Explore the topics below in order to find our experts answers to your most frequently asked questions. We are frequently asked about the world of exterior joinery and facade joints and below we try our best to share our specialist knowledge. If we do not answer your question here, please get in touch with our expert team.
- What is an impregnated tape?
- Is it necessary to apply a sealant over the top of the tape?
No – the tape is weather resistant to a minimum of 600 Pa (equivalent to 70mph – violent storm category). If a tape is ‘capped’, this will negate the vapour permeability, potentially causing problems due to moisture entrapment, and could also facilitate three-sided adhesion of the sealant by adhering to the face of the tape and preventing movement of the sealant resulting in adhesion failure to the sides of the joint.
- How does the tape function?
The resin impregnation and the high level of compression result in a closed cell structure which is highly weather resistant but remains vapour permeable so that any moisture which may be trapped behind can escape as moisture vapour and ensure drying of the joint.
- Are impregnated tapes suitable for movement joints?
The tape can accommodate movement across its thickness (joint width) whilst remaining stable within the joint. The level of movement capability is likely to be in excess of typical silicone type sealants.
- How do I select the appropriate size of tape?
In order to do this, determine the joint width, and any variation along the length of the joint. Select the tape thickness range which includes the defined tolerances. The tape width is determined by the available depth into the joint but also subject to being at least equivalent to the maximum thickness, eg 15 (tape width)/7 – 12 (tape thickness range); 20/8 – 15; 20/10 – 18, and being located at least 1 – 2mm inside the joint.
- What guarantee of performance do illbruck tapes carry?
The premium illbruck impregnated tape, TP600 has a 15 year performance guarantee and also a 10 year insurance backed guarantee* as part of the i3 System. TP600 & TP450 hold BBA accreditation. Subject to correct selection and application, illbruck impregnated tapes have a life expectancy in excess of 25 years.
*under the conditions specified by CPG UK
- What is a multi-functional tape?
This is an impregnated tape which combines the three functions of weather resistance, thermal and acoustic insulation, and airtightness. When compared to sealing a window perimeter joint using three separate products (see illbruck i3 System), there is a significant time saving, typically 80%. These tapes are wider and usually fit across the full depth of the window frame.
- What is the life expectancy of impregnated tapes and how does this compare to silicones?
Impregnated tapes have been in service for over 25 years and hence, that is the minimum predicted service life currently. This compares with silicones on the basis of the correct grade and correct application being used. Silicone is frequently selected inappropriately, and applied without primer and/or backing rod where applicable. There are fewer criteria to satisfy with impregnated tapes.
*under the conditions specified by CPG UK.
- What are the differences in how membranes function (with reference to façade applications)?
A membrane may be used for sealing the perimeter of windows or protecting the backing-wall on a façade. The membrane may need to be vapour-permeable (eg breather membrane) or vapour tight (eg vapour control layer) and can have a fixed or variable level of vapour permeability, the latter being referred to as an ‘Intelligent’ membrane. A membrane can be both airtight and vapour tight, and can even also be vapour permeable (see ‘Intelligent’ Membrane below).
- What is ‘EPDM’?
- Are all membranes basically EPDM?
Absolutely not! This is a very common misconception in that the EPDM reference is often used for applications which clearly don’t require the properties of this type of membrane or where it may be inappropriate for use, and even where a non-EPDM membrane is actually being used. The term ‘EPDM’ should not be used generically to cover all façade applications as problems can and will arise due to the potentially misleading terminology. The only time a membrane should be called ‘EPDM’ is if it actually is!
- What is an ‘Intelligent’ Membrane?
These membranes are so-called due to their ability to promote the drying out of a building by having a variable ‘sd’ (equivalent air layer thickness) value whereby as localised humidity increases, the sd value decreases (the membrane becomes more vapour-open) and the sd increases (becomes more vapour-tight) in less humid conditions.
- Can a membrane be exposed for long periods to weather and UV?
An EPDM membrane can be exposed to both weather and UV indefinitely. A typical breather membrane (NOT an EPDM material) is normally covered within a few weeks or months of application so doesn’t need to be permanently durable without protection. Some membranes need to be covered within six to twelve months due to potential UV degradation but would resist weather ingress in the meantime. Although most breather membranes will resist typically 600 Pa driving rain resistance, they are normally effectively secondary seals due to being protected by rainscreen or similar cladding which acts as the primary seal.
- What criteria should be considered when comparing breather membranes?
Breather membranes need to be capable of withstanding driving rain (usually to a minimum of 600 Pa) and by definition need to be vapour permeable and the measurement of this is by reference to the membrane’s vapour resistance (measured in MNs/g – Mega Newton seconds per gram). Another widely used measure is the ‘sd value ’ – this is the equivalent air layer thickness in metres (m). In the case of both measurements, these can only be stated based on the specific thickness of the material. For optimum vapour permeability, the vapour resistance of a membrane should be < 0.6MNs/g.
- What criteria should be considered for vapour control layers (VCL’s)?
- What criteria should be considered for membranes used on a ‘relevant’ building – ie over 18m high where the Approved Document B (AD B) regulations apply in relation to reaction to fire?
Whilst all materials fixed to the external wall have to be non-combustible (Class A1) or of limited combustibility (A2-s1, d0) to EN13501-1, there are certain exemptions including for membranes, which are required to be minimum Class B-s3, d0. illbruck ME010 Façade UV & Fire Membrane achieves Class B-s1, d0 when tested with SP025 Adhesive. Most membranes, including illbruck ME220 (EPDM) and ME501/ME508 (Intelligent) are Class E as are most sealants.
More information can be found in our Approved Document B 2019 Fire Safety.
- How are membranes fixed?
There are various options of self-adhesive strips or full face self-adhesive, enhanced acrylic self-adhesive, gaskets and proprietary site applied adhesives.
- Is it safe to apply one type of membranes next to another?
All illbruck membranes are compatible with each other and although not all adhesives are appropriate with all membranes, it is possible to bond different types of membrane to each other by selecting the correct adhesive. In terms of vapour control, it is recommended to always use a more vapour open membrane to the exterior to facilitate escape of moisture and avoid damage within the wall construction.
- What guarantee of performance do illbruck membranes have?
Apart from 3rd party testing for properties such as air and weather tightness and reaction to fire, most illbruck membranes have BBA accreditation, thus satisfying the requirements of various specifiers, clients and building warranty providers.
- What means are there for understanding the principles of how and where to use membranes and for practical training?
CPD seminars and webinars are available which include information on the relevant building physics and regulations relating to membranes. The ‘illbruck assured’ training programme delivers both theoretical and practical training and can be tailored to suit individual clients’ needs. Site delivered ‘tool-box talks’ are also regularly provided on request.
- What is the ‘i3 System’?
This is a window (or door) perimeter sealing system providing three functional levels: Weather and airtightness and insulation. By installing appropriate products which provide these functions, a robust seal is achieved which will ensure that the weather and energy saving properties of the window will be maintained. Why install a highly rated window (eg A++ to BFRC WER scheme, or the lowest U-value possible) without a similarly performing perimeter seal?
- What is the i3 System comprised of?
There are different product options:
External seal – weathertightness: TP600/TP450 Impregnated foam tape, or ME500/ME501/ME501 VV/ME508 Intelligent Membranes.
Middle seal – thermal and acoustic insulation: FM330 Pro Foam Air Seal (PU foam).
Alternatively, the i3 System can be installed with all three levels provided from a single product – TP650/TP652/TP653/TP654 Trio. These are multi-functional tapes which reduce the installation time by up to 80% compared with the conventional three separate products.
- What performance guarantee does the i3 System have?
The system has BBA accreditation and additionally has a 10 year warranty subject to product and installation details being recorded (see i3 literature for further information).