Preservatives & finishes

Timber near seawater

Q: We are a structural engineering consultancy managing a project involving refurbishment of an existing outdoor pool and its surrounding timber deck. The contractor has used H3-treated pine to replace some joists. We see a potential durability issue as the deck is located over sea water in a harbour and is potentially in the splash zone of tidal action. AS1684.2 provides advice relating to treatment levels and H6 is recommended for marine environments but that may be excessive.
What would the recommended treatment level be? What are the implications of allowing the contractor to use H3-treated pine as this timber is already on site? Could we expect to get 20-year design life out of the treated pine? Read Answer

ACQ now goes to H5

Q: I am drafting a deck/pergola and have been told by council that cross bracing at the proposed 850 mm height will be almost ineffective, and that I should concrete the posts in rather than using post stirrups. They recommended H5 treated timber. I am wondering what is H5 treated timber? Is it just CCA pine or treated with another product? Is there another product I can concrete into the ground that isn't CCA? Read Answer

Tackling the ‘yellow’ peril

I have just installed a modern American oak staircase with cantilevered treads. I want to keep to the original natural ‘whitish’ colour but I have been told this is not possible without eventual yellowing. Please suggest the best product for sealing the stairs that would also be hard wearing. Read Answer