Base collar (starter)

A short tube with one disc that sits on the base jack of a modular scaffold and gives the first ledger connection just above the ground.

Also called: starter, starter collar, base element, base standard, starter piece

A modular scaffold does not begin with the first standard but one step lower, with the base collar. This short tube with a single connection disc sits directly on the base jack and creates the first node just above the ground. The lowest ledgers attach here, forming a level base rectangle before any long standard is in place.

That has two benefits. The whole scaffold can be aligned on this rectangle, because everything built on top inherits its position. And jack extension stays small, because the ledger level is so low. Without a collar the first ledgers would hang on the lowest disc of a normal standard, which ends up awkwardly high or low depending on how far the jack is wound out.

Design and variants

The base collar has two parts: a lower tube section that slides over the jack thread and an upper tube of 48.3 mm into which the standard is inserted. Between them sits the rosette or perforated disc. The part is steel, galvanised.

• Standard version: one disc, overall height mostly around 0.20 to 0.25 m.
• Base standard with two discs: some systems offer a longer starter with two closely spaced discs, so the first ledger level can be chosen in finer steps.
• Mobile versions: with a seat for castors or heavy-duty feet.

Setting it up

1. Lay the ledgers of the first bay on the ground to mark the standing points.
2. Place sole boards at these points and stand the jacks on them.
3. Slide the collars over the jacks; they rest on the jack nut and move up and down with it.
4. Hook the ledgers into the small holes of the discs and insert the wedges loosely.
5. Level the rectangle, starting from the highest ground point, by turning the jack nuts.
6. When everything is right, drive the wedges home. Now the standards can go on.

What to check

• The collar must rest fully on the jack nut, not on a thread half wound out.
• Stay within the permitted jack extension; the collar sometimes tempts people to wind out further than allowed.
• On slopes watch the distance to the wall – a rectangle set too far from the facade leaves a fall edge on the inside.
• A few instructions allow the collar to be left out in specific cases. Whether yours does is stated in the system's documentation.
• Used collars are among the hardest-worked parts in a yard because they stand in mud. Look for bent discs, concrete in the holes and crushed tube ends. If a jack will not slide in easily, the lower tube is usually deformed.

Small part, big effect

Experienced crews often spend more time on the first bay than on the next three lifts together. That is deliberate: whatever starts crooked at the base collar gets worse with height. A properly levelled base saves a lot of rework when decking and connecting ledgers. Collars are listed together with standards.