SIPS Specifications

Standard Details

SIP Specifications | Standard DetailsEnter your email address for access to our Technical Downloads, We will use it for marketing purposes for Sip Build UK and not pass on to any third party or ever sell your personal information.

External Cladding - Walls

As soon as possible after Hemsec by SBUK SIP panels walls have been erected, a breathable membrane, e.g. TF200, should be fixed directly to the panels. External cladding should be installed over the breathable membrane.

The following are examples of external cladding for walls:

Thermal Properties

U–values (W/m2.K) for Hemsec Building System Walls with Various Thicknesses of Additional Insulation and Different Breathable Membranes.
Hemsec SIP Specification details
The λ–values detailed below are quoted in accordance with BS EN ISO 6946:1997 and BRE report (BR443:2006)

Thermal Conductivity

Thermal conductivity (λ–value) of the OSB/3 component of Hemsec by SBUK SIP panels should be taken as 0.13 W/m.K. The thermal conductivity of the insulation core of Hemsec by SBUK SIP panels is 0.028 W/m.K.


In addition to the excellent U–values that can be achieved by walls and roofs constructed using the, Hemsec by SBUK SIP panels the closed cell structure of the rigid urethane insulation core of the panels does not allow movement of air within them.

The insulation will not sag or physically deteriorate over time, as may be the case with other insulating materials.

Air leakage levels can be as good as 0.08 air changes per hour at normal pressures (approximately 1 m3/hour/m2 at 50 Pa). Standard results would be 3 air changes per hour. This is subject to the quality of the overall build.

The Facings

The Hemsec SIPs panel comprises of BBA Approved 15mm Internal and 15mm External Oriented Strand Board (OSB)
grade 3 facings. OSB/3 has a thermal conductivity value λ of 0.13 W/mK.
Manufactured to specification EN 13986 and EN 300:2006, OSB/3 comprises of strands of softwood bonded
together using a formaldehyde free synthetic resin.
The OSB boards are responsibly sourced and comply to FSC and PEFC chain of custody requirements.
Further information and Certification can be obtained on request through Hemsec SIPs.

The Core

The core of Hemsec by SBUK SIP panels are a closed cell Polyurethane rigid foam system with zero Ozone Depletion Potential (ODP) supplied by BASF
Polyurethanes Europe.
The PUR core is CFC and HCFC free providing a < 5 value for GWP, as specified by various regulatory bodies.

Structural Dimensions

Hemsec by SBUK SIP panels are available in the following standard size(s):


Water Vapour Resistance

Assessed to be acceptable in relation to the intended use of the
building and any limitations regarding climatic zones


Hemsec SIPs are manufactured from the highest quality materials, using state of the art production equipment to rigorous quality control standards, complying with ISO9001:2008 standard, ensuring long-term reliability and service life.

The panels will have comparable durability to that of OSB/3 to BS EN 300 : 2006, therefore, provided the installation remains weathertight and damp-proof; a life of at least 60 years may be expected. The long life expectancy of our product will reduce energy consumption of a building over its’ lifespan.

Resistance to Solvents, Fungai and Rodents

The rigid urethane insulation core is resistant to dilute acids, alkalis, mineral oil and petrol. It is not resistant to some solvent–based adhesive systems, particularly those containing methyl ethyl ketone.

Adhesives containing such solvents should not be used in association with Hemsec by SBUK Building System.

Hemsec Building System components, which have been in contact with harsh solvents, petrol, mineral oil or acids, or components that have been damaged in any way should not be used.

The rigid urethane insulation core and facings used in the manufacture of Hemsec by SBUK SIP panels resist attack by mould and microbial growth and do not provide any food value to vermin.

Strength & Stability

The permissible vertical load resistance for Hemsec by SBUK SIP panels is sufficient for the System’s use as loadbearing partitions, separating walls, the inner leaf of external walls and pitched roofs in dwellings up to four storeys high.


Resistance to Airborne Sound

Weighted apparent sound reduction index for separating walls achieves a sound reduction of (Rw) of 44 dB

Weighted apparent sound reduction index for all other walls achieves a sound reduction of (Rw) of 37 dB

Fire Performance

Panel Internal and External OSB and CPB facings have Class 3 surface spread of flame to BS476: Part 7:
1987. When Hemsec SIPs are used as part of a through-wall build up they pass the requirements of BS476 Part
21 fire resistance of load bearing walls and have achieved up to 75 minutes fire rating. Non-Load bearing walls
can achieve up to a 90 minute fire rating (BS476 Part 22:1987).