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How to insulate a shed: insulation pricing, materials and expert advice…

If you are thinking about getting a brand spanking new shed for your garden you might be wondering whether it is worthwhile to insulate a shed.

Do you spend a lot of time in your shed and want to make it more comfortable to work in?

Need to keep paper, stock or materials safe and dry in your garden shed?

Do you want to know how to avoid dampness, moisture and mould in your shed?

If you’ve invested a heavy amount of dosh in your shed then you’ll want to make the absolute most of it all year round.

And that’s where shed insulation can come in handy. We have been insulating garden sheds for over 30 years – that’s a lot of cosy sheds. So, it’s safe to say we’re kind of the experts when it comes to insulation for sheds.

There’s a fair bit of information out there on how to insulate a shed but not much reasoning as to what is the best way and why.

That’s why in this blog we’re going to cover all of the following:

  • The benefits of insulating your garden shed
  • Bubble wrap vs fibreglass wool vs foil-backed compression insulation: which is the best material?
  • What material do we recommend for lining your garden shed?
  • What does it cost to insulate your garden shed?
  • How long does it take to insulate a garden shed?
  • Step-by-step on how to insulate your shed walls, roof and floor
  • Garden shed insulation FAQs

We’re really keen on giving you all the information you need to make your shed comfortable and cosy. And don’t forget if you are early in your shed planning journey then insulation is something we can help with for G&M garden Sheds.

What are the benefits of insulation for sheds?

Insulating your shed creates the best environment for both you and your shed all year round. There are two key factors when it comes to insulating a shed:  temperature control and moisture control.

The benefits of insulating your garden shed include:

  • Keeping heat in your shed: Insulating your garden shed means you can get better use out of your shed all year round, especially in those winter months in Scotland. Therefore if you’re planning on using your shed as a room to work or play in – insulation allows you to get the most advantage from your building.
  • Keeping your shed dry: are you storing valuable items or perishables, or do you want to extend your shed’s lifetime? Shed insulation controls the temperature in your building to minimise moisture build-up. This can wreak havoc on your prized possessions and on the timbers of your shed.

So, if you’re planning on using your shed to store valuables, or something other than outside toys and garden equipment – then YES, shed insulation is probably a great choice for you.

What materials do you need to insulate a shed?

So, let’s talk about some of the materials that you need will need if you want to turn your garden shed into a cosy little workspace.

1. Shed Framing

Shed Framing

Firstly, you need to determine your framing size to figure out how much room you have to fit in your Insulation.

Gillies and Mackay’s framing is 70mm allowing 50mm of insulation and a 20mm air gap.

The air gap is important because it allows the exterior wall to breathe and stops moisture from traveling through to the interior of the building (more on this later).

If your framing is less than 75mm you may need to use a thinner board of insulation to accommodate the air gap.

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2. Insulation: Bubble wrap vs fibreglass wool vs foil-backed insulation

There are a couple of different types of materials that you can use when it comes to insulating a shed. So, let’s look into them to see which solution is best (and safest).

Can you use bubble wrap for insulating your shed?

Using bubble wrap for insulation is dangerous if you plan on putting electrics in your Shed, which is often the case if you’re thinking of lining and insulating your shed in the first place🔥.

So polystyrene or bubble wrap is a major no-no! They can combust with electrics and set the whole shed on fire.

Not cool.

Can you use fibreglass wool for insulating your shed?

Fibreglass wool as insulation is ideal for bathroom areas and for soundproofing but can be a real nightmare to handle and fit.

Do not follow the advice in this article – we do not recommend this solution.

Can you use foil-backed insulation for insulating your shed?

Realistically this leaves you with one good option: Foil-backed compressed insulation is the best and easiest to work with, and we highly recommend this option for your shed.

foil backed shed insulation

Ecotherm foil-backed compressed insulation has the best U-value for efficiency and is completely safe with electrics.

There are three main brands of foil-back compressed insulation to look out for: Kingspan, Celotex, and Ecotherm – they all do the job and are readily available from warehouses such as Wickes.

Here are a few foil-backed insulation recommendations to help you with your search:

How to insulate your shed walls, roof and floor: step-by-step instructions

Right! Now that you know you need to do it, and what materials you are going to need, let’s get right into how to do it.

If you are buying a shed from Gillies & Mackay then you can speak to us when you are ordering and we can take care of this for you. But if you already have a shed and want to DIY then this should help you out…

How to insulate your shed walls and roof…

First up, it’s the insulation of your garden shed walls and roof.

Step 1: Protect the wood with an anti-fungal treatment…

Your shed wall won’t be accessible once you’ve insulated so you need to consider extra preservation. You can either use the same wood protection you have used on the outside, or you can buy an anti-fungal/pesticide wash to treat the internal (some companies do this already, so check with your manufacturer).

anti-fungal treatment for shed insulation

Step 2: Create the cavities

Add a 20mm x 20mm strip of wood (preferably treated) down the side of each stud (frame).

This will create a cavity between the external wall and the insulation that’s ideal for electrical wires and eradicates damp penetration.

If you have a shed (or even part of your shed) that will be particularly exposed to the weather, you can apply a breather membrane after the building has been built. This requires cutting the membrane to the size between each section of framing.

Don’t forget to leave an air gap for ventilation between the weatherboard and the insulation. Without this, if any moisture penetrates the weatherboard it can cause mould or rot as the moisture will have nowhere to go. We recommend using 50mm foilback Ecotherm insulation with our 70mm framing, leaving a 20mm gap.

Foilback insulation is important – the foil does the same job as a breather membrane would and creates a damp-proof course. To make sure your air gap is ventilated drill some air holes to create a trickle gap. This gives any moisture that penetrates the outer cladding somewhere to go, which means it won’t build up between your cladding and insulation.

Creating the cavities for shed insulation
Creating the cavities

Step 3: Cut the insulation sheets to size and slot them into place

Measure each wall section. If you’re fortunate your shed will be made to exact centres – e.g. 600mm.

Next, you cut each section from your 2.4m x 1.2m sheet of foil-backed insulation. You should get 2 sections from each sheet.

Slot the section into place (on top of the 20mm strip, creating a gap between the wall and insulation as mentioned) and repeat on all 4 walls.

Complete the same process for the roof.

cut the insulation
cut the insulation to size

How to insulate your shed floor…

Insulating your floor isn’t going to be easy if your shed is already assembled – normally the insulation sits between the floor joists. This is why we usually recommend that it’s done as the building is being assembled if you fancy it.

However, investing in a decent underlay and laminate (should your frame size allow) will give you adequate insulation.

If you’ve not assembled your shed yet, follow the same process as the walls for the underside of the floor (add skirting once assembled to keep it neat).

Now all your insulation is in place you can think about lining options.

Lining the inside of your shed

At Gillies & Mackay we opt for 16mm Redwood V’d Lining. However, this isn’t always as readily available to you and I’d suggest calming it down a bit as 16mm Redwood is a bit over the top if you’re doing a DIY job.

MDF beaded board for shed insulation

Maybe opt for something like a 9mm MDF Beaded Board available from accessible warehouses. It’s a profiled sheet that looks like cladding (see image above).

It’s also neat and easy to work with, so if you’re not quite as skilled as our joiner team (who have serious skillz), then you should be able to work with it.

How long does it take to insulate your garden shed?

If you decide to insulate your shed yourself, it’s likely to be a weekend job depending on your DIY competency.

If you hire a manufacturer or supplier to do it for you it’ll be a half-day or full-day depending on the size of the job.

Gillies & Mackay offer the option to line and insulate your shed as you order your G&M building. So definitely speak to our guys during your consultation if it’s something that you fancy.

How much does it cost to insulate your shed?

Oh yes, the big questions. Sure in an ideal world, EVERYONE would insulate their shed from the off. Keeps it cosy and even if you don’t need it right now, you might in the future.

But, of course, there are costs associated with insulating a shed. So let’s look into what they are depending on whether you DIY it or get

How much does it cost to DIY your shed insulation?

If you are going to do it yourself, using 50mm insulation, here are some approximations based on £23 including VAT per sheet of foil-backed insulation.

Note: You may find that the prices will be cheaper if you buy in bulk. These prices are not 100% accurate but should give you a good indication of the prices to expect.

Small shed/summerhouse – 8’x 8′

To insulate the walls, floor and roof you will need approximately 10 sheets of 50mm foil-backed insulation. Based on the prices above, this will cost approx. £230 including VAT.

Add 8 sheets of lining at approximately £55 = £440

Total price for 8′ x 8′ = £670 including VAT

Medium shed/summerhouse – 10′ x 10′

To insulate the walls, floor and roof you will need approximately 15 sheets of 50mm foil-backed insulation. Based on the prices above, this will cost approx. £345 including VAT.

Add 12 sheets of lining at approximately £55 = £660

Total price for 10′ x 10′ = £1005

Large shed/summerhouse – 16′ x 12′

To insulate the walls, floor and roof you will need approximately 24 sheets of 50mm foil-backed insulation. Based on the prices above, this will cost approx. £555 including VAT.

Add 19 sheets of lining at approximately £55 = £1045

Total price for 16′ x 12′ = £1600

How much does it cost for a professional to insulate your garden shed?

If you don’t want to insulate your shed yourself, you can expect to pay roughly double the costs for a manufacturer or supplier to do it for you. A local company will be able to help you with this if you already have your shed installed.

If you are buying from us and want to insulate your shed, you can expect the lining, insulation, fitting and finishing price to add on around 70-80% of your building price. That’s almost double the price of your building.

You can see our shed prices here to figure out what that means in actual pounds.

Garden Shed Insulation FAQs…

This is one that we get a lot of questions about, so we’ve turned some of our most commonly asked questions into a little FAQ section. If you have any other questions then you can let us know.


Thanks for the article on insulating sheds, very clear! I noted you did not use a breather membrane before inserting the insulation board or a vapour barrier before boarding it out – is there any reason for this?


Breather membranes are best applied when a building is being built. At Gillies & Mackay, we insulate the Sheds retrospectively after the single-skinned version has already been delivered (i.e. deliver the building on Monday and come back to insulate it on Wednesday). To apply it you would need to put one sheet on each panel underneath the framing which would be very difficult to do retrospectively.

Applying a breather membrane after the building has been built requires cutting the membrane to the size between each section of framing. As long as a sufficient gap (our framing is 70mm and we recommend using 50mm Ecotherm insulation) is allowed for ventilation between weatherboard and insulation then that is sufficient enough for any shed.


Your article about insulating a summerhouse is helpful, but I still am not sure how to get the insulation sizes right and how exactly to attach the sheets?


The size of insulation depends on the thickness of the framing. You don’t attach the insulation. It slots in between the framing.

For example, our framing is 70mm thick which means, we use 50mm Insulation leaving a 20mm gap between the back of the insulation and the inner wall.

If your building is an interlocking log (no framing) you’ll not be able to follow the instructions I have made.

If your building does have framing – but the framing thickness is less than 70mm you’d be better off using 25mm insulation to make sure you still have an air gap between the back of the insulation and the inner wall.

Keeping the cut of the insulation tight to the size of the gap between each frame will hold it in place, alternatively, you can attach 25mm strips to the inside of the frame to create a more structured gap.


I’d like to thank you for a very useful article on shed insulation. I’ve read a lot of conflicting info on this online, as you know is out there, a lot of it either seems overkill for a workshop or just outright odd.

I have a few further questions to follow up on your article, and I’d be grateful for your advice here, please.

1. When using foil-backed insulation, on the floor walls and roof, is there any requirement for a Tyvek type membrane?

2. What about foil tape over the joints?

3. Ventilation. If the external and internal cladding is direct to the studs, how does the 25mm cavity get ventilated? Same question for the roof too.


1) If your building is already assembled you cannot fit the membrane – the whole point of the membrane is that it runs past the internal frame (or behind it, like weatherboard/membrane/frame – you can only really fit this when the panels are being made.

Or if you’re choosing to re-clad the exterior instead of the interior. The short answer no, membrane is not needed as it can’t do its job – that’s why we leave a gap/cavity instead and some drilled moisture holes to let the excess moisture escape.

2) Yeah you can use foil tape, I tend not to side with the full seal as again, moisture – but that’s because Scotland loves the rain.

3) Drill small holes right through the bottom frame, through the flooring out to the external. The roof should be fine as there are natural gaps at the facias and under the eaves. This is all assuming the Shed is constructed in the same, if not similar, way to a G&M.


Hello just been reading your article and watching your videos on ‘how to insulate your summerhouse/shed they are great and really informative!

Just a bit confused about adding a cavity part before moving into the insulation. I can’t quite understand this part do you add a piece of wood in between the frames on the inside? How do you create the gap?!


So if you think of the piece of wood as a packer – a small strip of wood on either side of the framing creates a space between the insulation and the internal side of the wall.

Final words from Gillies & Mackay on insulating a shed…

So, if you’re wondering what we recommend then let us tell you. Here at Gillies & Mackay we fully recommend insulating your shed/summerhouse. It’s completely worth it and allows you to have an amazing #ShedLife all year round.

Insulating your shed is especially important if you are using it as a garden office or workshop, and it will help to protect everything on the inside from the cold, dampness and moisture.

If you’re starting from scratch and looking for a fully lined and insulated shed –  book in for a consultation with us to get started with your Shed Life:

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