Projects & trades · 6 min read

Rendering a facade: the right scaffold for render work

Q: Can I render the facade in stages, one elevation at a time?

Yes, that is normal practice. Each elevation is a separate area and the transitions at the building corners do not show. What matters is that each elevation's finish coat is completed without a break.

Q: May render be mixed on the scaffold?

Small amounts in a tub are usual. A mixer, water and bags add weight and wet the deck, though. Larger batches are better mixed on the ground and pumped or lifted up.

Q: What if it rains during render work?

Protect fresh render against driving rain with sheeting or a cover. If rain has already marked the surface, the plasterer decides whether it needs reworking. After heavy rain, also check the ground under the base plates.

Q: How do I clean the scaffold after rendering?

Remove mortar while it is still fresh, with a scraper and water. Hardened mortar on frames and decks makes the parts difficult to connect and hides damage. Everything should be clean and dry before it goes into storage.

Q: Does lime render need a different scaffold from cement render?

The scaffold itself is the same. Lime renders often need longer intervals between coats and react more to rapid drying, so plan for nets or sheeting and a longer standing time.

Q: Can the plasterer work from the inside bracket?

Yes. An inside bracket fitted and boarded as the instructions require is a full working platform and brings the plasterer closer to the wall, which helps at cornices or under overhangs. Its permissible load is stated in the manufacturer's instructions.

Rendering is work against the clock. Once the mortar starts to stiffen, the surface has to be ruled off, floated or textured at exactly the right moment. A scaffold that gets in the plasterer's way costs time, and it shows in the result: as bands at the height of each lift, as a ragged edge at a window, or as a patch where a tie used to be. For coordinating with other trades, see facade renovation scaffolding.

Wall distance: measure to the finished render

The gap matters twice here. For fall protection, European practice generally keeps the gap between deck and wall to no more than 300 mm (12 in); local rules may set other limits. At the same time the plasterer needs space for straightedge, trowel and float. If the deck is too close, the rule cannot be guided cleanly and the tools keep hitting scaffold parts.

In practice 200–300 mm to the finished render surface works well. Include the planned thickness: a mineral base coat is usually 15–20 mm, plus a few millimetres of finish. On an old building with uneven masonry it can reach 30–40 mm in places. And if the scaffold goes up before the old render is hacked off, the gap changes again in the other direction.

Where a roof overhang, a plinth or cornices push the gap too wide, close it with an inside bracket. Position the bracket so the plasterer can reach over it to the wall rather than having to work around it.

Load class and material on the deck

Render usually comes in 25–30 kg bags. Ten bags on one bay already weigh 250–300 kg, plus mixed mortar, water and two people. A standard 2.57 × 0.73 m bay has just under 1.9 m² of deck; class 3 with 2.00 kN/m² allows around 380 kg evenly spread. A small stock of bags plus the crew nearly uses up the class.

Two site rules follow. First, class 3 is the minimum for render work. Second, spread material over several bays and lift only what will be used within the next hour. Anyone wanting to keep pallets of bags at height needs a higher class that the system really achieves at the chosen bay length, as explained in load classes and width classes.

Machine rendering: pump, hose and short routes

Larger facades are mostly sprayed by machine today. The pump or silo stands on the ground and the mortar travels up through a delivery hose. That relieves the deck, because few bags go up, but brings its own demands:

Machine position: firm, level and as close to the scaffold as possible; every extra metre of hose raises the pumping pressure.
Hose route: a full hose is heavy and moves while pumping. Run it up along the standards and fix it there, not loosely over the guard rail.
Walkways: the hose must not cross the deck where people walk. Plan its path on the wall side or in a bay that is not used as a route.
Communication: the person spraying cannot see the machine, so use radios or agreed hand signals.

Pump and hose are washed out at the end of each day. The washing water carries mortar and must not run under the base plates or into the drains. If the silo stands on the pavement or road, it needs the same permission, barriers and lighting as the scaffold itself; in the UK this normally means applying to the local highway authority for a licence (details in scaffolding on public roads).

Coat by coat, and protecting the fresh surface

Before the first spray pass, windows, doors, sills and everything else that must stay clean is masked, which is quicker and neater from the scaffold than from a ladder. Cover paving and patios under the scaffold too; dried mortar splashes hardly come off. A typical sequence on a solid wall:

Preparation: remove old render, clean out joints, pre-wet or prime. Rubble goes straight to the skip.
Spatterdash or bonding coat: a thin key coat over the whole area in one go, so the scaffold must be complete.
Base coat: spray, rule off, level. This is where wall distance counts. A common rule of thumb for mineral base coats is about one day of curing per millimetre of thickness; the manufacturer's data decides.
Reinforcement: mesh embedded in a skim coat where needed, especially at window corners and changes of material.
Finish coat: apply and texture. This coat forgives no laps.

Fresh render is sensitive. Strong sun and wind dry it too fast, and driving rain washes out the binder. A debris net noticeably breaks sun and wind, sheeting also keeps rain off, and both must be allowed for in the tie design. In hot climates such as the Gulf region, shading and early starts often matter more than anything else. Many manufacturers specify at least +5 °C for air and substrate during application and curing, so late-autumn work in northern Europe needs heated enclosures or postponement (see scaffolding in winter).

Avoiding lap lines at lifts, corners and reveals

The most common visible defect on newly rendered facades is horizontal bands at the level of the lifts. They appear when the upper area is finished and already stiffening before the lower area is joined to it; the joint dries differently and shows in raking light. The organisational remedy is simple: for the finish coat, put at least one person on every lift, all moving across the facade in the same direction. A two-storey house with three lifts therefore needs three plasterers plus someone feeding material. Where that is not possible, place day joints where nobody will notice them: at corners, downpipes, window bands or colour changes.

Lift height plays a part too. With the usual 2 m spacing, a plasterer reaches comfortably from knee height to just above head height. If a cornice or a band of windows runs exactly at deck level, adjust the pattern during erection, for example with a compensation frame in the bottom lift.

Corners decide whether a facade looks crisp. The plasterer sets corner beads and draws the arris in one pass, so both faces must be within reach from one position. If the scaffold returns around the corner with a fully boarded corner, that is easy; if it stops at the corner with an end guard rail, there is nothing to stand on round the other side. Window reveals are the second critical spot: mesh corners, stop beads and narrow strips are done by hand, and a window sitting awkwardly between two lifts means overhead or stooped work. With long rows of windows, match the lift height to the sill height.

Ties, patching and common mistakes

Ties are literally in the way. The plasterer works around them, and after dismantling small spots remain to be filled. To keep them inconspicuous:

Where the approved tie layout permits, set ties close to reveals, downpipes or edges where a repair shows less.
Keep some finish render from the same delivery; later batches often differ slightly in shade.
Seal the drill holes properly before patching.
Patch from the scaffold while it still stands, releasing the ties one by one from the top down.

Typical mistakes: wall distance measured to the old surface instead of the finished render; a class 2 scaffold because only painting was planned at first; pallets of bags on one bay; the pump hose laid across the deck; sheeting added without revising the ties; too few people for the finish coat; no render kept back for the tie spots; and nothing laid on the ground below.

Not every render job needs a full facade scaffold. A new plinth, a crack repair on the ground floor or a garage wall can often be done from trestles or a mobile tower (compare facade scaffold or mobile tower). Once a larger area must be rendered without laps, the fixed scaffold wins: several people work above each other and nothing has to be moved while the render sets. Agree render system, coat thickness and hand or machine application with the plasterer first, then set the lift pattern for the finish crew, and only then order material. The scaffolding calculator lists frames, decks and brackets for your facade; add inside brackets for projections and a few spare ties.