Tying scaffolding to the building: tie components, tie patterns and pull-out tests
A facade scaffold is a tall, very narrow structure. A run 0.73 m deep and 12 m high cannot stand on its own; it relies on the building. The ties couple the two, carrying wind, the effects of slightly out-of-plumb standards and the extra load from netting into the wall. Whoever fits the ties decides how safe every lift above them is.
Why a scaffold needs ties
Forces act on a scaffold in three directions. Vertical loads from self-weight, people and material go down the standards into the base jacks. Perpendicular to the facade, wind pushes the scaffold towards the wall or, at corners and edges, sucks it away. Parallel to the facade, forces arise from wind at an angle, from a hoist attached to the scaffold, or from a scaffold that is not quite plumb. Diagonal braces stiffen the scaffold along its length, but only ties transfer these forces into the structure.
Wind is not the only risk. A heavy stack of blocks on the outer edge of the deck, or a worker leaning out over the guard rail, also shifts the centre of gravity. That is why ties are part of the load-bearing structure assumed in the system's design, not an accessory.
The components of a tie point
- Scaffold tie: 48.3 mm steel tubing with a hook formed at the wall end. The short version is coupled to the inner standard and resists forces at right angles to the wall only. A long tie spans both standards and is coupled to each.
- V-tie: two ties set at an angle so that they form a triangle with the wall. This arrangement also takes forces parallel to the facade. Each leg needs its own anchor.
- Eye bolt and plug: typically a galvanised eye bolt of around 12 mm in a nylon expansion plug. For perforated bricks, aerated concrete or insulated facades there are special plugs, resin anchors and stand-off systems.
- Coupler: the coupler on the standard is part of the tie. A torque of around 50 Nm is widely used for EN 74 couplers; the binding value is the one in your system's instructions. A loose coupler makes even the best anchor useless.
Which walls hold an anchor?
Before drilling, find out what the wall is made of. Tap it, drill test holes in inconspicuous places and look at drawings if there are any.
| Wall material | Suitability | Practical note |
|---|---|---|
| Reinforced concrete (slab edges, beams, walls) | good | Put tie points at slab edges or ring beams where possible |
| Solid brick, solid calcium silicate | good | Keep to the plug's drilling depth and edge distance |
| Perforated brick, hollow blocks | limited | Drill without hammer action, use suitable plugs or resin; test |
| Aerated concrete | limited | Only with plugs made for it; expect lower capacity |
| Render, joints, unbonded brick slips or cladding | unsuitable | The anchor must reach the structural wall behind |
| External insulation (ETICS) | unsuitable | The eye bolt must pass through the insulation into the structure |
| Timber cladding, infill panels | unsuitable | Move to structural timber or masonry; ask an engineer |
Old buildings hold surprises: behind sound-looking lime render there may be crumbling brick with sandy mortar. For insulated facades, see our guide to scaffolding for external wall insulation.
The tie pattern and what changes it
The tie pattern states at which standards and at what heights ties sit. It is given in the manufacturer's instructions for assembly and use and depends on system, width, bay length and cladding. There is no universal figure, so the following factors matter more than any rule of thumb:
- Cladding: an open scaffold lets most wind through. Netting increases the wind area noticeably, sheeting dramatically. The pattern gets denser accordingly, often up to a tie at almost every node.
- Brackets and fans: inside and outside brackets change how loads are distributed. Many instructions require extra ties on standards that carry brackets.
- Top lift: the scaffold above the last tie level is a free cantilever, and its permitted length is limited.
- Ends and corners: end frames lack the continuity of a long run and are usually tied more closely.
- Hoists and pulleys: extra forces that the standard configuration often does not cover and that need a separate check.
Worked example
Take an end-of-terrace gable 15.4 m long and 8 m to the eaves. Six bays of 2.57 m give seven frame lines and four working lifts. Suppose the instructions for your unclad width ask for two tie levels on every frame line and a third on each end frame: 7 × 2 = 14 ties, plus 2 = 16 tie points. If V-ties are required at each end on both levels, add four more ties and anchors. Keep 10–20 % spare plugs and eye bolts for holes that hit a cavity. If netting is coming later, calculate the pattern for the netted scaffold from the start. These numbers are assumptions that show the method, not your system's values. For the rest of the material, the scaffolding calculator gives a quick estimate.
Fitting a tie correctly
- Work only from a fully decked lift with complete edge protection.
- Mark the drilling point just below the deck, close to the node of the standard. A tie halfway between two nodes puts the tube in bending and is not allowed in most standard configurations.
- Avoid window reveals, shutter boxes and downpipes.
- Drill as the plug manufacturer specifies; switch off hammer action in perforated brick.
- Clean the hole with a pump or brush, otherwise the plug cannot expand fully.
- Screw the eye bolt home until it no longer turns by hand and the eye is horizontal.
- Hook the tie in, couple it to the standard and tighten to the specified torque.
- Tick the point off on the tie plan.
Pull-out tests
You cannot see whether a plug holds. Where the strength of the substrate is not reliably known, a share of the anchors is proof-loaded with a tester that pulls on the eye bolt. The test load is set somewhat above the required tie load, and masonry is usually tested more extensively than concrete. The exact test load and number of tests come from the instructions and the guidance applicable in your country. Test first where the wall looks weakest: damp areas, lightweight blocks under windows, old repairs. If one anchor fails, increase the number of tests, change the anchor type or move the ties. Record location, anchor type, test load and result; the record belongs with the scaffold documents.
When the facade cannot be tied
Glass facades, listed stonework where drilling is not allowed, or a free-standing gable after partial demolition offer no anchorage. Options are buttresses and outriggers with enough ground space, through-ties braced inside window openings, or a wide free-standing structure. Each of these has to be calculated for the specific building by a qualified engineer before any material is ordered.
Missing ties, eye bolts or couplers can be bought individually in our wall tie section.