Walk-On Rooflight Installation in York

A walk-on rooflight is a pane of structural glass set into a floor, a terrace or a patch of paving, so that daylight can drop through to a room that has no window of its own.

In ordinary rooflights the glass is there to be looked through and kept out of the rain. Walk-on glass has a second job: it has to carry people. It is built from several layers bonded together, framed in metal, and seated on structure that has been checked for the load. From above it looks like a clear square set into the surface. From below it looks like a skylight in the ceiling.

The people who ask for one usually have a particular room in mind. It might be a basement kitchen that has only ever had electric light, a hallway under a landing, or a utility room tucked beneath a terrace. In each case the space above is somewhere you still want to walk, sit or put a chair, so a normal rooflight would take that space away. Walk-on glass gives you the daylight and keeps the floor.

If you simply want light and nobody will ever stand on the roof, a flat roof rooflight is the simpler product. We will say so at the survey if that is the better fit.

The glass is not thicker window glass. It is a laminated build-up, designed so that if one layer is ever damaged the others keep carrying the load.

A typical unit has a toughened or heat-strengthened outer layer facing the walking surface, then one or more further layers bonded to it with a clear interlayer. The interlayer holds the pieces together if a layer cracks, which is why you can stand on it with confidence. Where the glass also has to keep heat in, a sealed unit sits under the walking layers, with a heat-reflecting coating and an argon-filled gap, and a laminated pane on the room side.

The top face is treated so that shoes grip. Most makers fire a pattern of ceramic dots into the surface, or acid-etch it, and both leave the glass clear enough to see through. Our guide to how thick walk-on glass is explains why the answer depends on the span and the use, not on one number.

Every unit is made to size for your opening, so it is ordered after the survey measurements are confirmed, not before.

The most important decision on a walk-on rooflight is made before the order goes in: what weight the glass has to carry, and where it will be carried to.

Think about how the surface will really be used. A landing is crossed by the family and the occasional laundry basket. A terrace might hold a table, four chairs and a planter. A courtyard may take a barbecue, or a delivery person with a trolley. Each of those puts a different load on the glass, and the glass is built up to match. Larger panes and wider spans need thicker build-ups, because glass bends a little under load and the design has to keep that movement small.

The makers publish the loading their units are tested for, and we work from those figures, not from guesswork. Where the opening is large, or where it interrupts a beam or a slab, a structural engineer sets out the support and we build to that drawing. You are given the maker's loading details at handover, so there is a record of what the glass was chosen for.

Tell us about the heaviest thing that will ever stand on the glass, and we will design the build-up around that.

From a survey in Heworth

The question about how walk-on glass loading works goes through point loads, spread loads and what the figures on a data sheet mean for a household.

Glass is only as sound as the structure under it, so the opening is formed, trimmed and supported with the same care as the glass.

Cutting a hole in a floor or a flat roof removes some of the timber, steel or concrete that was carrying load. The members either side of the opening are trimmed with doubled joists or a new beam, and the loads are carried round the opening to the walls or posts that support them. In a timber floor that means new trimmers hung from the joists beside the hole. In a concrete slab it may call for a lintel-style support set into the slab's edges, with the cut made cleanly and the steel exposed and treated.

We take photographs of the hidden work before anything is covered, so you have a record of the trimmers, the bearings and the insulation. Those photographs are handed to you with the rest of the paperwork. They are also what a registered building control approver or the council's Building Control team will ask about if they inspect.

When the structure is not what you expect, we tell you before the glass is ordered. Old floors can be lighter than they look, and a basement ceiling that seemed solid may turn out to be a thin slab with a joist hidden in the wrong place. That is why the survey includes a careful look from the room below as well as the surface above.

Standing on glass should feel ordinary after the first step, and it should stay easy to look after.

The anti-slip surface does most of the work. A fired dot pattern gives the sole a bumpy texture to grip, and an etched finish does the same job with a softer, frosted look. Either way the glass is intended to be walked on, in shoes or socks, and the pattern is designed to keep its grip when it is damp. If you are worried about wet leaves, algae on a shaded patio or a child carrying a drink, there is more detail in are walk-on rooflights slippery.

A walk-on rooflight outdoors collects the same dust and leaf mould as any paving. A wash with a hose and a soft brush once the weather turns is usually enough, and the handover includes cleaning advice written for your glass.

The glass is for the room below, so a good fit starts by looking at that room: its height, its use and what the light will fall on.

A basement kitchen with a rooflight overhead feels different the moment the first daylight arrives. The colour of the units becomes clearer, the walls look taller, and the room is no longer something you only use after dark. A hallway under a landing gets the same lift, and the stairs stop feeling like a tunnel. Because the glass is horizontal, it brings light from directly overhead, which spreads over the floor and the work surface. Pale walls and ceilings then carry that light further across the room.

The soffit, the underside of the opening, is lined and finished so it looks like a neat recess rather than a hole. We build it to splay slightly if the room's proportions suit it, then plaster and leave it ready to paint. A downlight or a shallow LED strip can go in the reveal if you want the glass to glow after dark, which is a pleasant effect in a basement room on a winter evening.

In a room that gets warm in summer, where the glass sits makes a real difference. Glass that faces open sky will heat up the room below more than a pane that is shaded by a wall or a tree. Solar control coatings are available, and we note the options in the written quote.

A roof terrace over a living space is one of the places where walk-on glass can solve two problems at once: a usable outdoor area and a lit room beneath it.

Many York houses have a flat-roofed rear extension or a first-floor flat roof beside a bedroom window. Turning that into a small terrace gives you somewhere to sit, and a walk-on pane in the surface lets daylight reach a bathroom, study or landing underneath. The roof has to be built or checked to suit: falls to the outlets, an insulated build-up, a walking surface that spreads load, and guarding where the edge is high enough to need it.

A terrace may need planning permission even when a rooflight alone would not, because of how it overlooks neighbours. The rooflight rules are in the planning section later on this page. A terrace adds structural and overlooking questions of its own, which walk-on rooflights for roof terraces covers.

Below ground, daylight is scarce and the glass is working harder, so the detail at the edge needs the most care of any part of the job.

Many terraced and Victorian houses in York have cellars. Some have been turned into kitchens, studios or playrooms, and a few have a light well outside the front or rear wall. Walk-on glass over a light well, or set into a paved yard above the cellar, brings daylight down without losing the surface above.

Outdoors, the frame sits in a recess with falls and outlets so water runs away from the glass. The perimeter is detailed so that paving, resin or timber decking meets the frame cleanly, with a movement joint that stops it cracking. Below ground, the room underneath also has to stay dry, so the junction between the frame, the surrounding structure and any waterproofing is built to be continuous.

The guide to walk-on rooflights for basements and light wells is the place to start if your light is going into a lower room.

A hole in the floor of a heated room is a place heat can escape, so the glass has to be as well insulated as a window.

When walk-on glass sits between a heated room and the outside, it is an outer element of the building, and its thermal performance matters. Where it only separates two heated spaces, such as a landing above a hallway, the heat loss is small and the glass is chosen mostly for strength and light. The sealed unit, the frame and the way the edge is insulated together decide what the finished rooflight achieves.

For existing homes, the guidance in Part L of the Building Regulations sets a limit of 2.2 W/m²K for rooflights, and the maker publishes a figure for each unit so it can be checked. We use that figure, not an estimate, and it goes into the paperwork. A metal frame carries heat quickly, so a thermal break in the frame, or a frame that sits on insulation, is worth having. How the numbers work is set out in are walk-on rooflights insulated.

Ask for the U-value of the whole unit with its frame, not only the glass at its centre.

From a survey in Bishopthorpe

If you are thinking about upgrading your home's performance in general, our energy efficient rooflights page covers the wider choices, and we can talk them over at the same visit.

Walk-on glass can touch both systems, and the answer depends on whether the glass is in a roof, a floor or the ground.

Planning first. For a house, the roof-alteration rules normally cover a rooflight that stands no more than 150mm proud of the roof plane and never tops the roof's highest point. Facing a side slope, the glass has to be frosted and fixed shut, unless any opening part sits over 1.7m up from the floor. Walk-on glass in a floor or in the ground inside the house is not a roof alteration, so planning rarely comes into it, but a roof terrace may need consent because of the way it looks over neighbours. Flats and maisonettes have no permitted development rights for rooflights, and a listed building needs listed building consent. A house in a conservation area keeps its permitted development unless an Article 4 direction has taken it away on that street, which the council can tell you. Every condition is spelled out in the skylight planning permission guide.

Building Regulations are the bigger question. A new opening in a floor or roof needs approval for its structure and its thermal performance. Replacing a rooflight whole, frame included, counts as a controlled fitting and must be notified. Where that applies we send the notice ourselves, either through the council's Building Control team or a registered building control approver, and the certificate comes to you at handover.

Before the survey is over, we tell you which route your job takes. The page on whether walk-on rooflights need Building Regulations answers the common cases, and the structural drawing, where one is needed, forms part of the application.

After the novelty wears off, the questions are practical ones: where the sofa goes, what the dog does and whether the children can play on it.

Walk-on glass is designed to be used, but the loading figure assumes the load is spread in a sensible way. A narrow chair leg puts all its weight through a small point, which is a different test from a person standing. The page on whether furniture can stand on a walk-on rooflight explains this properly, and we cover your own furniture at the survey.

Pets and children are generally fine on the glass. Dogs' claws can scratch an unprotected surface over time, so a glass that gets a lot of paw traffic benefits from a harder surface treatment. Children tend to find the glass fascinating at first, and a clear view down is often a pleasure to them. If a low terrace opening worries you, the layout can be adjusted so the glass sits a little way from the edge.

Rugs and mats are best kept off the glass. They trap grit and grind it into the surface, and they hide the light you paid for.

Walk-on glass is fitted in a clear order, and you will know that order before the first dust sheet goes down.

We schedule the work so the room below is out of use for as short a time as possible. The floors and stairs between the front door and the work area are covered, furniture is moved or wrapped, and a screen goes up around the work area where possible. Outdoors, the roof or paved area is protected, and before the team leaves each evening it is sealed against rain, so the room beneath stays dry overnight. The same team carries on from start to finish, and waste is taken away.

Glass of this size is heavy, so the lift is planned in advance: who will carry it, which route it takes through the house and where it will rest on the way. A heavy unit is carried in through the wide route and not manhandled through the narrow one.

The mix of houses around York means walk-on glass turns up in several quite different places.

In the terraces of the Groves and South Bank, a cellar below the back room is the usual candidate, with glass set in the yard above. A pair of 1930s semis in Acomb or Dringhouses is more likely to want glass on a landing or in a flat-roofed extension. Villages such as Haxby, Strensall and Copmanthorpe have bungalows with flat-roofed additions where a small terrace or a hatch-sized pane over a utility room fits well. Houses on lower ground near the river may have cellars that call for particular attention to damp and drainage, which is a reason to do the survey properly.

Where the building is listed or in a conservation area, the glass is usually best set into a rear yard or interior floor, where it is out of view from the street. A conservation rooflight may suit the roof instead, and we are happy to talk through the alternatives.

There is no single price, because the glass, the structure and the finish around it all change from house to house.

The biggest factors are the size of the glass, the load it must carry, the way the opening is formed and the finish around it. A small panel in an internal landing involves little more than a trimmed opening and a made-to-measure unit. A large terrace panel needs an engineer's drawing, a heavy lift and weatherproofed edges. Access matters too: glass that has to go through a narrow hall costs more to move than glass that can be lifted in from outside.

We give you a written quote that prices each part separately, so you can see what the glass costs, what the structure costs and what the finishing costs. If an engineer is needed, that is listed separately, as is any Building Control fee. The survey is free, and you are under no obligation after it. Our walk-on rooflight cost page goes through what sits behind each line, and the site-wide costs guide shows how our quotes are put together.

The glass is rarely the largest line on the quote; the structure around it often is.

From a survey in Poppleton

When the glass is in, the last job is to make sure you know how it is built and who to ask if you have questions.

We walk you round the finished work: the glass from above and from below, the frame, the drainage and the soffit. You are shown how to clean it and what to avoid. We hand over the product details, the maker's loading information and warranty, the 10-year workmanship guarantee, the photographs of the hidden work, and, if the job was notifiable, the Building Control paperwork.

You can read how the guarantee works on our guarantee page, and the broader services overview shows the other products we fit, from lanterns to sun tunnels. When you are ready, a free survey is the first step, and the form at the foot of this page is the quickest way to ask for one.