Cracks Perpendicular to Grain in Wood Beams/Columns

[jonnywalker]

This structure supports a waterslide and is wet a significant amount of the year. As you can see if you look closely at the pictures attached there are small cracks running perpendicular to the grain of the timber.
Based on this article,

http://forestpathology.cfans.umn.edu/microbes.htm,

and the fact that the structure is constantly wet, I believe that this is brown rot (61% sure). This is occurring at both columns and beams.

I was wondering if I could get a couple of opinions on what people thought was going on in these pictures. I've inspected a number if different timber structure, but this is the first time I have come across anything that looks like this. I have come across brown rot but it is usually brittle and this is not the case with these pieces (yet). It is also worth noting that I did not drill the wood to see the condition of the core which should have been done. Your expertise is greatly appreciated as always!

 

[dik]

Serious Load Reduction issues... major overhaul...

Dik

 

[jonnywalker]

Wow that is what I was thinking too I just didnt want to say it out loud. Clients wont be happy. What would you suggest as the cause?

 

[msquared48]

Could be rot, but I am wondering if the beams could have heartwood in them, particularly the last of the three photos, that would be far more susceptible to the cracking and deterioration of a continupusly wet environment.

I will have3 to admit that I have seen less cracking in asphalting paving that has failed than these beams.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

Mike...
The second photo shows what looks like extreme dry-rot, aka brown rot, conditions. Without undertaking any tests, if dry-rot, then it has likely lost over 90% of its capacity.

Dik

 

[msquared48]

That's true dik if that is the case. What did the ice pick say?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

"Help, I'm sinking"... Use my handy Swiss Army Knife and on a couple of occasions have embedded it to the handle (hilt?)...

Dik

 

[jonnywalker]

Unfortunately I was not able to probe the members in the first link or the last link. I did probe the member in the second link and it was solid; no penetration. It seems to me that if you can see the cubical pieces in the wood, then the damage has already been done and the wood is now 'dry-rot' and has been significantly compromised (Dik estimated 90%). Is that a safe assumption?

Does white rot have the same effect on the structural capacity of wood as brown rot does? From what Ive read brown rot is the rot to really worry about. Would you recommend two different solutions to white rot and brown rot? How long do each of the rots take to become significant? I read something that said colonies can establish themselves within 7-10 days with optimal conditions, but how long would it take for the wood to lose its structural capacity if afflicted by brown rot? or if afflicted by white rot?

Any good references would not go to waste!

Thank you for the responses and thanks to Mike for the heads up about posting in 2 forums!

Dik:

I found another thread where you recommended a book, 1989 The Encyclopedia of Wood Revised Edition / Sterling Publishing Co, I was wondering if you thought it was worth purchasing. I have wood codes and design books, but they do not have a lot of information regarding damaged wood and fungus that destroy it. Id like to read more about the effects of white rod on timber and how it effects its structural capacity. Brown rot seems pretty straightforward (dangerous), but I'd still like to have more references. These are the websites I have been reading:

http://ohioline.osu.edu/hyg-fact/3000/3300.html

http://forestpathology.cfans.umn.edu/microbes.htm

http://www.buildingpreservation.com...our-rots&catid=8:timber-infestation&Itemid=85

 

[dik]

Ron... jump in anytime!

There may be a newer edition out. My current issue is 2007. It is published by the USDA and printed by Skyhorse Publishing. I've found it to be a useful text... as I recall, it wasn't too pricey. To me, it's a good book to have.

There are some other texts/publications, I'll see if I still have a bibliography... this is something where Ron can also provide a 'bunch of info'... I'll see what I can dig up.

White rot, works on the lignin, leaving the lighter cellulose can be as big a problem, although, in my experience, not as fast and is more species selective.

See the attached from another article:

White rot fungi

White rot fungi can degrade all cell wall components, including lignin. They often cause a bleaching of normal wood coloration. Their ability to metabolize large amounts of lignin in wood is unique among microorganisms. The thousands of
species that cause white rots are a heterogeneous group that may degrade greater or lesser amounts of a specific cell wall component. Some species preferentially remove lignin from wood leaving pockets of white, degraded cells that consist entirely of cellulose, while others degrade lignin and cellulose simultaneously. Degradation is usually localized to cells colonized by fungal hyphae and substantial amounts of
undecayed wood remains even after advanced decay has occurred. A progressive erosion of the cell wall occurs when components are degraded simultaneously or a diffuse attack of lignin may occur by species that preferentially remove lignin .

Strength losses are not significant until late stages of decay. White-rot fungi are common parasites of heartwood in living trees and are aggressive decomposers of woody debris in forest ecosystems.

Dik

 

[Archie264]

Is it really so bad as to downgrade the capacity by 90%? (I'm asking more than advocating, as I'm certainly no wood expert.) If the probe indicated solid wood I would have thought there was still a significant amount of remaining capacity.

In another thread there is guidance given for gauging the remaining strength of wood members after a fire; is this that far removed from that, or do these cracks run so deep that it wouldn't be fair to compare them to surface charring? Then again, I had a tree house collapse under me as a kid from plain old wet rot, so I'm not for ignoring warning signs.

I stand ready to eat crow.

 

[dik]

No crow...

but, your material can lose 30% or more of the strength without showing signs of deterioration or weight loss... and damage is progressive... the 'little critters' go dormant when they are dry... Judging from photo 2, the hyphae are likely thoughout the material... you can use an incremental borer and microscope to confirm...

Dik

 

[Archie264]

Thanks, very interesting. I need to learn more about wood rot. I'll be watching this thread.

 

[berkshire]

I think DIK has it right. Bore and microscope.
Also in your last picture you have a shot of the planking also showing rot.( left center of the picture.)
Was this lumber pressure treated before installation? Some of it appears to have a greenish cast, however that may be just the light.
B.E.