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Can we use I-joists as wall studs? I know that they will be adequate in bending, but what about carry tension and compression?

Woodsolutions Answer +

In Australia timber I-joists are marketed solely for use as floor joists. There is nothing in principle against using them for wall studs, but you would have to check with Australian producers to see whether they would warrant their products being used in this way, and whether they have the relevant structural design criteria. You will find phone numbers for technical assistance on company websites.


I have an existing, free-standing carport that is getting built in to become an enclosed garage. Its roller door opening will become 4.8m.
What size beam applies here? Since it's not carrying the roof and just spanning the gap?

Woodsolutions Answer +

Although the new beam will not be carrying any roof load, presumably it will carry the weight of the roller door. You will need someone to do a structural design check, taking into account the weight of the door and the strength of whatever kind of timber you choose for the beam. Perhaps the roller door supplier can provide this service. Otherwise an engineering practice in your area could provide this service.

Roller door support

I have a project in which some existing steel posts need to be moved. The posts support existing 290x90 timber bearers and do not have any visible markings and have been painted over. Is there any way we can determine the grade of the timber in order to carry out a design check of the existing bearers for the new required span? If so can you recommend anyone who can carry out this service?

Woodsolutions Answer +

Accurate visual stress grading requires the surface of the timber to be visible so knots, sloping grain and other features can be assessed. However, if the bearers are a hardwood species knots are usually a minor issue. Although the timber is painted, strength reducing characteristics other than knots, such as significant splits, wood rot or termite damage, would be visible and can be discounted after a careful inspection. If the timber is a softwood it's a little more difficult since knot size and frequency play a bigger part. Once the timber species is identified it can be placed into a Strength Group and the range of achievable stress grades can be determined. It's then a matter of assuming a conservative stress grade that you are comfortable with for your design check. If you are unsure of the timber species, and there are no reliable records, a small sample could be taken for identification. We suggest you contact Dr. Jugo Ilic who is an authority on wood identification. If you email Dr. Ilic at he can advise on the required sample size and fee for service.


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