Beamed loft bedroom with a small rooflight in the slope above the bed

Conservation Rooflights in Derby

A thin-framed rooflight that sits with an old roof, not on it.

Slim frames that sit close to the slates, fitted over the stair, desk or bath that has gone without daylight for decades.

Book a free survey

Free survey
Fixed written quote
10-year workmanship guarantee

Three places an old roof can let the day in

Stone-walled loft room under exposed beams with a roof window — Over a stone-walled loft room, where the old beams stay dark without a slim roof window.

Bedroom in an older loft with a timber beam and a slim rooflight — In an older loft bedroom, a slim rooflight fitted beside the timber beam.

Insulated loft under oak rafters with a roof window at the gable end — Over a desk in a loft room, with the view of the sky at eye height.

Ten years on our workmanship. In writing.

Surveyed before we price
A fixed written quote that does not change on the day
Building Control notification handled

How the guarantee works

Brick cottage with a clay-tiled roof and a slim rooflight in the slope

The full guide

Conservation rooflights for older Derby roofs

A conservation rooflight is a slim, low-profile unit made for slate and clay roofs where appearance counts. This guide walks through the stair, the glass, the frame, the roof, the choice against a standard window and the consent routes, in the order you meet them. It explains how Skylark Skylights fits conservation rooflights across Derby and about 30 road miles around, from the first survey to the last bead of sealant.

Stair and landing
Glass and types
Frame and flashing
Slate and tile roofs
Choosing the unit
Consents and rules

Callout 1

Start with the dark corner, not the catalogue

Most people who ring about a conservation rooflight begin with a room. The landing is gloomy. The back bedroom has a sloping ceiling and one small window. The bathroom sits under the roof with no daylight at all. What they mean, once you stand in the house with them, is a particular place. It is the turn of the stair, the corner where the desk would go, the end of the bath where someone lies and looks up. A skylight, which is the word most homeowners use, is chosen to put daylight on that place. A rooflight, which is the trade word for the same family of products, is specified the same way.

A conservation rooflight is the version made for roofs where appearance matters. It has a slim frame, usually in steel or a steel-look finish, and it sits low against the slates or tiles instead of standing proud of them. Older Derby houses are exactly where that matters. Terraces from the Victorian and Edwardian years, the gables of larger villas, outbuildings and converted barns all carry roofs that people notice from the street. A bulky white frame sitting a hand's width above the slope reads as a modern patch. A slim unit that follows the roof plane reads as part of the building. The full definition and the parts of the unit are set out in What Is a Conservation Rooflight?, which is worth reading before you look at any quote.

Why the spot comes first

Conservation rooflights are usually specified in a few set sizes along the roof slope, and the opening between the rafters has to be framed by a carpenter before the unit goes in. Move the rooflight a metre up or down the slope and the daylight lands somewhere else in the room below. So the survey starts inside. We stand with you at that place, mark it on the floor plan, look up at the roof from that spot, and then go outside to see which slates sit above it. Only then do we talk about frame size, glass and finish.

This is also why a rooflight in an older house is rarely a straight swap from a catalogue picture. The rafters may be at irregular spacing. The ceiling may be lath and plaster that needs care when an opening is cut. The slope may already carry a chimney stack, a valley or a soil vent pipe that limits where a unit can go. Each of those facts changes the answer, and each is easier to see in person than to guess from a photograph.

Rooms that suit a conservation rooflight

The rooms we are most often asked about in older houses are the landing and stairwell, the loft room or attic bedroom, the bathroom, and the kitchen at the back of the house where a lean-to meets the main roof. Each has a different spot. On a landing the spot is the half landing or the top step, and the light needs to fall down the stairwell. In a loft room it is the desk or the bed, and a rooflight at the right height also gives you a view of the sky when you sit. In a bathroom it is usually the bath or the basin. In a kitchen it is the worktop, and the unit has to avoid putting glare on the hob or the screen of a tablet propped against the splashback.

Light from above is brighter than light through an ordinary wall window of equal area, and it reaches further into the room. A single well-placed unit can do what two wall windows cannot, particularly in a terrace where the neighbouring house is a few metres away. English houses face no daylight rule under the Building Regulations, so nothing forces the choice. You make it because the room is hard to live in, and because the light is worth having.

What a survey looks at

The free survey is the first step. Nothing is priced until the room, your chosen corner and the slope above it have all been seen. We measure the rafter positions, check the slope and covering, look at the ceiling below, and ask what you want to be able to do in the room. Should the house be listed, or stand in a conservation area, we say so early and point you to the right route for consent, which is covered in the sixth chapter below. After the survey a fixed written quote follows, and it holds when the day comes. The survey form is at the quote band, or message us on WhatsApp, 07880 284133.

A bulky white frame reads as a patch on an old roof. A slim one reads as part of the building.

Callout 2

Single, double or slim double: choosing the glazing

The glass is where a conservation rooflight differs most from the roof windows people know. A standard roof window carries a thick sealed unit in a deep frame with a cover flashing around it. A conservation rooflight is built around a narrower profile, so the glazing is thinner and the frame shows less. The trade-off is between the look of the unit, the way it performs as a window, and what the building and the planning officer will accept.

For a house in England, the thermal side is governed by Part L of the Building Regulations. Table 4.2 of Approved Document L gives the limits for existing homes. Where the unit is a roof window, 1.4 W/m²K is the figure to hit, and a Window Energy Rating of B is the alternative test. A rooflight, lanterns included, gets 2.2 W/m²K to work with. Which of the two your unit counts as comes down to the construction and to how the maker classifies it, which we confirm before ordering. The longer discussion of U-values is in the energy efficient rooflights section of the site.

Single glazing

Single glazing gives the slimmest possible profile and is sometimes requested for a listed building where the aim is to match an original cast-iron or steel rooflight as closely as possible. It loses heat quickly, it mists with condensation more readily in a damp room, and it will not meet the Part L limit on its own. Where it is used, it is normally in a listed or sensitive setting and the Building Control position is discussed with the officer, because Part L allows for special consideration where meeting the standard would unacceptably alter the character of a historic building. Single glazing is not the default choice for a bedroom or bathroom.

Double glazing in a slim profile

A slim double-glazed sealed unit is the usual choice for a house. The two panes are set a few millimetres apart in a thin spacer, so the unit is far narrower than a standard roof window pane but holds heat in the room far better than a single sheet. The glass can be toughened on the outside with laminated glass underneath, which is the arrangement that stays in place if the outer pane is struck, and which is commonly specified for rooflights above a bed or a bath. A coating on one pane reduces heat loss and can cut glare. Some people ask for a self-cleaning outer surface, which helps where the slope is awkward to reach.

Opening or fixed

Many conservation rooflights are fixed, which keeps the profile as thin as it can be and means there is no hinge, handle or gasket to age. Where the room needs air, an opening version is available. It is usually top hung or hinged along one edge and propped open on a stay. Opening a rooflight in a bathroom or a kitchen helps clear steam, and a loft room that gets warm in summer benefits from the vent. Electric versions exist too, covered in the section on electric opening rooflights.

Finish and colour

The frame is normally supplied in a dark finish that sits comfortably next to slate or clay, and other colours can be ordered. The colour matters on the outside, where it reads against the roof, and on the inside, where it frames the sky. Some people want a white inner frame to match the ceiling, and some prefer the dark steel look against the plaster. We bring samples to the survey so you can hold them against the real slates and the real wall.

If you are comparing a conservation unit with a standard roof window for the same opening, a longer side-by-side sits on the conservation or standard comparison page. The VELUX range includes models designed for conservation use, and the main VELUX windows page explains the size codes if you are working from an old unit's label.

The glazing choices, laid out plainly

How the usual glazing options compare in an older house.
Glazing	Profile	Heat held	Where it suits
Single glass	Thinnest	Low	Listed, matching original
Slim double	Thin	Good	Most older houses
Laminated inner	Thin	Good	Above beds and baths
Opening slim double	Slightly deeper	Good	Bathroom, kitchen, loft
Fixed slim double	Thinnest double	Good	Landing, stairwell

Callout 3

How the frame meets slates, tiles and timber

A rooflight is only as good as the junction between the frame and the roof. A fine unit in a poor flashing leaks at the first heavy rain, and the stain turns up on the ceiling below long after the work is signed off. On a conservation rooflight the junction has a second job: it has to look right. That means a low kerb, a flashing that follows the roof plane, and a frame that does not stand higher above the slate line than it must.

The kerb and the upstand

Most conservation rooflights sit on a timber kerb built up from the rafters, or fit directly onto a lowered upstand. The aim is a flush look. A kerb that is taller than needed will lift the glass off the roof and show a visible side wall. The roofer sets the unit as low as the slate or tile will allow, which usually means working the flashing into the covering rather than laying a deep apron over it. The result is a thin visible edge of metal where the glass meets the slates, and very little else.

What gets checked at the roof edge

Roof covering: slate, clay tile or concrete tile, and its condition
Rafter spacing: where the trimmers will bear in the loft
Upstand height: the lowest kerb the covering will allow
Flashing: lead or kit, matched to the covering
Ceiling below: lath and plaster or plasterboard, and the splay

On a pitched roof the flashing is normally lead or a lead-substitute, dressed over the slates at the head, the sides and the sill, and worked into the courses so rain cannot run behind it. A steel conservation unit often comes with its own purpose-made flashing kit for the slate or tile type. We use the kit that matches the roof covering you actually have, and we check it on the survey so that the right one is ordered the first time.

Structure under the roof

Cutting an opening in a roof means taking out part of one or more rafters. The load they carried has to go somewhere, so trimmers are fixed across the opening and the cut rafters are supported by them. In an older house the rafters may be at wide or uneven spacing, and the timber may be tired. We look at the roof structure from the loft on the survey, and where the unit needs a bigger opening than the spacing allows, the carpentry is part of the written quote. A new opening alters the structure of the roof, and that is building work. Approval comes through the local authority or a registered building control approver, and the Building Control notification is our job whenever the work calls for it. Everything is fitted to the regulations in force today.

Insulation and the light well

The shaft between the underside of the roof and the ceiling is the light well. It can be a short splay in a loft room or a deeper box where the ceiling sits some way below the rafters. The well should be insulated so that the cold roof does not drop the temperature of the surfaces around the opening, which is where condensation tends to start. It should also be lined and finished, with the plaster angled so that the light spreads outward into the room instead of stopping at a narrow slot. A wider splay at the ceiling edge makes the same rooflight feel larger from below. Our carpenters and plasterers work with a splay angle that suits the spot you have chosen.

Condensation is the usual complaint about a poorly detailed rooflight. If the well is cold, the glazing is single, or the room produces a lot of steam, moisture will form on the inside. A slim double-glazed unit, a warm frame and an insulated well deal with most of it. The advice in stopping condensation on a skylight goes through the causes.

When a rooflight sits in a flat roof

Not every older house has a pitched roof over the part you want to light. Rear extensions, outhouses and lean-tos often have a flat or very low-pitched roof. A conservation-style flat rooflight is fitted with a kerb and upstand that allow for the correct fall, and the same slim look is available. The details differ from the pitched case, so the flat roof rooflights page covers that case. A glazed lantern is another route for a larger space, and the roof lanterns page explains when one makes sense instead of a single unit.

On an old roof, the flashing decides whether the rooflight leaks and whether it looks right.

Callout 4

Fitting into slate, clay and old tile

The roof covering decides how the work is done more than any other single factor. Slate, clay plain tile, pantile and concrete interlocking tile all take a rooflight, but each is cut and flashed differently, and each reacts differently to being disturbed. The first job on any older roof is to see what is there and judge whether it will stand being worked on.

Slate

Natural slate is common on Victorian and Edwardian houses and is the roof that conservation rooflights were designed for. The slates are held with nails or hooks and overlap in courses. To make an opening, the slates around it are lifted, numbered or stacked in order, and the surrounding battens are cut and made good. Good slates are reused where they are sound. Slates that are cracked or laminating are replaced, and the replacement is matched as closely as can be found. A full account of what to expect is in Do Conservation Rooflights Suit Slate Roofs?. The short version is that they do, and that the slim frame lies close to the slate and follows its line.

Clay and concrete tiles

Clay plain tiles are small and numerous, and the opening has to respect the bond so that the courses either side line up. Pantiles and larger interlocking tiles are cut to the frame with flashings that fit the profile. A flashing kit made for a flat slate will not seal against a pantile, so the kit is matched at the survey. Older clay can be brittle, and the roofer takes care when lifting it. Where tiles break, reclaimed or new matching tiles are used.

From survey to a sealed roof

Survey inside and out
We mark the spot, check rafters, covering and ceiling, and photograph the slope.
Fixed written quote
You receive the quote in writing, and the figure holds when work begins.
Strip and frame
Slates are lifted, the opening is cut and the trimmers are fixed.
Set and flash
The rooflight is set low, flashed into the covering and tested for water.
Light well and finish
The shaft is insulated and the plaster is splayed to spread the daylight.

Do not guess the condition

A roof that looks fine from the pavement can be tired from the loft. Nail fixings rust, battens soften, and lead goes dull and thin. Before we agree where the rooflight goes, we look from inside as well as out, and we say so if the surrounding slates or battens are near the end of their life. Replacing a rooflight on a worn roof can reveal faults that have been hidden, so it is cheaper in every sense to know first. We can include any extra work in the same written quote.

Chimneys, valleys and neighbours

A rooflight cannot sit where a valley, hip or chimney stack is in the way, and in a terrace the party wall sets a limit on how close it can go. Flashings need room to turn corners cleanly. The placement of the unit is therefore a three-way balance between the spot below, the roof structure and the roof detail. Sometimes a unit a little to one side serves the spot almost as well and avoids a costly lead detail. We say so when that is the case and let you decide.

The weight of access

Older houses often have a narrow stair or a tight loft hatch. Large steel-framed units can be heavy, and the glass has to be carried in whole. The survey includes the route the unit will take into the house, because a rooflight that cannot reach the roof is no use to anyone. On many terraces, scaffold or a roof ladder is needed to work safely on the slope, and that is part of the plan. For a straightforward single rooflight the time on the roof is normally a day or two.

Callout 5

Conservation unit or ordinary roof window

Not every older roof needs a conservation rooflight. Some are better served by a standard roof window, and some by neither. The decision depends on where the roof can be seen from, how the house is designated, and what you need the window to do. It also depends on whether the rooflight has to open, because the standard ranges have a wider choice of opening styles and accessories.

Where it can be seen

A rooflight on the rear slope of a terrace, behind a parapet or wall and out of sight from the road, will not alter the street scene. A rooflight on a front slope will. In a conservation area, the council pays more attention to what the public can see, so the front is where the slim profile earns its place. At the rear the question is more open. If the house is listed, the position of the roof inside the curtilage and its visibility are secondary to the effect on the historic fabric, and the answer is a matter for listed building consent in either case.

What the unit has to do

A loft bedroom might need an opening that is also a means of escape. This is where a roof window must be chosen with care. Approved Document B only lets a roof window act as an escape route where the storey sits within 4.5 m of the ground. Convert the loft of a two-storey house and the escape is a protected stair instead. Where a roof window can be used, the clear opening must be 0.33 m² or more, with 450 mm minimum across both directions. Many conservation rooflights are fixed or have small openings, so they do not meet that test. If you are converting a loft, our page on roof windows for loft conversions goes through the rules, and the main roof windows section covers the wider range.

Cost is part of it

Conservation units are made in smaller runs from steel and slim glazing, and the fitting takes more care. They usually cost more than a standard roof window of the same opening. The difference comes from the frame, the glass and the detailing. We do not quote prices on the site because each roof is different, but the costs page explains what moves a quote, and the survey gives you the figure in writing before you decide.

Mixing the two

Some houses use both. A conservation rooflight on the front or the visible side, a standard roof window at the back where an escape opening is needed, and a flat rooflight on the extension. Matching the frame colour and the glazing tone across the units keeps the house looking consistent from inside and out. The right mix is a matter for the survey, and we give an honest view of which unit suits each spot.

What a planning officer may ask is covered in the choosing guide. If you are still deciding between a rooflight and something that brings light further into the building, a sun tunnel may be worth a look for a hall or landing with no usable roof slope.

The front slope is where a slim frame earns its place. The back slope is where a standard window may do the job.

Two ways to light the same landing

Conservation rooflight

Slim frame, close to the slates
Suits front slopes and listed roofs
Often fixed or small opening
Made in steel-look finishes
Detailed and fitted with care

Standard roof window

Deeper frame and cover flashing
Suits rear slopes and new roofs
Wide choice of opening styles
Can serve as escape if sized
Broad range of sizes and brands

Callout 6

Listed homes, conservation areas and consent

Before any older roof is cut, the question of consent has to be answered. The answer depends on whether the house is listed, whether it sits in a conservation area, and what the rooflight will look like from outside. None of these steps is complicated, but each has to be done in the right order, and the order is set by the council, not by the installer.

Houses in general

On an ordinary house, a rooflight usually falls under permitted development (Class C), and that route carries conditions of its own. We do not repeat them here. Our planning guide lists them, and the official wording is on the Planning Portal. Householder rights stop short of flats and maisonettes, so a rooflight in a shared or flat-block roof usually needs planning permission. The planning authority for Derby is Derby City Council, and its website at derby.gov.uk explains how to apply or check.

Conservation areas

Inside a conservation area, an Article 4 direction can take permitted development away. That means a rooflight that would normally be allowed may need a planning application. Whether an Article 4 direction covers your street is a question for the council, and we advise you to check before work starts. Derby has conservation areas, and the Derwent Valley Mills World Heritage Site runs along the river through Derby, including Darley Abbey, with Milford, Belper and Cromford further up the same valley. If your house is in or near one of these, ask the council what applies. The page on Derby conservation areas and rooflights goes through the questions to ask and how to find the answers.

Listed buildings

Most alterations to a listed home need consent from the council, and cutting into the roof nearly always counts. The listing covers the whole building, inside and out, and often the historic fabric inside the roof as well. The aim of conservation officers is to keep as much of the original structure and covering as possible. Slim steel units that match the style of the period are the kind that officers tend to look on favourably, but each case is judged on its own facts. For the process and what to put in an application, see Conservation Rooflights in Listed Buildings, and the guidance published by Historic England.

Building Regulations, as a separate matter

Planning and Building Regulations are two systems. Even where no planning is needed, a fresh opening in the roof still needs Building Regulations sign-off, through the local authority or a registered building control approver. A like-for-like swap counts as controlled fitting in Part L, so the replacement unit must match the U-value described earlier, and replacements may be self-certified by a competent person scheme. The Building Control notification is ours to deal with when the work is notifiable.

What we do with the paperwork

We can describe the proposed unit, size and position in a form that fits an application, and provide the manufacturer's drawings. The application itself is yours to submit as the owner, or through an agent you choose. Starting the work before consent is in place can lead to enforcement, and in a listed building it can be a criminal offence, so we wait for the decision. The 10-year workmanship guarantee, in writing, begins at completion and is set out on the guarantee page. To begin, send a survey request through the form and tell us the address and whether the house is listed or sits in a protected area.

Older roofs, slim frames and consent

Is a conservation rooflight the same as a skylight?

A skylight is the homeowner's word for a window in the roof, and a conservation rooflight is one kind of it. The difference is in the build. It has a slim frame and sits close to the roof covering, so it suits slate and clay roofs on older houses. A fuller definition is on the page What Is a Conservation Rooflight?

Can I have one fitted if my house is listed?

Possibly, but you will need listed building consent first, since most changes to a listed building require it. The council decides, with advice from its conservation officer, usually after seeing drawings of the unit and its position. We can supply the manufacturer's details for your application and we wait for the decision before starting. The route is explained in the listed buildings page of this section.

Do conservation rooflights leak more than ordinary ones?

No unit leaks because it is slim. Leaks come from poor flashing, a damaged covering or a badly set kerb. A conservation rooflight with the right flashing kit for your slate or tile, set on a properly framed opening and tested for water, is as dependable as any other. The roof around it matters as much as the unit.

What size should the rooflight be for a landing?

It depends on the stair, the ceiling height and the slope. A landing under a pitched roof usually suits a single unit placed over the half landing, with a splayed light well to carry the daylight down. We mark the spot at the survey, measure the opening, and suggest the size that lights it without glare. A larger unit is not always better.

Will a conservation rooflight meet the heat loss rules?

It can, if it is specified correctly. Part L 2021 draws a line between the two product types in Table 4.2 of Approved Document L. Roof windows are held to a U-value of 1.4 W/m²K, though a Window Energy Rating of B is accepted in its place. A rooflight gets 2.2 W/m²K to work with. Before ordering, we confirm which heading your unit sits under and that it clears the figure.

How long does the work take?

On the roof, a straightforward single rooflight takes a day or two. Any internal finishing, such as plastering the light well, follows after that, and the timing depends on the ceiling and the finish you choose. Where consent is required, the wait for the council comes before any work begins. We agree the sequence with you in the written quote.

Do I need scaffold for a rooflight?

Often, yes. Working on a slate roof from a ladder alone is not safe for a job that involves lifting slates, cutting rafters and setting glass. Whether you need a full scaffold, a tower or a roof ladder depends on the height and the slope, and we confirm it at the survey so it is in the written quote and not a surprise on the day.

Book your free survey

Where do you want the light? Tell us in the form: the worktop, the stair, the desk.

No obligation. We survey before we price.
We cover Derby and 30 miles around.