A house purchase is probably the largest financial commitment you'll ever make, yet many buyers rely on nothing more than a lender's valuation before exchanging contracts. That valuation protects the lender, not you. It confirms the property is worth roughly what you're paying, but it won't tell you the roof needs replacing or that damp is creeping up behind the plaster in the back bedroom. A proper survey gives you an independent opinion on the building's true condition.

Depending on the property's age, you might commission a condition report, a homebuyer report or a full building survey. Each goes into a different level of depth, but the method is the same: a chartered surveyor visits, inspects everything they can safely reach, and reports on defects, risks and anything needing further investigation.

The Roof and Chimney

The roof is the first line of defence against British weather, so it gets close attention. The surveyor examines the covering — clay or concrete tiles, natural slate, or a flat felt or GRP system — checking for slipped, cracked, missing or perished units. On pitched roofs they'll inspect ridge and hip tiles, mortar pointing, and the flashings around chimneys, valleys and dormers, since these joints are the most likely to let water in.

The chimney stack gets separate scrutiny: spalling brickwork, failing flaunching at the top, insecure pots and cowls. A leaning or eroded stack isn't cosmetic; it can drop debris or channel water straight into the roof space. Guttering and downpipes matter too, because overflowing gutters are a leading cause of damp walls below. Surveyors work from ground level, windows and ladders where safe, so anything they can't see will be flagged as a limitation. A flat roof near the end of its life — often fifteen to twenty years for felt — will almost always be noted.

Walls, Damp and Structural Movement

Inside and out, the surveyor reads the walls like a story. Externally they check brickwork, render, stone and cladding for cracks, erosion, blown mortar and failed pointing. Cracks get particular attention: hairline vertical cracks are often just settlement or thermal movement, but stepped cracks following mortar lines, or diagonal cracks wider than a few millimetres, can point to subsidence, failed lintels or inadequate foundations.

Damp comes in three forms the surveyor will try to distinguish:

• Rising damp — moisture creeping up from the ground where the damp-proof course is missing, bridged or damaged, usually showing as a low tide mark.
• Penetrating damp — water entering through the fabric, often around failed pointing, cracked render, blocked gutters or defective flashings.
• Condensation — the most common of all, caused by poor ventilation and heating patterns rather than a defect, though it leads to mould and timber decay if ignored.

Timber is inspected wherever accessible: floorboards, joists, roof timbers and lintels, looking for wet rot, the more serious dry rot, and woodworm. The surveyor will also note cavity wall insulation and whether it risks bridging damp.

Floors, Drainage and Services

Floors — suspended timber or solid concrete — are checked for bounce, movement, unevenness and signs of damp or insect attack. Drainage is inspected through accessible manholes and inspection chambers, looking for blockages, cracks, root ingress and whether surface water drains away properly. Where there's doubt, a specialist CCTV drain survey can be arranged.

Services are assessed visually and non-invasively. The surveyor notes the age and apparent condition of the wiring, the consumer unit, earthing and bonding, then looks at the boiler, its flue and visible pipework, flagging lead supply pipes in older homes. Gas appliances without a recent service record will usually be referred to a Gas Safe engineer. In older properties they may mention asbestos-containing materials, and in some regions, radon risk or Japanese knotweed in the garden.

A survey is not a structural engineer's report, a full electrical test, or an invasive investigation behind walls. Where the surveyor has suspicions, they'll recommend a specialist — and that recommendation is worth taking seriously.

What the Findings Mean for Your Offer

When the report lands, don't panic at every red mark. Surveyors use condition ratings, and most findings fall into "monitor" or "routine maintenance". What matters is the small number of genuinely significant defects: a failed roof, active damp, structural movement, an aged boiler and wiring, or drainage problems.

Your options depend on what's found:

• Renegotiate the price if the defects weren't reflected in what you agreed to pay.
• Ask the seller to complete repairs before completion, with evidence when done.
• Commission specialist reports — structural engineer, damp and timber, drainage — to establish the true cost.
• Walk away if the problems are severe, expensive or likely to recur.

If you need a mortgage, the lender may hold back a retention until essential works are done, which affects your deposit and timescales. Get quotes before renegotiating so your figures reflect real prices. A good survey isn't a reason to lose the house — it's the information that lets you buy it with your eyes open.