James Jones Timber Systems Division forms partnership with Ockwells to offer stairwell protection systems to UK housebuilders.

James Jones & Sons’ Timber Systems Division, the maker of the UK’s market-leading I-Joist system, JJI-Joists, has entered into a partnership with specialist building and protection materials manufacturer Ockwells, which will see it recommending Ockwells’ Stairwell Hatch System to all JJI-Joist customers in the future.

After months of research in to available stairwell protection systems, James Jones’ Timber Systems Division has opted to recommend the Ockwells temporary site protection system because of its superior build quality, flexibility in applications of use and the simplicity of installing the system to house building and construction sites without adaptation to existing build practices.

Independently tested and verified, the Ockwells Stairwell Hatch System is designed to provide full cover platforms over the stairwell openings in various combinations to suit all build sites and conditions. Once installed, the system prevents falls through large stairwell opening whilst giving access for operatives and materials.

The system is designed to be lightweight for handling and ease of use on site and it allows safe and fixed access to a ladder prior to a staircase being fitted. The system comprises three parts – hinged and framed glass reinforced plastic (GRP), a steel ladder plate for securing a ladder and a steel box sections adjustable telescopic joist, which allows openings next to party walls to be accommodated by the system.

Speaking of the joint venture Mark Tilston, Systems Development Manager for James Jones’ Timber Systems Division, said: “Stairwell protection systems is something that our business has been investigating and researching for a while now and we are delighted to have found in Ockwells a partner that provides a robust and safe solution for all JJI-Joist distributors and end users.

“The Stairwell Hatch System is well designed, solidly manufactured and above all, it works. They have also produced a simple step by step installation guide which gives you clear advice on many applications. The system allows you to continue using crash deck systems and bird cage platforms which is unique. Their product has been independently tested to give you confidence.”

John Gray, Sales Director at Ockwells, said: “Ockwells are delighted to be partnering with James Jones’ in this new and exciting development. Having spent a great deal of time developing the Stairwell Hatch System it’s great to see that our customers are seeing the benefits from our safety system.

“As well as providing a safe working platform over stairwell openings, the Stairwell Hatch System is also very cost-effective, being reusable means that the initial investment is quickly recouped when compared to the cost of using sacrificial joists, which can run into hundreds of pounds per plot. We believe that the combined expertise of James Jones’ and Ockwells will result in significant health and safety, and cost benefits to James Jones’ customers.”


Premier Guarantee Technical Standards Manager, John Gilbert, provides technical guidance on the treatment of Cross Laminated Timber. The recent interest in ‘modular buildings’ as a solution to the housing crisis and current skills shortage, has brought forward the potential use of ‘CLT’ (Cross Laminated Timber) as a structural panel to produce wall panels or indeed modular pods.

A number of CLT products have third party product approval for the use as a structural plank for construction uses. However, it is also important that manufacturers have a quality management process to ensure consistent quality. Usually these approvals and manufacturing processes are for the solid plank and therefore full designs of the construction including its external cladding. are required on a site by site basis. CLT as a structural timber product isn’t preservative treated. It is also difficult to ‘post treat’ the panels due to the compact layers of softwood timber making penetration of the preservative across the full cross section difficult to achieve. So, it is important that the design keeps the CLT panel completely dry, particularly at ground level and around critical junctions.

Where structural timber, such as these wall panels are to be used in an external wall construction consideration should be given whether timber treatment is necessary if the species of the timber isn’t sufficiently naturally durable.

The vulnerability of timber in external walls is particularly critical where the timber is positioned in certain areas including at the horizontal damp proof course without the inclusion of a treated sole plate. Whilst the use of CLT panels in external walls is a relatively new occurrence in the UK, wall panels incorporating CLT have been successfully used in Europe.

Premier Guarantee are actively involved with the Structural Timber Association and have recently supported and endorsed technical guidance produced by the STA. The recently reviewed CLT guidance is available via:

STRUCTURAL TIMBER ASSOCIATION: www.structuraltimber.co.uk

BM TRADA: www.bmtrada.co.uk


Where projects are proposed that incorporate CLT wall panels; they must not be used with a render or other cladding system that is directly bonded to the wall panel. A drained and vented cavity must be provided.

The CLT panel must be suitably protected as follows:

At DPC level:

The CLT wall panels can be positioned directly onto the horizontal dpc (over the substructure

walls) without a treated timber sole plate providing that:

• The DPC extends at least 50mm past the face of the CLT and in the case of on the cavity wall side- extends down 50mm below the horizontal DPC without bridging the cavity.

• The lowest level of the CLT panel where it sits onto the horizontal dpc must be not less than 150mm above the finished ground level. The residual cavity must extend 225mm below the lowest horizontal DPC level.

• Open brick perpends / Weeps should be sited under the external horizontal DPC in the cladding at 1200mm centres.

• Measures to prevent cold bridging at the substructure wall / ground floor / CLT wall panel junctions must be in place.

• Ground levels immediately in front of the external wall should slope away from the building cladding.

• CLT panels must not be constructed into ‘troughs or pockets’ e.g. for an internal wall panel on a structural slab. The risk of hidden damage from accidental water leaks could lead to moisture collecting around the panel.

Above horizontal DPC level:

• All exposed end grain to the wall panel must be suitably treated (e.g. end grain edges of the panel or where holes are cut through the panel to form openings – windows, doors, flues etc.) The end grain sealant should extend 50mm onto the panel sides.

• There must be a drained and vented cavity with a minimum 50mm residual cavity retained.

• The external wall insulation must be a ‘breathable’ type insulation and directly fixed to the CLT wall panel.

• An approved breathable membrane must be installed to protect the insulation on the cavity side.

• Suitable approved wall ties must be used which are secured to the CLT panel.

• The CLT panels should be protected on the ‘Warm side’ by a suitable vapour control layer

(vcl) unless interstitial condensation risk analysis calculations prove that the risk of interstitial condensation will not occur within the construction.

• The structural engineer must provide details of suitable mechanical fixings to secure the CLT panels to the substructure.


• The project using CLT panels must be supported by full structural design specifications.

• General construction should follow the guidance contained within Timber frame section of the Technical Manual.

• Detailing for Gas membranes must be considered on a project by project basis and you should consult with our Warranty Surveyor for further advice.