TLX Gold has now been used in over 25,000 roofs in the UK and is fully BBA certified and endorsed by the LABC.

TLX Gold has been designed for today’s roofer. Whether it’s a roof refurbishment or new build project it improves thermal performance and eliminates the risk of condensation. It vents moisture like a breather membrane and yet insulates like non-breathable PIR board. TLX Gold is Sd intelligent (the more moisture present, the more it breathes) which is why there’s no condensation risk, even without a vapour barrier.

TLX Gold comes with a product performance guarantee, is fast to fit, and many solutions do not need to remove existing insulation. TLX provides you with solutions that have a guaranteed U-value, condensation risk and an estimate of payback calculations.


  • Upgrades thermal performance externally without risk of condensation
  • Heat reflecting, waterproof and airtight
  • Maintains roofline and maximises internal headroom
  • Fast and easy to install, certified and guaranteed
  • Externally fitted with minimum disturbance
  • Provides an improved insulation solution
  • CE marked, BBA certified, LABC approved build-ups
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In 2010 revisions to Part L were introduced. Specifically, roofers are now further challenged when a house is to be re-roofed or at least 50 percent of the roof area is to be repaired and a requirement is triggered in Part L1B to upgrade the thermal performance.

It may however not be possible to deliver a thermal performance upgrade to Building Regulation standards in all instances – perhaps the roofline cannot be raised since the house is either semi-detached or terraced, or a historic building whose appearance cannot be altered – and there may be a need for the roof insulation to remain breathable.

Relevant excerpts from Part L1B

L1B – Conservation of Fuel and Power

Approved Document L1B of 1st October 2010 defines re-roofing as “renovation of a thermal element” – stripping down the roof to expose the rafters and then rebuilding. The performance of the roof should be improved to achieve a U value of 0.18 W/m2.K.

When renovating elements of traditional construction particular considerations apply – the aim should be to improve energy efficiency as far as is reasonably practicable without prejudicing the character of the building or increasing the risk of long-term deterioration of the building fabric. The risks of interstitial condensation must be considered.

Buildings which are listed, in a conservation area or monuments are exempt from energy requirements, to the extent where compliance would unacceptably alter the character or appearance of the building.

If achievement of the 0.18 U value is not technically or functionally feasible, or would not achieve a simple payback of 15 years or less, the element should be upgraded to the best standard that is feasible, and which can be achieved within a simple payback of no greater than 15 years. Part L1B Appendix A: Practical considerations with respect to an increase in structural thickness (particularly in terraced dwellings) may necessitate a lower performance target.

If it is not technically feasible to upgrade the roof to U = 0.18 W/m2.K, but it is necessary to improve the roof as much as possible without introducing a risk of condensation.

Renovation of a thermal element is distinct from a retained thermal element, where an existing element becomes part of the thermal envelope. In the case of a roof that is a retained thermal element, it is only necessary to upgrade the thermal performance if it does not meet a threshold value of 0.35 W/m2.K. If it is not feasible to upgrade to the required standard, a lesser performance should not be worse than 0.7 W/m2.K.

C2 – Resistance to Moisture

Approved Document C2 Resistance to Moisture (6.10) states that a roof will resist damage from interstitial condensation if it is constructed in accordance with BS5250. A condensation risk analysis should be carried out on any proposed renovated roof structure. In addition, excessive moisture transport into the roof through moist air movement must be avoided by sealing junctions, gaps and service penetrations.

Regulation 7

Regulation 7 Materials and Workmanship states that building work should be carried out with adequate and proper materials. To ensure a material is suitable, it should comply with British or other national standards, be covered by a certificate issued by an ETA issuing body (such as BBA or DIBt), have a CE mark, or be certified by a UKAS accredited body.

All our standard TLX Gold solutions come with guaranteed U-value calculations and condensation risk analysis.


The temperature inside most houses is maintained at a comfortable level of around 20°C in living areas and 17°C in bedrooms. In the UK, the outside temperature is generally lower than this, especially in the winter. Heat flows from the warmer interior of the house, through the fabric of the building, to the outside. The U value expresses the rate at which heat is lost through a part of the house – such as roof, walls or windows. The U-value is expressed in units of Watts of power for every square metre of roof and for every degree temperature difference between the inside and the outside, or W/m2.K.

Part L1B 2010 requires a renovated roof to have a U-value of 0.18 W/m2.K. If the roof has an area of 70 square metres, and the temperatures inside and outside are 17 and 5°C, then the rate of heat loss through that roof is:

0.18 × 70 × (17 – 5) = 151 Watts

The U value of a roof is calculated by breaking the roof structure down into separate layers – such as plasterboard, insulation, rafters and underlay. The thermal resistance of each component is added together. Any materials of high thermal conductivity, such as timber rafters, form a cold bridge through the structure, and must be accounted for in the calculation, as must fixings and any poorly fitted insulation. The inverse of the total thermal resistance of the roof, plus allowance, gives the U-value for that roof structure. Examples of U-value calculations are shown in the TLX Gold solutions.

All TLX Gold U-value calculations are carried out according to BS EN ISO 6946.

Condensation Risk

In general, the water vapour pressure inside the house is also greater than the vapour pressure outside. As well as heat trying to escape the building, so too water vapour tries to escape through the building fabric to the outside. The main mechanism by which water vapour is eliminated is through adequate ventilation. However, vapour will also try to diffuse through the walls and roof.

TLX Gold alters the temperature gradient across the insulation so that condensation is less likely to form in the air gap above the PIR or mineral wool, and ensures that even if condensation should occur then it is able to evaporate through the breathable TLX Gold.

These days there are few guarantees that don’t come with a page full of small print so TLX think you will like their product assurance pledge. Whether you are a builder, roofer or homeowner TLX keeps their promise simple and provide you with peace of mind where you need it most.

Reassurance for roofers

As a roofer you want to know your product choice is fit for purpose and will deliver to required Building Regulations. With TLX Gold you can tick that box. Tested to demanding British and European standards, TLX Gold achieved a BBA certificate in 2015.

All TLX Gold compliant solutions have also achieved LABC Registered Details. Registered systems for TLX Gold help speed up the building regulation process by sharing technical details and recognising Building Control assessments made by others in the LABC network.

TLX Gold, TLX Silver and UV membrane products are guaranteed for 25 years. What this means is that that not only does TLX Gold deliver on product performance, but we also guarantee our U-value and condensation risk calculations. You can be confident you have made the right choice for you and your customers when you install TLX Gold.

Reassurance for householders

TLX Insulation, part of Web Dynamics is the only insulation manufacturer to have become an associate member of the Government licenced TrustMark Scheme. Supported by the building industry, retail and consumer protection organisations, TrustMark has the largest database of accredited tradesmen in the country and as a member they support you by only recommending reliable tradesmen and demonstrating that they require high standards of installation from them. TLX products are also backed by the NFRC (National Federation of Roofing Contractors) and TLX only recommends the installation of their products by NFRC and TrustMark approved roofers. NFRC and TrustMark approved roofers offer a warranty on their work which will also honour a roofer’s guarantee in the event that they cease to trade. TLX product assurance pledge which includes their U-value and condensation risk calculations will give you long term comfort and peace of mind.

Don't just take our word for it...