the ply as one option.

I'll think on some more about my best options

[lindyw]

Thanks @MitchellMc .

I've been thinking that I might need to do something with the concrete floor.

Building a room within the shed is certainly an option but maybe above my budget as I also want to put in some glass sliding doors...maybe they will go in the roller door space although it's not the best orientation for painting light.

I have thought about building a false wall in front of the roller doors so I might have to cost out the room in a shed idea.

Lots to decide on before I start- appreciate the advice.

Lindy

[MitchellMc]

Keep us updated @lindyw. The community and our helpful members are here for you every step of the way. Reach out anytime you need assistance.

Mitchell

[Dayne]

Hi @lindyw!

Concrete garage floors typically do not have black waterproof plastic under them, as the rooms are not designed to be habitable.

Crommelin's Dampstop is a common solution/product used when converting garages, as it is a negative moisture barrier designed to stop dampness rising through.

You can leave the Dampstop as a final finished flooring (grey in colour), or install tile, vinyl or carpet on top. 

Click here for the Product Information Sheet!

[lindyw]

Thanks @Dayne . I'll look into it as it sounds a good option for the floor.

Lindy