About multi-layer foil - heat reflecting membranes - bubble foil insulation

Thermo reflective foils were created to overcome the condensation problems intrinsic in the use of single foil insulation products when used in temperate climates.

Thermo reflective foil products are manufactured in a number of differing styles, however their common denominator is their ease of installation. Their dramatically reduced thickness, results in less space requirements when compared to traditional insulation products.

Heat Reflecting Foil Membranes were originally developed for space exploration. In domestic and commercial premises they can only be used to complement fibre or foam insulation materials, because, if used incorrectly, they will promote condensation within the structure, resulting in dry-rot in wooden components.

Multi-foil is now commonly used to replace or complement bulky, old fashioned, dry insulation products. Multi-foil is very easily and quickly installed, and dramatically reduces the space that is wasted by traditional insulation products.

Why chose multi-foil insulation in favour of single reflective membrane

To negate potential problems of condensation being created on single thermo reflective foil products, and consequent dry-rot, multi-foil insulation was created. Soft dry fibre and/or foam insulation is positioned between the various reflective layers of multi-foil insulation, some of which may be waterproof membranes. The resulting multi-foil does not permit extremes of temperature to conduct through the material and cause condensation.

Single thermo reflective foil attracts condensation In temperate climates a single foil insulation, if incorrectly installed, can react in a similar manner to a bathroom mirror when the hot water tap is run. The cool temperature of the mirror, exacerbated by the cold wall behind the mirror, is affected by the temperature change, resulting in condensation. Unlike single foil products, multi-foil insulations act like a double or triple glazed window, which uses the airspace between the glass layers to slow down the transfer of temperature differences from one side of the window to the other, thereby inhibiting condensation and heat loss or gain.

Unlike a window that mists due to temperature fluctuations, multi-foil insulation deters the onset of condensation. The soft dry insulation inhibits the creation of condensation caused by dramatic temperature fluctuations, because the dew-point is never reached. They also eliminate the cold bridging problems to which single composite thermo reflective foil products are suggestible.

The concept of Multi-foil insulation

Conventional Insulation such as fibreglass, PUR Boards reduce heat transfer by trapping air or gas; they reduce convection as the primary method of reducing heat transfer.

Traditional insulation is not as efficient at reducing radiant heat transfer, which is often the primary mode of heat loss through a building envelope; these products like most building materials have very high radiant transfer rates.
In other words standard forms of insulation are good radiators of heat.

Multi-foil Insulation use layers of Polyethylene coated foils spaced with wadding and closed cell foams, the low emissivity surfaces are very effective in reducing radiant heat transfer ... in fact the metalized foils can reduce radiant heat transfer by as much as 97%

While the internal house temperature may be constant, the outside temperature varies continuously under the effect of climatic conditions (rain, wind, freezing, and snow), solar radiation, and night time radiation evaporation etc.

The behaviour of multi-foils in relation to these conditions is different to that of homogenous, thick insulation products. Multi-foils dynamically combines the four energy transfer modes

The longevity of foil insulation

Clearly, all insulation is intended to last for the expected lifetime of a modern building. Regarding the guarantees on foil insulation, we would suggest the period of guarantee relates primarily to the effectiveness of the aluminized layers to continue their job of reflecting infra-red energy. As and when the aluminium tarnishes, it becomes less effective. Therefore, the quality of the lacquer coating on the outside of aluminized foil is vital, while the components of aluminized polyester and the like must be of sufficient quality not to inhibit the reflective qualities of the insulation.

Our Current Thermo Reflective Foil Product List

Gen-X® Multi Foil from Euroform

Gen-X 33mm - 15m2 BBA certified to achieve 0.2 U-value and guaranteed for the lifetime of the building structure to which it is incorporated. High water vapour resistance with a measured value in excess of 6000MNsg.

Certification:

BBA Certificate No 08/4543: BM Trada 3961Certificate: Part L Building Regulations Compliant: NHBC Accepted:

Description:

Launched, Summer, 2008 this new product is a multi-layer foil insulation, complete thermal insulant, air leakage & vapour barrier in one.

Gen-X® helps seal your roof against climatic elements such as wind and damp whilst at the same time retaining ventilation. Using reflective technology, Gen-X helps prevent your roof space from overheating in summer by reflecting the electromagnetic radiation from the sun whilst retaining warmth in winter. Gen-X is ideal for applications requiring a dual layer of insulation. Lightweight, Space-saving, Minimal truss depth,Minimal additional insulation requirement, Combined vapour barrier in one, Does not cause allergies or dust.

Technical characteristics

Roll Size 1.2mtrs x 12.5mtrs
Thickness 33mm
Layers 7
Weight 13kg per roll
R-Value 1.9m2 K/W
Resistance to tearing 300-450N (nail shank) (BS EN 12310-1)
Flammability Class 'E' BS EN ISO 11925-2

 

TLX Silver™ Multi Foil from Web Dynamics

TLX Silver 30mm - 12m2 RollB BA certified to achieve 0.2 U-value and guaranteed for 25 years

Certification:

BBA Certified No 06/4379: Meets Part L Building Regulations

Description:

TLX Silver is an insulation material comprising outer layers of coated metallised film, laminated to a nonwoven polypropylene fabric enclosing the core and welded along both long edges. The core of the product consists of five layers of polyester fibre wadding separated by four metallised film layers.

Technical characteristics

The product comprises11 layers, of which 5 are reflective films.
R-value m2K/W= 1.69 Tested battened over rafters to BR443. R-value includes cold bridging of timbers
Core R-value m2K/W= .92
Dimensions = 1.2m x 10m x 30mm
Yield = 12 m2
Weight = 8 kg - 70m/m2

TLX Rafterfit™ Multi Foil from Web Dynamics

TLX RafterFit Roll - BBA certified to achieve 0.2 U-value and guaranteed for 25 years
Certification:

BBA Certified No 06/4379: Meets Part L Building Regulations.

Description:

RafterFit, like TLX Silver, uses layers of infra-red reflecting film to reflect heat back into insulation containment cells. The system optimises fibre density, thickness and volume to reduce conduction and convection. Ideal for loft conversions and refurbishments where the original roof remains. Perfect for loft conversions requiring 50mm air gap Saves the hassle and mess of cutting and fitting PUR between rafters and. Three times faster to fit than PUR between 100mm rafters with 400mm spacings.

Technical characteristics

The product comprises11 layers, 5 of which are reflective films.
Core R-value m2K/W = .91 Tested without battens. R-value does not include cold bridging of rafters
Dimensions = 520 x 10 x 30mm
Yield = 4.2m2
Weight = 6 kg - 70m/m2

Triso Super 10 multi-Foil from Actis Actis Tri Iso Super 10 Roll

Certification:

BM Trada

Description:

Actis Tri Iso 10 is a new, improved, version of the popular Tri Iso Super 9 insulation. Actis Tri Iso Super 10 gives increased thermal efficiency and is still only 30mm thick. The product has been tested under real conditions by TRADA Technology Limited who have declared it as being equivalent to 210 mm of mineral wool.

Technical characteristics

The product comprises19 layers, 8 of which are reflective films.
Thermal efficiency : U-value*=0.19 W/mK (as measured under real conditions by TRADA Technology Ltd. and certified as equivalent to 210mm of mineral wool, when installed in a pitched roof application, by BM TRADA Certification Ltd. (Certificate no.0102 dated 03 April 2006)

Triso Sols Under-floor Multi Foil Insulation from Actis

Actis Triso Sols for underfloor heating

Certification:

None

Description:

Actis Triso Sols floor / under-floor insulation is ideal for renovation or new build. Due to its slim proportions, just 7mm thick, it allows for extra headroom. It complements hot-water under-floor heating systems, and can also be used below the screed on a standard floor

Technical characteristics

Uniformly reflects the heat from hot-water under-floor heating systems back up into the room.
Eliminates thermal bridging at floor perimeter
Quick and easy installation.
The grid markings facilitates the laying of heating pipes
The product comprises19 layers, 8 of which are reflective films.

 

Which is better, Gen-X, Actis Tri Iso Super 10 or TLX Silver?

Gen-X – for and against

Gen-X mirrors the Actis and TLX Silver multi-foil concept, but at 33mm is 10% thicker
Gen-X is made in Britain.
Gen-X has less layers that Actis and TLX Silver , but one has to consider what is the benefit of the extra layers?
Gen-X manufacturers, Euroform, have done a great deal of research and development. And, have attained certification from both the BBA and BM Trada, and as such must be accepted by Building Control throughout the UK.
Gen-X is guaranteed for the life equivalent to that of the structure to which it is incorporated
Gen-X costs less than Actis Tri Iso Super 10 or TLX Silver
Gen-X does not require foil backed plasterboard in an under-roof installation, thereby saving in excess of £2.00 per board, excluding VAT
Gen-X's BBA Certificate specifies 75mm of PIR Board as opposed TLX Silver's 70mm.

Actis – for and against

Actis was the first multi-foil insulation to come to the market, and is commonly associated with multi-foil insulation as a consequence.
Actis is imported from France.
Actis has more layers than Gen-X or TLX Silver, but thiner than Gen-X and the same is the same thickness as TLX Silver.
Actis make claims about their product that have not been scientifically proven by a strict examining body such as the BBA.
Actis certification through BM Trada on April 3, 2006.
Actis may not be accepted by a number of Building Controls throughout the country.

TLX Silver – for and against

TLX Silver mirrors the Actis multi-foil concept.
TLX Silver is made in Britain.
TLX Silver has more layers than Gen-X but less layers that Actis.
TLX Silver manufacturers, Web Dynamics, are diffident in their claims about their product, and have invested a great deal in research, development, testing and certification.
TLX Silver holds a current BBA Certification, and as such should be accepted by Building Control throughout the UK.
TLX Silver is guaranteed for 25 years
TLX Silver costs less than Actis Tri Iso Super 10, but more than Gen-X
TLX Silver's BBA Certificate states that polystyrene spaces must be fitted between the multi-foil and the plasterboard ... not a requirement with Gen-X.

Summary

Our view is that there is no discernable difference between the effectiveness of these products, although Gen-X is thicker and has better thermal values.

You should not expect to achieve a U-value of 0.20 by utilising a single layer of Gen-X, Actis Triso Super 10, nor TLX Silver, on their own.

Should you elect to choose Actis, we would recommend that you follow the TLX Silver installation instructions which are the most detailed and accurate.

The strength of Actis's BM Trada Certificate cannot be compared to that of a BBA Certificate. And, as such, may not be accepted by Building Control, in contrast to BBA certification when applied in accordance with a valid BBA Certificate.

Manufacturers

Actis Super 10 and Triso Sols
Unit 1, Cornbrash Park, Bumpers Farm, Chippenham, Wiltshire. Tel: 01249 446123

Gen-X Multi-Foil from Euroform Products Limited
The Heliport, Lyncastle Road, Appleton, Warrington WA4 4SN. Tel: 01925 860999

TLX Silver & RafterFit from Web Dynamics Ltd
Moss Lane, Blackrod, Bolton, Lancashire BL6 5JB Tel: 01204 674 730

 

Page last updated Tuesday, June 1, 2010