Fixings For Insulated Plasterboard

hand holding the end of a sheet of insulated plasterboard
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Last updated: 23/7/2026

Quick answer: Insulated plasterboard combines a layer of rigid insulation bonded to the back of standard plasterboard, and is widely used on external walls in both new builds and retrofitted older properties. The insulation layer creates a gap between the plasterboard face and whatever is behind it, which changes what fixings you need. For light loads, standard plasterboard fixings work fine. For anything heavier, you need to anchor into the masonry or timber structure behind the insulation. If the board sits up to 45mm proud of the wall, a specialist dot and dab fixing like Corefix Connect will do the job. For thicker insulation, you’ll want a longer sleeved masonry fixing. If you’re fixing to the ceiling, always try to locate and fix into the timber joists above.

So you want to hang something on the wall, and your wall happens to be made of insulated plasterboard? Basically what this means is plasterboard backed with a sheet of insulation, in thicknesses from about 20mm to over 100mm, which helps increase energy efficiency and lowers your bills and carbon footprint. Some boards also have a foil vapour barrier between the plasterboard and the insulation.

Insulated plasterboard is widely used in new builds, but also in older ones that have been retrofitted. It’s usually used to improve the insulation of external walls and can be added to, for example, brick walls without taking up much extra space. But it does mean you’ll need to think about fixings for insulated plasterboard.

man wearing a backwards baseball cap drilling into a white wall

How do I know if I’m dealing with insulated plasterboard?

You’ll obviously know if you added it or built the house yourself, but how can you work out what kind of wall you have if you’ve moved in with no information to go on?

Generally, an uninsulated wall sounds more hollow when you knock on it compared to insulated, but this isn’t always reliable, especially if you’re inexperienced.

You’re more likely to encounter insulated plasterboard on an external wall. It can be used internally too, but it isn’t usually the most cost-effective option for internal insulation. If you’re hanging something from the ceiling, bear in mind that insulated plasterboard can also be used for overboarding ceilings.

You won’t necessarily have to cut holes in your walls to find out what’s there if you already have holes to look through, like an electrical socket or switch. Removing the cover of an outlet or switch and looking into the space around it may help you see if the plasterboard is insulated (just turn the circuit off first and check the outlet for power with a circuit tester). Another option is to drill a small pilot hole, or remove a small part of the plasterboard somewhere out of the way, and use a torch to see in.

insulated plasterboard

I’ve definitely got insulated plasterboard, what do I do now?

You’ll need to work out whether you’re fixing to the plasterboard itself or the masonry behind it, how the insulated plasterboard has been installed, and how thick the insulation is.

If the board is attached directly to the masonry using dot and dab or drywall adhesive, you can either fix to the masonry through the insulation (recommended for heavier items like TVs), or fix to the plasterboard itself with plasterboard fixings and a bit of extra help. More on that below.

If your insulated plasterboard is attached to timber studwork, you can simply screw into the timber studs with wood screws, as long as they’re long enough to reach through the insulation and the stud is in a convenient position. Alternatively, you can fix directly to the rear of the plasterboard by making a hole within the insulation.

 

OK, I can fix to the masonry, what do I do?

If you’re fixing to the masonry through the plasterboard and insulation, you’ve got a couple of options. With thinner insulation, you can use regular dot and dab or masonry wall fixings, like Corefix Connect, which secure the load to the masonry behind the plasterboard with a reinforcing steel core, as long as the distance from the front face of the plasterboard to the masonry is no more than 45mm.

With thicker insulated plasterboard, you may need a different approach.You should still go with a masonry fixing, but having some kind of sleeve going through the insulation will protect it from being damaged by the screw. For example, you could use a masonry fixing together with a long screw and a space plug through the insulation, as shown in this video by Ultimate Handyman:

How to fix to an insulated wall

What if I’m fixing to the insulated plasterboard itself?

For fixing light loads to insulated plasterboard, like lamps, small mirrors or pictures, just use regular small plasterboard fixings like Corefix Twist or the One Universal Hook. If you’re fixing heavy items to insulated plasterboard and can’t anchor the load into timber studs or masonry, you’ll need heavy duty fixings suitable for insulated plasterboard. Fixings designed to open and spread out behind the plasterboard, like Corefix Strap or Gripit, let you fix heavier loads directly to the plasterboard by spreading the weight.

Corefix Strap is an adjustable toggle fixing that can handle materials up to 50mm thick, ideal for insulated plasterboard as long as there’s a minimum 51mm cavity behind the insulation for the toggle to open and grip. With fixings that hook directly behind the plasterboard layer, like Gripit, you may need to clear a space in the insulation with a special undercutting tool to make sure the fixing can open properly and work its magic. These mount onto a regular power drill, so just make sure you pick one that’s the same size as your fixing and you’re sorted.

I’m hanging a heavy radiator/cabinet/sculpture, how strong is insulated plasterboard?

If you’re securing the load to the masonry or timber studs, you’re unlikely to have an issue as long as you use enough fixings. But what if you’ve got very thick insulation, or no masonry or timber studs to fix to? A plasterboard wall is stronger than you’d think, since the force of any weight pushes down through it, and fixings like Corefix Strap spread the load effectively behind the insulation. Even so, we’d recommend using as many fixings as you can to spread the weight, with ideally no more than 30kg per fixing (check the safe working load stated on the packaging for each fixing).

hanging plant pots

 

What about fixing to the ceiling?

If you’re fixing something heavy to an insulated plasterboard ceiling, we recommend securing the load to the timber ceiling joists with long wood screws wherever you can.

Fixing heavy loads to ceiling plasterboard alone isn’t a good idea, as the force will be pulling OUT of the plasterboard rather than along it (tensile load), which makes it much weaker. For lighter loads like small hanging plant pots, you can still fix straight to the plasterboard, but we recommend using a fixing designed for ceilings.

Have you got questions about fixings? Get in touch with us and our team will be happy to help. 

Frequently Asked Questions

Insulated plasterboard is a composite board with a layer of rigid insulation bonded directly to the back of standard plasterboard. It comes in a range of thicknesses, typically from around 20mm up to over 100mm of insulation depth, and is widely used on external walls in new builds and older properties that have been retrofitted for improved energy efficiency. It can also be used on internal walls and ceilings, though external wall application is most common.

If you are fixing to an external wall, insulated plasterboard is more likely than on internal walls. Tapping the wall can give a rough indication, though insulated board sounds less hollow than a standard dot and dab wall, which makes it harder to identify this way. The most reliable method is to remove the cover from a nearby electrical socket, turn the circuit off first and test for power before doing so, and look into the gap around the back box to see whether there is insulation behind the board. Drilling a small pilot hole in an inconspicuous spot and using a torch to look inside is another option.

It depends on the thickness of the insulation. Specialist dot and dab fixings like Corefix Connect work in insulated plasterboard as long as the total distance from the face of the plasterboard to the masonry behind is no more than 45mm. For thicker insulation, you will need a longer masonry fixing combined with a sleeve or spacer to protect the insulation from being damaged by the screw as it passes through.

For heavy items like TVs, shelves, or radiators, anchoring into the masonry or timber structure behind the insulation is always the most secure approach. On walls where the insulated board is fixed directly to masonry, use a dot and dab fixing like Corefix Connect for insulation depths up to 45mm, or a sleeved masonry fixing for greater depths. Where the board is fixed to a timber stud frame, use wood screws long enough to pass through the insulation and engage fully with the timber behind.

For lighter loads such as small pictures, mirrors, or hooks, standard plasterboard fixings will work on the plasterboard layer of an insulated board. For anything heavier, fixing to the plasterboard alone is not reliable, as the insulation layer behind it provides no structural support and the plasterboard face is not designed to carry significant loads on its own. Where no masonry or timber is reachable, toggle-style fixings that spread the load behind the board, such as Corefix Strap, can be used provided there is enough cavity depth behind the insulation for them to open properly.

Fixing to an insulated plasterboard ceiling is only advisable for light loads, and even then only using fixings specifically rated for ceiling use, since the tensile force pulling outward from the ceiling is a much more demanding load than the shear force on a wall. For anything heavier, fixing into the timber ceiling joists above the board is strongly recommended. Locate the joists with a stud finder and use screws long enough to pass through the board and engage with the timber fully.

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