#28 ~ Secrets of Structural Engineering with John Cranna

Roger speaks with Duncan, a homeowner left without heating for more than 2½ years after a disastrous air-source heat pump installation under the UK Eco4 government scheme. Installers got the heat-loss calcs wrong, fitted undersized radiators, never commissioned the system, and even added solar panels without checking the roof structure — causing further damage. The result: a cold home, big bills, and emergency repairs. This isn’t an isolated case. With minimal inspections and installers chasing grant money over quality, thousands risk poor installs, damp, and structural issues — with no real safety net. Duncan has now launched a charity to support others caught in the same situation and to push for urgent reform of government-backed retrofit schemes.

Thermally broken lintels minimise heat transfer through the building envelope to meet Part L of the Building Regulations. Catnic’s thermally broken lintels use two folded steel sections bonded to a high-strength, thermally efficient core, achieving psi values no greater than 0.05 W/mK without additional brackets or cold bridges. Traditional steel lintels create significant thermal bridges by crossing the insulated cavity. Separating the inner and outer steel sections breaks this thermal convection and reduces heat flow by over 90%, depending on the design. Catnic thermally broken lintels are available to suit 90-205mm cavities, in standard, heavy or extra heavy duty load capacities. ________________________ Summary ❄️ Thermally broken lintels slash heat loss by eliminating cold bridging. 📐 Fit cavity widths up to 225 mm, with future options for arches and bays. ✅ Independently verified with BBA certification and BRE thermal modelling. 🛠️ Powder-coated steel for strength and durability, with installation guidance. 📊 Free structural calculations and lintel schedules from Catnic. 🌍 Central to a “fabric first” approach — boosting efficiency before adding tech like heat pumps or solar. Find out more about Catnic: go.skill-builder.uk/catnic

Roger visits the Pipelife Academy in Cork, Ireland, to discuss heat pumps and renewable energy technology with Mike Geary.

Roger travelled to Ellesmere Port to get a plastering lesson from Kirk Johnstone. The guys took a break and Kirk shared some insights on plastering life.

Roger looks at heating systems and explains their features and benefits as energy efficiency and sustainability become increasingly important, homeowners have various home heating choices.

Roger has a chat with Russel Pieters from MSA Safety about staying safe on-site and how to choose the correct head protection.

Should you leave your heating on constantly? or are you better off using your timer? Roger gives us his money-saving advice to reduce your fuel bills this winter.

Roger has a chat with Abergavenny-based Structural Engineer John Cranna. He has worked on large buildings, including constructing the Lloyds of London building. Since becoming self-employed, he has gained experience in the smaller scale of construction for domestic and commercial design. He provides a personal, friendly, cost-effective solution to your structural engineering and building needs.

Roger Bisby has a chat with Dan Cox about his life as a carpenter and how becoming an inventor came naturally.

Roger and Sam discuss working with type 1 diabetes and how to stay motivated and energised as self-employed tradesmen.