Question answered
Snagging a new-build roof
The short answer
Snagging a new-build roof means checking the covering, fixings, flashings, valleys, gutters and eaves for faults, and recording each one with a dated photograph and a written list for the builder. Look for slipped, cracked or loose tiles, ridges and verges that rely on mortar alone, poorly dressed lead, untidy valleys, sagging gutters and torn underlay in the loft.
A roof that looks finished from the pavement can still hide faults that only appear after the first winter. Snagging is the careful check, before and just after you move in, that finds them while the builder is still on the hook.
Tiles, fixings and what BS 5534 expects
Start with the covering. From the ground, or from a safe place with binoculars, look for tiles that sit proud, slipped courses, cracked or chipped tiles and gaps in the pattern. Lines should run straight across the slope and the overlaps should look even.
The fixings matter as much as the tiles, and you will rarely see them. Wienerberger's guidance says each single-lap tile needs a minimum of one mechanical fixing, with the detail worked out for the plot, taking in the house's position, its elevation and the wind it faces. In Marley's account of BS 5534, the outer edge of the roof gets double fixing.
You cannot check nails from the pavement, but you can ask the builder for the fixing specification and the tile maker's name, and keep both with your papers. If the answer is vague, that is itself a finding. A roofer's survey can then confirm what is actually on the roof, with photographs.
Ridge, hip and verge fixings
The ridge runs along the apex, a hip is the sloping edge on a hipped roof, and the verge is the edge at a gable end. They are where the wind pulls hardest, so they are where careless work is most expensive to put right.
Since the 2014 revision of BS 5534, the ridge and hip courses cannot rely on bedding alone; mechanical fixings go in too. On a new roof, look for cracked or crumbling mortar, tiles that rock when the wind gusts, and a ridge that is not in a straight line. Dry-fix ridges, tested against BS 8612:2018, use clips and fixings rather than bedding alone, and they should be fitted as the maker intends.
Verges deserve a close look. A verge cut ragged, a gap between the last tile and the wall, or mortar slumped and stained below it will let rain in. These are quick to fix at the start and awkward to repair after a storm. If the roof is on the coast side, be firmer with the builder about this detail.
Lead, valleys and the chimney stack
Flashings are the strips, normally lead, that seal the roof where it meets a wall, chimney or other upstand. On a new roof, look for lead that is creased, torn, left short or held with a bead of sealant rather than chased into the wall and worked down across the covering. Sealant is a sign someone ran out of time.
Valleys are the internal channels between slopes, and they should be clean and straight, with the tiles cut neatly either side and no gap showing the liner. Look at the chimney as well. The flashings at the base and the back gutter behind the stack are among the first places water finds a way through.
The lead should be thick enough for the job and laid without kinks. Leave anything to do with the code of lead to the roofer's survey, which will say what is on the roof and whether it suits the position. Photograph every flashing before the builder's scaffold comes down, since that is the easiest time to get them looked at.
Gutters, eaves and the loft
Water should reach the gutter, run to the outlet and leave. Check that gutters have a gentle fall, brackets are not far apart, joints are tight and the downpipes stand clear of the wall. After rain, a gutter holding standing water or dripping at the joints tells you it needs adjusting.
Look at the fascia and soffit, the boards at the eaves, for gaps, splits and ragged cuts. Birds and insects will find a gap before you do. From the loft hatch, if reaching it is safe, check the inner face of the roof. The underlay should lie flat and be free of tears. Sunlight showing through anywhere means the covering above is not tight.
Check that insulation has not been pressed into the eaves, because that blocks airflow and leads to condensation. Our guide to the signs of poor roof ventilation shows what to look for. Debris left in gutters or the roof void, such as offcuts, packaging and spilled mortar, is another typical snag.
Recording the snags and getting them fixed
A list the builder cannot dispute beats a conversation. Photograph each fault with something in the frame to show where it is, write the date on the list and send it in writing. Keep copies. Check your purchase paperwork for how long the builder has to return and what the sale terms say about defects, and ask the solicitor if anything is unclear.
If the new home is a flat, the roof may not be yours to fix alone; the leasehold flat roof survey page explains how to approach that. A homebuyer's report may mention the roof, but the homebuyer survey roof guide explains how little of it a general surveyor can see.
Our survey covers the outside and the loft, and the photographs and written quote follow for any repair the builder does not put right. Where a fault points to the original build, the report you hold becomes useful evidence. More checks sit under roof inspections and surveys.
New-build roofs: two more points
Should the roof be snagged before I complete or after I move in?
Both, where you can. Look from the ground before completion and note anything visible, then check the loft and gutters once you are in, ideally after a spell of rain. Report each item in writing as soon as you find it.
Is a new roof guaranteed to be free of faults?
No. Poor fixing, careless flashings and blocked ventilation can all show up in the first winters. A new roof has had less time to fail, which makes faults easier to trace to the build, so a survey in the early years is worth the effort.
Tell us about your roof
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