David Smith St Ives Limited Origional Factory jji joist services, servicing zone Working in the Second Factory jji joists, i-joists
jji joists, i-joists

jji joists

David Smith is an authorized distributor of James Jones & Sons’ JJI-Joists. Established in 1905, James Jones & Sons Ltd is committed to excellence in customer service, quality products, superior engineering, and prompt delivery.

The JJI-Joist is a structurally engineered timber joist, combining high-grade softwood with an engineered composite panel. Using advanced technology these components are combined to produce an innovative alternative to conventional construction timber. They are produced on the first purpose-made I-joist production line in the UK, custom built to produce JJI-Joists to UK preferred dimensions.

The JJ-IntelliRoof™ is a fully engineered panelised solution for fast onsite erection of a fully decked, insulated, watertight, braced JJI Joist Room in Roof. The system is independent of the building construction method and can be used with traditional masonry construction or timber frame with equal ease.

BJ-Beam, is a high specification engineered Glulam beam. This forms a structural unit of great strength and dimensional stability to compliment the JJI-Joist for high load and rim beam applications.

JJI-Joists are available in a range of sizes familiar to the UK Construction Industry with joist depths ranging from 195mm to 450mm. JJI-Joists are constructed from 9mm OSB web and C24 softwood flanges ranging from 45mm to 97mm in width. Refer to Product Range and Sizes. Due to the unique form of the JJI-Joist British Board of Agrément Approval, it is possible to design and produce large volumes of non-standard JJI joists to allow for particular span and depth situations that cannot be covered by the standard range The 220 JJI joist also provides a more cost-effective way of complying with Part E (sound) of the Building Regulations for intermediate floors, as no insulation is required when it is installed at 400mm centres and above.

Whatever size company you are part of, be it a large main contracting company or a sole trader, the new Part L Building Regs affect you. Since air leakage is a major cause of failure to comply, the Cullen Gripper is a useful tool in the battle to ensure compliance. The Cullen Gripper is an easier to use option than masonry hangers. Designed for use in conjunction with the JJI joist, the Cullen Gripper provides an airtight seal at joist end, and can be used on both external & party walls.

jji joists vs concrete

The JJI joist is FSC accredited. Whilst concrete scores very poorly environmentally JJI joists have a BRE Environmental Profile and are ‘A’ rated under most applications defined by the ‘Green Guide to Specification.

The loadings on foundations can be reduced as JJI joists are much lighter than concrete.

Using JJI joists, a floor system can be pre-assembled as a cassette panel, resulting in a more accurate and easier installation.

Generally, lead times are 2-3 weeks, compared with up to 16 weeks for concrete.

jji joists vs solid timber

Number of joists to install cut by over two thirds.

Number of hangers required cut by 75%.

JJI joists are available in lengths up to 12 metres.

No extra insulation between joists.

Longer spans for more design flexibility.

Installing services through the property is easier.

jji joists vs metal web

Holes from MVHR are not hindered by metal struts or lateral stiffening timbers.

JJI i-joists are the system of choice for the service engineers.

Freely available design software for beam and integrated hole analysis.

Cut to length is easier as no solid blocking or metal to cut through.

jji joists - total solution

JJI works closely with manufacturers of wall hangers, ties and fixings to provide a full package. In addition JJI co-operates with floor deck manufacturers, especially Steico (UK), to develop new combined solutions.

Installing Steico Weather Dek2® deckboard onto JJI joists is one solution to ensure compliance with the 40dB requirement of Part E of the Building Regulations without requiring additional insulation or special plasterboard.

Adding WeatherDek2 Fast Fix increases the acoustic performance of the floor to 41dB giving you even better sound resistance. Steico Weather Dek2® also conforms with European manufacturing and environmental certification (EN312/ISO 14001) which ensures the highest level of raw material selection, baseboard quality and manufacturing control. All boards are stamped for ease of identification, giving added assurance.

Joist A+ B+ C D Timber
Depth 47mm 63mm 72mm 97mm Grade
yes C24
yes yes yes yes C24
220mm yes yes yes yes C24
235mm yes yes yes yes C24
245mm yes yes yes yes C24
300mm yes yes yes yes C24
350mm yes yes yes yes C24
400mm yes yes yes yes C24
450mm yes yes yes yes C24

* jji joists are available up to 12m in length.

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David Smith St Ives Limited
Marley Road
St Ives
PE27 3EX
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