Load classes: the specification question that decides the price

Every scaffold is designed to carry a working load, and the load class chosen drives nearly everything else about it: how long the bays can be, how many boards wide the platform is, how the standards are spaced, how often it is tied, and consequently how much material and labour the job takes. It is the single specification decision with the largest effect on price, and it is routinely the one least clearly agreed.

The classes run from light duty inspection access at the bottom end, through general building work, up to heavy duty masonry and demolition loadings. The convention and the duty descriptions are set out in the relevant European standard and in industry guidance, and the exact figures are the kind of detail to take from current standards and TG20 guidance rather than from memory or from what the last job used.

The variation argument that starts at enquiry

The familiar sequence: an enquiry arrives asking for access scaffold to a gable. The scaffolder prices a general-purpose scaffold, because that is what most jobs are. On site, the client's bricklayers start loading out pallets of blocks onto the working lift, the scaffold was never designed for materials storage at that intensity, and the conversation that follows is about who pays to upgrade it.

That conversation is nearly always lost by the scaffolder, not because they are wrong but because nothing in writing says what the scaffold was for. The client reasonably says they asked for a scaffold to build a wall from; the scaffolder reasonably says materials storage was never priced. Absent a stated load class on the quotation, there is no document that settles it.

Asking the question the client can actually answer

Clients rarely know their load class and will not be helped by being asked for one. They can, however, answer concrete questions: what trades will use it, will materials be stored on the scaffold and roughly how much, will there be a loading bay, is anything being lifted from or through it, will sheeting or netting go on, and is any debris being dropped into it.

Those answers map onto a class, and the useful discipline is to record both: the client's description of intended use in their own terms, and the class derived from it, on the quotation. When use changes later — and it often legitimately does — the quotation shows what was priced and the variation conversation starts from a shared baseline rather than from recollection.

Sheeting and netting change the structure, not the finish

Treating sheeting as a late addition is a persistent and expensive mistake. Cladding a scaffold dramatically increases the wind load it must resist, which drives tie pattern and often requires a bespoke design where an unsheeted scaffold of the same geometry would have been compliant under standard configurations.

A client who asks for sheeting after erection is not asking for a cover; they are asking for a different structure. Scaffolders who price sheeting as a day rate and an area of material, without revisiting the design and tie schedule, are absorbing a structural change as a finishing item — and carrying the risk of a scaffold that is now inadequately tied for its loading.

Loading bays, and the gap between designed and actual

Loading bays are designed for a stated capacity, and that capacity is a number, not a general permission to load. Where the bay's rating is marked and the site understands it, the system works. Where it is not, the bay is treated as the place heavy things go, and the heavy things get heavier as the job progresses.

Marking the rated capacity at the bay, and recording on handover that it was marked, costs almost nothing and shifts the position materially if the bay is later overloaded. It is also the kind of detail that distinguishes a contractor in front of a principal contractor assessing competence.

Adaptations are where the class quietly changes

A scaffold erected to one class and then adapted — a lift added, a bay bridged over a new access route, boards doubled up to take a different trade — may no longer sit within the configuration it was designed against. Adaptations made by whoever was on site, without reference to the design, are a recurring theme in scaffold incident reports and in disputes.

Recording every adaptation against the scaffold, with who made it and under what authority, serves three purposes at once: it keeps the design current, it evidences control to the principal contractor, and it provides the basis for charging work that was done and routinely goes unbilled. Most scaffolding contractors lose more money to unbilled adaptations than to disputed variations.

Putting the class on the paperwork that travels

The class should appear on the quotation, on the handover certificate and on the scaffold tag, in terms a site manager can act on. A tag that states the duty and what the scaffold may and may not be used for turns an abstract classification into an instruction at the point of use, which is where it matters.

None of this requires a heavier process. It requires one question asked at enquiry, one line on the quotation, and a record of what changed afterwards. The contractors who do it consistently are not better engineers than those who do not; they simply have fewer arguments about what was agreed.

TG20 compliance and where bespoke design begins

A large share of ordinary scaffolds can be erected to a compliant standard configuration, with a compliance sheet produced to evidence it. That route is quicker and cheaper than bespoke design, and the commercial temptation is to keep stretching it until a scaffold that genuinely needs engineering is erected against a compliance sheet it does not quite fit.

The boundaries are the familiar ones: unusual geometry, heavy loadings, sheeting or netting beyond the standard envelope, bridging, cantilevers, loading bays over certain capacities, foundations other than firm level ground, and ties that cannot achieve the standard pattern. None is a judgement call in the moment — they are known in advance, at enquiry, if the right questions were asked.

Recording which route a scaffold took, and the compliance sheet or design reference, against the scaffold itself is what makes this auditable later. A yard that produces compliance sheets but cannot say which scaffold each belongs to has the paperwork and not the evidence.

Handover, and the gap before first use

The handover certificate is the moment responsibility for use passes to the client, and it should state what the scaffold was designed for in terms the receiving site manager can act on. A certificate naming a load class and nothing else is complete and unhelpful; one that also says what the scaffold may be used for, what it may not, and what the loading bay is rated at, is usable.

The practical gap is between completion and handover. Scaffolds get used before they are formally handed over, routinely and with nobody intending anything improper, because the trades are waiting and the certificate is in somebody's van. Tagging the scaffold at the moment it becomes available for use — and tagging it unmistakably when it is not — does more to control that than the certificate does.

Where a scaffold is handed back for adaptation and returned, the same discipline applies on the way out and the way in. The interval when a scaffold is incomplete and still physically accessible is the one that produces incidents.