Horsham has a roofing problem that most towns do not, and it shapes a good share of the scaffolding work here.
Horsham stone is a sandstone quarried from the Weald, split into thick flat slabs and used as a roofing material across this part of Sussex for centuries. The roofs are beautiful, they last the best part of a century when maintained, and they are extremely heavy.
How heavy is worth putting a number on. The Stone Roofing Association gives an indicative figure of around 180 kg per square metre for traditionally laid Horsham stone. Natural slate is roughly 38 kg per square metre. So a Horsham stone roof weighs something in the order of four to five times what a slate roof weighs, and that is before anything is stacked on a scaffold.
Those figures are indicative rather than exact. Weight varies with the quarry, the thickness, the mix of slab sizes and the head lap, so on any specific job the real figure comes from the supplier.
If you are having one repaired, stripped or relaid, the scaffold is not an afterthought. It is doing structural work.
STAK Scaffold covers Horsham and the surrounding parts of West Sussex from a yard in Caterham.
Three things make this different from a tiled or slated roof.
The slabs have to be stored at height. On a stone roof job the slabs are lifted off, sorted, and relaid. They are too heavy and too awkward to keep carrying up and down, and they are valuable enough to be a theft target left in a front garden overnight. So they stay on the scaffold, which means the scaffold has to be designed to carry a substantial stacked load on the working lift rather than just the weight of two roofers and a bag of tools. That is a design calculation, not an assumption. A standard domestic scaffold specified for light access loading is not the right structure for a stone roof.
The lifts have to be set out for graded work. Horsham stone roofs are laid with the largest slabs at the eaves and the smallest at the ridge, and single-lapping is a system particular to these roofs. The roofer works up the slope in graded courses, so the scaffold lifts need setting where the work actually happens rather than at generic intervals.
The roof structure underneath may be in question. Part of the reason these roofs get stripped is that the timbers below have been carrying that weight for a very long time. Where the structure is being repaired or replaced, the scaffold may need to take temporary loading from the building itself, which is a support scaffold rather than an access one and a different design again.
Most of the buildings carrying these roofs are old, many are listed, and where they are, listed building consent may be required before anything is fixed into the fabric. That is a Horsham District Council matter.
Strip a stone roof and the building is open, often for weeks, because sorting and relaying graded slabs is slow work. A temporary roof over the scaffold keeps the weather out of a building that is standing open, keeps the roofers working through wet days instead of stopping, and protects the timbers that are exactly the thing being repaired. On a stone roof job it is usually the difference between a controlled programme and one that drifts through a wet autumn. It has to be designed in from the start, because the scaffold beneath has to carry the temporary roof as well as the stacked slabs.
Not every Horsham job involves stone. The town and the district have a large stock of Victorian and Edwardian housing, extensive modern estates, and a busy commercial centre.
Domestic. Reroofing in tile and slate, chimney work, extensions, loft conversions, rendering and external decoration.
Commercial. Access scaffolding for retail, office and industrial premises, support scaffolds, and protection scaffolding during cladding or demolition.
Rural and agricultural. Barn conversions and outbuildings across the district, where access is usually easier but the structures are often older and less predictable than a house.
If any part of the scaffold sits on a public road or pavement, the licence does not come from Horsham District Council. West Sussex is a two-tier area. Horsham District Council handles planning and listed building consent, but the highway authority is West Sussex County Council, and it issues scaffolding licences. West Sussex requires a minimum of 10 working days notice from application to the date the scaffold goes up, and contractors have to notify the council as soon as the scaffold comes down. STAK handles the application as part of the job. On a private driveway no licence is needed, which covers a good proportion of the residential work in the district.
Ordinary scaffold inspection asks whether the structure is still sound. On a stone roof job it has to ask something else as well: what is on it today, and is that what it was designed for.
A working lift signed off empty is not the same structure once several tonnes of graded slab are stacked along it. So the loading gets checked as carefully as the stability, and where the stack is placed matters as much as how much of it there is. Concentrating slabs at one point on a lift designed for distributed load is how a properly built scaffold gets into trouble.
Everything is erected in accordance with the Work at Height Regulations 2005, BS EN 12811 and HSE guidance, following TG20 and SG4, with written sign-off before handover and re-inspection through the hire.
The credentials behind that are ConstructionLine and ConstructionLine Social Value registration, SafeContractor approval, SSIP through Acclaim and DTS, Alcumus SafePQQ, Environment Agency registration and Scaffolding Association membership.
Worth a word, because two prices for the same roof can describe two different structures.
A scaffold engineered to carry stacked slab uses more material and takes longer to put up than a standard access scaffold. A support scaffold taking temporary load from the building itself is a different job again. If one quote is noticeably cheaper, the question to ask is what loading it has been designed for, not what it costs.
On a conventional tiled roof or an extension, none of this applies and the usual variables of access and duration take over.
Every quote follows a free site survey, which on a stone roof establishes what is coming off, where it is going while the work happens, and what condition the structure underneath is in.
The Stone Roofing Association gives an indicative figure of around 180 kg per square metre for traditionally laid Horsham stone, against roughly 38 kg per square metre for natural slate. That is four to five times the weight. Figures vary with the quarry, slab thickness, size mix and head lap, so the exact number for a specific roof comes from the supplier.
Yes, but it needs designing for the load rather than treated as standard access scaffolding. The slabs are stacked on the working lift while the roof is sorted and relaid, so the structure has to carry that weight. A scaffold specified for light access loading is not suitable.
Because they are too heavy and awkward to keep moving up and down, and valuable enough to be a theft risk if left at ground level. Keeping them at working height is normal practice, and it is why the loading has to be designed in
West Sussex County Council. The district council handles planning and listed building consent, but the county council is the highway authority and issues scaffolding licences.
West Sussex County Council requires a minimum of 10 working days from application to erection. Contractors must also notify the council as soon as the scaffold is removed.
No. A licence is only required where part of the structure sits on a public road or pavement.
Usually worth it. Sorting and relaying graded stone slabs is slow, so the building stands open for longer than a tiled reroof would. A temporary roof keeps the weather off the exposed timbers and keeps the work moving through wet days
Yes, along with Broadbridge Heath, Pulborough, Rudgwick, Warnham and the surrounding villages.
Every quote starts with a free site survey. On a roofing job, and especially a stone roof, that visit establishes the loading the scaffold has to be designed for.
Call the office on 01883 330188, or email office@stakscaffold.co.uk with a few details about the job. Lee (07802387774) and Jack (07522676940) both take calls directly if it’s easier to speak to someone on site.
