Pre-Purchase Building Survey Checklist

Summary

A pre-purchase building inspection is not a survey — it carries no professional liability and produces no legal document. What it does is give a buyer, or their contractor, 30–60 minutes of structured looking before committing to a survey fee of £600–£1,500. Done well, it identifies the key risks, informs the survey level decision, and sometimes reveals defects serious enough to reconsider the purchase before any money changes hands.

For tradespeople, this is an increasingly useful service to offer in a pre-purchase advisory capacity. Many buyers have a trusted builder or plumber and will ask "can you come and look at this before I buy it?" Being able to walk a property systematically and give a credible assessment — identifying what you can see, what you cannot, and what would need further investigation — builds client relationships and generates future work.

This guide covers a systematic internal and external walkthrough checklist, the specific warning signs that distinguish minor maintenance items from significant structural or damp problems, and the questions to ask the seller or estate agent that a survey report cannot ask.

Key Facts

• Roof — visible sagging, missing or broken tiles/slates, ridge and hip tiles loose, lead flashings lifting or cracked are all visible from ground level with binoculars or a telephoto camera
• Chimney stacks — assess repointing condition, flaunching (cement cap) cracked or missing, chimney pots tilted or missing cowls; indicates maintenance history
• Gutters and downpipes — overflowing or missing gutters leave marks on the wall below (green algae, efflorescence, dark staining); failing gutters are the most common source of penetrating damp
• Brickwork — stepped cracks in mortar joints are significant; horizontal cracks in mortar (especially low down near DPC level) can indicate foundation movement; spalling bricks indicate moisture ingress
• DPC level — the damp-proof course is usually visible as a line of engineering bricks, slate, or bituminous felt approximately 150mm above ground level; check if soil, paving, or render is bridging the DPC
• Windows and doors — misaligned, sticking, or visibly out-of-square frames indicate movement in the structure; diagonal cracks from corners of openings are a structural concern
• Internal cracks — hairline cracks in plaster are normal settling; cracks wider than 2mm that follow a diagonal line from corners of doors or windows, or run through brickwork, are structural indicators
• Floors — a visible slope (marble-test) or a springy feel in timber floors indicates joist failure, rot, or subsidence; wet patches or sound hollow spots under tiles suggest failed adhesion or sub-floor water ingress
• Basement or underfloor void — if access exists, look for: standing water, white tide marks (salts from historic flooding), corroded steel joists, ventilation bricks blocked (causing dry rot risk)
• Boiler age and type — an A-rated condensing boiler (post-2005 typically) needs servicing; a G-rated non-condensing boiler is a replacement item (£1,500–£2,500); an oil or LPG-fired system means ongoing fuel costs different from mains gas
• Consumer unit — old rewirable fuse boards (Wylex wooden boxes), early plastic MCB boards without RCDs, or signs of amateur wiring are indicators for a full EICR
• Insulation evidence — loft insulation visible, cavity fill blown-hole evidence in external brickwork, underfloor insulation in basement or sub-floor void — all affect EPC rating and running costs

Quick Reference Table

Detailed Guidance

External Walkthrough — What to Look At

Start with the roof — Use binoculars or a telephoto camera to inspect from the pavement. Look for: sagging ridge or hips; missing, slipped, or broken tiles; moss accumulation (indicates moisture retention and potential tile degradation); lead flashings around chimney stacks and at abutments. Any visible sag or structural deformation is a significant indicator — commission a Level 3 survey and potentially a specialist roofer's report.

Chimney stacks — if visible, assess the pointing condition between the bricks, the flaunching (mortar cap) around the chimney pot bases, and whether any pots are tilted or absent. A stack in poor condition needs repointing and flaunching at minimum (£500–£1,200 per stack scaffold), and possibly lead soakers and step flashing work.

Gutters and downpipes — walk the entire perimeter looking at the wall face below gutters and downpipes. Dark staining at the foot of a wall from a broken downpipe, green algae on the render below a consistently overflowing gutter, or white salt efflorescence on the brickwork are all indicators of water ingress. These are usually fixable (new gutters, repointed flashings) but trace the water path internally before assuming the fix is simple.

Brickwork and pointing — stand back and scan the entire wall face. Look for: stepped cracks following mortar joints (indicates differential settlement — one part of the building moving at a different rate from another); horizontal cracks (indicates wall tie failure in cavity walls, or foundation sliding movement); spalled bricks where the face has blown off (freeze-thaw damage, often in older clay brickwork — expensive if widespread).

DPC and ground levels — the DPC is the most important detail to check near ground level. Walk around the full perimeter and confirm that paving, rendered plinth, and soil are all clearly below the DPC. A single garden border raised against the wall is low risk; render applied down to ground level covering the DPC, or a patio raised above DPC level, is high risk for penetrating or rising damp.

Extensions and alterations — identify any extension, garage conversion, or loft conversion. Check visually whether the junction between old and new looks sound — differential settlement produces a characteristic crack running down the line of the addition. Ask the estate agent for planning and Building Control history for all additions.

Internal Walkthrough — What to Look At

Enter each room and pause. Stand in the doorway and look for: doors that visibly don't align with their frame; floors that slope perceptibly toward one corner; walls that are out of plumb; cracks running diagonally from corners of windows or doors.

Cracks — categorise each crack:

• Hairline cracks (<1mm) in plasterwork: normal thermal and settlement movement; no concern
• Fine cracks (1–2mm) in plasterwork: note and monitor; may be drying shrinkage in newer properties
• Cracks wider than 2mm, especially if they follow a diagonal, or pass through brickwork: structural indicator; commission Level 3

Damp indicators — tide marks (usually pale yellow-brown, with a horizontal top edge), white salt crystals on plaster or brickwork, black mould in room corners or behind furniture (condensation), musty smell on entering a room, and cold clammy patches on walls are all damp indicators. Touch the wall at suspected damp areas — cold and slightly soft plaster is a positive indicator.

Floors — test for spring in timber floors by walking across firmly. A bouncy or spongy feel is not just old age — it indicates wet rot or structural joist failure. For solid floors, look for cracks, hollow areas (tap with a knuckle), or raised sections that indicate sub-floor water ingress.

Loft access — always request access to the loft space if possible. Key observations: insulation thickness and coverage (no cold bridging at eaves), evidence of water ingress (wet or stained timber, active daylight through the tile course), condition of structural timber (colour — fresh white means new timber after repairs; dark grey-green means old and potentially compromised), and the general condition of the roof structure.

Boiler and heating system — note the boiler make, model, age (from the data plate inside the door), and service sticker. Check the system pressure gauge (1.0–1.5 bar cold is normal for a sealed system). Look for leaks around pipework in the boiler cupboard — pipe joint staining, drips, or rust trails. If an LPG or oil system, locate the tank (external) and note condition and access.

Consumer unit — identify the type (old rewirable, MCB only, split-load with one RCD, RCBO-per-circuit). Rewirable fuse boards are from pre-1980s and indicate an ageing electrical installation that likely needs full EICR assessment. MCB boards without RCDs are from the 1980s to early 2000s — not illegal but outdated. Note any obvious amateur wiring — incorrectly clipped cables, cables in walls not in conduit, junction boxes accessible in cupboards.

Questions to Ask Before the Survey

• When was the roof last worked on? Do you have contractor receipts or guarantees?
• Is there planning permission and Building Control sign-off for the extension/loft conversion?
• How old is the boiler, and is there a recent service certificate?
• Has there ever been any flooding, damp treatment, or structural investigation?
• Are there any known boundary disputes or party wall issues?
• Is the drainage shared with neighbouring properties?
• How old are the windows and are they FENSA or CERTASS certified?

The answers do not prevent you commissioning a survey, but they indicate what to focus the survey on and sometimes reveal issues that are not yet visible.

Frequently Asked Questions

Can a builder walk a property in place of a survey?

A builder can give an informal commercial view — roughly how much the obvious defects would cost to fix. This is a useful input to a purchase decision. It is not a survey, cannot be relied on legally, and does not assess structural integrity or confirm planning compliance. Commission a RICS survey for protection; use the builder's walkthrough to decide which level.

What should I do if I spot a serious defect before exchange?

Document it (photographs with scale reference, written notes with room location, date, and time). Inform your solicitor and surveyor immediately. Serious structural defects found before exchange give you negotiating leverage — price reduction, repairs by the seller before exchange, or withdrawal from the purchase. After exchange, the right to withdraw on unfound defects is significantly more limited.

How do I estimate remediation costs from a walkthrough?

You cannot produce reliable costs from a walkthrough — too much is concealed. What you can do is identify which trades are likely involved (structural engineer, roofer, damp treatment, electrician, plumber) and give a rough bracket. A property with a failing G-rated boiler, single glazing, and uninsulated walls is a £15,000–£30,000 improvement project before considering structural issues. A property in apparent good condition with a modern boiler may need only cosmetic work. These brackets inform the offer, not the budget — the survey and specialist reports firm up the actual costs.

Regulations & Standards

• No regulatory framework applies to an informal pre-purchase walkthrough

• Consumer Protection from Unfair Trading Regulations 2008 — estate agents cannot misrepresent property condition; sellers cannot actively conceal known defects

• Property Misdescriptions Act 1991 (repealed 2013, replaced by CPR 2008) — property descriptions must be accurate

• RICS Home Survey Standard — once a RICS surveyor is commissioned, they are bound by this standard; the pre-purchase walkthrough is separate from this

• RICS 'Choose a Survey' — guidance on which survey level to commission

• HomeOwners Alliance Guide to Surveys — consumer-focused guidance

• Money Saving Expert Surveys Guide — practical buyer-focused breakdown of survey options

• [rics homebuyer vs full structural|RICS Level 2 vs Level 3 survey — which to commission after the walkthrough](/wiki/surveys/rics-homebuyer-vs-full-structural|RICS Level 2 vs Level 3 survey — which to commission after the walkthrough) — the natural next step after a pre-purchase inspection

• [structural engineer survey|when the walkthrough reveals potential structural issues requiring an engineer](/wiki/surveys/structural-engineer-survey|when the walkthrough reveals potential structural issues requiring an engineer) — escalation from survey finding

• [damp survey what to expect|specialist damp survey when the walkthrough flags damp evidence](/wiki/surveys/damp-survey-what-to-expect|specialist damp survey when the walkthrough flags damp evidence) — follow-up to visual damp findings

• [cracked walls|crack categorisation guide for assessing wall cracks during a walkthrough](/wiki/fault-finder/structural/cracked-walls|crack categorisation guide for assessing wall cracks during a walkthrough) — field reference for crack assessment