Roof Lantern Installation
Flat-roof glazing sized to the room and detailed into the kerb below it.
View this service →Affluent commuter town, large detached. What that means for getting glass into a roof here is the whole of this page.
Flat-roof glazing sized to the room and detailed into the kerb below it.
View this service →Flush and kerb-mounted units into single-ply, felt and GRP flat roofs.
View this service →Roof windows trimmed into slate, clay and concrete tile without proud flashing.
View this service →We install VELUX alongside Fakro, Keylite and Roto roof windows.
View this service →Actuated opening units, rain sensors and controls, wired and commissioned.
View this service →Specified on U-value and g-value, not on the brochure photograph.
View this service →Brentwood roofs are bigger than average and more complicated than they look. The town grew from a medieval road junction into a school town and then, once the railway arrived, into a place where London money bought space. What that left is a stock of large detached houses on wooded plots, a tight protected core around the High Street, and a wide Green Belt ring of villages where a roof alteration is a planning question before it is a building one.
Sunspire installs rooflights across Brentwood, Warley, Pilgrims Hatch, Hartswood and the villages south of the town. This page is about the specific things a Brentwood roof asks for that a smaller house does not.
On a modest semi there is one sensible place for a rooflight and the conversation is short. On a five bedroom detached house at Hartswood or off Ingrave Road there are frequently six or seven distinct roof planes, and three of them could take glass.
So the survey starts by choosing between them rather than by measuring one. The criteria are the room underneath, the compass bearing, whether the plane is visible from the road, and what is holding it up. A plane that is perfect on the first three and sits over a structural spine wall on the fourth is not the answer. Working through that properly at the start saves a change of mind after the scaffold is up.
Brentwood’s conservation area covers the High Street, the ruins of the chapel of St Thomas, and the older fabric around the school. Several buildings within it are listed in their own right, and the frontages that face the street are watched closely.
Inside that boundary a unit cut into a visible slope has to read as though it could plausibly have been there for a century, which in practice means a conservation rooflight with a slim cast frame, a central glazing bar and a flush setting in the plane of the tiles. Rear slopes out of public view are usually treated more leniently. On a listed building, listed building consent runs separately from planning and is required for alterations affecting character.
Warley carries a distinct roofscape: nineteenth century military and institutional buildings, the terraces and villas built to serve them, and then a large amount of later housing on the ground the army released.
The older Warley fabric is Welsh slate on a steep pitch, which takes a low profile flashing kit dressed tight and rewards careful handling because slate is thin, brittle at the nail hole and easily broken by walking on it. The later housing is concrete tile at a shallower angle and behaves like any postwar roof. Within one street those two conditions can sit side by side, so the kit is chosen from the covering on the actual house.
The large Brentwood houses were rarely built as a single rectangle. A rear wing, a service range, a later garage wing, and each junction produces a valley where two slopes meet and water is concentrated.
A valley carries the run-off from both planes, so it is the busiest water route on the roof and the least forgiving place to put anything. A rooflight is kept clear of a valley by a comfortable margin, ideally a full tile course plus the flashing side upstand, so that the side flashing is never asked to work against water arriving from an adjacent slope. On a roof with several valleys, that constraint alone can decide which plane the glass goes into.
Most of Brentwood borough outside the built-up area is Green Belt, and the villages south and east of the town sit inside it. That does not stop roof glazing, but it changes the paperwork on any project that involves a new roof to put it in.
Where an extension needs planning permission because permitted development rights are limited or already used up, the roof design becomes part of that application rather than a later detail. Sizing and positioning the glazing before the drawings are submitted avoids a variation afterwards. Where the glazing goes into an existing roof rather than a new one, the usual permitted development rules apply and the question is much simpler.
The town sits between Weald Country Park and Thorndon, and mature trees are part of what people pay for here. Tree preservation orders are widespread and blanket orders cover parts of several roads.
Two consequences follow. A scaffold cannot be erected through a protected canopy and material cannot be craned over one without agreement, so the access plan is drawn early on wooded plots. And a slope in permanent shade under a large oak gains much less from a small rooflight than the same unit on open ground. Where the canopy dominates, the sensible move is a larger opening with neutral glass rather than a small one with heavy solar control.
The bigger detached stock carries better materials than the estate housing, and better materials take more careful handling.
Brentwood plots often slope, and a sloping plot invites a lower ground floor with a terrace above it. Where that terrace is the only roof over habitable space, the only way to light the space below is through the surface people stand on.
A walk-on rooflight is heavier than it looks. The glass is several laminated layers with a slip resistant top surface, the frame carries a point load as well as a distributed one, and the structure below is designed rather than assumed. It is one of the few places where the glass is genuinely the expensive half of the job, and it is very quiet from above and quite dramatic from beneath.
Below roughly a metre and a half, timber trimming carries the opening: doubled rafters either side, trimmers above and below.
Beyond that, and particularly where the opening runs across the span rather than with it, the load has to be taken somewhere and a steel is the usual destination. That changes the shape of the project rather than blocking it. A steel brings a structural calculation, a longer lead time, a heavier lift and a different Building Control conversation. Finding out about it at design stage is routine. Finding out after a finish has been chosen is not.
The specification that Brentwood clients most often arrive asking for is a flush unit with no visible frame from outside, sitting almost level with the roof surface.
Those units are achievable and they are unforgiving of a poor kerb. With little or no upstand of frame above the glass line, every millimetre of weather protection comes from the timber kerb underneath and the way the covering is dressed up it. The industry figure of 150mm from finished surface to the top of the kerb applies with more force here, not less, and the fall around the unit has to take water away rather than let it linger against the glass edge.
A number of Brentwood properties carry glazed garden rooms, pool enclosures or heavily glazed rear additions, and those spaces run at a much higher humidity than the rest of the house.
Warm moist air rises, meets the coldest surface it can find, and condenses there. In a room like that the rooflight is usually that surface. The answers are a better thermal specification so the inner pane runs warmer, and mechanical ventilation that removes the moisture rather than relying on an opening unit alone. Specifying glass for a pool room the way you would for a bedroom produces water running down the reveal every winter evening.
Several of the better Brentwood roads are private and unadopted, maintained by the residents or by a management company. Some have width restrictions, some have soft verges and none of them welcome a heavy delivery in February.
That affects logistics rather than design, but it affects the price. Where a lorry cannot reach the house, materials transfer to a smaller vehicle and waste leaves the same way. Where a management company controls the road, notice is given before a scaffold goes up. Both are established at survey and priced then rather than discovered on the first morning.
Orientation drives the glazing choice, and on a treed plot the effective orientation is not always the compass one, because a mature canopy on the south side behaves like permanent shade.
| Plane faces | What actually arrives | Glazing call |
|---|---|---|
| North, open | Steady cool light all day | Neutral glass, generous area |
| South, open | Strong overhead gain in summer | Solar control, area disciplined |
| South, under canopy | Dappled and much reduced | Neutral glass, larger opening |
| West | Low hot sun from four o’clock | Solar control plus shading |
A big lantern or a wide flush unit gathers a lot of rain, and above a quiet sitting room the drumming is noticeable. It is generally described as pleasant in the first winter and less so by the third.
Laminated glass in the outer pane damps it, because the interlayer absorbs vibration a single thickness transmits. An asymmetric unit, where the two panes differ in thickness, breaks up the resonance instead of reinforcing it. Both are ordered with the unit and neither is retrofittable, so the decision belongs at specification rather than at handover.
Blinds for roof glazing run in side channels within the frame, because a hanging blind on a sloped or horizontal surface simply sags away from the glass.
Those channels are part of the unit. Retrofitting proper integrated shading to a lantern that was not ordered with the provision means an external cassette or a compromise, so a large south facing lantern is specified with its shading from the outset. Electric operation is worth taking on anything out of reach, and the wiring for it is trivial at first fix, as covered on the electric rooflight page.
Installing a new rooflight or replacing an existing one is notifiable work under Building Regulations in England. Part L covers thermal performance, Part K applies where there is a risk of falling, and Part B applies where a unit serves as a means of escape.
Sunspire handles the notification as part of the job. Planning permission is a separate question, and for most Brentwood houses rooflights fall under permitted development provided the unit projects no more than 150mm beyond the existing roof plane. Those rights are commonly restricted in the conservation area, removed on some Green Belt sites by condition, and limited by covenant on several of the private estates.
On a large house the useful first message is a photograph of each candidate roof plane rather than one of the house, plus the room dimensions and a note of which way the rear faces. That is enough for a range by email.
The survey then fixes the plane, the structure, the covering and the access, and turns the range into a written figure. Brentwood sits with Shenfield and Hutton on the areas we cover page, and the costs guide sets out what moves a number between those two stages.
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.
Fill in what you can. It opens WhatsApp with the message ready to send.