Achieving Part L with a Fabric First approach

With Part L compliance getting its legal teeth later this month, housebuilders and residential asset owners have been busy preparing themselves for a new age of low-carbon, energy-efficient homes Steve Callow, Housing Manager at MPA Masonry explains how.

Currently applicable to any new build since its introduction last summer, developers have been busy, adapting their businesses to meet the regulatory requirements outlined by the standard. Now the game’s all about achieving that ultra-low U-Value (of 0.18 W/m2k or below) and 31% carbon reduction to stay compliant.

Of course, there are a wide number of ways in which these results can be delivered, but when inflation is high, consumer budgets are tight and housing sector margins are squeezed, it’s about how it can be done efficiently and economically, without compromising on quality, safety and comfort.

Furthermore, the construction industry is only now finding its feet following the global resource shortage, comprising everything from structural materials and electronic components to heavy machinery and access to skilled labour. It’s prompted a period of reflection and encouraged operators in the sector to assess supply chains and re-evaluate how they build and what they build with. 

A systematic solution

It’s important to add Part L is only one of a raft of legislation influencing these decisions with the BSA and FSA also encouraging a reappraisal of building methods. 

Yet the fact remains developers still need to deliver fit-for-purpose housing which matches the legal requirements of the updated building codes. With one eye open to the incoming Future Homes Standard, optimising our approach to the fabric of housing is key. Given the longstanding accepted methods of masonry construction, this can be applied to safety as well as sustainability. However, for the purpose of this article, we’ll stick to the latter. 

As many reading this will appreciate, it’s not a hard outcome to achieve. For instance, masonry cavity walls, which we’ve been using for centuries, provide a ready, tried and tested example. Aside from achieving target u-values, correctly specified, work in the industry is just about to come to fruition to provide robust thermal bridging details, further optimising operational carbon savings. Feeding into the bigger picture, this will help the sector progress further towards Net Zero 2050.

It’s important to understand, a masonry fabric first approach has already been used in showcase projects that already met the next raft of changes expected in 2025. Some of these go on to further improve energy efficiency by layering in different solutions such as ASHP, PV panels and MVAC where exceptionally low air tightness values were achieved. 

Encouragingly, this is an industry-wide move to provide developers with all the tools required to achieve any level of enhancing their target, going as far as to make even Passivhaus very achievable. What’s clear is that the new era of low-carbon homes is now on us, and in two years’ time, fabric first will become the default and the correct approach to adopt for developers. 

Consistency is key

The industry is about to undergo its biggest change seen in many years with the advent of the Future Homes Standard. This new approach to Part L, by any other name will take a further step on from the enforcement we are looking at today. 

Addressing the material composition of homes is now vital, and wall constructions, including previously under-considered factors like thermal bridging, will certainly come to the fore as we bring U-Values down significantly from where they stood a decade ago. 

Robust and uniform detailing made available will also improve consistency, further enhancing consistent comfort and living standards for occupiers, while lessening the opportunity for snagging, error and unexpected issues on site. 

Building better homes

Part L should be regarded as an opportunity to build better homes, rather than another inconvenient change to building regulations. Efficiency through fabric first, as I’ve highlighted above, is not hard to achieve. Cavity walls are not new technology, they already account for three-quarters of all housing built but subtle modifications to standards can achieve significant gains.  

There is a growing push in the industry towards off-site or modular builds. These have their issues when it comes to longevity, sustainability and the concerning recent examples of financial failures in this sector. Recent work within our industry has highlighted that the lowest fabric values needed for some of these developments will be an issue for offsite construction, with the additional insulation requirements needed being unrealistic in these scenarios. 

The standard, as implied in the word, needs to apply across every residential property, but I hope, in the appetite for lower-embodied carbon structural materials, we’re able to keep to the methods we have at our fingertips to deliver on those requirements.

My biggest concern is that a read made solution is already on the table, waiting to solve the problem of the day with very little need to add cost through innovation. There will always be a place in the market for alternatives to traditional masonry builds, but these are proving difficult to make work in the medium to long term and there are serious challenges in developing a sustainable and holistic model for this sector.  

That aside, given the current financial cost of living squeeze, those housebuilders who can maximise operational efficiency by using a fabric-first approach will be delivering added value not only to potential occupants, but the industry as a whole.