Thermal performance and air-tightness of the SIP wall is determined by the thickness of the core material and its thermal properties. Thru-Wall consists of a polyurethane closed cell core material, sandwiched between OSB3 to BS EN 300:2006.
For ease of use the chart to the right has been calculated using the method required by the Building Regulations Part L2 (England & Wales), Building Standards Part J (Scotland), BS EN ISO 6946:1997 and BRE report (BRE443: 2006)
Thermal conductivity (k value) tested to BS EN 13165 = 0.024w/mk based on an aged thermal conductivity
90%+ closed cell = virtually zero moisture absorption
Mean density = 45kg mtr cu. Minimum not less than 38kg.
| SIP Thickness | 125 mm |
150 mm |
180 mm |
200 mm |
225 mm |
250 mm |
| OSB 3 | 15mm | 15mm | 15mm | 15mm | 15mm | 15mm |
| Polyurethane | 95mm | 120mm | 150mm | 170mm | 195mm | 220mm |
| 2010 Building Reg. 'U' Value* | 0.30 | 0.30 | 0.30 | 0.30 | 0.30 | 0.30 |
| SIP's 'U' Value | 0.25 | 0.20 | 0.16 | 0.14 | 0.12 | 0.10 |
*These ‘U’ values are extracted from the new 2010 ADL1A document and are the highest values to be compliant. However, the achievement of the TER is likely to require significantly increased fabric performance ‘U’ values than those quoted in the chart – exactly what the Thru-Wall SIPS system can provide.