Rooflight and skylight installation in Shrub End

What hips take away

Usable slope area. The corners of the main slopes are gone, so a wide unit or a run of several units has less room than the roof appears to offer from the ground.

Head height in the loft. A hipped roof loses volume at both ends, and it is exactly the volume where a loft conversion would put the useful floor area. Hipped lofts convert to smaller rooms than gabled ones of the same footprint, which is why hip to gable conversions exist and why they cost what they do.

Structural freedom. The hip rafters at each corner are structural members carrying the corner of the roof, and there is no cutting into them. An opening has to sit clear.

None of that prevents a skylight installation. It means the position is decided by the structure rather than by preference, and a survey is genuinely necessary here rather than a formality.

What hips give back

Orientation choice. A gabled house facing north to south has slopes facing only east and west. A hipped house of the same orientation has some slope facing every direction.

That matters more than people expect. North facing slope gives even, cool, glare free light all day with no solar gain at all, which is the best light in any building for a kitchen work surface, a study or a studio. Specify it for thermal performance alone and spend nothing on solar control. A south or west facing slope wants solar control glass as standard and, on a large unit, thought about shading.

On a hipped roof you frequently have the luxury of choosing, and that is worth using rather than defaulting to whichever slope faces the garden.

Rooflight or dormer

The question that comes up on every Shrub End loft conversion.

A rooflight sits in the plane of the slope, needs no planning permission in most cases, costs a fraction as much, and gives better light per pound because it faces the sky rather than the horizon.

A dormer adds standing headroom and floor area, gives a conventional window and a view out at eye level, and is much more expensive. On a hipped roof it may also require planning permission depending on size and position, where a rooflight generally does not.

The honest answer is usually both, in that order: rooflights for daylight across the room, and a dormer only where floor area with standing height is genuinely needed. A conversion lit entirely by dormers is an expensive way to get a dark room.

Coverings

Clay plain tiles on the older interwar properties, concrete interlocking tiles on the post war ones, and a fair number reroofed in the last thirty years in something different again from the original.

The flashing kit follows the covering and it is not interchangeable. Ask any quoting installer which kit is specified for your covering by name, because a universal kit on a profiled tile is where cheap quotations save money and where installations leak.

Old clay plain tiles are brittle and a proportion will break on removal however careful the work. Matching weathered clay is difficult, and the usual answer is to take sound tiles from a hidden slope and put the new ones there.

Access

Generally good. Most Shrub End properties have driveways or front gardens with space for a tower, and semi detached layouts usually allow side access to the rear. Two storey rear slope work will normally need scaffold, but it can stand on private land, which avoids the licence and the cost that comes with pavement scaffold elsewhere in Colchester.

Telling them apart

It takes a minute and it saves a visit.

Condensation shows up on cold mornings, is worst in the depths of winter, forms evenly across the inner face of the glass, and bears no relation to whether it has rained. It clears as the day warms up.

A leak follows rain, and usually follows a particular kind of rain, driven from one direction. It arrives at one point rather than spread evenly. It leaves a mark that is still there when everything has dried.

Misting inside the sealed unit is neither. If the moisture is between the two panes and cannot be wiped off either face, the perimeter seal has failed. That is a unit at the end of its life rather than an installation problem, and it happens at fifteen to twenty five years.

There is one case where water on the inside genuinely does mean a fault. If it is forming on the reveal, the plastered surround, rather than on the glass, the usual cause is a missing insulation collar. The collar closes the gap between frame and structure, and without it the reveal is cold enough to condense. It is a separate order line on any quotation, it is the first thing dropped from a cheap one, and the symptom appears months later.

Ventilation is the actual fix

Where condensation is the diagnosis, no amount of work on the window solves it. What solves it is moving air.

An opening at the highest point of a room lets warm moist air leave, and as it goes it pulls drier air in through anything open lower down. That is stack ventilation and it clears a room in minutes where a wall window alone takes hours. It only works if something at low level is open too: a rooflight on its own in a sealed room moves very little.

In a hipped roof house the rooflight is often high and awkward to reach, which is the practical case for a motorised opener with a rain sensor. A window that closes itself when it starts raining is a window that actually gets left open. Where running mains cable through a finished ceiling would mean lifting floors and chasing walls, a solar powered opener needs no connection at all and goes in within a couple of hours.

Choosing the glass

Two numbers get quoted and they describe the same product differently, which is where quotation comparison goes wrong.

Centre pane U-value measures the glass away from the edges and ignores the spacer and frame, which is exactly where heat escapes. It is always the better figure and it is what marketing quotes.

Whole unit includes glass, spacer and frame weighted by area. It is what the building experiences and what Building Regulations use. It is always worse, frequently by 0.4 or more.

A rooflight advertised at 1.0 and another at 1.4 may well be identical performance described two ways. Ask both installers for whole unit figures or you are comparing nothing.

Beyond that, specify by orientation. Solar control on south and west facing slopes, nothing extra on north, and a warm edge spacer throughout, because an aluminium spacer shows as a band of condensation around the edge of the glass on cold mornings and gets mistaken for a failed unit.