Insulation
PIR boards, mineral wool, cavity batts, EPS, and insulated plasterboard for achieving building regs U-values in walls, floors, and roofs of a domestic extension.
Aluminium Foil Tape: The Cheapest Material That Will Make or Break Your Insulation
The UK guide to aluminium foil tape for PIR insulation: why untaped joints lose 20-30% of R-value, acrylic vs rubber adhesive, width selection, and what to buy from £5 a roll.
Cavity Wall Insulation Batts: Partial Fill, Full Fill, and the Mistake That Costs Thousands
UK guide to cavity wall insulation batts for extensions: DriTherm 32 vs 37, partial vs full fill, retaining clips, 0.18 U-value target, and the mortar dropping problem nobody warns you about.
Compressible Expanding Tape: The Window Sealing Detail That Determines Your Air Test Result
The UK homeowner's guide to compressible expanding tape for window perimeters: how the three-plane sealing system works, brand and price comparison, and how to make sure your installer uses it instead of foam.
EPS Insulation: The Budget Floor Board That Needs More Thickness but Saves You Hundreds
UK guide to EPS polystyrene insulation boards. EPS70 vs EPS100 grades, thickness for Part L compliance, correct floor build-up, cable contact ban, and prices from £6-12/m².
Grey Graphite EPS: When the 25% Thickness Saving Is Worth the Premium
UK guide to graphite EPS insulation. Lambda 0.030 W/mK, EWI thickness for Part L 0.18 W/m²K, UV deformation risk, fixings, and prices from £6.50/m² for 50mm boards.
Insulated Plasterboard: The One-Board Fix for Cold Solid Walls
UK guide to insulated plasterboard (thermal laminate): PIR, phenolic, and EPS types compared, dot-and-dab vs battens, VCL sealing at sockets, and the thickness that actually meets Part L.
Loft Legs: Boarding Out a Loft Without Wrecking Your Insulation
UK guide to loft legs (175mm and 300mm): why compression destroys insulation, how to spec, install, and price them, and when LoftZone or timber battens are the better choice.
Low-Expansion Foam: The Right Foam for PIR Insulation Gaps (and Why Standard Foam Will Ruin Your Floor)
UK guide to low-expansion polyurethane foam for sealing PIR insulation: why standard foam pushes boards out of position, how to choose between gun and straw cans, B1 fire-rated vs airtight FM330, and the COSHH legal duties homeowners miss.
Marmox Thermoblock: The Cold-Bridge Block Most Builders Will Try to Skip
Marmox Thermoblock is the load-bearing thermal break that stops your extension leaking heat at the wall-floor junction. What it costs, why builders omit it, and how to make sure yours doesn't.
Mineral Wool Insulation 100mm: Glass Wool vs Stone Wool, Where Each Goes, and How to Install It Without Itching for a Week
UK guide to 100mm mineral wool insulation: glass wool vs stone wool differences, lambda values, loft and stud wall installation, acoustic air-gap principle, PPE, and current prices.
Perimeter Edge Strip for Screed Floors: The 8mm of Foam That Stops Your Floor Cracking
The complete UK guide to perimeter edge strip: why your screed needs it, how to install it around doorways, what to buy, and the three jobs it does at once.
Pipe Lagging: How to Pick the Right Foam, Where It's Legally Required, and Why a £20 Roll Stops a £33,000 Claim
UK guide to pipe lagging: WFR 1999 cold-water rule, Part L hot pipe insulation, PE foam vs Armaflex, 9/13/19/25mm wall thickness, and current 2026 retail prices.
PIR Insulation Board 100mm: The Standard Thickness for Extension Floors and How to Get It Right
The UK homeowner's guide to 100mm PIR insulation: why it's the default for extension floors, how it meets Part L 2021, brand comparison with prices, and the installation details that determine whether your floor actually performs.
PIR Insulation Board 120mm: Flat Roofs, Upgraded Floors, and the Joist Depth Problem
The UK guide to 120mm PIR insulation: where it's specified, how it meets Part L 2021 for flat roofs and floors, the joist depth trap, and how to buy Celotex XR4120 at the right price.
PIR Insulation Board 50mm: Where It Works, Where It Doesn't, and How to Install It
The UK homeowner's guide to 50mm PIR insulation: which walls and roofs it suits, how to cut and fit it, brand comparison, and the joints mistake that wastes 30% of your insulation's performance.
PIR Insulation Board 75mm: The Combination Thickness That Fills the Gaps
75mm PIR insulation explained for UK homeowners: where it meets Part L on its own, where it needs layering, costs from £22-28/board online, and the combination builds that make 75mm the right choice.
Proprietary Vapour Control Membrane: Intelligent VCL, Polythene, and the Specification Trap That Costs Homeowners Walls
UK guide to vapour control layers: intelligent VCL vs polythene vs flat warm-deck AVCL, NHBC 6.2.12 and 7.1.10 requirements, sd values, current prices, and how to install one without ruining it.
Sheep's Wool Insulation: When to Pay the Premium, Which Brand to Trust, and How to Stop Moths Eating Your Walls
UK guide to sheep wool insulation: Thermafleece vs Isolena vs Black Mountain, lambda values, moth risk, heritage applications, current prices, and why no VCL is needed.