Rooflight Installation in Cumnor

The village on the slope

Cumnor sits on rising ground west of Oxford, on the ridge that runs above the Thames towards Boars Hill and Wytham. The old core, around the church and the lanes off it, is stone cottages on the higher ground. Around and below it are later houses and estate development from the twentieth century, arranged along roads that follow the contours.

So most Cumnor properties sit on a plot that falls in at least one direction. Gardens step down. Drives run up. Retaining walls are common. Rear gardens are frequently a metre or more below or above the house, and the useful flat ground is often a terrace rather than the whole plot.

This is pleasant to live in and it is a complication for anybody who needs to put a working platform against the building.

Why access decides the price here

On a level plot, reaching a rear roof slope is straightforward. A mobile tower is wheeled into position on flat ground, levelled with its own adjusters, and the job proceeds.

On sloping ground, a tower may not be usable at all. Towers have limited adjustment in their legs and a strict limit on how far out of level they can be founded, and beyond that the answer is not to improvise but to use something else.

That something else is usually a scaffold, built to suit the ground, with the base levelled by adjustable jacks on sole boards or, where the fall is greater, by stepping the structure. It takes longer to erect, it costs more, and it needs a design where the ground is genuinely awkward.

The result is that two identical rooflight jobs, on two identical houses, can differ substantially in price because one has a flat garden and one has a bank. It is not a mark-up. It is a different amount of work happening before anybody touches the roof.

What a surveyor is looking at outside

Half of a Cumnor survey happens in the garden, and it is worth knowing what is being assessed.

The fall across the area where a platform would stand, and in which direction. The bearing capacity of that ground, since a scaffold concentrates load onto small areas and soft or made-up ground under a leg is how a structure moves. Retaining walls near the base, which are frequently older than the house and were never designed to take a lateral load from a scaffold beside them. Whether there is a route to get materials in at all, and whether that route involves steps.

Also overhead. Cumnor has mature trees and, on some roads, overhead lines. Both impose exclusion distances that are not negotiable.

None of this is exotic and all of it is easier to establish before a quotation than after.

Getting materials to the roof

A rooflight is awkward rather than heavy, and on a sloping site the route it takes matters.

Where a house sits above its road, everything is carried up. Where it sits below, everything is carried down, which is harder rather than easier with something fragile and wind-catching. A large unit through a narrow side passage on a slope is a genuine consideration and occasionally the reason a unit goes up through the roof opening from inside rather than being lifted from outside.

Waste comes back down the same route. Stripped covering, old timber and an old unit all have to leave, and on a stepped site that is hand-carrying rather than a short walk to the van.

Parking, and the twenty-minute problem

Many Cumnor lanes are narrow, with parking on one side and passing places rather than two clear lanes.

Where the van cannot stand near the house, everything takes longer, and the effect is cumulative across a day rather than a single inconvenience. It also affects deliveries: a scaffold lorry needs somewhere to stand while it unloads, and a lane it cannot turn in is a problem to solve in advance rather than on the morning.

If you have a drive we can use, say so at the enquiry stage. If you do not, say that too, because it is better priced in than discovered.

Two building stocks, two different jobs

Access aside, Cumnor has the same split as much of the county’s fringe, and it runs down the hill.

The older core carries stone cottages with steep pitches, hand-cut roofs, irregular rafter spacing and coverings of stone slate or later clay tile. Openings go where the structure allows, the perimeter is hand-worked lead, and the conservation area covers a good deal of it.

The later housing, on the roads spreading out from the centre, is concrete interlocking tile over trusses with felt beneath the battens. It is the simplest roof in the county to fit a rooflight into: a proprietary flashing kit sized for the profile, an opening between two rafters, and a finished job in a day. The trusses are the only real constraint, since their diagonal webs cannot be cut without a designed alteration.

The planning authority for both is Vale of White Horse District Council, not Oxford, which surprises people who consider themselves as living on the edge of the city.

Working at height on a slope

Two things change when the ground falls away, and both are safety matters rather than preferences.

The first is that the height to the eaves on the downhill side can be substantially greater than on the uphill side of the same house. A single-storey rear extension that is a metre off the ground at one end can be three at the other, and the platform, the edge protection and the method have to suit the worst case rather than the average.

The second is that the fall zone below a working area is bigger and often includes a bank, steps or a wall. Exclusion below the work is wider on a slope for the same reason a dropped tool travels further.

This is why we will not simply lean a ladder against a rear elevation on a hillside plot and get on with it, and why the quotation will name the access method rather than leaving it unstated.

The view, which is the reason people are asking

Cumnor’s position is why most of these enquiries exist. From the higher ground the outlook is over the Thames valley towards Oxford and out across the vale, and a rooflight placed with that in mind is a different proposition from one placed only for daylight.

Placing for a view means setting the unit lower in the slope than daylight alone would suggest, so that the bottom of the glass is within the sight line of somebody sitting or standing rather than only somebody looking up. A cill height of around 900mm to 1100mm above the finished floor is the usual target.

The trade is that a lower unit distributes light less evenly into the depth of the room. Where a room can take two units, one set low for the view and one higher for light distribution is a better answer than a single compromise. Where it can only take one, decide honestly which of the two you actually want, because the position cannot be adjusted later.

Exposure on the ridge

The higher parts of the village are more exposed than the sheltered lanes below, and the difference shows in driven rain rather than in wind speed alone.

Practically that means laps at the upper end of the range rather than the minimum, particularly on the west and south-west facing slopes taking the prevailing weather, and lead sized and fixed so it can move without splitting. It is not different work, it is the same work specified with less margin spent.

Access methods, and what each one suits

The method is chosen at survey and named on the quotation. An installer who has not said how they intend to reach your roof has not finished pricing the job.

Programme, and why hillside jobs run longer

A flat-site rooflight is often a single day on site with the access arriving and leaving the same day.

On a sloping plot the shape changes. Scaffolding goes up a day or two before, comes down a day or two after, and both visits need the lane clear and somebody able to let the crew in. So a job that is one day of roof work becomes a week of elapsed time, with three separate visits in it.

That is worth knowing when planning around it. The roof work itself is still one day, the house is still habitable throughout, and the roof is never left open overnight. It is the calendar that stretches, not the disruption.

Weather matters more too. A scaffold already erected means the roof work can take the first settled day available, which is an advantage. But erecting or striking a scaffold on a slope in high wind does not happen, so both ends of the programme carry their own weather dependency.

What we take on here

New rooflights and replacements, in the cottages, the later houses and the converted outbuildings. Conservation-grade units where the designation calls for them and standard units where it does not.

What we do not do is remedial roofing or scaffolding as a separate service. Where a job genuinely needs a designed scaffold, that is arranged and priced as part of the work rather than left as your problem to solve.

What to send with an enquiry

Where in the village the house is and whether it sits above or below the road. What the roof is covered with. Whether the plot is level anywhere useful, and whether there is a drive. Whether the building is in the conservation area, and if you do not know, say so and we will check.

A photograph of the garden side of the house is worth more here than anywhere else we work. On a Cumnor plot, the ground tells us most of what we need to price the job.