Can you replace a rooflight without scaffolding?

Two lifts instead of one, and the awkward one goes downwards

This is the difference nobody thinks about until the day. On a new opening, material travels up: a unit, a flashing kit, timber, some tiles. On a replacement it travels both ways. The old unit comes out whole if it can, in pieces if the frame has swollen into the opening, and it has to be got down without dropping it and without walking backwards down a ladder holding it.

An old glazed unit is heavy and it is an unhelpful shape. A one metre by one and a half metre double glazed sash with a timber frame around it is a genuine two person lift, and it will not be lifted from a tower platform with the same margin it would be lifted from a boarded scaffold lift with a handrail behind you. That single consideration decides the platform on a large number of jobs.

Why a straight swap is a shorter job at height

The reason a tower is on the table at all for a replacement is duration. A new opening involves stripping the covering, cutting rafters, fixing doubled trimmers, forming and squaring the opening, then setting the unit. A like-for-like swap uses the structural opening that is already there. The covering comes back, the old flashings come off, the old unit lifts out, the timber is checked, the underlay is renewed locally and dressed properly around the new frame, the new unit goes in and the new flashing kit ties the covering back.

On a straightforward slope that is a single day outside rather than two, and on a low roof one day is exactly the sort of duration a properly erected tower handles. The moment the work runs into a second or third day, because courses are being taken back, because the kerb is being rebuilt or because timber has been found soft, a scaffold that stands for the duration becomes the only workable answer.

Flat roofs, where the question is edge protection rather than height

Most rooflight replacements in this county happen on flat roofs, and a flat roof changes the question. The crew are not standing on a slope, they are standing on a deck, and what matters is the unprotected edge around them rather than how they got up.

A single storey flat roof over a kitchen extension is usually reached with a tower or a well footed ladder, but the working area still needs an edge, and that means a temporary handrail system or a scaffold with a boarded lift and guardrail running along the open sides. Where the flat roof is enclosed on three sides by the house and a boundary wall, only one run of edge protection is needed and the job becomes simple. Where it is a freestanding garage roof open on all four sides, the protection costs more than the tower saved. This is settled at survey by looking at what is around the deck, not by looking at the rooflight.

Single storey rear extensions in the vale, where a tower earns its place

The flat roofed rear extension behind a Gloucester or Tewkesbury terrace, with a dome or a 1990s rooflight on it, is the case where the tower genuinely works. The deck is typically two and a half to three metres above a yard, there is a hard surface to stand on, the unit is a manageable size, and the whole job is a day.

Two conditions have to hold. There must be firm level ground to foot the tower, which a paved yard gives and a sloping garden does not. And there must be a route to get the tower and the new unit in, which a rear alley or a side passage allows and a landlocked garden reached only through the house does not. Where either fails, the tower saves nothing and the job goes back to scaffold.

Two storey slopes, and the platform that has to stand for the week

A roof window on the main rear slope of an interwar semi at Longlevens, Hucclecote or Warden Hill puts the working line six or seven metres above the garden. A three storey Cheltenham terrace with a parapet puts it above nine, and the platform there also has to reach the parapet with a boarded lift at the right level and a proper edge.

Town addresses add lead time as well as cost. A Gloucester or Cheltenham street frontage may need a licence from the highway authority to stand on the pavement, sometimes with a gantry beneath, and a terrace often needs a neighbour’s agreement to tie in or to land a lift over their garden. Both are dealt with before a date is offered, because a scaffold booked without a licence is a lost week.

Cotswold stone slate, where the courses decide the platform

On the wolds roofs through Painswick, Bibury, Northleach and Chipping Campden, a replacement is never a one day job and the platform question answers itself. The courses above the opening are stripped back up the slope, the new frame set, and the courses re-laid downwards to re-establish the diminishing gauge. Slates are 20 to 30mm thick and the roof loading runs well over 100 kilograms per square metre, so a stack of salvaged stone has to be staged somewhere solid.

That means a boarded scaffold lift with room to sort and stack slates by size, roof staging above it spreading load across the covering rather than concentrating it on a few slates, and a platform that stands until the reclaimed stone arrives and the last course is back. There is no tower version of that job.

Broken glass, an old dome and the route the waste takes down

Replacement generates more to bring down than new work does, and some of it is sharp. A misted unit is intact and manageable. A cracked one, a dome that has gone brittle enough to break as it is unscrewed, or a 1980s sash whose glass is loose in a perished bead all need to be taken down in a controlled way, bagged or crated on the platform, and lowered rather than carried.

Behind the glass comes the rest: old lead flashings, brittle underlay, cut timber, an old kerb where it is being rebuilt, plus the packaging the new unit arrived in. Full disposal is covered at do you remove the old rooflight and dispose of it. For the access question, the point is simply that a boarded lift with a rubbish chute or a lowering point handles all of that, and a tower platform the size of a dining table does not.

Roof ladders and staging above the working lift

Once a platform is up there is a second question on a pitched roof: how the crew move above it. On a 30 degree concrete tile slope with the unit close to the eaves, most of the work is within reach from the lift. Higher up the slope, or on the 45 to 55 degree pitches normal on Cotswold stone and Forest of Dean slate, roof ladders and staging come into it, hooked over the ridge and spreading load across the covering.

That equipment needs the scaffold beneath it as its base and its edge protection, so it is not an alternative to a platform. On a brittle old Welsh slate roof the staging is also protecting the covering from the people working on it, which is a second reason it goes on the quotation.

How the platform is settled before a date is offered

Access is itemised separately in a fixed price so it is clear what is platform, what is unit and what is labour. Where several units on the same elevation are being changed together, one platform covering all of them is much better value than three separate visits, and the sequence then runs from the top of the slope downwards so the roof is closed every evening. The reasoning is at replacing several rooflights at once, and the pricing process is on the costs page.

The Stroud valleys deserve a line of their own. In Chalford, Rodborough and Nailsworth the terraces step up the hillside, the route in is a shared lane or a flight of steps, and scaffold components are hand carried, sometimes a long way. That takes longer and it costs more, and it is priced from a survey where the lane has actually been walked so the figure holds. Coverage across the county is on the areas pages.

For a first view, email info@severnskylightsgloucester.co.uk with a photograph of the whole elevation taken from far enough back to show the ground beneath it. The ground is the half of the picture that answers the access question, and it is the half people leave out.