treated pine vs hardwood for bearers and joists outdoors

[russ34]

which is going to last longer [assuming both unpainted]?

[Bleedin Thumb]

Treated pine. CCA bearers and joists are guarenteed for 40 years I think. You cant use CCA treated decking boards. Do a seach of this site, there has been lots of threads.

[ausdesign]

Yes CCA but I'd possibly qualify that with 'seasoned F8 (mgp10)pine - CCA treated'.
I had an interesting call a few weeks back from people who had a deck built & weren't happy with the job.
I started to take notice (usually steer well clear of building disputes) when they said that one of the main beams underneath was cracking.
Anyway it was close by . . . . . .
Turned out it was a bearer that was the problem - two 100*50's nailed together; but I swear both bits of timber (in fact all the timber - bearers & joists) were around F4 garden grade with both having the biggest knots & the uncanny thing was that the knots lined up perfectly - straight out of the same tree.
The chippie was trying to pass it off when the owner started about his insurance company & that if someone fell through & killed themselves etc etc
Made me think even though you may not need a permit somewhere down the track the azaleas may hit the fan.

[russ34]

i have nailed bearers together too but in size rangeing fromm cca 190 by 35 up to kd hardwood 240 by 35......knotty 100 by 50 sounds rather rude doesnt it....you really have to wonder about the mentality of tradesmen doing things like that in situations where peoples lives may be at risk.....thanks for the replies

[tisme01]

cca is guarenteed for a minimum of 40 upto 50 years depending where you go that covers termite and fungal rot of timber you wont get any guarentee with hardwood

[glock40sw]

cca is guarenteed for a minimum of 40 upto 50 years depending where you go that covers termite and fungal rot of timber you wont get any guarentee with hardwood

G'day.
Ummm... I built my back deck with 8x2 Tanalith E treated spotted gum joists.

Tanalith E treated hardwood out lasts CCA treated wood by 10 to 15 years.

Ask Koppers-Arch.

CCA pine will be rotted and long gone and the Spotted Gum will be still standing as good as the day it was installed.

Pine is a 4 letter word and considered to be noxious weed to a hardwood sawmiller.

I have seen termites travel over hardwood just to get to Pine.

[Bleedin Thumb]

Hi Trevor,
Koppers - Arch may make the claim but I doubt that treated hardwood will out last treated pine.

As you probably know when you treat hardwood in an autoclave the treatment cannot penetrate the heartwood as the cellular tissue is closed and lined with tannins and resins. This means that the treatment is only effective on the outside of the log.

I'd guess that if you are treating saw plank that doesn't contain heartwood you would be OK but as its not a clear destinction of what is heartwood and whats not... and given the fact that sawmillers like every one else in society will try and get as much as they can from a given resource.......I just wouldn't feel safe not to get untreated timber if I was using treated hardwood on a regular basis.

The reason the guarantee period of TP is going up is that has proven the test of time since it was introduced.

Another reason I would prefer to use TP over THW is that it is lighter and I'm always on the lookout for ways that make the job easier.

[glock40sw]

G'day.
Fair enough.
BUt untreated spotted gum truewood is durability class 2.
That means it will out last treated pine.

Treated hardwood sapwood will also outlast T/Pine.

But, as you say, treated pine is lighter to work with.

[Bleedin Thumb]

Trevor do you know of a web link that has Aussie Hardwoods and their durability classes shown. It would be handy thing to have.
PS what do you mean by true wood?

[glock40sw]

G'day.
Pine has sapwood and heartwood.
Hardwood has sapwood and truewood and heart in the centre.
Heart in hardwood is the very centre where the pipe (hole) is and it is usually full of mud. Hardwood heart is of very little use unless it is tight heart.
Hardwood landscape timber is usually heart included. SO are some large endsection timbers like bridge girders and piles.