Thin-Joint System and EcoHomes Assessments

EcoHomes is an environmental assessment scheme for new and renovated homes. Administered by BRE it sets standards of environmental best practice criteria against which developments can be measured. The criteria cover: energy, transport, pollution, materials, water, land use and ecology, health and well-being.

H+H Celcon’s Thin-Joint system combines the use of energy-efficient lightweight aircrete blocks with quick-setting thin-joint mortar which speeds the construction process. It is recognised as a Modern Method of Construction (MMC) by the Housing Corporation. MMC focus on systems which speed the construction process, cut waste, minimise the effect of construction on the environment and create an energy-efficient home to live in.


Aircrete contains tiny air bubbles, which give Celcon blocks outstanding insulation properties. Exceptional thermal performance can be achieved whether building cavity or solid walls – 100mm Celcon Solar blocks with thin-layer mortar, as part of a cavity wall construction can deliver a U-value better than that currently suggested for amendments to Part L in 2005. Celcon Foundation blocks can achieve additional savings in floor heat losses. Using Celcon Plus and Jumbo Plus blocks with Thin-layer mortar means less thermal bridging with fewer and thinner joints compared to 440mm long blocks with traditional mortar.

The Pollington 2 plant in Yorkshire, where blocks for the Celcon Thin-Joint system are produced, has been specifically designed to achieve the highest standards of efficiency and energy performance. Features include a combined heat and power centre, recycling of autoclave steam and compressors which automatically match compressed air production to factory needs.

Green Guide to Housing

External walls, ground floors (beam and block floors) and internal partitions built using Celcon aircrete can achieve “A” ratings according to the Green Guide to Housing.

Training Support

Our skilled thin-joint demonstrator team will be able to offer hands on training to designated site Thin-Joint block layers. They can also return to site during construction to assist in the maintenance of Thin-Joint laying quality.


Being lightweight, Celcon aircrete blocks require less fuel to transport from H+H Celcon’s four factories to site and once there, less energy is needed if they need to be moved mechanically around the site.


In place at each of its four manufacturing plants H+H Celcon has an Environmental Management System which conforms to environmental management standard ISO 14001:1996 and is third party accredited by BSI.


PFA (Pulverised Fuel Ash) is used as a major raw material for the manufacture of Celcon blocks. This is a by-product of coal-fired power stations. Aircrete blocks can be cut on site using a block saw and the off-cuts used elsewhere, so minimising waste.


H+H Celcon’s Pollington 2 plant has a comprehensive water management system which retains rainwater and wastewater from the manufacturing process. This significantly reduces the quantity of water that needs to be drawn from mains supplies.

Land Use & Ecology

Celcon products are manufactured predominantly from the by-product of another industry in plants which are designed to use the minimum amount of energy and to recycle water used in the process wherever possible. Celcon Foundation blocks can be used in soil conditions unsuitable for many other types of masonry, because of their resistance to sulfate attack and frost damage.

Health & Well-Being

With their unique micro-cellular structure, with millions of tiny airbubbles which do not interconnect, an effective barrier against moisture penetration is formed. The exceptional thermal performance of Celcon blocks ensures that occupiers can help in keeping their heating costs down. The inherent sound insulating properties of aircrete make it ideal for controlling noise transmission between adjoining rooms or properties – a significant factor governing residents' quality of life.

The EcoHomes rating system is split into the 7 following categories:

  • Energy
  • Transport
  • Pollution
  • Materials
  • Water
  • Land Use and Ecology
  • Health and Well Being

Each category is subdivided into 2 to 5 sections

H+H Celcon products can influence the ratings/credits in the following 5 sections in 4 categories:


Section Ene1– CO2 emission

This relates to CO2 emission for the whole development and is calculated in Kg/m2/year. The data used to obtain the final figure is typically taken from SAP calculations (note: as this is for the whole development, worst case SAP values should not be taken as they may be unrepresentative). The following examples of ‘main’ build components, incorporating Celcon products, can be used to significantly enhance ratings/credits for this section.

External Walls

Brick/100mm Cavity Batt insulation with 0.037W/mK conductivity/100mm Thin Layer Celcon Solar Plus Block/12.5 Plasterboard on dabs.

U-Value = 0.25W/m2K

Ground Floor

Beam and Celcon Floorblock/100mm insulation with 0.039W/mK conductivity /19mm Plywood decking on timber battens.

U-Value around 0.21W/m2K depending on house type.

Section Ene2 – Building envelope performance

Compliance with this section once again relies on the information supplied within the SAP calculation. It is basically a function of how well the dwellings perform above the minimum Target U-Value requirement as stipulated via the Building Regulations.

Using the specification set out in section Ene-1, it is often possible for section Ene2 to achieve maximum ratings/credits (100%).


Section Pol1 – HCFC emissions

The Celcon component of the foundations, ground floor, external and internal walls does not require the use of ozone depleting substances during their construction. Maximum ratings/credits (100%) can be achieved if the associated products also comply.


Section Mat4 – Environmental impact of materials

The Celcon external wall and ground floor constructions detailed in Section Ene1 above both obtain “A” ratings according to the Green Guide for housing. Celcon internal Aircrete partitions will also achieve an “A” rating.

“A” rating achievement relates to 100% rating/credit achievement for these constructions.

Health & Well-Being

Section Hea2 – Sound insulation

2 leaves of 100mm Celcon Standard thin layer blockwork, separated by a 75mm cavity and finished both sides with 8mm internal scratch finished render plus 12.5mm plasterboard on dabs achieves Robust Standard Detail (RSD) status and is recognised as such in the new Part E of the Building Regulations. Construction built to RD E-WM-7 will be capable of achieving a mean airborne performance which is at least 50dB DnT,w+Ctr. This is 5dB better than the mean airborne Part E performance standard which is 45dB min DnT,w+Ctr. Maximum EcoHomes Credits should therefore be achievable for tests specifically related to this Party wall construction (Note: EcoHomes compliance does specify pre-completion testing regardless of RSD status).

This information has been sourced, reviewed and adapted from materials provided by H + H Celcon.

For more information on this source, please visit H + H Celcon.


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