Best Loft & Wall Insulation — Insulation Spacer (2026)
2 loft & wall insulation matching material “Insulation Spacer”, hand-picked from UK Amazon listings.
Not sure which one to pick? Read our Best Loft & Wall Insulation UK (2026) guide.
These Insulation Spacers are designed to optimise the performance of your loft and wall insulation systems. They create a crucial air gap, significantly improving thermal efficiency by reducing heat transfer – a key factor in minimising energy loss from your home. These spacers are typically used between rigid board insulation (like PIR or rockwool) and cavity walls or lofts, ensuring consistent and effective insulation.
These spacers are manufactured from high-density polyethylene (HDPE), a durable plastic known for its resistance to moisture and temperature fluctuations. This material’s stability ensures long-term performance within your loft or wall space. The HDPE is also lightweight, making installation easier without adding unnecessary weight to the structure.
When used correctly, these Insulation Spacers contribute significantly to meeting building regulations regarding thermal performance. They are a cost-effective solution for improving the insulation of existing structures and can be incorporated into new builds. Ensure you select the correct size for your application to maximise their benefit.
#1 Pick
Loft Leg XL Flooring LoftLegs 300mm Insulation Spacer - 12 Pack- Insulation Spacer
- 300mm, 12 Pack
£23.99
Pros
- Raises loft boarding clear of insulation so it stays uncompressed for full thermal value
- Screws straight into joists with no cutting or extra fixings needed
- 300mm height suits a deep top-up layer without squashing it flat
Cons
- Needs the loft boards bought separately to complete the raised floor
#2 Pick
The Loft Riser Stilts, 175mm Height Loft Insulation Spacer, Attic Stilts, Plastic Loft Risers, Loft Stilt Legs, Loft Flooring Legs (32 Pack)- Insulation Spacer
- 175mm, 32 Pack
£45.59
Pros
- 175mm height lifts boarding clear of insulation to keep it uncompressed
- Plastic construction is lightweight and easy to carry up into a loft
- 32-pack suits a decent sized loft boarding project in one order
Cons
- Loft boards need to be bought separately to complete the raised floor
FAQ
What is an air gap and why is it important?+
An air gap is a space filled with still air between layers of insulation. This reduces heat transfer through convection, which is the movement of warm air upwards. Maintaining this gap significantly improves the effectiveness of your overall insulation.
How do these spacers fit into a cavity wall?+
These HDPE spacers are placed horizontally within the cavity wall, positioned between the external brickwork and the internal boarding. They ensure consistent contact with both layers of insulation, maximising thermal resistance.
What types of insulation can I use with these spacers?+
These spacers are commonly used in conjunction with PIR (polyisocyanurate), rockwool, or mineral wool insulation boards. The key is to maintain a consistent air gap between the spacer and the insulation board.
Are these spacers suitable for external walls?+
Yes, these HDPE spacers are designed for use on external walls. Their moisture resistance ensures they won’t degrade due to exposure to the elements, providing long-lasting thermal performance.
What is the typical thickness of these insulation spacers?+
These spacers are typically available in thicknesses ranging from 10mm to 25mm. The optimal thickness will depend on your specific application and the required air gap dimensions – consult manufacturer specifications.
Do I need to use a sealant when installing these spacers?+
While not strictly necessary, applying a bead of flexible sealant around the edges of the spacer can further improve weatherproofing and prevent any potential moisture ingress. However, ensure the sealant is compatible with the insulation material you are using.
How do I calculate the correct amount of spacers I need?+
Measure the length and depth of the cavity wall or loft space where you’ll be installing the spacers. Divide the total measurement by the spacer's width to determine the number of spacers required for each run.
Are these spacers suitable for damp environments?+
The HDPE material offers good resistance to moisture, but it is still advisable to avoid direct contact with rising damp. Ensure your insulation installation addresses any underlying moisture issues before applying these spacers.
What are the potential downsides of using air gaps?+
While beneficial, excessively large air gaps can reduce their effectiveness. Maintaining a consistent gap size and thickness is crucial for optimal thermal performance. Also, ensure the gaps aren't bridged by any structural elements or fittings.
How do these spacers compare to traditional felt insulation?+
HDPE spacers offer superior thermal resistance compared to traditional felt insulation due to the creation of a consistent air gap. Felt can compress over time, reducing its effectiveness, whereas HDPE retains its shape and performance for longer.