All guides
Thermal insulation: EPS, polyurethane and mineral wool compared by the numbers
The key number for any insulation material is thermal conductivity λ. What it means, a comparison of common materials using values published in a peer-reviewed study, and how to work out equivalent thickness.
Roof insulation in a hot climate: layer order, the inverted roof, and mistakes that waste insulation
The roof is the part of the house most exposed to the sun. The order of layers in an insulated roof, why an 'inverted roof' with XPS boards is preferred, the difference between thermal and waterproof insulation, and common installation mistakes.
Radiant barriers (reflective foil): how they work, what they really save, and why they don't replace insulation
Reflective aluminium foil is sometimes sold with exaggerated figures. What the Building America guidance from the US Pacific Northwest National Laboratory says: how radiant barriers work, why they need an air space, and how much they actually cut cooling costs.
Spray polyurethane foam: excellent insulation, provided it's done safely — what the US EPA says
Spraying polyurethane onto roofs and walls gives a continuous, seamless layer of insulation, but it contains sensitising chemicals (isocyanates). The benefits, the health risks, and why the building must be vacated during and after spraying.
Protecting a house from solar heat: roof, windows, walls and shading — what actually helps, and in what order
Where solar heat enters a house and what to prioritise: roof insulation and protecting the waterproofing, low-SHGC windows and thermally broken frames, radiant barriers and their limits, and external shading. With figures from official sources and the limits of advertising claims.
Sound insulation between flats and rooms: voices, footsteps and pipes, and why a strong wall alone is not enough
Sound comes in two kinds: airborne, like voices and TV, and impact, like footsteps. We explain STC and IIC ratings, what the International Building Code requires between dwelling units, National Research Council Canada findings on block walls and flanking, and what works in new and existing buildings.
Roofs and slabs: the roof layers from slab to tiles, waterproofing and insulation, cracks, and access for maintenance
A concrete roof in our homes is not one layer: a structural slab, then falls, then waterproofing and insulation, then a protective layer. The role and order of each layer in conventional and inverted roofs, when cracks are serious, and what to ask the designer; leaving loads, spans and openings to the structural engineer.