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optimist
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# Posted: 18 Sep 2014 07:03pm
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I want to build a small (10 to 12 ft square) cabin to be used as a utility "shed". I've got plenty of deadfall that's still relatively solid, standing dead, and stuff that just doesn't know it's dead yet. Not much caring about bark since I plan to bandsaw the logs to consistent thickness...similar to the old tobacco cabins in my area. So, can I use what I have at hand or am I asking for a world of trouble?
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Nirky
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# Posted: 18 Sep 2014 08:01pm
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That's what I got, and I'm doing it. Structurally sound. I wonder if the blue fungus inhibits other insect infestation?
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MtnDon
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# Posted: 18 Sep 2014 08:13pm
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Standing beetle killed pines are used commercially. No problems as far as I know. The wood retains its strength. No benefits as far as insect resistance. Sometimes people will pay extra for nice blue stain T&G boards.
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Don_P
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# Posted: 18 Sep 2014 09:03pm - Edited by: Don_P
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From the Nat'l Grade Rule,
Insect holes: pin holes, grub holes and toredo holes are handled on an "equivalent smaller" basis. Equivalent smaller shall mean that the area occupied by all the holes shall be added together and treated as the maximum size hole permitted. For example 12 1/4" holes shall be accepted as equivalent to a single 1" hole. The poorest face shall govern.
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Relatively solid is a huge problem, by the time we detect decay the mechanical properties of wood are already all over the road and not for the better. If it has been down for any length of time or if it shows signs of incipient decay, use it for a non structural part, trim, panelling, flooring, shelves, cabinets, etc. If in doubt use it for formwood, something to run the wheelbarrow on, or heat
The SPIB pocket grading card is here;
http://www.spib.org/docs/2dimension_eng.pdf
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Don_P
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# Posted: 18 Sep 2014 09:27pm
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Just saw the posts above, I was slowly leafing through the grading book. Blue stain, sapstain, is not a decay fungi. It is going after the sugar in the cell lumen, the cavity within the cell, rather than eating the cell wall itself which is what the rotters are doing.
Bluestain is generally limited to the sapwood, where the sugar is. The heartwood of the tree is where the spent by products of the tree's growth are stored, yup the pretty colors that create heartwood... tree poop  Anyway, bluestain is usually the first fungi to move in after a tree is cut. It is not considered to be structurally harming the wood but it is indicative of the right conditions for decay fungi to move in. If you are drying bright lumber and it is getting bluestain, change the drying conditions to something more agressive. Bluestain is everywhere in the environment and is in the bark. Beetles can take it into the wood with them helping to spread it in beetle killed standing dead trees. In that case the blue is already there when you cut the tree. I spread the spores with the sawblade, I've noticed if the blade cuts thru bark while entering the log the wood is much more likely to develop bluestain than the boards that come off after I've knocked the cover off the log.
Ways to slow fungi;
dry the wood, fungi need ~25% or higher moisture content.
Cool, most fungi are dormant below ~40 degrees F
Deny it oxygen, this was the reason for ponding logs and the reason you'll see sprinklers on the log decks at some large mills.
Poison the food, the alphabet soup of preservatives. Borate will stop decay fungi but will not prevent bluestain.
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Nirky
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# Posted: 19 Sep 2014 02:51am
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Quoting: Don_P bluestain is usually the first fungi to move in after a tree is cut.
Bluestain is the blue stain fungus spread by the pine beetle, it does not move in after the tree is cut. It blocks nutrients causing the tree to starve to death.
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MtnDon
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# Posted: 19 Sep 2014 09:47am - Edited by: MtnDon
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It is true that the pine beetle kills live trees. Entire devastated forests can be found in CO and other parts of the west all the way north into Canada. However, a fresh cut pine may be the preferred wood for the pine beetle, not the standing live trees. The standing live trees can produce extra sap in an attempt to plug the holes in the bark and cambium layer where the beetle entered. The bluestain fungus acts to curtail that. So we have a tree in distress and fighting for its life. Cut trees can not fight back so the beetles and fungus have a heyday when it comes to cut trees/logs.
If you've ever seen a standing pine with globules of sap scattered around the surface of the bark you are seeing the tree's beetle defense at work. We have a pine that hs been successful; we saw the sap blobs 5 years ago. We left it as an experiment. to see how things would turn out. The globules have turned hard and dry and the tree lived. However, many trees fail to survive when the beetle infestation is high and the trees stressed by drought. A cut pine OTOH provides easy access to the beetles and has no means of defense.
In our woods I can cut a pine that is healthy, no blue stain present at all. If I leave log sections on the ground or stacked, within a week I can find fine dust from the holes the beetles bore. If I let those sections sit for a month or so blue stain begins to show. It can be seen on the cut ends, it can be found when cutting off a section.
Leaving fresh cut pines or sections of pine laying around is a sure fire way to 'grow' more beetles that will infest more pines.
If we can't haul the wood away right away, and if we do not intend to burn the wood as trash very soon, we cover all the piles with clear 6 mil plastic, with the edges of the plastic buried in a shallow perimeter trench. Leave it that way in the summer and the heat will kill the beetles and the larvae. The wood in those piles can still develop blue stain as there might already be a few beetles in there, but any beetles are killed and hopefully their life cycle interrupted enough to make a difference.
In winter it does not matter so mch as the beetles are inactive. Once the wood has dried the beetles will leave the wood alone. When cutting a tree for the timber, strip the bark right away, removing hiding place under the bark that the beetles need to reproduce. But cutting when the weather is warm and the wood is fresh, and leaving it is an open invitation to the beetles to take up residence. Fresh cut pine is like an incubator for pine beetles.
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optimist
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# Posted: 19 Sep 2014 02:45pm
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Great information. Thanks guys.
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Don_P
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# Posted: 19 Sep 2014 11:11pm
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Definitely, I was not aware of bluestain's role in the western beetle killed pines.
Doing some googling, this is a good article;
http://northernwoodlands.org/articles/article/blue_stain_fungi
This one goes into more detail on what Nirky was describing;
http://en.wikipedia.org/wiki/Blue_stain_fungus
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ThomD
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# Posted: 21 Sep 2014 12:15am
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One thing you can do is test wood for real. If the wood isn't visibly bad it is possibly OK for posts, but beams are another mater.
A neat set-up is to get a bathroom scale, and ideally weld or bolt a simple frame such that you can place the scale on a plate, and place a pump jack on the scale, then there are risers on either side that hold a piece of wood such that when the jack is cranked, the sample is the forth side that resists the jack, which in turn presses on the scale. You can get real graded pieces of wood, and cut them to some reasonable size (will depend on the span, etc...). say whatever the minimum width is and maybe 3/4"x3/4". So the idea is when you pump up the jack it will deflect the sample wood, such that you can read the pressure at which the sample breaks, or better still a given degree of deflection occurs, or both. One is stiffness, the other is strength.
With this simple tool, you can accurately quantify the properties of sample wood, ad compare graded species as a baseline to your found species.
While the described version might sound complicated, anywhere you can find a place where you can place a scale on a level surface, place a jack on it, and hold down a sample of wood, you can do this. A couple of side by side wooden chairs with people sitting on them to hold down the sample under the chair seat, with the scale and jack between, for instance. Use some imagination.
By the way, I leaned this trick at a wooden aircraft factory...
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Don_P
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# Posted: 21 Sep 2014 09:09am
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remember that a point load at midspan produces twice the bending moment compared to a uniformly distributed load. Deflection is also about doubled with a midspan point load compared to a uniformly distributed load.
I have offered to proof load timbers to check that their grade is at least equivalent to the need but have been denied by inspectors. Generally in wood a proof load is double the design load, if the beam is designed to carry a 1000 lb load set it on horses that simulate the bearings and uniformly hang 2000 lbs of weight on it. By comparison, in steel, a very consistent material, the factor of safety is 1.6:1, in rope which can have hidden damage and is often not rigged with redundant backup, the safe working load is 1/5 the ultimate strength of the material.
One takeaway though is that mechanical properties, strength, stiffness, compressive strength, etc get weaker rapidly before we have good visual cues. Test loading a few samples and trying to visually make judgements about the rest of the sticks in the stack would be risky. Testing every stick in a pile would be pretty time consuming.
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ThomD
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# Posted: 21 Sep 2014 03:21pm
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Testing a few pieces is not going to be more risky than not testing them at all. You don't have to use this kind of wood, but if I was going to, I would test it. Testing a subset of total wood is exactly what the graded wood goes through.
Interesting reading, and I know you are not going to get past the regulators in all cases, if you are subject to them.
Still having numbers is the least of our problems. I build boats, and people are always making substitutions in materials, without asking design permission, and there aren't any regulations for private vessels in NA, and people sail off over the horizon with their families...
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ThomD
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# Posted: 21 Sep 2014 03:24pm
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I do think one problem with this actual case is scaling for the bug holes in question. On the positive, smaller samples would test low, presumably, so if even then they were comparable, you would have at least that to go on.
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