ENERGY EFICIENT HOUSES

SIP Kits - TEK Kingspan Building System - FAQ’s

Q: What is a U-value?

A: A U-value is a numeric method of assessing heat loss through a given element such as a wall, roof or floor U-values are stated in W/m²K (Watts per metre² Kalvin). This expresses the rate at which heat transfers through 1m² of an element where the temperature difference between the internal and external is 1°K.

Q: How is it calculated for TEK?

A: U-values are calculated using the methods in the following standards:

BS EN ISO 6946: 1997 (Building components and building elements – Thermal resistance and thermal transmittance – Calculation method) BR 443: 2006 (Conventions for U-values) BS EN ISO 13370: 1998 (Thermal performance of buildings – Heat transfer via the ground – Calculation methods).

All elements, except for a ground floor, are calculated using BS EN ISO 6946 and BR443. Both methods work on what is known as the combined method. 

Q: What is a Cavity Barrier?

A:Cavity barriers are intended to restrict the spread of flame or smoke within a concealed space or cavity. As with all construction systems, it is imperative to control the spread in these spaces as the effects of fire in such locations can very often remain undetected until it has taken a significant hold on the building structure. A cavity barrier is described in Approved Document B (Fire Safety) as:

‘A construction, other than a smoke curtain, provided to close a concealed space against penetration of smoke or flame, or provided to restrict the movement of smoke or flame within such spaces’.

The cavity barriers can be of the following materials:

- Preservative-treated timber battens; minimum 38mm x cavity width.

- Calcium silicate, cement-based or gypsum-based boards, at least 12.5mm thick.

- Wire reinforced mineral wool or mineral wool blanket at least 50mm thick.

- Polythene sleeved mineral wool or mineral wool slab that is compressed in the cavity.

Q: Chain-of-Custody?

A: The chain-of-custody records the path that timber products take from their initial source in the forest via any manufacturing and engineering process, distribution and stockists through to the end user. Each individual piece of timber will have a record that will trace it back to its source to demonstrate that the product has been obtained from a well managed, legal and sustainable forest.

Chain-of-Custody and the TEK Building System All buildings that are constructed with the TEK building system, including all necessary timbers products supplied, can be given with a full chain-of-custody. Certification can be issued using any of the following three schemes:

FSC -Forest Stewardship Council Certification Scheme PEFC -Program for the Endorsement of Forestry Certification SFI          -Sustainable Forests Initiative

All of the above schemes vary, but their intention is the same; to demonstrate that the source of timber is documented and controlled throughout the entire chain.

A chain-of-custody for the TEK building system can only be issued once the final design and engineering for each element of the system is confirmed and ready for delivery. All suppliers in this chain, for products such as the OSB, joists, and structural timbers, will need to demonstrate certification for the products they have supplied so that a chain-of-custody for the TEK building can be verified.

Q: What is Disproportionate Collapse?

A: Disproportionate collapse is the inability of a building to withstand collapse disproportionate to its use in the event of limited accidental damage or failure to part of the structure. In such a situation the majority of the building or subsequent floors and structural walls will need to have the ability to retain the majority of their structural integrity should a localised area of the structure be damaged and can not therefore be relied upon for structural support.

Q: What is LPCB and LPS 1181?

A: The LPCB is an abbreviation for the Loss Prevention Certification Board, which is a subsidiary of BRE Certification Ltd. The LPCB issues certification for Loss Prevention Standards (LPS).  One standard that is referred to with a great deal of regularity, especially insurance underwriters, is LPS 1181. This standard is a fire safety standard for cladding systems that is very often referred to for products that do not fall within its remit.

Q: Why Have Renewable Technologies?

A: The energy used to heat, light and run our homes accounts for 27 percent of all the UK’s emissions, which is around 40 million tones. The introduction of the Code for Sustainable Homes and increases in up coming Building Regulations and Technical Standards raises the need to consider and include renewable technologies in new buildings.  Regulatory requirement in conjunction with a genuine environmental need to reduce CO2 production means that in addition to increases in performance of the building envelope, renewable energy will need to be included in future building designs

Q: What is a Breather Membrane?

A: BS 5250 (Code of practice for control of condensation in buildings) describes a breather membrane as a “vapour permeable membrane with a vapour resistance less than 0.6MNs/g”. A breather membrane must effectively offer resistance to the passage of external moisture and wind driven rain due to inclement weather, while giving little resistance to the passage of internal vapour. Products classed as breather membranes in the context of BS 5250 are mainly used in vertical applications and can not normally be used in a roofing application unless they have a vapour resistance of no more than 0.25 MNs/g.

Permeable membranes for pitched roofing applications such as Nilvent are classed as vapour permeable underlays and should have a vapour resistance of not more than 0.25 MNs/g.

Q: What Does a Vapour Barrier Do?

A vapour barrier or vapour control layer reduces the volume of gaseous vapour that passes from the interior of a building to the external due to the effects of vapour pressure. If the passage of vapour is reduced then the likelihood of condensation occurring in the structure (interstitial) is reduced or even eliminated as there is little or no vapour available to cool into condensate towards the colder side (exterior) of the structure. It is described in BS 5250 (Code of practice for control of condensation in buildings) as “material of construction that substantially reduces the water vapour transfer through any building component in which it is incorporated”.

Q: What is the Code for Sustainable Homes?

A: The Code for sustainable homes is a Government initiative set up to improve the sustainability of new homes and is currently aimed at setting minimum standards for affordable/social housing. With the intent of it being optional for the private sector. The code uses a star rating system that is derived from a points scoring method based on the BRE’s Eco-Homes rating. The more stars a building has been awarded, the better its sustainability.

Q: Can the TEK Panel be chased out for Back Boxes?

A:Chasing out parts of the OSB/3 facing of the TEK panel to allow for back boxes for sockets and light switches etc. is not permissible. This could raise problems with issues such as fire resistance; if the OSB/3 facing is chased out and the foam exposed, the fire resistance is lowered at this point as the urethane core does not have the same fire resistance offered by the OSB/3. The structural stability of the panel would be affected, especially if the areas near openings or structural posts are chased out to allow for back boxes. Another issue raised is; suitability of the fixing substrate due to ether the OSB/3 being too thin to hold a screw thread or the urethane core being exposed which does not act as a fixing substrate. 

Q: Mortgages and Modern Methods of Construction

A: Modern methods of construction have successfully obtained mortgages over many decades and no real prejudice exists providing the technology used within the construction of the house is not deemed to be too ‘radical’. Steel frame, timber frame, ICF (insulated concrete formwork and SIPs (Structural Insulated Panels) are all now ‘common place’ in the modern house building market.

Q: Used in a TEK Building Settle?

A: All timber suffers with a degree of settlement across the grain. This is largely due to shrinkage from loss of moisture. For every 4% of moisture content reduction, cross grain timber shrinks 1% of its size.

Q: How Does This Affect a TEK and Timber Frame Hybrid Building?

A: If the timber used in a timber frame load bearing wall or party wall is ordinary softwood then there will be a difference in settlement between the timber frame and the TEK envelope which will increase snagging issues of new buildings. A TEK envelope will have a maximum settlement of 3mm per storey by the time floor joists, head binders and soleplates are taken into account. 

Q:What is required to Satisfy? The Council of Mortgage Lenders has out lined the requirements for MMC’s (Modern Methods of Construction) to be satisfied as follows:

1) Durability; the property must have a lifespan of at least 60 years.

2) Whole life costs; these are particularly relevant to lenders to the housing association sector. A property should have total costs over its operating lifespan that are equal to, or better, than traditional construction.

3) Reparability; properties should be capable of being repaired using locally available skills and should not present repair issues greater in extent or more complex than traditional designs.

4) Adaptability; designs should be flexible enough to allow for alterations or additions over the life of the property, e.g. fitting a conservatory.

5) Insurability; buildings insurance covering normal insured perils should be available on normal terms. If a building insurance is not available on a dwelling on normal terms then it is unlikely to be suitable to stand as loan security.

N.B. The above requirements can be satisfied as follows:

1) Durability; The BBA certificate for the 142 panel states on page 8, section 16.1 “The panels will have comparable durability to that of OSB/3 to BS EN 300: 1997, therefore, provided the installation remains weathertight, a life of at least 60 years may be expected”.

2) Whole life costs; this needs little explanation. While this currently has little relevance to private sector housing, the TEK systems whole life costs improves on the more commonly recognised methods.

3) Reparability; other than the TEK panel itself, all other aspects of the building for maintenance and reparability are no different to most other type of building method, and therefore can be repaired using locally sourced labour.

4) Adaptability; the TEK system can be adapted to accommodate minor alterations and extensions. As with all types of this work to a building, building control requirements will need to be satisfied.

5) Insurability; like with most other building methods the TEK Building System is insurable for what is recognised as normally insured perils. These perils are: fire, lightning, aircraft, explosion, earthquake, storm, flood, escape of water or oil, riot, malicious damage, theft or attempted theft, falling trees and branches, subsidence, heave, landslip, collision, accidental damage to underground services, professional fees such as demolitions and site clearance and public liability to any one else.