What is a skylight reveal?

A reveal is not the frame and it is not the glass; it is the finished opening between them, and it is built by whoever fits the rooflight rather than supplied with the unit itself.

Order a rooflight from a manufacturer and what arrives is a frame, a glazing unit and, on some products, an upstand or kerb to sit it on. None of that reaches the ceiling. The distance between the underside of that frame and the plasterboard of the finished room, however short or long, is made good on site: studwork or masonry lined, insulated where it needs to be, and plastered or boarded to match the rest of the ceiling. That lined section is the reveal. On a shallow flat rooflight it might be little more than a plaster edge a few centimetres deep. On a pitched roof window set into a loft, or a lantern over a kitchen extension, it can run through a genuine depth of rafter, insulation and roof covering before it reaches the frame at all.

It helps to think of the reveal as a short tunnel between the room and the glass. A tunnel with no length barely affects what you see; a longer one starts to frame the view, and depending on how its sides are lined, either keeps that framing generous or narrows it down. Our guide to frame profiles and sightlines covers what happens at the glass itself; the reveal is the part of the same sightline that sits below it, in the room.

The reveal's depth is mostly decided by the roof, not by taste, which is why the shape question only really starts once the depth is known.

A flat rooflight sits on a kerb built up to clear the insulation and the waterproof covering on a warm roof, and a well insulated flat roof can put the underside of the glass a good way above the ceiling before the reveal has even begun. A pitched roof window does the same job from the other side: the rafter depth and the loft insulation between them, often topped up to current standards well beyond older levels, both sit between the ceiling and the frame. A roof lantern is different again, its ridge and glazing bars standing proud of a flat roof on their own upstand, so the reveal below it is really the depth of that upstand rather than the roof structure itself.

None of this is a defect to be designed around. It is simply what the roof gives the room to work with, and it is one of the things checked at survey before any decision is made about lining. A deeper reveal is not automatically a worse one; it is a reveal that needs its shape thought through rather than left to chance.

Two reveals of the same depth, in the same room, under the same glass, can give completely different views depending only on how the sides are lined.

A square reveal runs straight up from the ceiling to the frame, at ninety degrees on every side, like a plain box let into the roof. A splayed reveal opens outward as it rises, so the hole in the ceiling is narrower than the hole at the frame. Sit dead centre under either one and the difference barely shows. Move off centre, to the edge of a bed or one end of a sofa, and a square reveal starts to behave like the tunnel it is: the near wall of the lining closes off part of the sky before your line of sight even reaches the glass. A splay eases that, because the wall your eye would have met has been angled back out of the way, so a wider stretch of the room keeps a clear sightline rather than only the spot directly beneath the frame.

Deciding which one suits a room, and by how much, is its own question with its own working, covered in full in our guide to choosing a reveal shape. What matters here is simply that the reveal is where that choice is made. The glass and the frame stay exactly as specified either way; only the plaster around them changes, and with it, how much of the sky the room actually gets to keep.

The reveal is one of the few parts of a rooflight job that costs nothing to plan properly and a full re-line to put right once the plaster has dried.

At survey, before any roof tile is lifted, we work out the eye position that matters in that particular room, the pillow, the sofa, the desk or the sink, and trace a line from there up through where the glass will sit. That line tells us how deep the reveal is going to be and whether a straight or splayed lining keeps it open from that spot. We draw the answer onto the sightline sketch that comes with every quote, alongside the frame position and any glazing bar, so the reveal is agreed on paper rather than discovered once the room is finished. Where an old rooflight is being swapped for a new one, the same drawing shows whether the existing reveal is worth keeping as it stands or worth opening up while the roof is already exposed, a question our guide to replacing old rooflights looks at from the roof side.

Once the roof is open, re-lining a reveal means disturbing plasterboard, studwork and sometimes insulation that has only just been made good, which is why the shape sits on the drawing before the job starts rather than being left to the plasterer's judgement on the day. What gets disturbed and made good afterwards is set out in our guide to making good inside after a rooflight is replaced.

Not every rooflight raises a real reveal question. A small, shallow flat rooflight over a bathroom, sitting close to the ceiling on a short kerb, rarely gives the plasterer much to think about either way.

It matters most on the jobs where depth is unavoidable: a loft bedroom conversion, where rafters and thick modern insulation sit between the ceiling and the glass; a lantern or large flat rooflight over a single storey kitchen extension, where the structure above the room can be deep by design; or a landing rooflight set well back from a stairwell, where the eye position moves as someone climbs the stairs rather than sitting still. Across Peterborough's Fletton-brick terraces and the newer trussed roofs of its townships, reveal depth varies house to house more than it varies street to street, which is exactly why it gets checked room by room at survey rather than assumed from the age of the property. Our Peterborough rooflight and skylight installation page sets out how that survey works across the wider area, and our guide to every type of rooflight and skylight compared is a useful next stop if you are still weighing up which product suits the room before the reveal is even drawn.

If you would like the reveal for your own room drawn out before any decision is made, book a home visit or message us on WhatsApp, and we will bring the sightline sketch with us.

Is the reveal part of the rooflight, or something the installer builds separately?

It is built separately, on site, by whoever fits the rooflight. The unit itself, the frame and glass and any kerb or upstand, arrives as a manufactured product; the reveal is the lining between that product and the finished ceiling, formed and plastered as part of the installation.

Does a bigger reveal mean a bigger rooflight?

No. Reveal depth is about how far the ceiling sits below the frame, which depends on the roof build-up, not on the size of the glass. A small rooflight in a deep roof can have a deeper reveal than a large one in a shallow roof.

Can the reveal be changed later if the shape turns out to be wrong?

Yes, but it means opening up the plasterboard and studwork around the opening again, which is disruptive to a finished room. That is why the shape is worked out from the eye position that matters at survey, before the ceiling is closed up the first time.

Does every rooflight and roof window have a reveal, whatever the roof type?

In some form, yes, because there is almost always some distance between the ceiling plane and the frame. On a shallow flat rooflight that distance can be small enough to barely register; on a pitched roof window through deep rafters or a lantern on a tall upstand, it becomes a real part of what you see.