dry rot experts

[Wiper]

Do any of you experts know the possibility/probability that dry rot (fungus) will occur in a product called timberguard. This is essentially pressure treated wood 100% encased in PVC type material.

The product is available in various sizes and can be used for pilings for docks, stringers/support boards for docks, pilings for boat lifts, whales for seawalls etc. It's production is based on a Naval study showing that wrapping pilings at the mud line was effective in minimizing the marine borer damage that markedly reduces the life of such pilings.

A company expanded on this idea producing a completely encased product. My plan was/is to use this product along with trex (or similar product) boards and stainless hardware etc. along with vinyl wall material and high tech tie back rods to hopefully more than double the longevity of the dock, seawall and boat lift supports with a 30-50% increase in cost (maybe only in my dreams).

I then thought about dry rot in boats due to encapsulated wood getting exposed to a small amount of water. It seems to me that this would be the exact scenario with this product (encased wood with nail/bolt holes = exposure to water and dry rot).

I can't seem to find much info. on the susceptibility of pressure treated wood to dry rot? Also, I have read that dry rot is more of a problem in a fresh water environment than salt, and my application is for salt water.

This is a great company with a long history, although this particular product has only been in use for about 5 years. It has a 20 year warranty (of course as is usual does not cover any labor), but as best as I could understand, it seems to only cover the encasement for the 20 years.

If this product functions as it theoretically should, I think it may be worth the additional expense for my application.

If any of you have any information relative to the potential for dry rot of this product, I would greatly appreciate it.

rick

[JackB]

You my already have read this but it would appear that encapsulation is a good way to fend off rot.
http://engineer.cmiwaterfront.com/ti...r-piling-2.php

[ndb8fxe]

Are these things encapsulated after they are cut to size? If you have to cut the product how do the cuts fend off damage?

[Wiper]

Thanks Jack. Yes, I had read that. The encapsulation appears to be quite good for fending off what it was intended to fend off, the marine borer, and there is reduced oxygen. However, I think the fungus of dry rot does OK in low oxygen situations. Also, if it can gain a foothold via a screw hole in the transom of a boat in which a little water soaks in, it will certainly be able to do so where bolt attachments to timberguard occur. Maybe the treatment and the fact that it is in a saltwater environment is enough to stop the fungus. As I mentioned above, the Naval study speaks volumes on the effectiveness of PVC wrappings, however, I'm not aware of a study on fully encased materials, which to some extent creates a potentially different environment. I guess my question is clearly based on my ignorance, but seems like there should be a clear answer somewhere, and again the fact that this very reputable company only warranties the encasing is perplexing.

ndb8fxe- Yes, they are encapsulated after being cut to a few standard sizes. However, invariably some timbers will need to be cut to size depending on needs, and the ends and/or damaged areas can be resealed.....or not. The resealing is as much for aesthetics as functionality....I think.

thanks again for any responses.

[tobnpr]

You are correct in that rot occurs from fresh water. The fungus cannot grow in salt water; salt water damage to wood is generally by marine boring organisms.
Just like wood that has been encapsulated in epoxy resin, all is well indefinitely until that barrier gets breached. Unpotted screw or bolt hole, or a crack- is all it takes for moisture to enter. Once it does, the epoxy effectively traps the moisture accelerating the rot process.

The encapsulated lumber sounds like a good idea in theory. You say it's "pressure-treated" wood, but that's not specific. The stuff you buy at Home Depot is treated with either ACQ or Borate; ACQ is better but still not up to marine grade. Pilings still use the old copper/cyanide formula that was made illegal for most uses. If lumber that has been treated in that method were encapsulated, and that was breached at some point allowing the wood to get wet, it would still last a good length of time IMO.

[76GMC1500]

Galvanized bolts may last longer in that app. than stainless bolts. You don't often see stainless hardware on a dock, especially in areas just above the waterline where fasteners may be wet and exposed to air. Use hot dip galvanized as it is a thicker coating. If you're really feeling rich, you could use Monel.

[thataway]

Pressure treated wood will dry rot, under the correct circumstances. A much better solution is to use the PVC pipe as casing--Jet in the pilings, with sections of PVC pipe in the center of the tubing, such as outer pipe 4 to 6", the inner pipe 2". Put a "shield of galvanized sheet metal at the bottom--and put rebar and a few feet oc concrete in the bottom. Jet the piling in place. Drill fill with concrete and rebar up to the level where you will be drilling the stringer holes. Put on the stringers, then fill the rest of the pipe with concrete and rebar. This is being used as a primary construction technique in a number of areas. A friend pumped the concrete over 300 feet over is house--and put in several dozen pilings. These are less expensive than pilings, or any synthetics--and are stronger--basically re-inforced concrete with a PVC (Or PAVC) covering--which sould last a very long time...