Timber Framers Guild Forums General General Forum Questions curing my timbers properly?

Hey all,

I wanted to ask for feedback on my timber drying method. I have several 12-15 inch diameter oak posts that I am drying. I have them stacked crisscrossed in several layers with gaps between the logs and sitting on some cedar boards off the ground. I have covered them with some black plastic left over moisture barrier and a tarp. The plastic hangs down to the ground to keep fresh air from flowing through. They are sitting in the sun so it gets hot in there, but my thinking is that it's not the heat, it's the humidity! (which should remain high under the tarps). I plan to occassionally spray water under there to make sure.

The wood seems to be checking pretty badly. Especially the posts that we de-barked. I was going to de-bark all of them right away to discourage insects (have a lot of powder post beetle around here), but now I am thinking I will leave the bark on and just spray with insecticide, then de-bark in the fall shortly before we need the posts for construction.

Appreciate your comments. -paul

(oh btw, we did moisture seal the log ends, and now I have also moisture sealed where we de-barked)

Sound's all wrong to me Paul. First, they must not be in the sun. That causes rapid heating and will cause uneven drying. Second. You want air circulation and no humidity. You definitely don't want to trap humidity under that tarp as it will create mold and mildew. If you are trying to dry evenly and as slowly as possible, do it in the shade, with plenty of air circulation, and have the ends of the pieces sealed with end grain sealer like anchor seal. Make a roof to keep the rain off of them, not a tarp. Some people will screw building sheet metal to the top of the stack. The point is to force moisture out the sides of log/stick slowly so it will dry more evenly. Unsealed end grain will allow water in the end of the log to rush out quickly, whereas the center of the log won't, creating stresses which will cause big checking.

Some log mills keep logs out in the open and keep them watered with sprinklers to prevent drying out. The way they do it will not create mold/mildew and is meant to give them time to cut them without drying out and checking.

I thought you had posted this very topic before?

Hi Paul;

I am not experienced with trying to control the rate of drying using high humidity. What you are doing sounds like a perfect way to grow mildew, which may not matter in your situation.

Interesting to hear there are lots of powder post beatles (PPBs) in your area. Just this winter I learned to kill these beatles by applying tupentine to the timbers. I have not tried it but it is nice to know a traditional way to deal with these bugs. The only way to keep them from re-infesting is to seal the pores such as by painting or coating the wood with wax or some other finish. These techniques do not work for me, but it's nice to know. PPBs seem to like humid environments and the sapwood of ash, hickory and oak more than other types of wood.

What kind of oak do you have?

Jim

Soak/store them in a pond. The bark will fall off as you handle them. If you don't have a pond, make one or rent one for the summer. It will save on tarps.

Tim

I guess I'm a bit puzzled by your approach also – That goes right to what it is you hope you might be working towards?

Retarding all drying just suggests it will then be hyper accelerated when you dry-in. At the same time, overall MC will not change appreciably in the near term, you don't say what specie, White Oak in particular gives up its bound water at an almost geologic pace, but no matter what the sub-species, at the diameter you are talking, seasoning is measured in years not months.

Oak checks, often, it checks big. But for drilling out the pith, (a Maine company still uses this technique and specialty 19th ca. machinery to produce check free solid architectural columns) little can be done to avoid that. If you are in many cases milling one face flat to attach to the cladding, you might do that now and this should be the side closest to the heart, as an attempt to concentrate most of the checking there, where it will be hidden against the walls. (you could perhaps put these faces in the sun for a few, or kerf this face, to encourage this) You will of course, have to mill or plane this surface flat again after the checking occurs.

I say bark 'em and best with it !

If you're looking to mill timbers, just go ahead and mill them if you know the sizes, then stack them with weight on them to reduce movement, in a shady spot with plenty of air movement. The smaller the stock, the better it will dry with reduced checking.

If you have any mold mildew now, just mix up a 10 percent bleach, 90 percent water solution in a sprayer and spray the affected area. I had some spruce starting to mold from the sap on the surface and hit it with the solution and cleaned them right up, the outside of the logs then had a chance to dry enough on the outside that they didn't form mold after that. Only 1 application was necessary.

I'd rather cut joinery in dry timbers than deal with larger checking in logs prior to milling.

Opps, sorry Paul - my memory is failing me, thought you'd been posting about building in the round...

Yes, mill the timber - Pond 'em, (is that maybe legislated against at this point?) or sprinkle/spray the tight pile (not crib-like with air space) sawlogs till then, but mill them at your earliest convenience.

They'll still check, but should do so more evenly, and you want your timber to begin to season, though that is still a slow process.

If you were to soak your logs in your own illegal pond, would two negatives make a positive?

Tim

Ideally, and in concurrence to other posters here, after the trees are felled the logs are debarked immediately and sunk in a pond or river for at least a month. The water helps leach sap from the log, which, once removed, will promote more even and thorough drying later on, and removes a source of food for insects.

Then the logs are pulled out and air-dryed for a few months. If left in the round, draw-knifing off the sapwood is wise, and the spine of the log should be kerfed and that kerf wedged. Wedges are tapped in a little more every week or so, depending upon drying conditions. This forces all, or nearly all, of the drying loads to manifest in the kerf, which will open up to a pie-wedge shape as the log dries.

If the timbers are converted immediately to baulks, that is a good thing, but if any of those timbers have the heart boxed, then the kerfing should be done. Sawing should be done so as to remove as much sapwood as possible.

Further drying is all good - if a radio-frequency kiln is available, I'd put the material in there. Otherwise, a solar kiln, say, and a long gentle drying cycle would be in order. The problem of course with certain woods, like Douglas Fir and some Pines, is that unless the sap is crystallized by sufficient heat in a forced drying process the material will have the propensity for pitch pockets and bleeding sap from time to time. Most clients aren't too fond of that oozing out onto their carpets and couch!

Some woods, like Yellow Cedar, can't be dried in kilns apparently, but I suspect this has a lot to do with the stubborn sap.

I'm with Brad - I'd rather cut joinery in dry timber than deal with the shrinking, checking, deformation, and drying issues that arise with green material. The shrinkage that occurs with green material renders the tightest of joints sloppy.

Oops, sorry left out some vital info. Yes, we are building with round columns so milling is out. The wood is Oregon White Oak. We don't really have the option to "build a pond" and there is very little shade available as we live in a prairie type environment. So, I am using the tarps to make shade. I had left the "sides" open for air circulation at first, but the logs were drying way too fast (judging by the significant checking) so I decided to wall-in with more plastic to try to slow it down some. There is still air circulation (left one side open) but not as much. Also, I am sprinkling occassionally. This seems to be working (slowing it down). I'm not too worried about mildew as I'm thinking that will all come off when I de-bark. Also, I am using a borite (TIMBOR) product which is anti-fungal. Barking seems to rapidly speed up drying so I think it's a good idea to wait on barking. I hear you. Make sure the logs are getting some air. I wish I could get them out of the sun, but... hmmm, maybe I can cover them with pine boughs or something... Screwing on roofing sounds great but I don't have any. We are operating with very limited $$$ resources. I know my methods sounds a little weird, but I am just kind of responding empirically/intuitively to what I see happening in front of my eyes (eg: barking the logs accelerates drying). I'll have to stick with the tarps most likely. Ok, here's my new plan: Perhaps I can Q&D manufacture a "tarp shed" so the tarps are not directly on the top logs. Also provide shade down the sides, but leave air ciculation. And then continue with the sprinkling and not de-bark for a few months (at which time the bark usually falls right off). Spray with Timbor. Thanks for all your thoughts.