XPS in-depth: seventy things we’ve shared in fifty newsletters
Four years and two months ago, Polyfoam XPS hit publish on the first issue of an email newsletter called The Build-Up. Our aim with the newsletter has never changed: support designers, specifiers and installers to deliver a better built environment.
We do that by providing interesting and actionable information, useful resources, and sharing news articles that tell a story of how the construction industry is evolving.
The insulation we manufacture can, at times, remain a relatively unknown or unheralded material. In some instances, it is even misunderstood entirely. As well as providing links to external news and technical information, every month we explore some aspect of extruded polystyrene (XPS) and its role in building design and construction.
Four years and two months is 50 issues. That’s a milestone worth reflecting on. To mark our half century, we’ve looked back through the archives and compiled seventy different things we’ve written and shared in our emails since early 2021.
Understanding XPS and its role in sustainable construction
In 2024, we celebrated 40 years of the Polyfoam brand. We know a thing or two about manufacturing XPS, so an ideal starting point for any new reader is how XPS is made and some of the different uses for XPS. There can often be confusion between different insulation types, including XPS and EPS, or XPS and PIR.
There have been lots of changes over four decades, including the move away from using HFCs in XPS. And we have changed as a business too, including drastically reducing waste from our factory and seeking to communicate more about how XPS can be recycled.
Sustainability is a complex topic, of which waste reduction and recycling are just two parts. In recent years, we’ve also seen the move away from Green Guide ratings to EPDs. Environmental product declarations merited a four-part discussion: what are EPDs, what life cycle stages are assessed by EPDs, can you compare EPDs from different manufacturers, and what credits can be claimed for EPDs in certification schemes.
Regulations and standards relating to XPS
A host of different regulations and standards help us to manufacture and supply our insulation in a responsible and more efficient way. Some of these can be directly tied to sustainability, like the responsible sourcing standard BES 6001. Others may be less well-known, but no less important to the way we run our factory: ISO 9001, ISO 14001, ISO 45001, and ISO 50001.
There’s the harmonised standard EN 13164 for CE and UKCA marking, which sets out the technical standard to which our products must be made. Then there are the standards that help us work with specifiers and installers to demonstrate how our products can help reduce heat loss and improve thermal comfort: ISO 6946 for calculating U-values and ISO 13370 for calculating ground floor U-values, aided by BR 443’s U-value conventions.
Complementing these posts, we summarised floor and roof U-values in Part L 2021.
We’ve also looked at standards and guidance documents that influence how insulation materials are chosen and installed: Regulation 7 of the Building Regulations and BS 5250 for the control of moisture in buildings. Plus, the role of BS 6229 and ETAG 031 in inverted roof design and specification.
Trusted product information about XPS
Giving readers continued confidence in using our products has involved telling the story of construction’s evolution over the last four years. For instance, we charted the launch of the Code for Construction Product Information (CCPI).
We’ve covered the many ways we as a manufacturer seek to communicate accurate and reliable information about our products. The importance of third-party certification, alongside our partnerships with NBS Source and Specified By, all contribute to helping specifiers find the information they need.
In an effort to provide practical guidance, we’ve looked at how to improve competence around insulation specification, and addressed the idea of specifying insulation with installation in mind. We’ve also told a personal story giving a roofing company’s view on what it means to work with a responsible product manufacturer.
XPS applications: ground floors and below DPC
Key qualities of XPS for ground floor applications are its loadbearing capability and its resistance to moisture. We examined the role it can play in the four categories of floor defined by BS 5250, and we considered how XPS might be best-placed to deliver ground floors in adaptable buildings.
Differences in compressive strength of different insulation materials can make or break specifications, so we did a deep dive with our practical guide to compressive strength, explained the units of measurement for compressive strength, and introduced compressive creep.
The difference between edge insulation and perimeter upstand insulation formed part of wider discussions on continuity of insulation at ground floor edges, how Part L addresses thermal bridging, and how to reduce condensation risk at floor edges.
Updated regulations and changes in approach to insulation continuity have led to XPS being specified more often at the base of cavity walls, below DPC level. As well as producing a complete below DPC white paper, we also published three blog posts: the moisture resistance requirements for external walls, BBA certification for cavity insulation below DPC, and using XPS below DPC.
XPS applications: inverted roofs
A crucial element of inverted roof performance is the ‘double act’ of insulation and WFRL (water flow reducing layer). Little wonder, then, that we’ve covered the importance of the WFRL and explained how inverted roof performance is tested, as well as looking at types of inverted roof waterproofing too.
You can also download our inverted roofing white paper, written in response to changes to BS 6229.
Getting the best from inverted roofs means understanding what can impact heat loss – from items affecting U-values that often aren’t considered in specification, to point thermal transmittances. Hybrid roofs remain an all-too-common technical enquiry, which warranted looking at hybrid roofs in BS 5250 and the role of suspended ceilings in hybrid roof calculations.
While not necessarily an inverted roof, we have also produced a guide to specifying car park decks.
XPS applications: swimming pools and basements
Ground floors, inverted roofs and below DPC applications account for the bulk of Polyfoam XPS’s technical queries. The material’s characteristics also make XPS ideal for insulating basements, either externally or internally.
Some national building regulations include U-value targets for swimming pool basins, so we have also looked at typical insulation thicknesses for pools.
Getting to know Polyfoam XPS better
As a business, we’ve had a lot of news to share over the last four-and-a-bit years. In addition to our 40-year celebrations, we launched our Handyboard product, issued brand new CAD details, overhauled our website, and commissioned a second production line. All of which brings us to 2025, and a look at what lies in store this year – including the completion of Hartlepool’s new Highlight leisure development, for which we have supplied the inverted roof.
Raising awareness of the Polyfoam name and what we stand for doesn’t just mean email newsletters, LinkedIn posts, and regular articles in Total Contractor and AT Journal. We’ve also started producing biographies of staff members, including Phil Hodges (National Sales Manager), Rob Firman (Technical and Specification Manager), and Gary Ferguson (Business Development Manager North and Scotland).
The eagle-eyed among you may have spotted that the above includes ‘only’ sixty-nine of the promised seventy links. The seventieth is something brand new.
It’s a publication designed to capture and distil everything we’ve produced over the last 50 months; to showcase our knowledge and expertise; and to lead the way in communicating transparently, accurately and responsibly about the life cycle impacts of an insulation material. Polyfoam XPS is proud to introduce: The Orange Book.