Author Topic: Waterproofing wood for outdoor projects?  (Read 824 times)

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Offline A.O.

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Waterproofing wood for outdoor projects?
« on: January 17, 2018, 11:31:54 AM »
So I have some projects coming up that I need to try to preserve the wood on. I wont be buying the wood but rather milling it from my trees, mostly Loblolly pines. Most above ground stuff will do ok with proper staining/treating. The parts I'm concerned mainly with are posts in the ground, and I have a couple docks/piers I need to build. Yeah, Cyprus or cedar would be the way to go but I have none on my property.

Any Ideas?

Offline MountainDon

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Re: Waterproofing wood for outdoor projects?
« Reply #1 on: January 17, 2018, 12:06:38 PM »
Buy PT posts. Those will last if you use the proper grade of treatment. We have some PT 4x4 posts I installed in 1985, some in 1991. Some are for fencing; about 12 are the basis of a roofed playground structure. I have never had to replace any. About 10-12 years ago I modified the playground a little and dug out two posts. They were still fine and I used them again. I all cases I simply pounded the dirt back in the holes, no concrete was used. If you are building a dock and the posts will be wet seek out the special grade for that use.

Just for comparison I have also made use of some ponderosa pine logs, 6 to 7 inch diameter for a "quick and dirty" fence repair at our mountain property. I used some preservative I got from the big box store on 2 posts, ran out and did not treat a third. I should have saved the effort. IIRC it only took about 3 years for the posts to be wobbly. I replaced them all last summer with PT. 

Oh, I also have a few steel posts used for assorted projects. Those are great too, some being as old as 20 years and solid as a rock still.

Of course those PT posts are the old CCA preservative, but if you use modern Non-CCA ground contact ACQ or CA you should have long lived posts too. Use fasteners and other metal parts that are approved for todays chemicals.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline A.O.

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Re: Waterproofing wood for outdoor projects?
« Reply #2 on: January 17, 2018, 01:02:19 PM »
I guess you missed the point of my post!

Offline hpinson

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Re: Waterproofing wood for outdoor projects?
« Reply #3 on: January 17, 2018, 02:06:39 PM »
Above ground? There are a variety of weather resistant penetrating wood sealers, and paint. Penothan is a brand that comes to mind for a quality sealer.  It needs to be re-applied periodically.  Paint, does an even better job, but needs also to be frequently replied, with the attendant scraping and prep. There are some sealer primers like Bioshield that discourage surficial mold.  Sun and weather exposure are going to drive how often you reapply.  I have pine window trim painted with Sherman Williams duration paint, white, that is in full southwestern sun exposure in the afternoon. It is a ferociously durable paint, but I have to redo it every six years or so. Dark colors are going to absorb heat, and light colors will reflect - all contributing to longevity.

Below ground? Not an easy outcome to achieve, especially with a softwood. PT wood has the preservative literally injected under pressure deep into the cellular structure of the wood.  Not something that most would be able to do.  Previously you could treat yourself with creosote, but that's too toxic I understand, and I don't think it is available anymore.

So you are left with surface protectants per above but water and insects will very likely make short work of that.  Are there termites or carpenter ants in your area?

Pine is not a naturally rot resistant wood like Cedar or Redwood.  I have cedar (Juniper) posts on my property that were placed probably in the 1960s and are still ok underground.  Redwood that was placed as a buried foundation for a garage in 1984 by a previous owner was completely degraded by 2004, and would crumble in your hand. Mine is a relatively dry environment too.  In parts of New Mexico, if you place any untreated wood on the ground, termites will have at it very quickly - takes a remarkably short time to degrade the wood fully.  In wet areas it will just rot.




Offline MountainDon

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Re: Waterproofing wood for outdoor projects?
« Reply #4 on: January 17, 2018, 02:39:41 PM »
I guess you missed the point of my post!

My point was that to insist on using locally sourced wood in an in ground application such as a post is a recipe for a lot of extra work later on and I dislike repair work later on if a better product or technique first will give more satisfactory results later on. It is not easy, maybe not possible, to use a wood like pine and a DIY preservative method that will last decades.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline A.O.

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Re: Waterproofing wood for outdoor projects?
« Reply #5 on: January 17, 2018, 02:40:29 PM »
Yeah, I was a painter/painting contractor for 20+ years so I understand how things work. Most of the "above ground" stuff I'm talking about are small outbuildings, shooting benches/houses and things like that. Was hoping to find a way to keep docks and posts from deteriorating too quickly. The docks would be of the floating variety so the wood wont actually be "in" the water but just above it..

Maybe that spray on sealer "as seen on tv" might work ;D :)

Offline A.O.

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Re: Waterproofing wood for outdoor projects?
« Reply #6 on: January 17, 2018, 02:41:55 PM »
My point was that to insist on using locally sourced wood in an in ground application such as a post is a recipe for a lot of extra work later on and I dislike repair work later on if a better product or technique first will give more satisfactory results later on.

I understand, but looking for something not commercial if can be done..

Offline hpinson

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Re: Waterproofing wood for outdoor projects?
« Reply #7 on: January 17, 2018, 02:48:32 PM »
LineX (a bedliner) or equivalent? Epoxy? Expensive!

« Last Edit: January 17, 2018, 03:19:43 PM by hpinson »

 

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