Roof Lantern Installation
Flat-roof glazing sized to the room and detailed into the kerb below it.
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Chelmsford localities
Rooflight installation in Chelmer Village
Late twentieth-century estate, trussed roofs. What that means for getting glass into a roof here is the whole of this page.
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In Chelmer Village
What we install on Chelmer Village roofs
Flat Roof Rooflight Installation
Flush and kerb-mounted units into single-ply, felt and GRP flat roofs.
View this service →Roof Window Installation
Roof windows trimmed into slate, clay and concrete tile without proud flashing.
View this service →VELUX Window Installation
We install VELUX alongside Fakro, Keylite and Roto roof windows.
View this service →Electric and Opening Rooflights
Actuated opening units, rain sensors and controls, wired and commissioned.
View this service →Energy Efficient Rooflights
Specified on U-value and g-value, not on the brochure photograph.
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The local detail
16 things worth knowing about Chelmer Village roofs
Chelmer Village went up as one planned estate on the east side of Chelmsford, mostly between the late nineteen seventies and the end of the nineteen eighties. That matters more than the postcode, because an estate built inside a single decade to a small number of house types has a small number of roofs, and those roofs behave in a predictable way once you know what is holding them up.
Almost every enquiry from Chelmer Village Way, Baddow Hall Avenue, Wickfield Ash or the closes off Waterhouse Lane runs into the same structural fact within ten minutes of a survey. The roof is trussed. What follows sets out what that means for the size, position and type of rooflight that is actually available, and what the rest of the estate’s construction adds on top.
- 01 What is holding up a Chelmer Village roof
- 02 Fink trusses, and the clear width they leave
- 03 Deep profile tiles and the flashing kit they need
- 04 Integral garages and the room they become
- 05 Rear extensions on an estate plot
- 06 Low thirties pitch, and what it gives you
- 07 Loft conversions above a trussed roof
- 08 Daylight for a landing with no window
- 09 Bathroom rooflights and the extract in the void
- 10 Orientation on a curved estate layout
- 11 Hips, valleys and the planes that stay clear
- 12 Access, driveways and where a tower stands
- 13 Permitted development on a nineteen eighties estate
- 14 Building Control, and who files it
- 15 The original units, thirty five years on
- 16 Working out a number for a Chelmer Village house
What is holding up a Chelmer Village roof
Lift a loft hatch anywhere on the estate and you will see prefabricated trussed rafters, almost always the W-shaped Fink pattern, sitting at six hundred millimetre centres. There is no ridge beam doing structural work, no purlins running through, and no boarding under the tiles. The covering is a concrete interlocking tile with a deep barrel or bold roll profile, laid over a bitumen felt underlay in the earlier phases and a breather membrane in the last of them. Pitches sit in the low thirties. Every one of those facts narrows the job before a product is discussed, which is why a photograph of the loft is as useful to us as a photograph of the roof.
Fink trusses, and the clear width they leave
A truss is not a rafter. The diagonal webs and the bottom chord are carrying load in tension and compression as a designed system, and removing one member changes how the whole component behaves. Cutting is possible where a structural engineer designs a trimming solution with a supporting beam, and on some jobs that is the right call. Where it is not, the opening has to live between two trusses. At six hundred centres that leaves a clear width of roughly five hundred and fifty millimetres, which lines up with the narrowest standard roof window codes. Two narrow units set a metre apart give more usable daylight than one wide unit anyway, because two shafts of light reach further across a ceiling than one.
Two narrow roof windows between trusses will nearly always beat one wide one that needed a steel to exist.
Deep profile tiles and the flashing kit they need
The concrete interlocking tiles used across the estate have a pronounced profile, with a barrel or roll standing proud of the trough beside it. A flashing kit designed for a plain tile or a slate bridges those troughs instead of following them, and the gap it leaves is where wind driven rain gets underneath. The correct kit for this covering has a deeper corrugated apron that presses down into the profile and soakers sized for the tile gauge. Matching a discontinued eighties tile is its own exercise, so the sensible approach is to lift and set aside more tiles than the opening strictly needs, then re-lay the sound ones around the new unit and keep the surplus in the garage.
Integral garages and the room they become
A lot of the house types here have a garage tucked under the main roof or in a link between two houses. Converted, it becomes a room with one window in a front elevation facing a driveway, which is neither private nor bright. Daylight from above solves both problems at once. Where the garage sits under the main slope, a roof window between trusses in the rear or side plane works. Where the ceiling is boxed below a shallow void, a sun tunnel carries daylight down through the void without needing a straight run. The conversion is notifiable work in its own right, so the rooflight simply joins a Building Control application that already exists.
Rear extensions on an estate plot
Plots on the estate are efficient rather than generous, and the common rear addition is three to four metres deep across most of the back elevation with a flat roof over it. That geometry suits a flush flat rooflight better than a lantern in many cases, because a raised structure on a shallow footprint reads as a lid rather than as height. Where the addition runs the full width and reaches four metres or more, a lantern earns its place. The decision is made from the room proportions and the ceiling height, not from a brochure. A kitchen with a two point four metre ceiling and a three metre depth wants glass in the plane, not above it.
Low thirties pitch, and what it gives you
Thirty to thirty five degrees is comfortable territory. It clears the fifteen degree minimum that most roof windows require by a wide margin, so the weathering is never the constraint. What the pitch does affect is the reveal. On a pitched slope the internal lining runs at an angle, and squaring the head and splaying the sill turns the opening from a slot into a spread of light across the ceiling. That detail costs a little plastering and nothing in glass. It is the cheapest improvement available on any pitched roof job, and on an estate house with a modest ceiling height it makes the difference between a bright room and a lit rectangle on the carpet.
Loft conversions above a trussed roof
Converting a Fink trussed loft is not a rooflight job with a conversion attached. It is a structural rebuild of the roof: steels or engineered beams take the load, the webs come out afterwards, and new floor joists span between supports. Rooflights are specified as part of that design, and because the trusses are gone by then the width constraint goes with them. The useful sequence is to settle the glass at design stage rather than at second fix, since the structural engineer needs to know where the openings fall before the beams are sized. A conversion designed around two well placed roof windows is a better room than one where the glass was slotted in afterwards.
Daylight for a landing with no window
Several house types on the estate have an internal landing lit only by borrowed light from the bedrooms. There is no roofline directly above it in the sense of an accessible slope, but there is a roof void, and a sun tunnel is designed for exactly this. A rigid tunnel of highly reflective tube carries daylight from a dome or flat collector on the slope down to a diffuser in the ceiling. Rigid runs deliver more light than flexible ones, and shorter runs deliver more than long. On a two storey house with a shallow void, the run is short and the result is a landing that no longer needs the light switch during the day.
Bathroom rooflights and the extract in the void
Fitting a rooflight over a bath or a shower cubicle brings two things forward. The first is glass specification, since a cold inner pane above a steam source will run with surface condensation every winter morning. The second is the extract fan, and on estate housing of this age the duct very often terminates in the loft void rather than at a tile vent or a soffit. Warm wet air discharged into a cold void condenses on the underside of the felt and drips onto the insulation, producing a wet mark on a bedroom ceiling that gets blamed on the new rooflight. Insulated ducting run to a proper terminal fixes it, and the loft is already open.
Orientation on a curved estate layout
Estate roads here curve, so two houses of the same type three doors apart can have rear slopes facing quite different directions. That single input changes the glass specification. A rear plane facing north or east takes a neutral double glazed unit and can be generous in area. A rear plane facing south west collects late afternoon sun in July at a high angle, and without solar control glass the room below will be uncomfortable by three o’clock. Checking the bearing takes thirty seconds with a phone compass in the garden, and it belongs in the first email rather than at the survey. Glazing performance is where that decision gets settled.
Hips, valleys and the planes that stay clear
Link detached and staggered terrace types on the estate carry hips over the link and valleys where a projecting gable meets the main slope. Both are places where water is already concentrated and where the covering is already doing complicated work. A unit set too close to a valley gutter puts its side flashing into the wettest line on the roof, and a unit set too near a hip runs out of full tiles to dress into. The workable rule is to keep a clear run of at least three hundred millimetres of undisturbed covering to any hip, valley or abutment, measured from the outside of the flashing rather than from the frame.
Access, driveways and where a tower stands
Estate roads are narrow and parked on both sides for most of the day, and driveways are frequently tandem with a car at each end. None of this stops the work, but it decides the method. A single roof window in a rear slope reached across a back garden is usually a tower and a roof ladder. A run of units, or anything on a front elevation over a pavement, is a scaffold, and a scaffold needs somewhere to land and a route to carry it in. That gets settled at survey rather than on the morning, and it is one of the reasons the second figure differs from the first.
Permitted development on a nineteen eighties estate
For most houses on the estate, rooflights are permitted development. The conditions are specific: the unit must sit no more than one hundred and fifty millimetres proud of the existing roof plane, and it must not rise above the highest part of the roof. Two things complicate it locally. Planning conditions attached to the original estate consent sometimes removed permitted development rights for particular phases or elevations, and a house that has already used its allowance on an extension may have less headroom than the owner assumes. A check against the planning history for the address takes minutes and happens before anything is ordered. The wider area coverage page sets out how the same check runs elsewhere.
Building Control, and who files it
A new rooflight or a replacement in an existing dwelling is notifiable work in England. It engages Part L for thermal performance, Part K where there is a fall risk, and Part B where the unit serves as means of escape from a habitable room in a roof. Sunspire handles the notification as part of the job. On an estate where houses change hands regularly that is worth more than it sounds, because an unnotified alteration surfaces years later when a buyer’s solicitor asks for a completion certificate and finds nothing on file. The certificate goes in the same folder as the ten year workmanship guarantee.
The original units, thirty five years on
A number of houses on the estate still carry their first generation of roof glazing: a domed polycarbonate unit over a bathroom or a garage, or an early timber roof window with a lacquered internal face. Sealed units have a working life of twenty to twenty five years and polycarbonate domes go milky and brittle well before that. The signs are consistent: misting between the panes, a chalky frame, or daylight visible at the edge of the internal lining. Replacing into the existing opening is frequently a single day, and it is the right moment to upgrade the glass, since the labour and the access are already committed.
Working out a number for a Chelmer Village house
Two figures, in this order. A range by email once we know the room, the roof plane and roughly what you want, and a fixed written price after a survey. The survey is where the trusses get measured, the covering gets identified, the extract duct gets found and the access gets settled. Neighbouring enquiries in Springfield and Great Baddow run the same way, since the estate housing on both sides of the Chelmer shares its construction. Whatever the forecast is doing, the roof is closed and watertight at the end of every working day, and the workmanship carries a ten year guarantee.
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We start with the building, the covering and the slope. Then we tell you what will suit it, and what it will cost, as a fixed written number.
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- Building Control notification handled
- New installations and replacements