Loft checks ยท 9 min read
What you can check from the loft yourself
A torch, a clear half hour and a careful eye will tell you a surprising amount about a roof without going near the slopes. This guide shows what to look for and where to stop.
The underside of a roof is where it admits its problems first. Water that gets past a slipped tile or a tired flashing seldom shows on the ceiling straight away. It runs down the underlay, along a rafter, soaks into the insulation and only then stains the plaster. By the time a brown ring appears over the bed, the fault has usually been there for some while.
That is why a look from the loft is worth doing once or twice a year. You need no ladder on the outside, no height and no tools beyond a bright torch. What you are checking is the evidence the roof leaves behind: marks, smells, light, sag and moisture.
This guide takes the checks in the order that makes sense with a torch in your hand. It also draws a firm line around what is sensible to attempt. Standing on the wrong part of a loft floor is a quick way to put a foot through a ceiling, and some of what you might find, such as old asbestos products, is best left undisturbed. If something looks wrong, a photograph is the most useful thing you can bring away. It is the first step of our wider guide to inspecting your own roof, and the notes below fit alongside it.
Getting into the loft without causing damage
Start with the practical side, because most loft accidents happen before anyone looks at the roof. Switch on a light if there is one, then bring a second source anyway. A head torch leaves both hands free, which matters on a ladder.
Where to put your weight
The floor of a loft is often just the ceiling joists with plasterboard fixed to the underside. The boards you can see, if any, sit on top of them. Anything between the joists is insulation lying on plasterboard that will not take a foot. Move from joist to joist, keep three points of contact where you can, and if there are no boards, lay a plank or a piece of ply across the joists to kneel on.
Keep your head clear of nails. Roofing nails and the points of clout nails often poke through the underlay and the battens, and they are sharp.
What to leave alone
Do not pull insulation about more than you must. Older loft material, textured coatings and some boarding can contain asbestos. The Health and Safety Executive advises treating any home built or refurbished before 2000 as though asbestos could be present in it. Look, photograph, and step back rather than breaking anything up.
Roofs also shelter wildlife. Both bats and active bird nests have legal protection, so if you find droppings, a nest or an animal, stop and photograph it from where you are rather than clearing it out.
Wear a dust mask, long sleeves and gloves. Check for loose wiring before you reach into corners. Then you are ready to look up.
Daylight, damp stains and dark timber
Turn the torch off for a moment once your eyes have adjusted. Pinpricks of daylight coming through the roof tell you something has slipped, cracked or gone missing. A thin line of light along the ridge or the edge of a gable wall is worth a photograph. A single bright dot, though, may only be a nail hole that the underlay has not closed over.
Then switch the torch back on and work along each slope slowly. You are looking for dark tide marks. They show up on the underside of the underlay, on the rafters and on the battens as rings or streaks, often darker at the edges where the water dried. A clean ring that has stopped growing is an old leak. A damp, glossy patch that looks wet to the touch is a live one.
Reading the age of a stain
Press a dry fingertip gently on the timber. Hard, dry wood with a pale edge is old. Soft wood that marks under a nail, or timber that feels cold and clammy, suggests moisture is still arriving. Lighter patches that carry a white or green bloom point to mould, which feeds on repeated damp.
Follow every stain uphill. Water travels down and sideways, so the wet spot is rarely right under the hole. A mark on a rafter low down might start from a slipped tile two metres higher up. Make a note of how far it sits from the chimney, the valley or the ridge, because those are where roofers look first.
Tracing a mark back to its source is the job of the person on the roof, so your notes on position are what count.
Insulation, moisture and the smell test
Insulation is a good witness. Dry mineral wool is fluffy and springs back when you lift a corner. Wet or compressed wool lies flat, looks darker and may smell musty. If you find a patch that is sodden, lift the edge carefully and look at the plasterboard below. A tide mark there matches what you may already have seen on the ceiling downstairs.
The smell of the loft matters too. A faint dry smell of old timber is normal. A sharp, sour or earthy smell means damp has been present for a while. Mould in the corners and along the cold edges usually points to condensation rather than a leak, which is a different job.
Condensation or leak?
The two look alike, and the difference changes the repair. A leak leaves stains in a line below a defect and gets worse after rain. Condensation shows as droplets, often on the underside of the underlay or the nail tips, and gets worse on cold mornings after a warm night in the house. It spreads over a wider area, including parts of the roof that are nowhere near a joint or a flashing.
Condensation points to air from the house reaching a cold roof space. Common causes are a bathroom or kitchen extractor ducted into the loft instead of outside, a gap round the hatch and gaps where pipes pass through the ceiling. Our guide to loft condensation looks at the causes, and the notes on ventilation below show what you can check yourself.
Photograph anything wet, with a coin or a ruler beside it for scale.
Ventilation at the eaves
A cold roof, where the insulation sits on the loft floor and the space above is left open, needs air to move through it. Fresh air usually comes in low down, where the slope meets the wall (the eaves), and leaves near the ridge or through the tiles. Loft insulation stuffed tight against the roof can shut off that route.
Go to the lowest point of the slope and look for a gap between the insulation and the underside of the roof. You should see daylight or feel a slight draught on a breezy day. Many houses have plastic eaves vents or a continuous ventilator that holds the underlay up, and they can be blocked by fibre or by old paint. If you can see the vent clear, that is a good sign.
What the guidance says
BS 5250:2021 sets out how moisture should be managed inside buildings. Marley's guidance on cold roofs gives figures for high-resistance underlay: a 25mm gap along the eaves for pitches of 15 degrees or less, and 10mm along the eaves for pitches above 15 degrees. Breathable underlay with low resistance is handled another way, and only when the ceiling below is well sealed. The rules follow the product, so which underlay your roof has matters.
You do not need a ruler for a first look. If the insulation is jammed against the roof and nothing shows, note it and ask a roofer. Opening up the eaves is a small job on its own and often cures a damp loft, but it should be done in a way that does not drop the insulation level. Our guide to checking roof ventilation goes deeper.
Timbers, sag and the underside of the covering
Now look at the structure. A healthy roof frame has straight rafters, tight joints and a ridge board that runs level. Sight along the line of the ridge from one end of the loft and then along a rafter. Any dip, bow or gap is worth recording.
Some movement is old and harmless. Houses settle, and a slight wave in a long slope can be decades old without causing any trouble. What matters is whether it is changing. Fresh cracks in the plaster below, doors that have started to stick or a new gap at the wall plate are signs that something has moved recently.
Rot, woodworm and fixings
Press a screwdriver tip into the foot of a rafter and into the wall plate, the long timber bedded along the top of the wall for the rafters to sit on. Sound timber resists. Soft, crumbling or stringy wood means rot. Woodworm leaves small round flight holes and fine dust below; old, inactive holes are common, but fresh pale dust is not.
Look at the nail tips poking through the battens. Orange rust on the shanks near a damp patch points to long exposure. On an older roof, tiles held by nails alone can start to slip once the nails give way, which is called nail sickness, and the nail heads are sometimes visible from underneath. A roofer can confirm that from outside.
Check around the chimney breast too. Damp on the brickwork or a stain on the timbers beside it suggests the flashing may be letting water through. A flashing is the lead strip dressed between the stack and the slope.
Do not try to lift tiles or push up the underlay from inside.
Photographs, notes and when to call a roofer
You have done the useful part of the inspection. Before you leave the loft, record it so that it can be compared next time and passed to someone else.
What to photograph
Take a wide photograph of each slope, then close-ups of anything unusual with a coin or ruler for scale. Note where each one sits: near the chimney, third rafter from the left gable, just above the bathroom. A rough sketch of the loft plan with crosses marked on it is more useful than a dozen pictures with no context. Keep the images in one folder with the date.
A single stain that is old, dry and not growing is something to watch, not to panic about. Revisit it after the next spell of heavy rain. Wet insulation, a stain that is darker than last time, timber you can push a screwdriver into, a visible dip in a rafter or daylight where there should be none are all reasons to ask a roofer to look.
What happens next
If you send us your loft photographs, we know where to begin once we are up on the slopes. Our visit ends with pictures of the cause and a clear call on the fault: fix it, hold it for now, or replace. Whatever the answer, you get a written total price after the survey, and we put forward the lightest job that does the work properly.
The roof inspections and surveys page explains how our own visits run, if you would rather not choose between doing the loft check alone and booking someone.
Stay on the joists, leave suspect materials alone and let the photographs do the talking.
Questions
Loft check questions
Is it safe for an older person to go into the loft alone?
It carries a real risk of a fall from the ladder or a foot through the ceiling, so ask someone to hold the ladder and stay in the house. If the hatch is awkward, there is no boarding or the climb is steep, send the photographs a family member takes instead, or have a roofer look from the loft and the outside. Never step between the joists.
Can I tell from the loft whether my roof needs replacing?
Not on its own. The loft shows leaks, wet insulation, sagging and rotten timber, but it cannot show how many tiles have cracked on the outside or whether the flashings are failing. Several faults in one place usually point to a repair. Widespread staining across every slope, plus soft timbers, makes a stronger case for replacement, which a roofer confirms from outside.
What if I find droppings or a nest in the loft?
Leave them where they are and take a photograph. Bats and the places they roost are legally protected, and so are active bird nests. Tell your roofer before any work starts, because the job may need to wait or be planned around the animals.