Slate and tile roofs over Thorpe Hesley homes, with skylights and rooflights to suit

What stays the same

Permitted development for a rooflight on a house is set by national law, so the same limits on projection, height and side windows apply here as in Leeds or anywhere else in England. The conditions are laid out in our planning guide for skylights and rooflights.

Local checks on the address

• Whether the house is on the statutory list; if it is, consent is required for any new rooflight.
• Whether the street sits in a conservation area, since an Article 4 direction there would take permitted development away.
• Whether the property is a house or a flat. A flat is treated differently from a house, and permission for roof alterations is usually needed, so Rotherham Council is the one to ask.

Houses in a row

Where a stone row has been divided or has shared roof structures, we look at whose roof the rooflight would go in and whether a neighbour's consent or a party wall notice may be involved. That is a legal matter between neighbours, and we flag it early so you can raise it.

Why the council matters to timing

If an application is needed, it goes in first. The quote is written once the position is clear, so what is fixed in writing matches what the council has seen.

Slate

Slate is thin and lies flat, which suits a flat flashing kit that steps under the courses along each side. Old slate can be brittle and the nails behind it may have rusted, so slates are lifted by hand and any that break are matched to the rest. They are cut to run over the flashing on the upper side.

Concrete tile

A concrete tile has a profile with ridges and valleys that a flat kit cannot follow, so the kit is made to match the profile and the tiles are relaid to fit the frame. They are heavier than slate and interlock, and a tile must go back in the course it came from.

Roofs that have been re-covered

A roof re-covered at some point in tile can sit on much older timbers. The rafters underneath are then old and the covering is newer, and we note both, because the frame is bolted to the timber and flashed into the covering.

Finding out which you have

From the road, slate looks smooth and fine-grained, and concrete tile shows regular ridges and a rougher face. In the loft, the underside of the covering shows which you have. We photograph the covering on the survey so the kit is ordered for the roof you actually have.

Estate houses and the loft

Newer estate roofs may be built with trussed rafters, which are lighter timbers in a triangle and cannot be cut like a traditional rafter. Where a truss is in the way, the opening may need to be placed between two, or the engineer's advice taken first. Because trusses carry the roof between the walls as a set, the engineer's advice comes before any are cut. The loft shows which kind of roof you have.

What the builder needs from us

The builder needs the position, the opening size and the height of the kerb. Makers differ on whether a listed size is measured inside or outside the kerb, so we give the builder dimensions that already allow for that. We can work from the plans at this stage and visit the site to confirm.

Joists and openings

Joists run one way across the roof, and an opening that fits between two needs only a short trimmer at each end. An opening that crosses a joist needs the load carried round it, which is more work. If the joists are not yet ordered, they can be set at the spacing the unit prefers. Tell us which covering the builder plans to use as well, because felt, EPDM rubber and GRP fibreglass each take their own upstand and weathering detail where they meet the kerb.

Which glazed roof suits the extension

An extension off a stone row has the old house wall at one end and the garden at the other, and the part of the floor in between lacks light. A roof lantern spreads light along that stretch, and a flat rooflight lights a smaller spot from a lower profile. How the size is worked out from the room is shown in roof lantern sizes.

The roof covering

Felt, EPDM rubber and GRP fibreglass are the usual flat roof coverings, and each of them wants its own upstand and weathering detail where it meets the kerb. We ask which one the roofer is using, so the detail at the kerb matches the rest of the roof. The thickness of the insulation and covering above the deck sets how high the kerb must stand, so the builder needs the build-up of the roof before the kerb is set out.

If the extension is already built

A roof that is already covered can still take a unit. The deck is cut open, the joists around the opening are trimmed, and a kerb is built up on the deck. It is more disruptive than doing it at the build stage, and the insulation and covering have to be remade round the new kerb, but it is routine work for a flat roof.

Planning in the extension's own permission

A lantern usually projects further than the permitted development class for roof alterations allows. Ask the council, or confirm that the extension's own permission covers it, while the roof is still being designed.