Aircrete, Acoustics and Building Regulations 

H+H Celcon Blocks have excellent sound insulation qualities enabling them to easily achieve acoustic requirements set out in Building Regulations. A unique cellular structure, made up of thousands of non-connected cells, allows Celcon Blocks to produce much better sound insulation than aggregate blocks of the same weight.

Part E of the Building Regulations requires reasonable standards of sound insulation for residential spaces. This is often measured via a Pre-Completion Test (PCT).

H+H aircrete offers the ability to construct a variety of masonry solutions to satisfy acoustic Building Regulation criteria. Elements include flanking walls, internal partition walls, separating walls and internal beam and block floors. 

Sound Insulation for Houses, Flats and Apartments

There is no need for Pre-Completion Testing (PCT) to satisfy Part E of the Building Regulations for new build houses, flats and apartments. Robust Details Limited (RDL) - - provide standard specifications for a number of separating and flanking wall constructions using Celcon Blocks in houses, flats and apartments.

Robust Detail designs are pre-tested to higher standards than those required by Approved Document E. Therefore, if you register your build with RDL and build in compliance with Robust Details, pre-completion sound testing is not required.

In order to be approved as a Robust Detail, each design must:

  • be capable of consistently exceeding the performance standards given in Approved Document E of the Building Regulations for England and Wales
  • be practical to build on site
  • be reasonably tolerant to workmanship

Flats and apartments can be built using Celcon Blocks throughout. Robust Details E-WM-6, E-WM-10, E-WM-13, E-WM-15, E-WM-23 and E-WM-24 for separating walls can be used for flats and apartments. When used in conjunction with the Robust Detail separating floor solutions E-FC-4,5, 8 or 9, there is no need for PCT of the whole flat.

Sound insulation for residential rooms

H+H provides a number of solutions for separating and flanking walls in rooms for residential purposes (such as hotels and hostels). These buildings are subject to the requirements of Part E of the Building Regulations. 
However, the use of Robust Details is not recognised as a suitable form of demonstrating compliance. Consequently, pre-completion acoustic testing is required on site.

Sound insulation for schools

H+H aircrete offers the ability to construct a variety of masonry solutions for schools and educational buildings to satisfy the required performance levels.

Building Regulations Approved Document E section 4 refers specifically to acoustic performance in schools and references Building Bulletin 93: Acoustic design of schools – performance standards

Due to the complexity of the design process, the document advises that “it is strongly recommended that the client require acoustic testing to be carried out as part of the building contract….In all but the simplest of project it is advisable to appoint a suitably qualified acoustic consultant at an early stage of the contract.”

The H+H technical department will be able to provide specific further details.

Thermal Mass and Aircrete

Aircrete has excellent thermal qualities, helping to create a comfortable environment. The high thermal mass of aircrete blocks helps regulate building temperature to minimise the effect of temperature extremes.

Houses with higher mass have a beneficial effect on the heating pattern in winter. By offering good thermal insulation, thermal inertia and airtightness properties, aircrete helps to keep the temperature at a more consistent level.

The same applies with higher summer temperatures. The increasingly high temperatures that are expected due to climate change have made overheating a potentially significant problem.

Thermal mass is recognised as one means of mitigating this. In a masonry build, the overall temperature will cool down as masonry blocks absorb and store heat during the daytime. This heat is then released during cooler night-time periods.

It is interesting to note that summer overheating is a problem typically associated with lightweight frame building systems.

Part L and Thermal Mass

Approved Document L identifies the Fabric Energy Efficiency Standard (FEES) of new dwellings as one of the metrics where compliance with regulations will need to be shown.

The FEES helps to ensure that a design has good levels of fabric insulation and heating systems that are future proofed. Document L recognises the overheating problem and requires designers to consider approaches that limit the effects of heat gains in summer.

Thermal mass is a contributor to the FEES. This underscores the importance of considering the 'Fabric First' approach to energy efficiency that H+H has maintained for decades.

Thermal insulation in new homes

Thermal insulation is an important consideration when designing new homes. The better thermally insulated a house, the less heat is lost from the structure. Building energy efficient dwellings requires the combination of heating technology and building fabric to be carefully thought out.

Commonly associated with board or mineral wool insulation, thermal insulation can be improved by choosing the right material for a home’s structure. Masonry is often a better choice than light-weight framing systems in this regard due to the intrinsic thermal qualities of bricks and blocks.

The chemical reaction that forms aircrete creates a structure where each block is made up of millions of non-interconnecting cells. With its own air pockets trapped in the block, aircrete provides inherent thermal insulation as well as complete water resistance and effective sound insulation.

U-value calculations are used to determine how well insulated a building element, such as an external wall, is. The lower the value, the less heat is lost from an element.

The most recent amendment to the Approved Document L of the Building Regulations, dated 2021, reduced the allowable U-value for external walls to 0.18 W/m2K.

The updated document also maintained an emphasis on “fabric first” approaches to energy efficiency and thermal performance for houses. More detail on the revision and standard wall details for Celcon Blocks is available for download on this page.

Aircrete solutions for better thermal insulation

Standard cavity-wall structures with a 100mm cavity filled with insulation and using either Celcon Blocks for the inner leaf, or Celcon Blocks in a solid wall construction with external wall insulation, can easily meet the thermal insulation requirements of Part L of the Building Regulations.

For groundwork, the use of H+H Foundation Blocks also offers improved thermal floor insulation. The aircrete blocks reduce heat loss from the ground floors, contributing to lower U-values.

Thermal insulation properties can be further enhanced by the use of H+H’s Thin-Joint masonry. The system combines the Celcon Plus and Jumbo Blok ranges with Celfix, a specially developed Thin-Joint mortar. This method of construction reduces the thickness of the mortar joints from 10mm to 2mm and ensures the joints are fully-filled, which increases the air-tightness of the wall structure.

H+H Celcon Blocks are also used to enhance home insulation when used in extensions, creating thermally efficient spaces and helping homeowners save energy.

Celcon Blocks have been used in a number of Zero Carbon and Passivhaus certified buildings. This demonstrates the potential for H+H aircrete to be used in the most highly-performing energy efficient homes.