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STAKKAbox™ Fortress

STAKKAbox™ Fortress is a range of modular and structural preformed access chambers, suitable for use in carriageway and footway environments.

The Fortress system is moulded in HDPE and possesses excellent strength to weight properties.

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Features & Benefits

Fast and Easy to Install

STAKKAbox™ chambers are significantly faster to install than conventional alternatives, with complete installations typically taking up to one hour. This results in reduced costs for the installer. No specialist equipment or plant is required in order to install the chamber and there is no need for specialist box builders.

Sectional & Twin Wall Design

Chambers are built to required depth by adding 150mm sections. Due to the twinwall design, individual sections are light meaning they can be manually lifted. Each access chamber possesses vertical and horizontal ribs,  resulting in a product that is strong vertically and on the sidewall. Most installations do not require specialist backfills, reducing installation costs.

Flexible During Installation

Chambers can be adapted to suit on-site conditions with standard tools to overbuild over existing networks, Introduce duct entries for cable entry and for top-section fine adjustment.

Smooth Outer Walls with Lip to ‘Key In’

Gaps in the outer wall will negatively impact the effectiveness of compaction around the chamber. STAKKAbox™ chambers have smooth outer walls and an outer lip which keys into the backfill.

Flat Pack Option

Fortress can be supplied in 'flat pack' format to make shipping more efficient as well as allowing flexibility in delivery and installation.



STAKKAbox™ Fortress is manufactured in nitrogen-foamed High Density Polyethylene (HDPE), of which up to 70% is recycled material.

HDPE possesses excellent strength to weight properties.


Available Sizes

Information on sizing

STAKKAbox™ Fortress chambers are formed by combining four interconnecting component parts to form each ring section. These sections are locked and secured using supplied screws. Using standard component parts allows for greater flexibility in chamber size and clear opening.

Download our product size guide for chambers in order to gain more information on available sizes.



Chambers can be adapted to suit on-site conditions with standard tools to overbuild around existing networks, introduce duct entries for cable entry, and for top-section fine adjustment.

Stakkabox Fortress Modular Content Adaptability

Load Rating

Fortress access chambers are suitable for installation in environments rated to D400 under EN124, in accordance with Cubis’ installation guidelines.

Suitable for carriageways of roads and areas open to commercial vehicles.


Options & Accessories

STAKKAbox™ Fortress can be supplied with the following accessories: