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How to insulate metal shed for an office?

I'm converting a metal shed to become an outdoor office. I'm unsure on the best approach to insulate.

I've read many posts on here but still unsure on best approach.

Based in Adelaide, so humidity not an issue, concerned about tempature in summer, was thinking about using Earthwool 75 wallbatt due to its acoustic and rvalue and foilboard for the ceiling but wondering if foilboard would be good for the whole thing?

There's no plastic or radiant barrier currently in the shed if i went with the earthwool for walls would I need to somehow retro fit that or is the moisture resistance of earthwool suitable?

(Skylight Will be removed)

Thank you.

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EricL

Hello @jasbart

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about insulating your shed.

I believe that you are currently at an advantage as your shed walls are supported with timber which technically will make it easier to install timber battens for the insulation. Since you've had a look at the discussions, I propose keeping the project simple and that is to build a timber batten frame to support the batts that will be installed in your wall. You can install Ametalin VapourTech Brane VHP (directly behind cladding). Then the wall can be covered with internal plasterboard lining.

The same process can be applied to your roof, or you may choose another product to insulate your roof. But because it will become an office, I recommend using the thickest insulation you can use.

Please have a quick look at these discussions:

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

Nailbag

Hi @jasbart

Other than being in a rigid form making it easier to install, the insulation properties compared to the Earthwool is not something I would use in a metal shed. Especially in the roof during an Adelaide summer.

First step is to ensure the shed is 100% water tight from rainwater entering through the end of sheets, especially along the base of the walls.

Obviously there is electrical wiring to be roughed in so, the first step is to install additional studs and noggins to support the back plates of switches and GPO's and clipping of light fittings. Then I would use a chisel to rebate flush runs of gal strapping to hold the batts in place ready for the internal wall cladding.

I would also consider installing a whirlybird combined with an internal vent you can open in summer and close in winter, just for that extra air flow and ability to draw heat out on super hot days. You may want to consider having the shed split AC pre-wired just in case down the track you need heating and cooling.

Though not cheap, these types of solar powered skylights will give automated free lighting to the shed since you don't have windows. The brightness adjusts with external ambient light. Some have remote controls to manually override. They only operate during daylight hours. I have installed several in dark lower level rooms in homes. They are available in different sizes and also this brand which I have used.

And lastly it would be great to record the project with procession photos with materials used etc to eventually share as a project with the community.

Regards Nailbag

jasbart

Thanks @EricL , to clarify are you suggesting that the vapour tech will be enough rather than going with the thermal break from Ametalin for its reflective properties?
as the framing is existing I guess I would just cut and fix the barrier to size between each stud before placing the batt over the top?

jasbart

Hi @snail,

Great advice, its been weather and waterproofed which is great, strapping sounds like an ideal approach for holding batts in place.

I think a window on install is high on the agenda to improve air flow - I did enquire about leaving allowance for an AC unit its only 3x3 so I could get away with one of the smaller A/C units

Thanks

Dave-1

Good Morning @jasbart

@EricL and @Nailbag have really thought of most things that were in my mind, right down to @Nailbag's suggestion of a whirly bird that can be shut off during winter.

Making sure the area is watertight, including the base of the doorway (water runing down from outside) would be a priority. I can see a little bit of light at the rear of the shed, top right so you may need some coping on the outside of the sheds roof.

And @Nailbag's suggestion to take plenty of photos for putting together a project would be interesting to read through. We have a lot of people wanting to do the same type of deal asking questions 🙂

Dave

EricL

Hi @jasbart

My apologies for the confusion. What I meant to say is that the Ametalin vapour tech needs to go first then followed by the Earthwool Batts and then covered by the internal plasterboard lining. The Earthwool Batts will be necessary in order to provide superior insulation.

If you need further assistance, please let us know.

Eric

JoZ

Hi Eric, with this method does there need to be any spaces between the metal shed, Ametalin vapour tech and the Earthwool batts, or can they all be sandwiched together?

Also if I am lining the shed with plywood sheets what minimum thickness would I need?

Many thanks,

EricL

Hello @JoZ

Welcome to the Bunnings Workshop community. It's sensational to have you join us.

You are correct about the installation sequence: the Ametalin VapourTech membrane should be installed first (facing the metal cladding), then the Earthwool Batts, and finally the internal lining such as plasterboard or plywood.

When it comes to spacing, the Ametalin VapourTech membrane is designed to sit directly against the shed’s metal sheeting without needing a gap, as its purpose is to manage condensation by allowing vapour to escape while preventing liquid water ingress. The Earthwool Batts can also be installed in direct contact with the VapourTech membrane. There is no need for an air gap between the membrane and the insulation unless specified by a particular product’s manufacturer.

The only crucial point is to ensure the VapourTech is properly sealed and lapped to maintain its vapour-permeable barrier function. The plasterboard or plywood lining can then be fixed directly against the wall frame in front of the batts.

If you are lining the shed with plywood sheets instead of plasterboard, the minimum thickness depends on the intended use. For general wall lining where you may want strength for fixing items like shelves or hooks, a 9 mm plywood sheet is generally considered the minimum. However, 12 mm plywood is preferred as it provides significantly greater rigidity and screw-holding capacity, especially in a shed or workshop environment.

If you need further assistance, please let us know.

Eric

JoZ

Thank you so much for a quick reply Eric. That is brilliant and helps clear up my confusion. Many thanks ☺️

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