![]() They are expressed as a fraction clear span in inches (L) over a given number. Maximum deflection limits are set by building codes. Only live loads are used to calculate design values for stiffness. In other words, how much a joist or rafter bends under the maximum expected load. Stiffness of structural members is limited by maximum allowable deflection. Perhaps the joists were strong enough if they didn’t break! But lack of stiffness leads to costly problems. For example, first-floor ceiling plaster would crack as occupants walked across a second-floor bedroom that was framed with bouncy floor joists. Strength and stiffness are equally important. Beams, studs, joists and rafters act as a structural skeleton and must be strong enough and stiff enough to resist these loads. The house acts as a structural system resisting dead loads (weight of materials), live loads (weights imposed by use and occupancy), like snow loads and wind loads. This article will focus on how simple beams like joists and rafters react to loading. If, when the loads of the house are combined, the house weighs more than the soil can support – the house will sink until it reaches a point at which the soil can support the load. Remember when your science teacher said: every action has an opposite and equal reaction? Well every building load has an equal “reaction load”. The structural goal of a house is to safely transfer building loads (weights) through the foundation to the supporting soil. A complete analysis of wood’s mechanical properties is complex, but understanding a few basics of lumber strength will allow you to size joists and rafters with the use of span tables. Wood is naturally engineered to serve as a structural material: The stem of a tree is fastened to the earth at its base (foundation), supports the weight of its branches (column) and bends as it is loaded by the wind (cantilever beam). ![]() For quality assurance the Futurebuild range is manufactured with independent audit processes and product certification.Īll Futurebuild LVL products are manufactured using a type ‘A’ bond with less than 0.5mg/L formaldehyde emissions from the final product (equivalent to E0).Using span tables to size joists and rafters is a straight-forward process when you understand the structural principles that govern their use. Characteristic Properties are determined in accordance with AS/NZS 4063.2:2010 and so comply with the provisions of the New Zealand Building Code through clause 2.3 for engineering design in accordance with NZS3603:1993 Timber Structures Standard.įuturebuild LVL is committed to manufacturing innovative engineered building products. Solid Futurebuild LVL products are manufactured in accordance with AS/NZ 4357, Structural Laminated Veneer Lumber. computeIT ®software suite available for specific engineering design.Supported by technical support and software from Futurebuild LVL.Residential Span Tables available - refer to brochures below.Available Forest Stewardship Council® (FSC®) certified (FSC® C007103) upon request.Manufactured from sustainably-grown NZ plantation pine.Stringent quality control - EWPAA certified.Each piece is branded for ease of identification.Untreated and H3.1 LOSP treated product available made to order subject to minimum volumes and lead times, Contact us for further information.Readily available H1.2 treated using a glue line and surface spray treatment to the requirements of NZS 3640.Veneers are bonded together using type 'A' (marine) bond, known for long-term durability in structural applications.Straight, true, strong, lightweight and dimensionally stable.hy90 Futurebuild LVL may be directly substituted for an equivalent section size SG8 which has been specified using NZS 3604, designIT for houses software, or subject to Specific Engineering Design.Less warp, twist and cup than double-sawn sections (90mm).45mm thick manufactured in 240x45 and 300x45 hy90 sections for use in joist and rafter applications.Manufactured to a target 88 mm breadth with a tolerance of -0 mm/+ 3mm (at the time of leaving the Mill) to fit within the framing. ![]() With a 19% increased stiffness and increased structural properties over SG8, hy90 is the ideal complement to hyJOIST mid-floor solutions Features & Benefits Hy90 is now also manufactured in a 45mm thickness in 240 and 300mm depths for use as floor joists and rafters in houses. Applications will typically be for load-bearing lintels in houses, garage door lintels and beams, or for beams where 90mm width is desired. Hy90 ® is a laminated veneer lumber (LVL) product initially developed for use as structural beams where the builder wants consistent performance, coupled with a material that fits within 90mm framing.
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