Specifying Insulation for Scottish Building Projects | Glasgow Architecture

Specifying Insulation for Scottish Building Projects: What to Check Before Ordering

17 September 2026

photo courtesy of Urban Union

For anyone planning a new build, extension or conversion in Scotland, insulation is no longer a late-stage purchasing decision. Before ordering PIR insulation boards or insulated plasterboard, project teams should confirm the construction build-up, board thickness and facer, plasterboard grade, quantities, accessories and site access for delivery. This article explains what Section 6 of the Scottish building standards demands, how the main product options compare, and what to verify before placing an order.

Why Scotland’s Section 6 energy standards shape material choice

Scotland operates its own regulatory framework, and guidance written for England or Wales should not be carried across unchecked. The scope of Standard 6.2, which deals with the building insulation envelope, is set out in the Scottish Government’s Technical Handbook 2022 (Domestic), Section 6.2, and project teams should work from that source rather than relying on secondary summaries.

That matters in a city like Glasgow, where much of the building stock consists of traditional tenements, sandstone villas or post-war housing now being refurbished or extended. For extensions and other works that extend the insulation envelope of an existing building, the maximum permitted area-weighted U-values for walls, floors, roofs and glazing depend partly on the energy performance of the building being altered, with different requirement columns for different starting conditions. Where listed or conservation-area properties are involved, related questions such as window restoration, energy efficiency and heritage compliance also come into play. Generic U-value figures quoted from English Approved Document L tables should never be assumed to answer a Scottish specification question.

The Section 6 guidance also addresses thermal bridging and air infiltration, reinforcing the case for insulation and membranes that can be detailed tightly at junctions. Where airtightness test evidence is not available, the handbook sets out the figures and conditions to apply rather than assumed values.

PIR boards, insulated plasterboard or both?

Once the regulatory target is understood, the practical question is which product format suits the build-up. PIR insulation boards are widely used for roofs, walls and floors: environmental product declarations for polyurethane rigid foam boards record thermal conductivity values in the region of 0.023 to 0.029 W/(m·K) depending on the product and facer, so the boards can deliver high thermal resistance in limited depth. They come in a wide range of thicknesses and facer types, from warm flat roofs to cavity and solid-wall upgrades. Where construction depth is tight, a rigid board with a low declared thermal conductivity may help a project meet its calculated target — though this is always a project-specific question to resolve through the thermal calculation and the manufacturer data sheets.

Insulated plasterboard takes a different approach by bonding a thermal layer to a plasterboard facing in a single product. On internal wall upgrades — common in conversions where external insulation is not an option — a single product can simplify fixing, finishing and sequencing on a busy programme. Internal insulation on solid walls does, however, raise moisture and detailing questions of its own; guidance such as the WTA planning guide on internal thermal insulation sets out the hygrothermal considerations that should inform the build-up choice. The trade-off is flexibility: separate insulation and plasterboard layers allow each element to be selected independently. Neither format is a universal solution; the decision should follow the drawings, the manufacturer data sheets and the fire and moisture requirements of the space.

On the supply side, specialist online distributors have changed how these materials are sourced for Scottish projects. Online Insulation, a UK company trading since 2015 from Leicestershire, stocks PIR insulation boards, insulated plasterboard and the related drylining categories from recognised brands including Celotex, Kingspan, Recticel, Rockwool and Knauf, delivered by kerbside pallet delivery across mainland UK. Rated around 4.5 stars from more than 1,500 reviews on Reviews.io and sourcing through over 100 UK distribution points, it illustrates the delivery-first model that many contractors now use instead of relying on local stock.

What should specifiers and contractors check before ordering?

Most ordering errors on insulation and drylining packages trace back to a small number of checks that were skipped. Before committing to a purchase, project teams should confirm the following:

Element and build-up. Confirm whether the product is for a roof, wall or floor application, and whether the build-up is warm, cold or hybrid. Board type, thickness and facer must match the specification and the manufacturer’s stated application range.
Board thickness and facer type. The required thickness follows from the thermal calculation, not from what happens to be in stock. Facer choice — foil-faced, glass-tissue or plasterboard-bonded — affects vapour behaviour and fixing method.
Plasterboard grade. Where rooms need fire-resistant, moisture-resistant or acoustic performance, the board grade must be specified accordingly, whether as a standalone board or as the facing of an insulated plasterboard.
Quantities and formats. Board sizes and coverage rates vary between manufacturers. Bulk orders are economical only if the calculated quantities, including cutting waste, have been checked against the drawings.
Accessories and interfaces. Building membranes, tapes, adhesives, fixings, cavity closers and sealants are part of the same system; missing accessories stall the follow-on trades.
Framing compatibility. Metal stud and track, MF ceiling systems and resilient bars must be dimensionally compatible with the board sizes and the intended lining build-up.
Site access for delivery. Kerbside pallet delivery assumes a vehicle can reach the site and that there is somewhere to land and store the pallets. On tight urban plots — a routine condition in Glasgow’s denser districts — this needs to be planned before the order is placed.

None of these checks is complicated, but all of them are cheaper to resolve at the ordering stage than after a pallet arrives on site.

Why a complete drylining order can simplify project coordination

Insulation, plasterboard, fire protection, metal framing systems, membranes and accessories are usually specified by the same team, installed by the same trades and detailed against the same drawings. Treating them as one material plan rather than a series of separate purchases reduces the coordination burden: interfaces between the insulation layer and the lining are considered together, fire-protection details are resolved alongside the board specification, and the number of deliveries to manage on site falls.

This is where the cross-category range of a specialist supplier becomes practically useful. Because Online Insulation carries the linked categories — PIR insulation boards, insulated and standard plasterboard grades, fire protection products, metal framing, building membranes and installation accessories — a complete drylining or roofing package can be bought as a single order rather than split across several merchants.

The wider principle applies regardless of where materials are sourced. Project teams that align the Section 6 requirements, the construction build-up, the accessory schedule and the delivery logistics before ordering will spend less time resolving mismatches on site — and stand a better chance of handing over a building envelope that performs the way the drawings intended.

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