In the UK, an estimated 40% of greenhouse gas emissions come from buildings, with 14% of this coming from the housing stock. Heating and powering buildings currently make up 40% of the UK’s total energy consumption.

However, changes to the building regulation act that have come into effect will mean new homes in England must cut down on their net carbon emissions by around 30%, and commercial buildings 27%.  This will increase in 2025 with the introduction of the Future Homes and Buildings Standard, that will need carbon emissions reduced by 75-80% less than homes built under current regulations. Existing homes will also be held to these standards when an extension or thermal upgrade is added. 

This all follows a major revision last year to BS 5250: Code of practice for Management of moisture in buildings. In addition to a general update to all parts of the previous Standard, this latest version contains new guidance on moisture risks other than condensation, a whole building approach to moisture-safe design, building context, the coherence of design and detailing interactions, as well as capacity and in-service conditions

The differences between ‘as designed’, ‘as built’ and ‘in service’ conditions are now more clearly understood and for cold pitched roofs in particular, BS 5250 gives prescriptive guidance based on the evidence of many years of successful use of ventilation products to prevent the harmful effects of excessive condensation build up in the roof structure and loft space.

The idea that a permeable underlay nullifies the need for ventilation is a common misconception which can cause faults with a buildings ventilation. There are a range of different types of permeable underlays, that all require their own method of instillation. The appropriate location and level of ventilation required is heavily reliant on the construction of ceilings. A ceiling with efficient seals around cable and pipe penetrations and an effective air and vapour control layer will need a reduced level of ventilation. 

Of course, other major faults in this area include ineffective installation, or poor product quality. Rafter rolls are a vital part of any eaves ventilation system In a cold roof, and it’s vital they are set to ensure that air from the eaves ventilators can pass between the underlay and insulation into the loft space. The rafter roll must be width enough to accommodate the depth of loft insulation. The lower the roof pitch, the wider the rafter roll needs to be to accommodate the insulation. 

Some rafter rolls products are cut in quality to save costs, and thinner materials are used without adequate design and manufacturing methods. This can lead to products collapsing when the installation is completed, reducing, or even closing off the air path completely. 

Manthorpe, however have no concerns over any such situation. Having been in the industry for over 30 years, they have extensive knowledge not only in the installation phase but through every step of the process. Nearly all of their manufacturing is done in house, and they regularly invest in new cutting-edge machinery and production processes. Because of this, Manthorpe have been able to stay on the cutting edge of the industry, and lead the market in more than just production. 

Manthorpe are now proud to roll out their new G500 series of roll panel vents, showcasing their prestige in product design. To ensure a continuous flow of air, the range is designed to remain sturdy and maintain the air gap needed between the roofing membrane/sarking board and loft insulation. Utilising strengthening ribs, the castellated profile of the vents are suitable for 400mm, 450mm or 600mm rafter centres. The product is ideal for both new builds and refurbishment jobs, and the panels roll out in one continuous 6 metre length. The panels are also well suited to jobs in which the rafter centres are inconsistent or unknown.

Tel: +44 1773 303 000