Forty-four metres of frontage and a line reading 'design fee TBC'
The elevation is forty-four metres long, the parapet coping sits a shade under twelve metres up, the scaffolder wants to be on site Monday, and what is holding the job up is one line at the bottom of his quote: design fee TBC, subject to survey. That line is not padding. It is the scaffolder saying he does not yet know whether this scaffold goes up against a standard compliance sheet printed off in his own office on Friday, or to an engineer for calculations, a drawing, a fee and a fortnight of lead time — and what decides it is mostly the wall you are both standing in front of, plus whatever the client has asked to hang on the outside of it.
Two questions sit inside that one. The first is scope: is every feature of this arrangement inside the range of configurations the standard guidance already covers, because the moment one feature falls outside it the whole scaffold becomes a designed scaffold and no part of it comes off a sheet. The second is the quantity the first one governs — how many ties, of which type, at what spacing, each carrying what duty, into a facade that has its own opinion. Get the second wrong and the ties are the failure mode, because a facade scaffold is not stable on its own. It is a slender frame leaning on a wall, and the ties are the leaning.
The order matters. Scope first, because scope decides who is allowed to answer the quantity question at all: a scaffolder can print a compliance sheet for a standard configuration, only a competent designer can produce a tie schedule for anything else, and no amount of experience converts one into the other. What follows is arranged around that fork — what pushes a job across it, what a tie physically is once you are across it, and the three site decisions that quietly move the answer after the sheet has been printed.
The list that pushes a job out of the standard configuration
The compliance-sheet route exists because most facade scaffolds are, structurally, the same scaffold: independent and tied, standard bays, standard lifts, standing on the ground against a solid wall. In the United Kingdom that route is NASC TG20, whose eGuide produces a compliance sheet for a configuration inside its published scope; step outside the scope and the job becomes a bespoke design under BS EN 12811-1, with the procedural control of BS 5975 around it. Prefabricated system scaffolds have their own route through BS EN 12810-1 and BS EN 12810-2. There is no compliance sheet in the United States: OSHA 29 CFR 1926 Subpart L requires a scaffold to be designed by a qualified person and to be constructed and loaded in accordance with that design, and gives the restraint requirement as prescriptive numbers instead, with ANSI/ASSP A10.8 alongside. Australian and New Zealand practice runs through AS/NZS 1576.1 and AS/NZS 4576.
What follows is the walk-round that decides which side of the fork you are on, done before the quote is accepted rather than after the wagon is loaded, because every item on it is visible from the pavement with a tape and twenty minutes. Any single hit sends the whole scaffold to a designer — not the affected bay, the whole scaffold.
- Anything on the outside face beyond the cladding options the sheet covers: shrink-wrap over a debris net, a printed scrim, an advertising banner, sheeting on an elevation the sheet assumed open.
- Bay lengths or lift heights outside the tabulated set — including the single long bay somebody has left over the shop entrance so the doors still open.
- A loading bay, a hoist, a rubbish chute, a protection fan, a pavement gantry or a temporary roof. Each is a load and a wind surface the standard configuration was not carrying.
- Bridging of any kind: a beamed section over an entrance, an omitted ground-level bay, or a run cantilevered off the building instead of standing on the ground.
- An elevation you cannot tie at the pattern the sheet calls for — a fully glazed shopfront, a listed facade with no consent to drill, an external wall insulation system with nothing structural within reach of a fixing.
- A return you cannot form, or a run that dies at a party boundary with no return at all, leaving the end of the scaffold unrestrained in the direction it is weakest.
- Standards landing on anything other than ground: a basement slab, a vault, a podium deck, a flat roof, a mezzanine, or another scaffold.
- Loading above the class actually specified — pallets of blocks stacked on a lift designed for one operative and hand tools is a different scaffold from the one on the sheet.
- A tie test below the duty the pattern assumes — the one that surfaces after erection has begun, and the reason preliminary anchor tests belong to the survey rather than to the first lift.
A tie is six things in a row, and the weak one is usually in the wall
Ask a crew what a tie is and most will point at the short tube going into the window. The tie is the whole chain: the coupler at the standard, the tie tube, whatever grips the building, the substrate that grip is in, and the structure that substrate is part of. Load has to pass through every link in both directions, because a facade scaffold is pushed toward the building by wind on the outside face and pulled away from it by suction on the inside of the gap, and the two cases are not symmetrical in what they demand of a fixing. A tie that only resists compression is a prop, and props are not what stops a scaffold peeling off a wall in a gale.
The types divide by what they grip and by what they are honest about. A through tie passes a tube through an opening onto a bridle inside the building and works in both directions on geometry alone, which is why designers like it and occupiers hate it. A box tie encircles a column, pier or return and does the same without going indoors. A lip tie hooks over a reveal or a parapet, is good in one direction and much less good in the other, and normally needs something else to close the loop. A reveal tie is a tube jacked across an opening on a threaded pin, depending entirely on friction and on somebody having wound the pin up properly — which is why the standard guidance caps reveals at no more than half a scaffold's ties, and why the pins carry a tell-tale and a re-check interval instead of being fitted and forgotten. An anchor tie is a drilled fixing with an eye or a ring, and it is the only type whose capacity is a property of the wall rather than of the scaffold.
Position is the fourth variable and the one most often lost on site. A tie is designed to land at or very close to a node — the point where the ledger and transom meet the standard — because that is where the frame can take a horizontal load without the standard bending between lifts. Ties moved down a bay to miss a window, or dropped half a metre to reach a lintel, transfer the same force into a member that was never asked to carry it. The distance a tie may be offset from the node is a stated tolerance in the design, not a matter of reach, and it is the sort of thing that gets adjusted on a wet Thursday and never written down.
Ties also stop the scaffold swaying along its own length, which is why the American rules are written as a grid rather than as a count. OSHA 29 CFR 1926.451(c)(1) restrains any supported scaffold whose height-to-base-width ratio exceeds four to one: the first tie goes at the closest horizontal member to that four-to-one height and repeats vertically at horizontal members every 20 feet for scaffolds three feet wide or less and every 26 feet for wider ones, the top tie sits no further than the four-to-one height from the top, and horizontally ties go at each end of the scaffold and at intervals not exceeding 30 feet measured from one end toward the other. Those are minima for a bare supported scaffold. Everything else on this page — sheeting, a fan, a facade that will not hold a fixing — makes the real pattern denser, and a scaffold extended two bays past its original schedule is not the scaffold that was designed.
What a tie is actually passing through
- Debris netting or sheeting — closes the outer face against falling material and turns the scaffold into a wind surface, which is what re-prices the tie schedule Perimeter Safety Debris Net Barrier Area Calculator
- Outer standard line and toe board — the guarded edge of every boarded lift; the toe board runs the full length of the run and is counted per lift rather than once Guardrail Toe Board Height and Quantity Calculator
- Boarded platform and transoms — the working lift itself, whose board count and service load class set how much of the leg load is people and material
- Inner standard line and ledger — set as close to the wall as the boards allow, because the gap left here is a fall route and a guarding decision in its own right
- Tie tube and anchor — the only member carrying wind out of the scaffold and into the building, working in tension one hour and compression the next Concrete Anchor Proof Load Test Calculator
- Facade and its substrate — the link nobody specified and everybody assumed, with an opening in it that decides whether a through, box, lip or reveal tie is even available
The facade gets a vote, and it votes by being pulled
Every tie schedule assumes a duty per tie, and that duty is a claim about the building until somebody puts a pull tester on it. The routine is two-stage. Preliminary tests, on sacrificial fixings before erection, establish what the substrate will give up: a small number of anchors taken well above the working duty, in each distinct construction on the elevation, to find out whether the wall or the fixing is the limit. Proof tests, on installed ties as the scaffold rises, confirm that the ones being relied on went in correctly — a stated multiple of the working duty, held without measurable movement. The first is a question about the wall. The second is a question about the crew.
Neither the multiplier nor the sample proportion is yours to invent. In the United Kingdom they come from NASC TG4, Anchorage Systems for Scaffolding, and from the design that names the tie duty, with the tensile test method in BS 5080-1. In North America the test method is ASTM E488/E488M, and for an anchor in structural concrete the qualification and design provisions sit in ACI 355.2 and the anchoring-to-concrete chapter of ACI 318 — alongside the manufacturer's published data or European Technical Assessment, which is what actually states the fixing's allowable load in a given base material. The site controls only the arithmetic falling out of those: the load to reach and hold, and how many ties in this lot must see it.
The failures cluster in a handful of substrates, all of them visible from the pavement. The outer leaf of a cavity wall is often a single 102 mm skin of brick tied back with wall ties of unknown age, so a fixing gripping only that leaf can pass a test while pulling on something itself held by corroded wire. External wall insulation puts anywhere from 50 to 150 mm of nothing between the drill and the structure. Thin-joint aerated blockwork, lightweight aggregate block, brick slips on a rail, terracotta faience and any masonry in a soft lime mortar all read as solid wall and behave otherwise under a tester. So does a steel frame with brick infill, where the panel carries nothing and the frame behind it is where the tie should have gone.
Lot discipline is what makes the sample mean anything. A lot is one anchor type, one installer, one base material, one day — so a facade with a concrete frame at the corners and brick infill between is two lots, and a rendered elevation concealing two substrates is two more, discovered only by drilling. Test across a boundary the design treats as separate and the certificate covers neither group.
Tie duty from the design, the multiplier and the sample proportion from the anchorage guidance and the specification, and the lot size from the elevation itself — the two numbers a tie test day actually runs on.
The tension the anchor is designed to carry in service.
How many times the design tension the specification asks the test to reach.
How many anchors this lot covers — one installer, one product, one condition.
The proportion of the lot the specification requires to be tested.
The floor the specification puts under the sample, whatever the percentage gives.
Proof load to apply and hold
2,700 lbf
The sample rate governs this lot. A proof test demonstrates that the installation holds the specified load without measurable displacement; it is not a capacity test and must not be taken to the anchor's ultimate. Confirm the specification's cap on the applied load, and confirm what counts as a failure and what happens to the rest of the lot when one occurs.
- Anchors to test in this lot
- 6 anchors
- Sample size before the specified floor
- 6 anchors
- Load applied above the design tension
- 899.24 lbf
- Anchors covered by each tested anchor
- 20 anchors
They open the calculator with your figures already in it
Concrete Anchor Proof Load Test Calculator: 2,698 lbf — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 2,700 lbf — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- Does not set the multiplier or the sample rate. Both are contract values, and a page that supplied them would be inventing the specification.
- Does not check that the proof load is safe to apply. A multiplier taken against a load close to the anchor's capacity can exceed the steel or the concrete during the test itself.
Sheeting is a tie decision before it is a weather decision
The most expensive sentence a client can say on a walk-round is that they would like it sheeted. An open tube-and-fitting frame presents very little to the wind; the same frame netted presents a partially permeable surface with a real force coefficient; wrapped in sheeting it is a solid sail forty-four metres long and twelve metres high, and every newton of that lands in the ties. Which is why the standard guidance tabulates tie patterns against the cladding condition, why a sheet printed for an open scaffold stops being valid the afternoon the netting goes on, why the wind actions of BS EN 1991-1-4 and the scaffold provisions of BS EN 12811-1 are part of a designed scaffold rather than an afterthought, and why Subpart L bars work on or from a scaffold in storms and high winds until a competent person says otherwise.
Netting is not a free middle option either. Its declared permeability and force coefficient belong to the specific product, and it clogs with dust through a render strip until it is markedly less permeable than the figure the design used — leave it up over a winter and by March the scaffold is carrying a load nobody signed for. Sheeting adds a problem of its own: it is fixed to the frame at intervals, and where those fixings are further apart than the manufacturer states, the sheet balloons and the load arrives at the ties as snatches rather than steady pressure.
The quantity itself is the easy part and it is worth having early, because it is the number the designer needs before anything else and the number the client is actually buying. Perimeter run against the vertical drop being screened gives the area, taken per elevation rather than as one figure so that the elevation you are permitted to leave open reads as a separate line. Note that a quantity is all it is: netting used as genuine fall-arrest rather than debris containment is a different product with drop-test data behind it, which OSHA 29 CFR 1926.502(c) addresses and a takeoff does not.
| Outer face | What the design has to be given | What it changes |
|---|---|---|
| Open frame | Bay length, lift height, boarded lifts, duty class | The baseline pattern the compliance sheets are tabulated against |
| Debris netting | The net's declared permeability and force coefficient, plus the elevations netted | A closer tie pattern, and a re-check if the net clogs or is left up out of season |
| Sheeting or shrink-wrap | Sheeted area per elevation, fixing centres, and the exposure of the site | Treated as a solid surface — normally outside the compliance-sheet route entirely |
| Sheeting plus a fan, gantry or temporary roof | The added dead load and the wind surface of each item, positioned | A bespoke design with the tie duties and leg loads recalculated together |
Run length against the drop being screened, elevation by elevation — the area you are buying, and the first figure a designer asks for once somebody says the word sheeted.
The total linear length of building perimeter or scaffold to be enclosed with netting.
The vertical height of netting coverage needed at each point along the perimeter.
Total netting area needed
5,070 ft²
This is a material-quantity takeoff only. If this netting is intended as fall-arrest protection under OSHA 29 CFR 1926.502(c) (not just debris containment), the specific net product must have certified drop-test/impact-energy data and be installed per its manufacturer's requirements and a qualified person's fall protection plan — this calculator does not verify that.
They open the calculator with your figures already in it
Perimeter Safety Debris Net Barrier Area Calculator: 5,070 ft² — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- Netting a scaffold changes what the scaffold has to resist. An open frame lets wind through; debris net turns it into a partly solid surface, and the load it collects goes straight into the ties. A netted scaffold needs a denser tie pattern than the bare frame it was designed as — the tie schedule follows whether the scaffold is bare, netted or sheeted — and adding net to an existing design without revisiting the ties is a well-known way to pull a scaffold off a building.
- The fixings are the quantity that gets forgotten. Net is tied to the scaffold at every eyelet along the top edge and at intervals down the standards, and adjacent panels are laced together for the full length of each seam. What the job actually needs beyond the area is a count of ties or clips per unit length of edge and a length of lacing cord per seam — order area alone and the net turns up with nothing to hang it by.
- Any opening cut into the net has to be re-edged. Hoist openings, loading bays, window access and cuts around tie tubes are not simple deductions from the area: a cut edge in mesh runs unless it is bound or roped, so each opening adds edge rope and fixings and takes that panel outside the edge detail it was supplied with.
Toe boards are counted by the lift, and they are the cheap way to keep the face open
Falling object protection on a facade scaffold is measured differently from falling object protection on a slab edge, and the difference is a multiplier people forget. A boarded lift has a guarded outer edge for the full run, ends at both extremities and a return at each corner — then the lift above has the same again, and the lift above that. Four working lifts on forty-four metres is not forty-four metres of toe board; with returns and ends it is comfortably over two hundred, before anybody cuts a piece. Note also that the geometry the check below quotes comes from the falling-object provisions of 29 CFR 1926.502(j) in Subpart M, while a scaffold in the United States is caught by the falling-object provisions of 29 CFR 1926.451(h) in Subpart L — the same minimum height and maximum gap, reached by a different route.
The inside edge is the one that gets argued about, and it carries a commercial argument pointing the opposite way from the last section. The gap between the boards and the wall is a fall route: OSHA fixes a maximum distance from the front edge of the platform to the face of the work unless that edge is guarded or the operatives are in arrest systems, and the Work at Height Regulations 2005 require a working platform to have no gap through which a person could fall, so a bay window or plinth holding the boards off the wall doubles the guarding for that bay. But a toe board and a brick guard close the outer face against falling material without closing it against wind, while sheeting closes both and pays for the second in ties, fees and lead time. Where the requirement is that nothing falls into the street rather than that no dust escapes, boards and guards do the job the scaffold was already designed for.
Run the perimeter as the total of every boarded lift including ends and returns, not as one lap of the building, and check the two dimensions the rule actually fixes while you are there.
The total linear length of platform/guardrail edge that requires a toe board.
The length of the toe board stock/lumber as supplied.
The vertical height of the toe board as installed.
The clearance gap between the bottom edge of the toe board and the walking/working surface.
Toe board stock lengths needed
17 board lengths
Measured against the two fixed figures in OSHA 29 CFR 1926.502(j), which this page restates and does not interpret. The board height entered is at or above the 3-1/2 in (9 cm) minimum. The gap above the walking surface is at or below the 1/4 in (0.6 cm) maximum. The 50 lbf (222 N) load capacity in the same paragraph is confirmed with the board's manufacturer and its material, not calculated here. Matching the figures quoted is not compliance. The rest of the requirement, and the installed work, are outside what this page can see.
- Toe board height
- 3.5 in (OSHA min 3.5in)
- Gap above surface
- 0.2 in (OSHA max 0.25in)
They open the calculator with your figures already in it
Guardrail Toe Board Height and Quantity Calculator: 17 board lengths — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- Checks the board and stops at the top of it. Where tools or material are stacked higher than the toeboard's top edge, the falling-object rules call for paneling or screening carried up from the surface or the board to the toprail — so a compliant 3-1/2 in board with pipe stacked a foot high behind it protects nobody underneath and is still a violation.
- Assumes an unbroken run along the edge measured. The board only works where it is fastened tight against the edge it protects: set back from the deck edge it leaves a slot that passes exactly what it was there to stop, and ladder access points, gates and hoist openings need their own removable protection rather than a gap in the run.
- Reads against the fall-protection rule for guardrail systems. A scaffold platform is governed by the scaffolding standard instead, and its toeboard provision is stricter on load — 100 lbf rather than the 50 lbf quoted on this page, on the same 3-1/2 in minimum height. Confirm which rule the platform falls under before treating the comparison here as the whole answer.
Reaching the anchor positions before there is anything to stand on
The preliminary anchor tests, the substrate survey and the photographs of every proposed tie position all happen before the scaffold exists, which means somebody goes up the outside of an occupied building on a ladder or in a powered access platform to do them. It is the point in the job with the least protection and it routinely gets treated as a five-minute look. A pull tester, a hammer drill, a battery, a bag of anchors and a clipboard is not a one-handed load, and a ladder is a poor place to be applying a reaction force to a wall.
Where a ladder is genuinely the right tool — a short survey run, a single test position, nothing to carry — the setup rules are fixed and worth checking rather than eyeballing. OSHA 29 CFR 1926.1053 sets the four-to-one placement ratio for a non-self-supporting ladder, a working length four times the distance the foot stands out from the wall, giving an angle of about seventy-five and a half degrees, and requires the side rails to extend at least three feet above any landing the ladder serves. UK practice runs the same geometry through the Work at Height Regulations 2005 and HSE guidance INDG455, with the ladder itself to the BS EN 131 series. None of them make a ladder a working platform: it is for access and short-duration work with a handhold kept, and a proof test is neither.
The same geometry comes back later inside the finished scaffold. A facade scaffold gets a dedicated ladder access bay, with the ladder tied at the stiles, extending above each landing, and a hatch in the boards that closes — not a ladder leant against the outside face, which is a much worse idea once netting is on and the face can deform. And while the scaffold is being erected, altered or struck, the scaffolders' own fall protection is a separate discipline again, set out in NASC SG4, Preventing Falls in Scaffolding Operations, and it applies to the very operations that put the ties in.
Working length measured along the rails against the distance the foot stands out, plus the extension above the landing — the two things that make a survey ladder either a tool or an incident.
The ladder's extended working length, measured along the ladder itself.
The horizontal distance from the base of the ladder to the wall or support it leans against.
How far the ladder's side rails extend above the upper landing surface, when used for access to that landing.
Base-distance-to-working-length ratio
4 :1 (target 4:1)
This restates OSHA 29 CFR 1926.1053's fixed setup-angle (4:1, ~75.5°) and landing-extension (3 ft / 0.9 m minimum) rules only. It does not check ladder duty rating/load capacity, the condition of the ladder or the surface it rests on, tie-off/securing requirements, or overall fall protection needs for the specific task — those must be verified separately by the user each time the ladder is set up.
- Resulting ladder angle from horizontal
- 75.52 °(target ~75.5°)
- Landing extension
- 3.5 ft (OSHA min 3 ft)
They open the calculator with your figures already in it
Extension Ladder Setup Angle & Placement Safety Checker: 4 :1 (target 4:1) — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Says nothing about what the ladder is near. An aluminum ladder raised into an overhead service drop does not have to touch it to flash over, and the rule is a clearance distance from energized conductors plus a non-conductive ladder for work on or near live equipment — neither of which any setup angle can satisfy. That clearance is judged before the ladder goes up, not after it is angled.
The leg load the sheet prints is a condition, not a footnote
A compliance sheet or a bespoke design does not only give you a tie pattern. It states a maximum leg load, and that figure is a condition of the whole document: satisfy the tie schedule and fail the leg load and you have not complied with anything. The load comes from the duty class the scaffold was specified at, and the service load classes in BS EN 12811-1 are a short table worth knowing by heart, because clients ask for a scaffold and describe a duty without realising they have done it. A scaffold sized for inspection access and then used to stack blocks is loaded two or three classes above what was printed.
Ties change that figure in a way that is not obvious. A properly tied scaffold hands its wind load to the building; an elevation that cannot be tied gets buttressed, rakered, guyed or ballasted instead, and every one of those routes puts substantially more vertical load into a small number of legs, at exactly the positions you were already worried about. So the moment an elevation loses its ties — a glazed shopfront, no consent to drill, a failed test — the base check is no longer the same base check. The load path went looking for somewhere else to go and found the ground.
What OSHA requires of the ground is that scaffold footings be level, sound, rigid and capable of supporting the loaded scaffold without settling or displacement, and it deliberately publishes no allowable bearing value, because that belongs to the site. So the check is a comparison you assemble yourself: the leg load from the design, the contact area you are genuinely providing, and an allowable pressure from a geotechnical report or a competent person's assessment of what the standards are landing on.
Sole boards are the cheap variable in that comparison and the one most often skipped on a paved frontage, on the grounds that flags look solid. They are also the only variable in it a scaffolder can change on the day without changing anything else on the sheet: the plate is whatever the system supplies, but the timber under it is a decision, and it is the difference between a bare plate concentrating a leg into a hand-sized patch and a board spreading the same leg over several times that.
| Class | Uniformly distributed service load | The scaffold people mean when they say it |
|---|---|---|
| 1 | 0.75 kN/m² | Inspection and very light access, no material stored |
| 2 | 1.5 kN/m² | Light trades — painting, cleaning, rendering by hand |
| 3 | 2.0 kN/m² | General purpose, the common default for a facade scaffold |
| 4 | 3.0 kN/m² | Masonry and heavier trades storing material on the lift |
| 5 | 4.5 kN/m² | Heavy duty, material handling on the platform |
| 6 | 6.0 kN/m² | Special heavy duty, normally a designed scaffold from the outset |
Take the leg load from the design rather than estimating it, use the contact area you are actually providing, and compare against an allowable value somebody has assessed on this site.
The load carried down through a single scaffold leg.
The actual ground-contact area under the leg — the base plate alone, or the base plate plus a sole board if used.
The allowable ground bearing capacity at this location.
Applied bearing pressure
2,730 psf
This is a first-pass bearing-pressure screening only (leg load ÷ contact area, vs. a user-supplied allowable value). It does NOT verify overall scaffold stability, tie-in/guying requirements (OSHA 1926.451(c)(1), 4:1 height-to-base rule), component structural capacity (1926.451(a)(1), 4x max intended load), sole-board bending/shear adequacy, eccentric or dynamic loading, or site soil variability. Allowable bearing capacity must come from your own geotechnical data or a competent person's site assessment — OSHA does not publish a universal bearing value. Per 1926.451(a)(6) and (f)(7), scaffold design and erection must be under a qualified/competent person; this calculator is not a substitute for that.
- Allowable bearing capacity (user-supplied)
- 3,132.82 psf
They open the calculator with your figures already in it
Scaffold Base Plate Bearing Pressure Calculator: 2,726 psf — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 2,730 psf — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- Treats the leg load as concentric on the plate. A leg out of plumb, or a plate not bearing flat, concentrates the load on one edge and the real peak pressure is higher than load ÷ area — which is the case that punches a sole board into soft ground.
- Assumes the full contact area bears. A base plate on uneven ground, or a sole board that has begun to bridge, carries on part of its area, and the figure you entered is the plate's size rather than what is actually in contact.
- Static load only. Nothing here accounts for material being landed on a lift, wind uplift, or the out-of-balance loads present while the scaffold is being erected or struck.
- Ground does not stay as it was measured. An allowable bearing figure taken in dry weather is not the figure after a week of rain, after a trench is opened alongside, or over a backfilled service.
Handover, the tie register, and the tie somebody takes out in week six
The document that ends the erection is a handover, and it should name what the scaffold is for as well as what it is: duty class, cladding condition, the tie pattern actually installed with the test certificates behind it, and the loads it must not be given. A handover saying only that the scaffold is complete and safe permits the next six variations without anybody noticing them happen. Inspection then runs on a fixed rhythm — in the United Kingdom before first use and at intervals not exceeding seven days for a working platform under the Work at Height Regulations 2005, plus after anything that could affect strength or stability; in the United States by a competent person before each work shift and after any occurrence affecting structural integrity, under Subpart L.
The register is the part that gets skipped and the part that matters most on a long hire. Every tie has a position, a type, a substrate and a test result, and every one of those is something a following trade will want to remove. Window fitters take out reveal ties to get frames in. Renderers take out anchor ties to close the face. Roofers take out top-lift ties to run an upstand. Each replaces the tie afterwards in perhaps two cases out of three, and the third is invisible from the ground because the tube goes back and the fixing does not. A signature against every removal and every reinstatement is the only realistic way to know, in week six, that the scaffold standing there is still the one that was designed.
The compliance-sheet route is not a lesser answer. It is what a scaffold being ordinary looks like, and most of this page is about noticing the specific ways in which yours is not — a banner, a fan, a bay omitted at a doorway, a rendered elevation hiding two substrates, a late request to wrap the lot. Each is cheap to spot on a Thursday walk-round and expensive to discover once the first lift is standing.
The elevation survey that decides which route the scaffold takes
Everything here is gathered before the quote is accepted, because each line is either a reason the compliance sheet still works or a reason it does not — and the second kind costs a design fee and a fortnight if it turns up later.
- Every distinct substrate on the elevation, mapped and photographed — Concrete frame, brick infill, rendered blockwork, insulated render, brick slips. Each is a separate test lot, and render conceals the boundaries until somebody drills.
- Available tie types per bay, opening by opening — Through, box, lip, reveal or drilled anchor. Reveals are capped as a proportion of the total, so a facade of openings and nothing else is already a designed scaffold.
- The cladding condition the client actually wants — Open, netted or sheeted, per elevation. Sheeting is a wind surface, not a finish, and it usually takes the whole scaffold outside the standard configuration.
- Boarded lifts, ends and returns as one linear total — Toe boards multiply by lift, not by building. Four lifts on a long frontage runs several times the figure anyone quotes from a plan.
- Duty class in writing, against what will really be stacked on the lift — The service load class sets the leg load the design prints, and a general-purpose scaffold used for masonry storage is loaded above what was signed off.
- What the standards are landing on, and what is under it — Flags, a podium deck, a vault, made ground or a basement slab. The allowable bearing value comes from an assessment of this site, never from a default.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.