Skylights and rooflights for steep-sided valley terraces in Todmorden

Reading the shade from the roof

On a valley house the shade changes with the season and the hour. The low winter sun can be blocked by the hill for a good while, while in summer it climbs over. We stand on the roof, or look from the loft, and see which part of the slope is overshadowed and which has a clear line up to the sky.

Where on the slope the unit sits

The upper part of a slope generally sees more sky than the part near the eaves, because it has less of the hill in the way. A unit set higher up the slope, over the room it lights, gives the most. The ceiling position below it may differ a little from the roof position above, so the well between them is angled.

The surfaces inside

A white or pale lining to the light well sends daylight down toward the floor, where a dark lining would soak it up. The splay at the bottom spreads the light, and the colour of the ceiling around the opening helps too. The room itself reads lighter without any extra lamp.

Cold glass and condensation in a valley house

Before the glazing is chosen we look at how the room is used, because a kitchen, a bathroom and a bedroom each make a different amount of moisture.

A damp, shaded house loses heat to the outside quickly. Glazing with extra panes, a gas fill and a frame that has a break in its metal keeps the inner surface warmer, which is the surface that collects moisture first. The result is a unit that clouds less and loses less warmth than an old single pane.

Our written quote is set at a fixed figure and names the room being lit, the unit and its size.

Staying on your own section

The unit is placed on the part of the slope that belongs to your house, away from the party wall line. The party wall rises between the rafters at the boundary, and the new frame needs clear timber on both sides. We check where it runs from the loft before marking the slates.

Chimney stacks and valleys

A stack on the ridge throws a rain shadow of soot and water onto the slates below it, and a unit placed right underneath is badly sited. We choose a position to the side, with enough roof around it that the flashing can be laid properly. The stack also limits the width of frame that will fit.

Slate and stone slate

The covering on older terraces is slate or heavier stone slate, and the two take different flashings. Slate lies flat and thin, and a kit for it is cut close to the courses. Stone slate is thicker and uneven, so lead is dressed to the surface. We lift the slates by hand and set the sound ones aside to be relaid.

Steep streets and access

Where the street climbs, the front of a terrace may be a storey higher than the back, and getting up to the roof needs planning. We put ladders and any platform on the side that stands firm, and the slates and the unit are lifted rather than carried across the roof.

A word about neighbours

Terrace roofs have neighbours on both sides, and courtesy goes a long way. Let the people next door know that scaffolding or ladders will be up for a day or two.

Work that reaches a shared wall can fall under the Party Wall etc. Act 1996, and a letter to the neighbour may be needed. A roof window that stays on your own section of the slope usually does not reach the wall, but we talk through the position before work starts.

Plaster and paint after the cut

An old terrace ceiling may be lath and plaster. We cut the line, support the ceiling, form the well and plaster the reveal, then leave the room ready for paint. The landing or bedroom below is covered first, and the floors are cleaned afterwards.

Signs that a roof window is finished

• Fog or droplets between the two panes of glass.
• A damp stain on the sloping ceiling beside the frame.
• A timber frame that is soft or stained along the lower edge.
• A hinge or catch that no longer closes the sash against the seal.

Old hole, modern unit

If the old opening is a standard size, the replacement is chosen to match, and the trimmers and rafters stay where they are. The old frame comes out, the slates beside it are lifted, a new flashing goes in and the slates are relaid to it. Because the opening is the same, the inside is barely touched, and only the reveal needs a new coat of paint. The plaster around the frame is checked for damp, and any soft area is cut back before the new frame goes in.

A different size, if you want one

Sometimes the old window is smaller than the room could use. A larger opening needs new trimming in the roof, so it is a bigger job and brings in the structure rules. It can be a good time to make the change, because the roof is open anyway.

Calderdale Council and the planning side

For a house in Calderdale the planning conditions that apply to a new rooflight apply to the replacement, and the skylight planning guide lays them out, and where the work touches the rafters we notify Building Control as well. Listing can call for consent even where the change is like for like, and a conservation area may add limits of its own.

What a newer unit does better

Today's roof windows are built to a tighter heat-loss standard than the ones put in a generation ago. The glazing is better sealed, the frame is tighter and the flashing kit is designed for the covering. The top-hung style swings out from its head and clears the sill, while the centre-pivot style turns on a middle axis and fits a spot above a bed.