Whether you’re already the proud owner of a timber workshop, or you’re thinking about adding one to your garden this summer, the age-old question of whether to insulate or not has probably crossed your mind.
You might have heard plenty of opinions – Joe next door reckons there’s no point buying a timber building in Scotland unless you insulate it. But if you’re only planning to use your workshop occasionally, do you really need a fully insulated setup?
It’s easy to get a bit lost in the world of insulation, especially when every building is different. In this guide, we’ll give you clear, practical advice on whether insulating your workshop is the right choice for you and when it isn’t.
Why should I insulate a single-skinned workshop?
Most workshops on the market are single-skinned. This means that one layer of timber forms the wall. Any single-skinned timber building is susceptible to moisture ingress. This involves moisture from the air passing through the walls to the interior of the building.
A little moisture ingress in a workshop is totally normal and can be rectified by ventilating the space regularly. However, when moisture builds up over time it can lead to rot and mould inside of your workshop.
Insulating a single-skinned workshop is a great way to reduce this risk. Adding insulation introduces additional layers to the wall, helping to stop moisture movement. The key feature here is an air cavity. Leaving an air gap when insulating helps prevent moisture from reaching the internals and causing damage.
Beyond moisture control, insulating also makes your workshop much easier to heat. It slows down how quickly heat moves in or out of the building, helping you stay warm in winter and cool in summer. This is especially useful if you plan to spend longer periods of time in your workshop.
Why should I insulate a 3-Tier Workshop?
At Gillies and Mackay, we build our Workshops using our 3-Tier specification. This is a layered wall construction with a built-in air cavity that keeps our Workshops completely watertight. Unlike single-skinned buildings, you don’t need to worry about water ingress here.
Our 3-Tier wall achieves the same result as insulating a single-skinned workshop in terms of moisture prevention – but it’s built into the structure from the start. Because of this, insulation isn’t required for performance.
However, you may choose to insulate your 3-Tier Workshop to improve temperature control. This will make the space more comfortable to use in all weather.
How do you insulate a workshop?
The process for insulating a single-skinned and a 3-Tier Workshop is slightly different. Let’s take a look at how it works:
Should I use an anti fungal treatment?
If your workshop is single-skinned, it’s best to protect the interior with an anti-fungal treatment before you add the insulation. This helps prevent mould growth from any trapped moisture, behind the insulation.
If you have one of our 3-Tier Workshops, this step isn’t necessary. The external cladding is pressure-treated to resist fungus and insect damage, and the internal OSB remains dry due to the built-in air cavity, so mould isn’t a concern.
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Should I create an air cavity?
Inside your workshop, you’ll see vertical framing. The depth of this framing determines how much space you have for insulation.
In a single-skinned workshop, you’ll need to create an air cavity. This can be done by fixing timber battens at either side of the framing, to leave a gap once you add insulation.
For example, if your framing is 70mm thick, adding a 20mm thick batten will leave a 20mm air gap, and then you have room for 50mm of insulation.
Our 3-Tier Workshops use 70mm or 95mm thick framing (depending on their size). Because the air cavity is already built into the wall, you can fit your insulation directly between the framing without leaving an additional gap.
What insulation should I use?
We recommend using foilback insulation for timber workshops. It’s easy to work with, offers good thermal performance, and the foil layer acts as a barrier to moisture.
Once your cavity is prepared, simply cut your insulation boards to size and fit them between the framing.
Should I insulate the roof and floor?
You can repeat the above process to insulate the roof of your workshop. Insulating the floor, on the other hand, is more complex because insulation is typically installed between floor joists during construction.
If your workshop is already assembled, a practical alternative is to use an insulated underlay with a flooring such as laminate. This will insulate the floor well without significantly raising the floor height.
Should I line a workshop?
Adding lining over the top of your insulation helps protect it from any damage, gives a clean, finished appearance, and allows you to easily fix shelves or tools to the walls.
Once insulated, you can fix your chosen lining directly to the timber framing. At G&M, we line the majority of our garden buildings with 16mm V’d redwood lining. For a DIY project, though, more cost-effective options include MDF, plywood, OSB and plasterboard.
The best lining material depends on how you plan to use the space. For a hobby or DIY workshop, OSB is a great choice as it’s practical and inexpensive. Whereas, for an at-home bar you might want a more finished interior, making plywood or plasterboard more suitable.
How much does it cost to insulate a workshop?
Insulation costs will depend on the material you choose and the size of your workshop.
An 18-pack of 70mm EcoTherm insulation from B&Q costs £695.52. Each board is 2.4m x 1.2m, and you can typically get two sections per board.
For example, a 10’ x 10’ G&M Workshop needs around 15 boards of insulation, making the 18-pack an ideal option with some allowance for waste.
Do I need to insulate a single-skinned workshop?
While single-skinned workshops can experience moisture ingress, insulation isn’t always essential. Here at G&M, our Sheds are single-skinned and still perform well without insulation thanks to their high-quality construction.
However, we do limit our single-skinned Sheds to 12’ x 10’ and under. We do this because larger single-skinned constructions are more prone to water ingress issues. If you’re considering a larger single-skinned workshop, choosing one with a solid specification and adding insulation is a smart choice.
Do I need to insulate a 3-Tier Workshop?
Our 3-Tier Workshops don’t require insulation for protection against moisture because of their layered construction. But if you plan to use the space day in, day out, insulation can make it more comfortable and reduce heating costs over time.
Which workshop activities actually need insulation?
If you’re using your workshop for basic storage, light DIY, or gardening, then insulation isn’t essential. Here, temperature control is unlikely to be a priority, and in single-skinned workshops, a small amount of moisture won’t affect how you use the space.
With a 3-Tier Workshop, your space will always stay dry, giving you the perfect environment for safe storage. However, if you plan to store valuable or perishable items in a single-skinned workshop, adding insulation becomes more important, as it helps reduce the risk of moisture build up damaging your space.
If you have a specific use in mind for your workshop – such as a gym, bar, or home office – adding insulation is a good choice, as comfort and temperature control will impact how you use the space.
Lastly, if you regularly store wet items in your workshop, adding insulation and lining helps protect the OSB interior in our 3-Tier Workshops and the cladding of a single-skinned workshop.
Should I insulate a workshop?
By now, you’ll know that insulation plays a different role depending on how your workshop is constructed. Single-skinned workshops rely on insulation to prevent moisture ingress, whereas 3-Tier Workshops are already protected and only need insulation for temperature control.
Ultimately, your decision will come down to how you plan to use the space, as well as the type of building you choose. While insulation isn’t always essential, in the right situation it can make a noticeable difference to comfort and usability.
If you’d like to see our 3-Tier wall in action, visit our Show Area in Errol, where we have a Workshop on display for you to explore.
