Conservation rooflights in Newport

The phrase has no fixed legal meaning, so it helps to say what we mean by it. Here, a conservation rooflight is a rooflight or roof window chosen and set to sit quietly in an older roof: low in the slope, slim in outline and finished to suit the covering around it. The aim is that the roof still reads as the roof, with a clear pane in it, and nobody on the road looks up at a bulge or a bright frame. Our what is a conservation rooflight answer takes the idea slowly, for anyone meeting the term for the first time.

The Welsh Building Regulations guidance draws a line that is worth knowing. Approved Document L (Wales) defines a roof window as a window installed in the same orientation as, and in plane with, the surrounding roof. A rooflight, in its terms, is a glazed unit installed out of plane with the roof, on a kerb or upstand. A unit sold for a heritage roof can sit in the plane of the slope, and which category a particular product falls into is checked against the guidance at survey, because the energy figure that applies depends on it.

Planning draws a second line, about projection and height, and the rule for each is in the planning chapter below. A firm exception applies: on article 1(5) land or within a World Heritage Site that permitted development route is closed for a rooflight going into a slope, as the planning chapter below sets out.

Sizes come next. Heritage roofs often carry modest openings, and a small, well-placed pane can light a landing or a bathroom well. Where a VELUX window is already in the roof and is being replaced, VELUX publishes a width and height for each size code, and the code is on a metal type sign at the top of the sash, which you can see once the window is opened. VELUX windows made after 1968 all have one. Our VELUX size codes explained shows how to read it.

By early afternoon the glass question usually takes over. Welsh guidance sets a different heat-loss figure for each kind of unit, quoted as a U-value, where a lower number means less heat escapes. Approved Document L (Wales) says a new or replacement roof window in an existing home should have a U-value no worse than 1.4 W/m²K, or a Window Energy Rating of band B. For a rooflight, the same guidance says it should have a U-value no worse than 2.2 W/m²K. These are guidance figures, written as "should", and they apply to different products, so each is stated as its own rule.

Measurement matters too. A rooflight's figure is worked out over its entire developed surface, an area often larger than the hole it covers, and a kerb supplied as part of one assembly with the rooflight falls under the same 2.2 limit.

Older houses get one more provision. Where a replacement window or roof window on a home of architectural or historic interest cannot reach 1.4, the fallback is a U-value of 1.2 W/m²K measured at the centre of the pane, or low-e secondary glazing. That fallback is for replacement windows and roof windows only. There is no such fallback for rooflights, and it never applies to a brand-new opening.

The glass itself has options. On its conservation roof window VELUX offers a coating that eases cleaning, laminated safety glass on the inner pane so that an accidental break does not drop glass into the room, and a rain noise reduction option. Availability differs between windows and glazing variants, so we settle the specification after the survey, with the maker's sheet beside us. For anyone sleeping under the slope, rain noise is worth raising, and laminated glass is a sensible point to weigh over a bed or a staircase.

Evening is when the paperwork gets read. Wales runs householder rules of its own. Two approvals are in play, planning consent and Building Regulations, and a conservation rooflight can raise both. Planning is where heritage roofs differ most from ordinary ones.

Under Class C of the Welsh householder rules, an alteration to a roof can be permitted development within limits: no more than 15 cm (150 mm) beyond the plane of the original roof slope, and no part higher than the highest part of the original roof. That route is closed on certain land. Welsh law then removes the route altogether for a house on article 1(5) land. That land includes conservation areas, National Parks such as Bannau Brycheiniog and Areas of Outstanding Natural Beauty such as the Wye Valley, among others, and there a new rooflight in the slope needs a planning application. Inside a World Heritage Site the same result follows, as a category of its own, and Blaenavon's Industrial Landscape is the local example. Being within the boundary is the test.

That gives Newport a real set of cases. Newport City Council publishes its conservation areas and their maps and appraisals, and Caerleon, Stow Park and The Shrubbery are among them. Some Newport conservation areas also carry an Article 4(2) direction, and the council says planning permission is required there for residential properties to remove, renew, alter or add external doors, windows and roofs. Monmouthshire, Torfaen and Blaenau Gwent publish their own lists, for example Monmouthshire's heritage pages and Torfaen's conservation areas.

An Article 4 direction elsewhere can strip these rights, and so can a planning condition set when the house was first approved. Flats and maisonettes do not have householder rights to begin with. Where doubt remains, the planners at the council can say how the rules apply, and for formal certainty there is the Lawful Development Certificate. Official advice starts with the Welsh Government's roof work pages.