When you buy a house, the roof is the part you are least likely to see properly. Viewings are short, the loft hatch is often painted shut and the person showing you round has every reason to talk about the kitchen. Yet the roof protects everything else you are paying for, and a surprise there can arrive as a bill of several thousand pounds in the first winter.
You do not have to be a roofer to ask good questions. Most of what matters is visible from the pavement, in the loft or on the seller's paperwork. This guide goes through all three, then covers two subjects that now catch buyers out: spray foam insulation under the rafters, and asbestos in homes built before 2000.
It also explains when a separate roof inspection is worth paying for. A mortgage valuation checks that the house is worth the loan, and a basic survey reports what the surveyor could see without opening anything up. Neither is a roofing survey, and the difference can matter in a place like Farnborough, where housing from the 1860s to the 1980s sits side by side.
Reading the roof from the pavement
Stand back across the road or at the end of the garden, in daylight, and look at each slope in turn. Binoculars help. You are looking for a roof that has a regular surface and a straight outline.
Lines and surfaces
A ridge that dips, a slope that bows between the walls or a row of tiles that waves instead of running straight suggests that the timber or fixings underneath have moved. Patches of tiles in a different colour mean earlier repairs, which is normal, but a roof that looks like a quilt has been mended many times and the reasons are worth asking about.
Tiles, ridge and edges
Look for cracked, slipped or missing tiles and for gaps where daylight might show through. Check the ridge, the line along the top where the two slopes meet, and the verge, the edge at the gable end. If the mortar there is crumbling, the tiles it holds may be loose.
Chimneys and flashings
Chimney stacks take weather on four sides. Look for leaning, cracked bricks, gaps in the mortar joints and lead or cement along the base that is lifting away. A stack that looks sound from the street can still have failed flashing where it meets the roof. Our page on the roofs by house age in Farnborough explains what tends to go wrong at different eras.
Gutters and walls
Green stains below a gutter joint, damp patches on brickwork beneath the eaves and plants growing in the gutter show that water has not been leaving by the proper route.
In the loft with a torch
Ask to go up. A seller who refuses a loft inspection is withholding information, and your solicitor can note it. If the hatch is awkward, ask politely for access before exchange rather than after.
What to look for
Use a torch and stay on the boards or joists, never on the ceiling plasterboard between. Study the roof from underneath. You are checking for daylight where it should not be, dark staining on the timber, damp patches around the chimney breast and the eaves, and a smell of mould or damp. Black spots on the timber and the underlay can be a sign of condensation, which suggests poor ventilation.
Underlay and timbers
The underlay is the membrane under the tiles. Old bitumen felt can go brittle and tear, so look for sagging pockets and loose edges. Sound timbers are dry, straight and firm. Dark, soft or crumbling wood needs a closer look by a professional.
Insulation and ventilation
Look at how the insulation has been laid, and whether it has been pushed hard against the roof. If it is pushed hard into the eaves, it may block the air gap that lets a cold roof breathe. Marley's guidance on cold-roof ventilation sets out eaves gaps for non-breathable underlay: 25mm on pitches of 15 degrees or less, and 10mm on steeper pitches. You do not have to measure it, but a buyer who finds insulation jammed into the eaves has found a question for the surveyor.
Water tanks and pipes
Check the tank and pipework for old stains below them. They show that the roof or the plumbing has, or had, a problem, and a stain on the boards under a pipe is a quite different story from one under a tile.
Spray foam under the rafters
Spray foam insulation is a polyurethane foam that is sprayed on the underside of the roof, where it expands and sets. It has been fitted to some homes in recent years, and it appears in more survey reports than it used to.
What RICS said on lending
RICS, the Royal Institution of Chartered Surveyors, announced a consumer guide to spray foam on 3 March 2023. The release reported unease among certain lenders, equity release providers among them, and said that unease was spreading to others. The practical effect was that some lenders began to ask questions about homes with foam in the loft.
Why a buyer cares
Once foam coats the rafters, nobody can inspect them properly, as the RICS guide itself points out. A buyer cannot see rotten rafters or battens under the foam, and a surveyor cannot report on what is hidden. The same guide warns that poorly fitted insulation can disturb ventilation and bring on moisture damage in the roof timbers.
What to ask
If the loft shows foam, tell your solicitor and your mortgage provider before you exchange. The RICS guide recommends checking whether the lender's policy allows such products. Ask the seller who fitted it, when, and for any paperwork. Our guide on roof survey costs shows what an inspection of a foamed roof can and cannot reveal.
Foam in the loft is a reason to ask questions and take advice. It does not by itself mean a house cannot be mortgaged.
Older homes and asbestos
Asbestos went into many building products right up to the closing years of the twentieth century. The Health and Safety Executive's advice for owners and managers is direct. Where a building dates from before 2000, or was refurbished before then, treat it as containing asbestos until a survey proves otherwise.
Where it hides on a roof
On a house, the places to be aware of include flat sheet garage and outbuilding roofs, rainwater goods, and the external soffits under the eaves. The HSE says asbestos insulating board, found in external soffits, is difficult to tell apart from non-asbestos equivalents by eye. Only testing settles the question.
What it means for a buyer
Asbestos that is sealed and left alone is not a danger in the way that disturbed material is. The problem arises when someone drills, cuts or breaks it. If the house has an older garage roof or soffits that may be asbestos-based, factor in the cost of testing and, if necessary, careful removal.
MyJobQuote gives about £325 for an asbestos survey and about £2,750 for removing an asbestos roof (Sep 2026, typical UK range, which will vary hugely with the size of the building).
What we do
If a survey photo shows panels that look like asbestos-cement, we stop and recommend testing before any cutting. The sample goes to a laboratory, and the result decides the method. Waste from such work travels on a consignment note and is double-wrapped and labelled, never put in an ordinary skip.
For solicitors and surveyors
Ask the seller whether an asbestos survey has ever been done. A recent report is useful, and a refusal to share one tells you something.
Papers to ask the seller for
The best evidence about a roof is often a document. Ask your solicitor to request the following, and read the replies for what they say and what they leave out, because an unanswered question is information too.
Completion records for a re-roof
If the roof was re-covered, ask for the building control completion certificate. Not every re-roof needs one. The Planning Portal sets limits of under 25 per cent of the building envelope and under 50 per cent of the roof, inside which an application is normally not required. A full re-roof is a different matter, and a covering that is 15 per cent or more heavier needs approval. In Rushmoor, the records sit with the Hart and Rushmoor Building Control Partnership. If a completion record was never obtained, your solicitor can discuss options with the seller.
Invoices and warranties
A dated invoice from a roofer for a repair or a new roof tells you who did the job and what was done. Any workmanship warranty paperwork should be passed on with the sale.
New-build cover
If the house is a recent build, look at the NHBC Buildmark paperwork. It runs as a builder's warranty in the first two years, followed by eight further years of NHBC insurance that covers defects in listed parts of the home, and the roof structure is worth checking against that list.
Planning history
Dormers, rooflights and loft rooms should show planning or Building Regulations records. Read the answer on how often a roof should be inspected to see what the seller's maintenance history ought to look like.
Is a separate roof inspection worth paying for?
For many buyers the answer is yes, in particular when the loft or the outside has raised questions. A roof inspection by a roofer is different from a general survey: it looks closely at the covering, the ridge and verge, the flashings, the chimney and the underside.
When it earns its fee
It is worth commissioning if the chimney or ridge looks tired, if the roof has been patched, if the loft shows damp, if there is foam or an older garage roof, or if the survey report uses wording such as 'further investigation recommended'. A report in a seller's hands can also help you negotiate.
What it should give you
You should receive photographs of every problem, measurements, and a clear split between repairs, wear that can safely wait and anything urgent. Ask for it in writing so you can compare it with the surveyor's report.
What it costs
MyJobQuote puts the average roof survey at around £300 (Oct 2026), with table rows of £100 to £200 and £200 to £350. That is a typical UK range, not a Fortis price.
Roof age, in context
Typical lifespans are not promises. HomeBuilding gives clay tiles 60 to 80 years, plain concrete tiles 40 to 50 years and Welsh slate over 100 years. A roof inside its range may need repairs but not replacement, so age alone should not put you off.
If you are weighing up a purchase, our Farnborough roofing homepage shows how a survey with photos and a single written price works.
