Best Multifoil Insulation for Garden Studios: 2025 Expert Review
DR Joinery
Expert Joiner & Garden Building Specialist
Turning a summerhouse or garden studio into a usable year-round space is a common goal, especially with the rise of home working. However, keeping a timber building warm during a Yorkshire winter requires more than just a portable heater; it demands proper insulation.
Multifoil insulation has become the go-to solution for garden buildings because it is thinner than traditional PIR boards (like Celotex or Kingspan) and easier to retrofit into irregular timber frames. But not all foils are created equal. Some are barely thicker than crisp packets, whilst others meet full building regulations.
In this review, I've categorised three insulation options I see on the market: a budget roll for basic draught-proofing, a high-performance system for serious home offices, and a space-saving compromise for tight renovations.
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Specs vs. The Real World
The Spec: "R-Value / Thermal Performance"
"Manufacturers often claim their foil is equivalent to 100mm of rigid foam board."
This is only true if you install it with creating proper air gaps (battens) on *both* sides of the foil. Without the air gap, the performance drops significantly. It relies on reflection, not just mass.
The Spec: "Quick & Easy To Cut"
"Can be cut easily with household scissors."
The budget stuff cuts easily. The high-quality multi-layered foils will gum up standard scissors properly. You'll need shears or a very sharp utility knife to get a clean edge.
My Top 3 Recommendations
Three options to cover different needs and budgets
The Stove Wizard Foil Insulation Folded 5m x 60cm Radiator Reflector Panels
The Stove Wizard
This is a basic, entry-level option suited for simple jobs. While marketed as radiator reflection (which it does well), it is essentially a double-layer bubble wrap with foil. It is perfect for lining a potting shed or tool store to stop condensation and take the chill off, but I wouldn't rely on it for a fully habitable home office.
The Good
- Very affordable for small projects
- Includes self-adhesive pads for quick fixing
- Easy to cut and manipulate in tight corners
The Bad
- Not sufficient thermal retention for a heated office
- Narrow width (60cm) means lots of taping for large walls
- Minimal acoustic insulation
Installer Tip:
Use this behind the cladding of a basic shed to act as a vapour barrier. Staple it directly to the frame, but ensure you tape over the staples and joins with proper aluminium foil tape, or moisture will get through.
Priced at £12.74 at the time of writing
Check Price on AmazonSuperFOIL SF19+ Multifoil Insulation 1.2m x 10m
SuperFOIL
If you are building a garden room to use daily as an office or guest room, this is the standard you should aim for. The SF19+ is a serious piece of kit; it is thick, robust, and certified for building regulations. It combines a radiant barrier, vapour control, and thermal insulation in one, offering performance closer to traditional PIR boards.
The Good
- High thermal performance for year-round habitation
- Built-in vapour control layer reduces damp risk
- Excellent radiant barrier for keeping heat out in summer
The Bad
- Significantly more expensive than bubble foil
- Thicker profile requires deeper battens (losing some internal space)
Installer Tip:
To get the rated performance, you MUST maintain an air gap on either side. Don't sandwich this tight between cladding and plasterboard. Battening out is essential for the foil to reflect the heat properly.
Priced at £119.99 at the time of writing
Check Price on AmazonSuperFOIL SF6 Multifoil Insulation 1.2m x 10m
SuperFOIL
The SF6 is the perfect problem-solver for retrofitting older summerhouses where you can't afford to lose much internal headroom or floor space. It sits between the budget bubble wrap and the thick SF19+, offering good thermal resistance without the bulk. It is ideal for lining roofs where rafter depth is shallow.
The Good
- Excellent balance of performance vs thickness
- Easier to handle and install overhead than the heavier rolls
- Does not require PPE or masks to install (unlike glass wool)
The Bad
- Less thermal resistance than the SF19+
- Still requires foil tape for all joints (extra cost)
Installer Tip:
When fitting this to a roof, staple it to the underside of the rafters. Then, counter-batten over it before adding your tongue-and-groove finish. This creates a service void for wiring whilst locking in the thermal benefits.
Priced at £89.99 at the time of writing
Check Price on AmazonFrequently Asked Questions
Does multifoil insulation actually work in garden rooms?
Do I need an air gap with multifoil insulation?
Can I use the cheap bubble foil for a home office?
Is multifoil better than rock wool for summerhouses?
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