Self-employed David Currie, 48, suffered a fractured arm and dislocated shoulder during the incident at Evans Wharf, Aspley Lock in November 2012.

Watford Magistrates’ Court heard that north London based Beacon Scaffolding had been sub-contracted to erect scaffolding around a four-storey block of flats to allow decorators to repaint windows and woodwork.

While erecting the scaffolding, Beacon’s workers were asked by painting and maintenance subcontractors to significantly increase the height of the first tier of scaffolding.

This alteration required a new layout design but the scaffolders continued to erect the scaffolding before these designs had been received.

Currie was working on the third level of the scaffolding when he lost his footing and stumbled through an unprotected ladder opening.

His outstretched arm fell between ladder rungs and the momentum of his fall caused him to fall to the second level below, dislocating his shoulder and fracturing his arm.

HSE found there were no preventative measures, such as protected ladder traps or guardrails, to prevent a fall from one level to another, and that access ladders between each level were too short and did not provide suitable handholds.

Beacon Scaffolding Ltd was fined £5,000 and ordered to pay £1,737 costs after pleading guilty to a single breach of the CDM regulations.

Speaking after the hearing, HSE Inspector Rauf Ahmed, said: “This incident was entirely preventable.

“This case highlights the importance of scaffolding companies arranging ladder access openings between scaffold levels in such a way to prevent falls, and provide ladders of a sufficient length to offer suitable handholds above landing places.

“There are a number of well-known ways of arranging safe ladder access to prevent falls like this, and our investigation found no evidence of these being in use at the scene of the incident.

“In addition, if there are significant design changes to a scaffold, it is important the new designs are followed.”