Using treated pine for bearers

[Kody]

I was going to use some "treated" pine for the bearers to screw the floor onto. I found some very high quality wood and brought it home to cut to length for the bearers. I was going to use the treated pine on top of the steel frame as it is so rot resistant. I now find out that this material is highly corrosive (extremely so), wont hold paint and wont accept gluing. The copper compound used to impregnate the timber will corrode the zinc on the bolts and leave them with no protection at all. The steel bolt then corrodes very quickly (caused by the copper compound) to the point where it all literally falls apart. Exit all the treated pine. A good idea that went horribly pear shaped! I will buy some Baltic Pine that I saw in Rockhampton and this timber will be the main form of wood that I will use for a lot of the construction where form is required but not for high strength structural areas. It certainly is a beautiful clear timber, almost devoid of knots and is a beautiful light colour. It also glues very well and paint sticks to it. I will use the treated pine now in the garden to make a small fence around our home size sewage treatment plant.

Kody

[48Rob]

Researching decisions is always wise!

Rob

[GPW]

What about slobbering all the bolts with the same black nasty stuff we put on everything else ??? I’ve got Treated wood for my bearers too ...

[NathanL]

Construction adhesive will adhere and bond treated lumber as long as it's not fresh out of the treatment process and still dripping. Tar paper can be used as a barrier between the wood and any metal as well if you have some on hand.

[GPW]

Cowboy , like floor joists ... the framing under the floor board(s) , some have it , some don’t ...some just bolting the plywood floor directly to the metal trailer frame ...

[86bigred]

we use treated pine and use galvanized threaded rod here in construction, actually it is in the building code, nothing corrodes. i guess copper coat antisieze compound is bad as well, my guess would be all the oil rigs arround me using this stuff on all the pipes and threaded studs is real bad. my i ask where you got this info, i have used lots of galvanized fasteners on treated lumber while working as an rv tech with no corrosion ether.

[GuitarPhotog]

I was under the impression (gathered from another thread here) that pressure treating did not increase its resistance to rot, only to insect invasion. I see from research on the 'net that PT also inhibits fungal rot, but does nothing for wet-rot, the biggest cause of wood failure in trailers (from water leakage).

<Chas>

[Kody]

I decided to use the treated pine in the garden and will use Baltic Pine instead for the bearers.
Here is some interesting info about using treated pine and galvanized bolts/screws.

http://woodworking.about.com/od/safetyf ... Lumber.htm

I am of the impression that "wet rot" of wood in trailers is actually caused by spores from fungi that are passed into the timber by water absorption especially into the end grain of the wood. Wood immersed in salt water for years remains basically the same and is well preserved by the salt. It's fresh water that causes all the hassles as it's laden with fungi spores and other things that eat wood. This is why it's so important to fully seal the edges of the ply in the TD with a laminating epoxy resin, applying at least two coats to seal it.

I saw the video on the news here in Aust. of the walkway in the US that collapsed killing lots of people. The failure was caused by the galvanized bolts corroding away rapidly by the copper compound in the treated pine. There was also a video on the news where a concrete walkway collapsed due to poor design and poor building techniques.
I'm also not in favour of using the treated pine as I have discovered that I am very sensitive (nose bleeds) to any dust or shavings from it. This has been the result of over exposure to the stuff.

Kody

[mezmo]

I wouldn't use the PT wood for anything you'd come in contact
with by touch or breathing - especially in a confined space. The
chemical off-gassing [I'm sensitive to various chemicals.] and
corrosion problems are enough to put me off. For as much as
would be needed in a TD/TTT, a naturally rot resistant wood/
lumber/timbre wouldn't be prohibitively expensive or that hard
to track down and would be worth the effort in my view.

Cheers,
Norm/mezmo

[lancew]

so all the decks i made in last 20 years are going to fall down and apart ? i mean they are held together with nails,screws, lag bolts <screws> and bolts. and the metal post holders that are sitting on concrete will rust to nothing due to using pressure treated lumber. dooooont think so. maybe i am seriously confused about this thread.

[48Rob]

so all the decks i made in last 20 years are going to fall down and apart ? i mean they are held together with nails,screws, lag bolts <screws> and bolts. and the metal post holders that are sitting on concrete will rust to nothing due to using pressure treated lumber. dooooont think so. maybe i am seriously confused about this thread.

The new chemicals being used (ACA and CA) are more corrosive than the previous (CCA).

I had cause to replace the decking on a porch recently that was built 18 years ago with CCA.
The decking had been replaced just a few years ago with the new chemically treated wood.

I found that many of the screws holding the new decking lumber were badly rotted (cheap galvanized screws).

After taking a few braces off the framing of the deck, I decided to rebuild the whole thing, as most of the old galvanized screws and bolts and all of the nails that were holding it together were badly deteriorated, to the point they had lost 75%+ of their mass.

Instructions call for "heavily" coated fasteners.
Box stores rarely offer them as consumers want cheap.
So, short answer is; if quality coated or stainless fasteners were used, probably not.
If cheap fasteners were used, maybe.

Rob

[Lgboro]

Some of the Chinese bolts and screws are probably not as advertised. A company here that manufactures large commercial ovens and dryers in the fairly recent past tried to save money using stainless bolts and fasteners from China. The result was equipment part failures and when analyzed the components in the metals could not be identified. The "stainless" parts had failed due to rust and severe corrosion issues and cost the company millions of dollars to correct.