A roof window is only as weathertight as the flashing kit and the opening it sits in. We size, fit and flash roof windows correctly for your roof covering, and repair or replace older units that are leaking, jammed or letting in condensation.
Traditional materials specialists · Photographic report on every inspection · Fixed-price quotes, never a day rate
15+ years
Experience, with 30+ combined years across the team
£2 million
Public liability insurance cover
10-year guarantee
Workmanship guarantee on re-roofs, new roofs and major works
Fixed price
Quoted work only, never a day rate
Photo report
Photographic evidence with every inspection
Recent work
Service overview
Roof windows sit within the plane of the roof itself rather than projecting out of it, which means they rely entirely on a correctly sized rafter opening and a properly fitted flashing kit to stay weathertight. Get either of those wrong and the window will leak eventually, no matter how good the unit itself is. Installation covers new openings formed in an existing roof, replacement of an existing unit with a new one, and fitting roof windows as part of a loft conversion or re-roof.
Repair covers the far more common call we get: an existing roof window that leaks around the flashing, will not open or close properly, has a cracked or misted pane, or has simply reached the end of its practical life after fifteen or twenty years of UK weather. Roof window flashings are a frequent source of roof leaks precisely because they sit at a junction: timber frame, glazed unit, and roof covering all meeting in one place, and any one of those elements failing shows up as water inside the room below.
We work with the roof covering you already have rather than treating every job the same. A flashing kit designed for plain tile will not weather correctly on a slate roof, and a kit sized for one make of window will not fit another's rafter opening. Getting the window, the kit and the covering matched correctly at the outset is what determines whether the installation is weathertight for the next twenty years or leaking within the first two winters.
The cost of leaving it
A roof window sits directly above living space, usually in a loft conversion or bedroom, so a leak there is rarely subtle for long. Left alone, a flashing or seal failure damages the timber and plaster around it and can spread to the surrounding roof covering.
A failed flashing lets water run down between the window frame and the roof structure, soaking the timber lining and the rafters either side. Left long enough, this leads to rot in exactly the timbers holding the window opening square.
Because roof windows are almost always fitted in finished, occupied rooms, a leak shows up quickly as staining or blown plaster around the reveal, damage that has to be redecorated once the window fault is fixed.
A roof window that will not close fully or lock properly is both a weather and a security gap, and on windows used for escape or ventilation in a loft conversion, a jammed mechanism can become a genuine safety problem.
Once the seal between panes has failed, condensation forming between the glass cannot be cleaned off and will not clear on its own. It is a sign the sealed unit has failed and will only get worse until the glazing is replaced.
Slates or tiles kept permanently wet by a failing flashing suffer the same freeze-thaw damage as anywhere else on the roof, so a window leak left too long can turn into a covering repair around the opening as well.
Our process
We examine the roof window itself, frame, seals, glazing, opening mechanism, and the flashing and surrounding roof covering, plus the ceiling and reveal inside where a leak is suspected. Free in most cases; jobs needing special access to inspect safely may differ and we tell you before we attend.
You get photographs of the fault, whether that is failed flashing, damaged glazing, a worn mechanism, or an opening that was never sized correctly, so you can see exactly what is wrong before agreeing to any work.
One figure covering the repair, replacement unit or new installation, including the correct flashing kit for your roof covering. No day rates, and the specification is set out in writing before work starts.
Typically two to three of our tradespeople on site. New openings are formed and sized correctly for the unit; replacement windows are fitted with a flashing kit matched to your roof covering; repairs address the specific fault found: flashing, seals, glazing or mechanism.
We check the window seals, opens and closes correctly, and that the flashing is weathertight, then walk the finished work with you with photographs of the result. New installations carry our 10-year workmanship guarantee; for smaller repairs we confirm in writing what is covered for your specific job.
What you get
Correctly sized rafter openings and flashing kits matched to your roof covering mean the window is weathertight from day one, not eventually sealed with mastic after it starts leaking.
Because we inspect the window, the flashing and the surrounding covering together, the actual cause of a leak or draught is identified rather than guessed at.
Installation, replacement or repair is quoted as a single figure before work starts. No day rates and no surprise additions.
Fitting the correct flashing kit and properly sized opening avoids the repeat leaks that come from a mismatched kit or a badly formed opening.
On slate and older tiled roofs we use flashing kits and fitting methods suited to the covering, so the installation does not compromise the roof around it.
Roof windows are worked on from proper access equipment with the room below protected, backed by £2 million public liability cover.
The detail
Roof windows fail almost exclusively at the junctions rather than the glass itself: the flashing, the opening size, or the seals around a moving frame. Getting each of those right is the whole job.
Every roof covering needs its own flashing kit because the profile, thickness and overlap of slates and tiles differs. A kit designed for plain tile will not weather correctly laid onto a slate roof, and a kit for a low-profile interlocking tile will sit wrong on a deep profiled tile. Using the wrong kit, or forcing one to fit with extra sealant, is one of the most common causes of a roof window leak that only shows up after the first heavy storm.
On slate roofs the flashing has to accommodate the flat, overlapping nature of the covering and is typically stepped and dressed by hand around the frame. On profiled tiles the flashing kit includes purpose-made pieces to follow the tile's shape at the head, sides and cill of the opening so water sheds correctly at every course.
The rafter opening has to be cut to the size specified for the window being fitted, with the surrounding timber trimmed and supported properly rather than just cut to roughly the right hole. An opening cut too large leaves the frame without proper support at the sides; one cut too small forces the frame in under strain, which distorts the seals and the opening mechanism over time.
Trimming timbers around the opening need to be structurally adequate for the span, particularly on wider roof windows or where more than one window is being fitted close together, since the trimmers are now carrying load that the cut rafters no longer do.
Centre-pivot windows rotate around a hinge roughly in the middle of the frame, which lets the outside of the glass be cleaned from inside by rotating the sash, and is the more common type for out-of-reach or steep installations. Top-hung windows open outward on a hinge at the top and give an unobstructed view and easier low-level access, but need to be reachable to clean externally.
Which type is right depends on the pitch of the roof, how the window will be reached for cleaning and escape, and how it is used day to day. We advise on this at the quoting stage rather than assuming one type suits every opening.
Beyond the kit itself, the weathering detail includes an underlay collar that directs any water reaching the underlay away from the opening, and correctly lapped flashing pieces at the head, sides and cill that shed water in the same direction as the roof covering around them. Any gap or reversed lap in this sequence is where leaks start.
On repairs, we frequently find flashing kits that were fitted correctly originally but have degraded, moved, or been disturbed by later roof work nearby: repointing, re-roofing sections, or aerial and satellite fittings; without being reinstated properly afterwards.
Condensation on the inside face of a roof window is usually a ventilation or humidity issue in the room, not a fault with the window. Condensation between the panes, or misting that will not clear, means the sealed unit itself has failed and the glazing needs replacing rather than the window as a whole.
Stiff or failing opening mechanisms, worn hinges, and perished seals around the sash are repaired individually where the frame itself is sound, which is usually cheaper and quicker than replacing the whole unit.
Roof windows fitted fifteen to twenty years ago or more often reach the point where the frame, seals and glazing have all degraded together, and repair stops being the sensible option. Replacement lets us also correct anything about the original installation that was not done well, an undersized opening, a mismatched flashing kit, or a unit that was never quite right for the roof covering it sits in.
On residential lofts this is usually a single-window job completed in a day; on commercial or larger residential projects with multiple roof windows, the same principles apply across each opening, and on period and listed properties we consider the visual impact and any planning constraints on rooflight positioning and appearance before specifying the work.
Questions
Something not covered here? Call 07711 933023 and ask. We would rather answer it honestly on the phone than have you guess.
It depends on whether it is a repair, a like-for-like replacement or a new opening, and on the roof covering and flashing kit needed, which is why we inspect before quoting. You get one fixed price in writing before any work starts.
Quotes and inspections are free in most cases. Jobs needing special access to inspect safely may differ, and we tell you that before we attend.
A single replacement window on an existing opening is usually a day's work. A new opening cut into the roof, or multiple windows, takes longer, and the expected duration is given with the quote.
Often, yes. If the frame and glazing are sound and the fault is the flashing, the seals or the mechanism, we repair those elements individually rather than replacing the whole unit.
New installations carry our 10-year workmanship guarantee. Smaller repairs are not covered by that guarantee unless we confirm otherwise in writing for your specific job, and we tell you which category your work falls into.
Correctly fitted with the right flashing kit for the roof covering, a roof window's frame and flashing should last for many years, though the glazing seal can fail independently of the frame and is replaced on its own when that happens.
Yes, emergency repairs are available for storm damage and active leaks. Call us and we will give you an honest answer on when we can attend rather than a fixed response-time promise.
Yes, and we advise on flashing detail and positioning that respects the character of the roof. Any planning or listed building consent needed for the window itself is a matter for you to confirm with the relevant authority before work proceeds.
Misting between the panes means the sealed glazed unit has failed and moist air has got in between the glass layers. It will not clear on its own and means the glazing needs replacing rather than the whole window.
We work from Maidenhead across Berkshire, Buckinghamshire, Surrey, Hampshire and Oxfordshire, including Reading, Windsor, Slough, High Wycombe and Henley-on-Thames. Just outside that? Call and we will tell you honestly whether we can help.
Where we work
Related services
A tiled roof is only as good as the details underneath it: battens, underlay, valleys, verges and flashings.
Natural slate is the covering most period and listed properties were built with, and the one planning departments usually want them re-covered in.
A leak is stopped once when the water path is traced properly, and paid for twice when it is patched where the damp shows.
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Next step
Book an inspection and you will get a photographic report of exactly what your roof window needs and one fixed price to sort it. Free in most cases, and no obligation to proceed.
151 Larchfield Road, Maidenhead, Berkshire, SL6 2SJ · Mon–Sat, 7am–10pm
