# Why is wood rotting ?



## SKC (Apr 7, 2010)

I just looked at a pergola job I did 5 years ago and witnessed a condition I been seeing more of the past 5 years than in my previous 40 years.
Wood 5-14 years old rotting, and not in any of the areas an experienced carpenter would expect to see. Exterior wood window sills with completly unnoticable rot in the middle of the sill not where casings meet sill (typical). Might notice a slight paint blister or nothing, but poke with a finger and through it goes, no logical or possible explanation of why water penetrated.

6x6 best quality Doug fir posts sitting on typical metal post brackets. 
Based with 1x6 and cap moulding, no wood touching grade on a paver patio, rotting , pushed a thin screwdriver 4" into it 2 1/2" above base cap. Doesn't make sense
The window job which was Marvin I installed in 1998, allegedly used a wood preservative (supplied to them by PP&G) to treat the woods from which the windows were made actually caused the rot. Thier were lawsuits and so on.

I am beginning to see some common issues with this rot in un-expected areas, a fair amount of what looks like mildew on same job area but not always seen at specific rotted area, sometimes no visible signs at all, sometimes what looks like paint blister.

I am wondering if anyone else is witnessing similar what appears to be unexplained rotting wood.
I am beginning to suspect these newer acrylic and latex paints are not only not doing thier intended job of protecting the wood from moisture but wicking and or trapping it ???.

I have been at this and seen enough over the years to explain most.
Lately I am puzzeled with what I am seeing, it's not making sense.
I also heard possibly newer growth trees used for making this wood from is a possibility. Been around myself long enough to have noticed the decline in lumber quality. ???
Please share any similar experiences or possible explanations.
I also believe in Good quality "oil base primers" for all exterior wood to be painted.
I am searching for others who are puzzeled by this and thier thoughts.

Thanks and looking forward to any responses or thoughts on this topic>


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## bconley (Mar 8, 2009)

Doug fir isn't going to cut it outside unless it is treated or old growth VG.
If you want it to last use cedar, redwood or some of the tropical hardwoods and pay attention to the details and maintenance.


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## katoman (Apr 26, 2009)

I think it's partly due to "genetically engineered" wood. The new fast growth wood has been altered to grow fast. This leaves it with wider growth rings, more porous cell structure.

This allows moisture to enter more easily. Not much one can do unless you want to search out old growth lumber.


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## Young_Buck (Jul 19, 2009)

Our available wood is crap, and there's nothing we can do about it in the next 150 years.


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## duburban (Apr 10, 2008)

are all sides coated?


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## Railman (Jan 19, 2008)

It all started when they took all the chemicals out of the paint that controlled the little bugs that cause rot, somewhere around the late 70's. It affects everything in the weather.
Joe


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## SKC (Apr 7, 2010)

That I think is just possibly part of the problem, (the new growth woods)


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## SKC (Apr 7, 2010)

Yes all sides coated and well mainted.


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## SKC (Apr 7, 2010)

You're right I have first hand witnessed the diminished quality of our typical wood supplies over the past 45 years.


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## SKC (Apr 7, 2010)

Railman said:


> It all started when they took all the chemicals out of the paint that controlled the little bugs that cause rot, somewhere around the late 70's. It affects everything in the weather.
> Joe


I agree, to be more specific, I have noticed this mold/mildew/black spotting on the exterior acrylic and latex paints mostly in the past 5 years on projects 5-14 years old. I have been and still am a believer of quality oil based primers on all exterior wood. 
The chemical content of paints I am sure changes often , beginning to see negative effects of it.


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## SKC (Apr 7, 2010)

katoman said:


> I think it's partly due to "genetically engineered" wood. The new fast growth wood has been altered to grow fast. This leaves it with wider growth rings, more porous cell structure.
> 
> This allows moisture to enter more easily. Not much one can do unless you want to search out old growth lumber.


I agree with you , I have first hand witnessed the diminished quality of our typical wood supply over the past 45 years, using new/younger growth trees, and possibly the geneticaly enginered stuff.


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## SKC (Apr 7, 2010)

Hey guys thanks for your responses, are you seeing much or any of the puzzeling rot that leaves you with no apparent conclusion of water penetration thru well painted window sills or other areas, making you suspicious of the paints and the woods being used, due to lack of any other explanation.


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## Tom Struble (Mar 2, 2007)

you can't have ''mild''slopes of 5-7 degrees on horizontal members like sills and drip caps anymore,you need to slope at least 15 degrees to shed water asap

we need stop using so much caulk trying to seal every crack,it don't work and can do more to trap water than keep it out

use the right wood species for the issue at hand will go a long way

when all else fails switch to pvc


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## WarnerConstInc. (Jan 30, 2008)

Tom Struble said:


> you can't have ''mild''slopes of 5-7 degrees on horizontal members like sills and drip caps anymore,you need to slope at least 15 degrees to shed water asap
> 
> we need stop using so much caulk trying to seal every crack,it don't work and can do more to trap water than keep it out
> 
> ...


How about a whole house made from pvc?


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## Tom Struble (Mar 2, 2007)

hemp


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## RobertCDF (Aug 18, 2005)

Wood is crap nowadays, and painting it is WORSE especially all 4 sides. Water WILL find a way in and when it's sealed on all 4 sides it just stays in and rots from the inside out. 

I love when I see a deck with a painted frame because I know they shortened the life 5-10 years when they painted it. 

As others have said look for better materials, manmade, steel, aluminum, etc.


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## duburban (Apr 10, 2008)

RobertCDF said:


> Wood is crap nowadays, and painting it is WORSE especially all 4 sides. Water WILL find a way in and when it's sealed on all 4 sides it just stays in and rots from the inside out.
> 
> I love when I see a deck with a painted frame because I know they shortened the life 5-10 years when they painted it.
> 
> As others have said look for better materials, manmade, steel, aluminum, etc.


Interesting point. A double vapor barrier principal. Anyone else agree with this? 

What about priming all sides of clapboards? I'll be doing this in a week or two.


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## Winchester (Jun 29, 2008)

new growth wood is nothing like what wood used to be.

Sapwood soaks up lots of water and rots fast.

Even if painted on all sides water will find a way to wick in and then the paint stops it from drying. Like Tom said, caulking is a culprit too, it might stop lots of water from getting in, but it also stops it from getting out.

IMO, instead of painting maybe try semi-solid or solid stains that are more "breathable" and use more naturally resistant types of wood.

PVC is also a great choice IMO, though I generally use western red cedar.


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## moorewarner (May 29, 2009)

I recently rebuilt some basement door openings out of fir (historic) and replaced some sills/sub-sills out of thermally modified/pt.

I would be happiest to switch to this for exterior wood replacement. 

http://www.accoya.com/

I just found a supplier out of Chicago that will do STL drops.


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## Big Shoe (Jun 16, 2008)

Tom Struble said:


> we need stop using so much caulk trying to seal every crack,it don't work and can do more to trap water than keep it out


 Ditto................All or nothing.


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