GFSL – HMP Wormwood Scrubs – Vent Clean & Access Door Installation


HMP Wormwood Scrubs is a men’s prison in West London and currently houses around 1,200 men within five main wings

Hydro-X Air were approached by GFSL to competitively tender the establishment ventilation clean, with there being two elements. The first was to install access doors which would enable us to complete the second element as this would enable us to clean the cell extraction systems across all wings.


Due to the size of the building and limited information, with it being a secure site, it required an in-depth survey to ensure the correct size doors and labour was allocated. For security reasons, our team were not allowed to take in any mobile devices and had to use a digital camera to document the condition of the vents at the site.

The security restrictions that come with working in this prison also resulted in an increased level of organisation from everyone to ensure that the engineers were named on the gate lists to gain access and that they prepared tool lists to present to security to help minimise downtime.


We phased the approach with access doors being installed prior to cleaning. This was at the request of the site therefore we attended and installed over 250 DW144 access doors.

Following installation of the access doors, we completed a full ventilation clean. This required extensive communication with the works department to access restricted areas at points of the day with minimal movement. Work was completed utilising our large negative pressure units and 30m brush cables. Due to the level of contamination within the ductwork, our site team needed to wear their respirators. All Hydro-X Air employees are given appropriate masks and complete annual face fit tests to check that the seal on the mask is suitable

Due to the nature of the site and the added complexities of access, an increased amount of Health and Safety and Work Quality audits were required. Thanks to the hard work of the team on this site, these are all passed and completed throughout the project.

Value added

The full system clean that was conducted resulted in the extracts working as they were initially designed to and were once again able to provide sufficient air changes to the room they service.

A heavily contaminated system reduces the cross-sectional area of the vents and ducts. This results in an increase in the demand on the plant and means that more energy is being consumed. During our time on site, the effects of this were highlighted as some plant was found to be beyond repair as the consistent strain on the system became too much. The repairs to these were separately quoted for and installed to ensure the air extraction system could once again perform optimally.


For more details about these services, visit our Ventilation Cleaning and DW144 Access Door installation pages