Conservatory Roof Insulation


How does Conservatory roof insulation work?

Conservatory insulation works very much in the same way as standard home roof insulation and should be treated as such, if the aim is to convert the conservatory into a liveable space. The use of a multifoil is an effective way to insulate as it controls the three forms of heat transfer: convection, conduction, and radiation. TLX Silver is flexible, lightweight and can be simply installed to the underside of the roof rafters, preventing heat from being lost through the building.

TLX Silver has inner layers of wadding which reduces heat loss by conduction through the multifoil. Wadding is interspersed with layers of film which prevents the movement of air. These layers work together to form an airtight barrier, in turn reducing the amount of warm air lost to the outside. It effectively acts as an insulating vapour barrier, managing the risk of condensation by preventing moisture entering the roof from the inside.

multifoil insulation conservatory roofHow to install conservatory roof insulation

Step 1: Firstly,the roof will need to be removed, exposing the rafters for ease of access to install the insulation.

Step 2: TLX Silver is installed to the underside of the rafters, secured in place with 38x38mm battens set crosswise; a standard plasterboard can be fitted underneath.

Step 3: Additional insulation can then be fitted in-between the rafters, ensuring an unventilated air gap is maintained between the multifoil and the rigid board. If mineral wool is used, an air gap is not required.

Step 4: Ventilation is then to be introduced above the insulation; the optimum air gap is 50mm.

Step 5: Fit an OSB board above the rafter, providing protection for the insulation against unwanted exposure to UV light. 

Step 6: A breathable membrane should then be installed above the OSB board.

Step 7:  Your chosen roof covering can then be fixed directly to the membrane or can be tile-battened before it is fixed, in accordance with the manufacturer’s instructions.

Further considerations:

It is important to ensure the TLX Silver does not come into contact with bare electrical wiring. Therefore, prep work needs to be undertaken beforehand to assess the likelihood of this. If bare wiring is present, they will need to be PVC coated or de-rated. Guidance should be sought from a qualified electrician.


  • Rolls of TLX Silver should be stored on a flat surface and protected from sunlight and weather
  • Ensure that TLX Silver does not come into contact with heat sources above 80 degrees Celsius

What to consider when fitting insulation in your conservatory

First and most importantly, the roof will need to be removed, ensuring it is a solid roof conversion. We would not recommend installing insulation simply to the underside of the existing rafters with no barrier above, as this would expose the product to UV light. Since the surfaces of multifoils and PIR board are extremely reflective and attract heat, the unventilated air space next to these materials would get incredibly hot, specifically in the summer months. To avoid this, the use of an OSB board beneath the tiles and waterproof underlay is an important requirement.

What is the best insulation for a conservatory roof?

It is recommended that TLX Silver is used in conjunction with PIR board or mineral wool for a solid conservatory roof build to achieve the optimum thermal performance. The use of TLX Silver will significantly reduce the amount of additional insulation needed to meet building regulation requirements, meaning head height can be retained for a more comfortable internal environment. TLX Silver is also lightweight and quick and easy to install, without the need to cut the material, minimising unwanted wastage. If the multifoil needs to be cut back to achieve a precise fit, this can easily be achieved with Kretzer Finny scissors. 

Where to buy conservatory roof insulation

TLX Multifoil Roof Insulation can be purchased at your local builders’ merchant, roofers’ merchant or major roofing distributor. Our TLX Silver 2 in 1 insulating vapour barrier is stocked at Travis Perkins Trading Co Ltd, Fortis member branches, Jewson, SIG and other independent merchants across the UK. If your preference is to order online, The Roofing Superstore can also be of assistance.

Pros and Cons of conservatory insulation

Like everything, there are Pro’s and Con’s to conservatory insulation, it’s all about getting the right balance and weighing up the benefits against the drawbacks and finding the best solution to suit the specific requirements of your build.

The cons of conservatory insulation:

  • PIR board is difficult to cut
  • It is difficult to achieve airtightness with PIR board
  • Mineral wool is messy to work with
  • Mineral wool is bulky, therefore awkward to fit in place
  • Mineral wool is an irritant

The pros of conservatory insulation:

  • TLX Silver is easy to install
  • TLX Silver is lightweight
  • TLX Silver provides complete air tightness
  • When used as part of a hybrid system alongside additional insulation, TLX Silver can be used to achieve U value requirements

Conservatory roof insulation panels

Roof insulation panels offer a direct replacement for a typical glass and polycarbonate conservatory roof structure. They are generally 24-32mm thick and are used to reduce heat loss through the roof. Homeowners may use insulation panels to make their conservatory useable throughout the year as they provide a thermal benefit in winter and reduce glare in summer compared to the alternative glass roof.


  • They reduce heat loss through the roof
  • They reduce external noise pollution
  • They are lightweight


  • Since they are a minimal thickness, they don’t offer much thermal benefit compared to a multifoil such as TLX Silver
  • They do not ensure air tightness since they sit where the glazing would ordinarily go
  • A greater thickness of additional insulation is needed to achieve building regulations

Do building regulations apply to my conservatory?

Building regulations would apply if your roof were intended to be a part of the habitable space within the home, for instance if the room has a heating source or if the adjoining doors are taken out to create an open living area. Generally, building control require a U value of 0.18w/m2k, however there is some leniency depending on the restrictions of your build or if the building is listed. If you require a bespoke U value calculation, our team of product scientists are on hand to offer expert advice, please don’t hesitate to contact us on the number below.

tlx insulation technical hotline