
The 9 best basement conversion companies in London for 2026, ranked by Beams (yes, we're biased), with real 2026 costs and the five questions to ask any shortlist.

The 9 best basement conversion companies in London for 2026, ranked by Beams (yes, we're biased), with real 2026 costs and the five questions to ask any shortlist.

Planning and party wall risk decide a loft conversion. Our pick, five questions to ask, what a London loft costs, and honest profiles of eight other companies.

2026 guide to UK side-extension costs. See what affects price and how to plan a smooth, budget-friendly build from start to finish.

What needs listed building consent and what does not, with worked repair and alteration examples, what a heritage statement contains, and what consent adds to a London programme.

Grosvenor, Cadogan, Portman, Dulwich and the rest each run their own consent process. Published fees, timescales and technical limits, verified at source.

In a square room with flat walls, modular usually wins. Bespoke earns its money on unequal alcoves, sloping ceilings and high Victorian ceilings.

Like-for-like re-roofing is permitted development. Building regs almost always apply. The 25% and 50% Part L thresholds, and when Article 4 forces slate.

Slate lasts 80 to 150 years, concrete tile 50 to 60, felt 10 to 20. How to inspect a roof properly and tell structural movement from a worn covering.

Retaining wall materials compared by realistic retained height, foundation, drainage detail and service life. Plus why the drainage fails first.