Purchasing a home is one of the most important financial decisions you will ever make. A property survey is your best protection against unexpected and costly surprises down the line.
So, what are the red flags on a house survey or, in other words, things that could become a deal breaker? Below, we break down the common red flags property surveyors may find and what they mean for you, as a buyer.
Red flags on a house survey
Red flags are issues found in properties that could introduce significant costs for the buyer. Although some of these are relatively common, they should be taken with utmost seriousness.
1. Structural movement (subsidence or heave)
One of the most serious red flags on a house survey is evidence of structural movement. This includes subsidence (when a building sinks into the ground) or, conversely, heave (when the soil underneath starts expanding and pushing the property upwards). These issues are typically attributed to adverse ground movement and can cause a building’s foundations to fail.
To find these issues, surveyors are looking for any evidence of cracking to the internal or external walls, uneven floors, bulging walls, or other signs of foundational movement. Structural issues can be incredibly expensive to investigate and repair, sometimes requiring major interventions.
2. Damp and mould
Damp issues are extremely common in Britain, but they can also be a warning sign of bigger underlying problems. The typical indicators include penetrating damp from faulty brickwork (leaks), rising damp due to a compromised, inadequate or missing damp-proofing system, or condensation issues due to poor ventilation.
If left untreated, damp can lead to mould growth, which not only causes materials to decay, but can also bring various health issues when living in such conditions.
3. Roof problems
The roof is one of the most important parts of your home, protecting it against the elements. Such issues as missing or cracked tiles, sagging rooflines, and damaged felt or underlayment can all result in leaks, water ingress, or major structural deterioration. Once a property has roof problems, the repairs are not cheap and cannot be ignored.
4. Electrical issues
Outdated electrical systems pose a significant safety risk but are, unfortunately, quite common in old properties. A property surveyor will be looking out for old or unsafe wiring, a lack of RCD protection, ageing or overloaded fuse boxes, and similar problems.
Although electrical issues can be quickly fixed, a full rewiring of a house can cost thousands of pounds, making it an important consideration when buying a property.
5. Plumbing or heating defects
Similarly, plumbing and heating issues can be commonly found in older properties, such as old or inefficient boilers, failing heating systems, inadequate water pressure, or corroded and leaking pipework.
These defects will often require major repair or replacement or, even worse, a full system upgrade, which would be a considerable outlay for a prospective purchaser when added to the other costs associated with purchasing a property.
6. Asbestos
It’s not uncommon for properties built before 2000 to still contain asbestos in roofing, insulation, floor tiles, or decorative coverings. Disturbed or damaged asbestos materials can release fibres and long-term exposure to asbestos fibres can lead to serious or even life-threatening health conditions.
Asbestos removal must be handled by licensed specialists, and the process can be very costly, depending on its location and quantity.
7. Japanese Knotweed or invasive plant species
Japanese knotweed is one of the most problematic plants for homeowners, as it is notoriously difficult (and expensive) to eradicate. Along with similar invasive plants, it can damage the foundations , masonry and drainage.
Any mention of knotweed should be investigated urgently, as it could even affect the outcome of your mortgage application.
8. Woodworm infestation or rot
Timber decay is another big red flag on a house survey, often caused by woodworm infestations or rot. The warning signs for woodworm are beetle exit holes found in timber and crumbling or weak wood, whereas rot can be recognised from musty smell, discolouration, changes in texture, and visible fungal growth.
Serious cases can require major timber treatment or full replacement, introducing potentially significant additional expenses.
9. Drainage problems
Drainage problems can often go unnoticed until they cause serious damage. Therefore, surveyors look for blocked or damaged drains and collapsed sections of pipework. If ignored, these issues can contribute to damp, flooding, or even weakening of building foundations.
10. Unsafe extensions and alterations
If a property has been previously extended or otherwise altered, it’s important to check whether this work was carried out according to the Building Regulations. If the survey finds issues of serious non-compliance, that may indicate an absence of Building Regulations approval; this could affect value as well as the more obvious and immediate health and safety concerns.
Similarly, failure to obtain planning consent could mean that a homeowner faces the need to seek retrospective approval or, in worst cases, face potentially costly enforcement action.
Amber flags (concerns but not deal-breakers)
It’s very rare that a property has no issues at all, particularly if it’s an older house. However, many of these are less serious or can be fixed relatively cheaply and easily. Some examples include:
- Worn pointing to brickwork – walls and chimneys
- Windows or doors at the end of their lifespan.
- Minor cracks in plaster (usually cosmetic).
- Insufficient insulation (resulting in higher energy costs).
- Old fixtures and fittings (not urgent but will need replacing).
While they’re not posing any immediate risks, amber flags are worth noting, as you want to budget for these fixes when buying the property.
What buyers should do next?
If the house survey has come back with some red flags, don’t panic – many of these issues are common and manageable with the right advice.
However, as a buyer, your main concern about house survey problems is who pays for them? This is typically resolved through negotiation: if the seller doesn’t agree to fix urgent issues before completion, buyers will seek a reduction in price, accounting for these fixes.
It’s always a good idea to seek specialist reports (e.g. a damp survey or a structural engineer inspection) as well as get quotes for the repairs highlighted before you exchange contracts. This will give you a clear idea of how much these issues will cost you, giving you a stronger negotiating position.
Get specialist legal advice
When it comes to red flags on a house survey, specialist legal advice can make all the difference.
As an RICS Regulated firm of Chartered Surveyors with years of industry experience, Trinity Rose are here to help you understand the seriousness of the issues found, make informed decisions, and negotiate confidently. Please don’t hesitate to get in touch.