11-26-2005, 02:46 PM
The borate is not suitable for ground contact protection and a barrier should always be employed between wood and concrete. The borate will not lessen the strength of the wood itself but you sould keep a few things in mind.
Plates are where the concrete meets the wood frame. Plates are also where the most weight load occurs (compression). This is why the highest grade of lumber is
normally specified for plates. Most Doug Fir lumber has a flat compressive strength of about 1,000 psi (I believe). Not bad but not that great either.
It is not desirable, over time, for a low grade wood to be used in this position so care should be used in choosing the right wood grade for the house plates.
U. Hawaii, Manoa entomology department does a lot of termite testing. In presentations I have attended the entomologist explained that there used to be very effective treatments for termites. They were so toxic however that the EPA has banned them now for a number of years. He also said that the hi-bor (borate) treatments now used have proven to be effective in their termite mound tests for approx. 3 years. Not too impressive in my opinion.
When using hi-bor treated lumber you should buy a gallon of hi-bor and every cut end and every rip should be dipped or brushed with the hi-bor treatment. To not do so simply compromises the treatment. Though borate is pressure treated it does not penetrate completely into the lumber. The larger the beam/post the less penetration.
A chain is only as good as it's weakest link. I have never yet seen a local carpenter do this. Only owner/builders seem to care.
Edited by - Rob Tucker on 11/26/2005 18:55:08
Plates are where the concrete meets the wood frame. Plates are also where the most weight load occurs (compression). This is why the highest grade of lumber is
normally specified for plates. Most Doug Fir lumber has a flat compressive strength of about 1,000 psi (I believe). Not bad but not that great either.
It is not desirable, over time, for a low grade wood to be used in this position so care should be used in choosing the right wood grade for the house plates.
U. Hawaii, Manoa entomology department does a lot of termite testing. In presentations I have attended the entomologist explained that there used to be very effective treatments for termites. They were so toxic however that the EPA has banned them now for a number of years. He also said that the hi-bor (borate) treatments now used have proven to be effective in their termite mound tests for approx. 3 years. Not too impressive in my opinion.
When using hi-bor treated lumber you should buy a gallon of hi-bor and every cut end and every rip should be dipped or brushed with the hi-bor treatment. To not do so simply compromises the treatment. Though borate is pressure treated it does not penetrate completely into the lumber. The larger the beam/post the less penetration.
A chain is only as good as it's weakest link. I have never yet seen a local carpenter do this. Only owner/builders seem to care.
Edited by - Rob Tucker on 11/26/2005 18:55:08
Assume the best and ask questions.
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