Can you board over foil insulation?

Author: Lorenz Turner  |  Last update: Thursday, November 27, 2025

If you plan to add an extra layer of insulation, you can install insulated plasterboards over the foil insulation.

Can you put drywall over foil insulation?

Can drywall be applied on top of the foil? Only if there is an air gap in the assembly; typically the air gap would be between the outer layer and the foil layer.

Can you board on top of insulation?

Boards for loft flooring can be installed on top of insulation using plywood, wood, or plastics. Installing loft flooring and boarding over insulation helps save space, prevent heat loss, and increase home value.

Does foil insulation need to be removed?

NT WorkSafe considers that the safe removal of foil from the ceiling space provides the greatest level of electrical safety. Alternatively, householders should consider the installation of safety switches for all final sub-circuits and sub-mains located in the ceiling space by a licensed electrical contractor.

Can you double layer insulation board?

If you need to increase insulation thickness or achieve a higher R-value, you can stack two sheets of Celotex insulation on top of each other.

Reflective Bubble Foil Insulation/Does It Work???

Can you double layer foil insulation?

Plus, in addition to being versatile, multilayer foil insulation is economical because the installation results in very little waste. You can either install a single layer or multiple layers of foil insulation, and you can mix it with other products.

Can I put insulation on top of insulation?

In many cases you can add new insulation on top of old insulation, unless the old insulation is wet, mouldy, or vermiculite. If the old insulation is dry but appears to have previously been wet, you should look for the cause and repair the problem.

What are the cons of foil insulation?

It is also worth to point out 3 main disadvantages of foil faced insulation such as:
  • It is generally more expensive due to being a metal-based product.
  • It is also important to note that in order for foil insulation to work correctly, it must be kept free of any dust.

Does foil insulation have an R value?

Foil insulation can provide an additional R-value when installed within an air cavity in the building frame. Roof sarking is installed in homes to reduce summer heat gains and reduce cooling costs. Aluminium foil insulation is a highly reflective material that rebounds radiant heat rather than absorbing it.

Which side of foil insulation faces out?

if it is hot outside, the reflective part of your foil insulation must face outside. if it is freezing outside, the best orientation of the reflective part is inside. if you press the foil side of the insulation tight up against the wall (foil facing outward), the radiant barrier will not work.

Should you leave a small gap between the insulation and the boards?

It is important to leave a small air gap between boards and the mineral wool in order to stop damp forming. Remember that insulating between the joists will create a cold roof space as the heat is kept underneath the insulation like a blanket.

Can I lay plywood over insulation?

Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.

Can I put foam board over insulation?

Yes, foam board insulation is an excellent complement to batt insulation. Foam board insulation can add insulation and eliminate thermal bridging when used in wall and ceiling assemblies insulated with batts. It can potentially replace the vapor barrier and house wrap as well.

What to put over foil insulation?

If you plan to add an extra layer of insulation, you can install insulated plasterboards over the foil insulation.

Do you need a barrier between insulation and drywall?

If you live in a colder climate, you'll be heating your home from the inside to keep the frigid weather at bay. That means most of the humidity will be generated from within, so the barrier should be installed between the drywall and the insulation.

Does foil insulation need an air gap?

Foil insulation is particularly effective at reflecting radiant heat, which can be beneficial in both summer and winter. However, in order for it to work effectively, there needs to be an air gap between the foil layer and the surface it's installed on.

Does foilboard need an air gap?

Does Foilboard need an air gap? In most applications, foil insulation requires an air gap of at least 25mm in order to insulate effectively for radiant heat. Installed without an air gap, and the effective R value of the boards will be close to zero.

Is foil insulation better than fiberglass?

Fiberglass passively blocks heat transfer due to the poor thermal conductivity characteristics of its glass fibers. Radiant barrier foil, on the other hand, actively prevents heat transfer using its thermal radiation properties. Learn more about these insulation options to identify the best one for your building.

Does foilboard sag?

Foilboard® is rigid and slimline and will not sag, shrink or delaminate over time. Lightweight and simple to install, it is ideal for bulk installation under concrete flooring of any size.

Do you need a Vapour barrier with foil insulation?

If you are installing insulation to the inside and/or outside of your external walls, then yes, you need vapour control to avoid any serious issues occurring. You should never miss this step.

What are the disadvantages of foil?

Health Risks of Aluminium Foil
  • Leaching of Aluminium into Food: When food is wrapped in aluminium foil, especially hot, acidic, or spicy foods, aluminium can leach into the food. ...
  • Kidney and Bone Damage: Prolonged exposure to aluminium has been linked to kidney and bone damage.

Does foil insulation keep cold in?

When foil insulation is specifically used in such cases, it acts as a barrier, reflecting a large portion of the heat away from your living space. As a result, it can keep your home or workspace cooler in the summer months.

Should I remove old insulation or just add more?

Removing old insulation is generally recommended if it's damaged, contaminated with mold, or infested with pests. However, if the insulation is in decent shape and just needs a boost, adding a new layer on top can be a cost-effective option.

Can you put plastic sheeting over insulation?

Yes, covering your insulation with a vapor barrier plastic before installing drywall is crucial. It prevents moisture buildup that can lead to mold, rot, and even structural damage. A polyethylene vapor barrier also adds a layer of fire protection, making your home safer.

Can I put too much insulation in my attic?

It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers.

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