Calculating U-values
Generally U-values should be calculated using BS EN ISO 6946.

Typical solutions for Part L are shown on the Product Selector. For a range of alternative solutions please contact the technical help line on
0113 232 0022

or sales@stocks-blocks.co.uk

Part E – Resistance to the Passage of Sound
Robust details – edition 2 January 2005
Aggregate block constructions to give performance airborne mean of +50 dB

Separating wall – Cavity masonry
Robust detail:
E – WM – 1
E – WM – 2
E – WM – 3
E – WM – 4
E – WM – 4 (March 2006)

Separating wall minimum values for airborne sound insulation Purpose built dwellings 45 DnT.w + Ctr dB.
The RSDs are designed to exceed this figure to ensure compliance.

Non-Robust Details
Single leaf party walls may be constructed but will be required to be tested. A robust detail is currently being prepared.
The BRE have tested this type of wall which gives the following results.
This is based on 100mm Stocks Dense Concrete Block (Density 2000 kg/m³ laid flat to give a 215mm wide wall with 13mm lightweight plaster Rw (C;Ctr) 54 (-1;-5)

Single leaf walls have been tested as an example the 140mm Insulite blocks gave the following with various finish conditions:

Acoustic Tests – Insulite Standard Solid Blockwork
Following our recent measurements please find below a preliminary summary of results in terms of the Weighted Sound Reduction Index (Rw) and Spectrum Adaptation Terms (C and Ctr) for the 140mm think Insulite Standard Solid Blockwork with various finish conditions.

Air Leakage
Air leakage is now a requirement in building regulations. A reasonable limit for the design air permeability is 10m³/(h.m²) @ 50 Pa.
The Insulite blocks display an excellent air leakage measurement, i.e.
100mm Insulite Paint Grade
3.68m³/(h.m²) @ 50 Pa
140mm Insulite Paint Grade
3.24m³/(h.m²) @ 50 Pa
The above painted with 2 coats of emulsion gave zero.
Please contact technical department for full test data.

British Standard Changes
Selection & Specification
BS EN 771-3 has replaced BS 6073-1 “Methods of Specifying Precast Masonry Units”.
A new BS 5628-1, 2 & 3: 2005 “Structural Code of Practice for Masonry
Euro code 6 “Design of Masonry Structures”
BSEN 998-2 specification or mortar for masonry

Technical Data
k value for Insulite Blocks is
0.40 W/m²k
k value for Dense/Fairtex Masonry Blocks is 0.99 – 1.25 W/m²k
k value for Ultralite blocks is
0.25 W/m²k (Values from CIBSE guide).

Movement joints – up to 10m uninterrupted spans
Tolerance categories – D1 & D2
Quality Control Category – 1 & 2
Vapour Resistivity – 70-120 MNS/gm
Thermal Capacity – 1000 kj/kgk
Drying Shrinkage – Insulite 0.025%
Drying Shrinkage – Dense 0.030%
Drying Shrinkage - Ultralite 0.030%

Other block walls tested, available on request.