Red flags on a building survey report — what to look out for
Your building survey report has arrived. It is likely longer than you expected, more detailed than you anticipated, and possibly more alarming-looking than it needs to be. Before you panic — or before you dismiss concerns you should take seriously — this guide explains what the genuine red flags are, what the less serious findings actually mean, and what to do when a survey raises something significant.
Understanding the traffic light rating system
RICS Level 2 and Level 3 survey reports use a condition rating system to grade the elements they inspect. Understanding what each rating means is the starting point for reading your report.
Condition rating 1 — no repair is currently needed. The element is performing satisfactorily and routine maintenance is all that is required. This is the best outcome for any item.
Condition rating 2 — defects that need repairing or replacing but are not considered urgent or serious. These are the most common findings in any survey report and should not alarm you. Most properties, even well-maintained ones, have a number of condition 2 items.
Condition rating 3 — defects that are serious and/or need to be repaired, replaced, or investigated urgently. This is the flag that requires your attention. A condition 3 rating means the surveyor has identified something significant enough to warrant immediate action or further investigation.
A report with several condition 2 ratings and no condition 3s is broadly reassuring. A report with condition 3 ratings — particularly on structural elements, the roof, or the drainage — warrants careful consideration.
The red flags that matter most
Not all condition 3 findings carry equal weight. Some are expensive but straightforward to fix. Others can indicate underlying problems that are more complex, costly, or unpredictable. The following are the findings that should prompt you to think carefully before proceeding.
Structural movement
Cracking associated with structural movement is one of the most significant findings a surveyor can make. The key distinction is between movement that is historic and stable — where the building has moved in the past but is no longer doing so — and movement that is active and ongoing.
Active structural movement, particularly where it is associated with subsidence (foundations sinking), heave (foundations being pushed upward, often by tree roots or shrinkable clay), or differential settlement (different parts of the building moving at different rates), can be very expensive to remediate and can affect your ability to insure and mortgage the property.
If your survey flags structural movement and recommends a structural engineer's report, commission one before exchanging contracts. Do not proceed without understanding the cause, the likely cost of remediation, and the implications for insurance.
What to look for in the report: References to diagonal cracking, stair-step cracking in brickwork, cracking that is wider at the top than the bottom, or cracks that run through bricks rather than around them. Any recommendation for a structural engineer or specialist investigation.
Serious damp
Damp is one of the most commonly found issues in older properties and ranges from minor condensation to serious structural dampness. The red flag version is penetrating damp that has caused damage to the building fabric — rotting timbers, damaged plasterwork, or failed damp proof courses — rather than superficial surface condensation.
The risk with serious damp is not just the visible damage but what it may conceal. Wet timber rots. Rotting structural timbers — floor joists, roof rafters, wall plates — can be expensive to identify and replace in full.
What to look for in the report: References to damp meter readings significantly above background levels, visible tide marks, damaged or rotting timbers associated with damp, a failed or absent damp proof course, or a recommendation for a specialist damp survey.
Roof condition
A full roof replacement is one of the most expensive single repairs a buyer can face — typically between £6,000 and £20,000 on a standard Hampshire semi-detached or detached property, depending on materials and size. A roof that is at or near the end of its serviceable life should be factored into your negotiation.
More serious than general wear is evidence of structural failure in the roof — damaged or deflected rafters, a sagging ridge line, or movement in the roof structure itself. These are more complex and costly than a simple re-roof.
What to look for in the report: References to widespread slippage, failed or missing flashings, a sagging ridge or roof plane, significant damage to flat roof sections, or structural movement within the roof space. Drone inspection findings will appear here if one was carried out.
Japanese knotweed
If your survey mentions Japanese knotweed, take it seriously. Japanese knotweed is an invasive plant species that can cause structural damage to buildings and hard surfaces, and its presence on or near a property can affect your ability to obtain a mortgage and insurance.
Remediation is possible but regulated, expensive, and typically takes several years to complete. Many mortgage lenders will not lend on properties with active Japanese knotweed within seven metres of the building.
What to look for in the report: Any mention of Japanese knotweed or other invasive species. The surveyor should indicate whether it is within the boundary of the property and how close it is to the building.
Electrical installation concerns
A surveyor cannot test the electrical installation — that requires a qualified electrician carrying out an Electrical Installation Condition Report (EICR). However, a surveyor can identify visible signs of an outdated or potentially unsafe installation — old-style fuse boxes, rubber-insulated wiring, insufficient socket provision, visible damage.
An outdated electrical installation is not necessarily dangerous, but it may need rewiring, which is a significant cost — typically £3,000 to £8,000 for a full rewire of an average-sized property.
What to look for in the report: References to an old-style fuse box or consumer unit, recommendations for an EICR, visible signs of old wiring (rubber or fabric insulated), or any suggestion that the installation is not to a modern standard.
Drainage issues
Drainage problems can range from a blocked gutter to a collapsed underground drain. The serious end of the spectrum — collapsed, displaced, or root-invaded drains — can be costly to excavate and replace, and the work is disruptive.
A surveyor will flag visible drainage concerns but cannot inspect underground drains without a specialist CCTV drain survey. If your survey recommends one, commission it before exchange.
What to look for in the report: Evidence of damp associated with overflowing gutters or downpipes, references to drainage concerns, a recommendation for a specialist drain survey.
Red flags that are less serious than they look
Some findings that can cause alarm in a survey report are actually routine and manageable.
A long list of condition 2 items — this is normal. A thorough surveyor on an older property will identify many items needing maintenance or repair. A long list of condition 2 findings is not a reason to walk away — it is a reason to understand the likely cost of addressing them over time.
Pointing repointing needed — mortar between bricks deteriorates over time and periodic repointing is routine maintenance, not a structural concern unless associated with water ingress.
Single-glazed windows — the report may note that windows are single-glazed and recommend replacement. This is a comfort and energy-efficiency issue, not a structural one.
Minor roof covering issues — a handful of slipped slates or tiles is maintenance, not a crisis. It only becomes a red flag if widespread.
What to do when a survey raises red flags
Do not panic. A survey that raises serious issues is doing its job. It is giving you information you need to make a decision.
Get specialist reports where recommended. If your surveyor recommends a structural engineer, EICR, drain survey, or specialist damp survey, commission them before exchanging contracts. These reports will give you a clearer picture of the cost and nature of the issue.
Use the findings to renegotiate. A survey that identifies significant defects gives you documented grounds to renegotiate the purchase price or request that the seller carries out remedial works before completion. Your solicitor can assist with this.
Consider whether to proceed. Some findings — active structural movement on a poor foundation, serious contamination, Japanese knotweed — may be grounds to withdraw from the purchase entirely. That is a decision you should make with clear information, not alarm.
Get independent advice on your survey findings
If you have received a survey report with findings you are unsure about, Altura Surveyors is happy to discuss them with you. We provide independent, plain-English advice with no interest in any outcome other than yours.
Call us on 01252 929125, email hello@alturasurveyors.co.uk, or contact us at alturasurveyors.co.uk/contact.
If you are yet to commission a survey, get an instant quote at alturasurveyors.co.uk/quote. We carry out RICS Level 2 Home Surveys and RICS Level 3 Building Surveys across Hampshire, Surrey and Berkshire.