I am curious how much checking effects a timber? I have not been able to find much on the topic. I am under the impression that up to a 1/4" is ok, am I right on that? I have customers ask all the time but really don't know the answer to this one. I use mostly Douglas Fir, Pine or Larch. Also, is there a way to tell if the timber is going to check before it does, to try and cull out the trouble ones?

Thanks,

Tim

Howdy Tim,

Try this link: [url=Wood Behavior]http://www.tfguild.org/forums/ubbthreads.php?ubb=showflat&Number=20924&page=1[/url]

Personally, I like checks. It seems that if timbers were culled for potential checking the price of timber would rise dramatically.

Hi Tim,

In very simple terms my experience with Douglas fir is that you are alright to use centrally located boxed heart timbers up to 6 x 6 without much fear of checking. Using timbers above that size is bound to result in checks opening up. With larger timbers where its a requirement to limit checking then it would be better to use free of heart or halved timbers, this way the wood can shrink back upon itself without checking about the heart. Keep in mind that other drying distortion patterns will take place depending on where the cut is positioned in the cross section of the tree. Checks run back to the heart and the juvenille wood and so when checks open up then this forms a perfect path for beetles to enter a timber and do their worst so they don't call timber framed buildings in England "half [halved]timber buildings" for no good reason.

Regards

Ken Hume

Oh,yes I can help you about this matter. and i suggest you to visit this site : http://www.careyandfox.co.uk/ which provide complete solution of Timber Related Problem.

Checks aren't problems.

Hi careyandfoxuk, I could not find anything regarding Checking in Timbers, could you be more specific as to where to find info on your site? Thank you

only when they say "checks in the mail....."

Hi Mo,

I wonder if you could expand a little on your statement above that "Checks aren't problems" please ?

Might not the location and extent to which a check opens up become a legitimate concern ?

Regards

Ken Hume

Well Ken, I guess I shouldn't be so absolute when I really have no idea of what I'm talking about. I guess I just said it, cause I like the way they look.

Maybe I should have said, "Checks aren't cosmetic problems."

Does anyone know of a case where a check caused a structural failure?

Well, If a check is discontinuous and not excessively large...I guess it's easier to show someone, but sufficed to say, "normal" checking is not considered a defect in timbers, and there is no need to reduce the rated strength of the timber. Checking is a natural part of the drying process whereby local stress is relieved. It occurs from uneven drying/shrinking of the timber. It is desirable to minimize it as much as possible. White pine will can commonly have timber with no significant checking, but hardwoods will usually have some degree of checking. Oak for example will usually check to some degree. We minimize checking by sealing the end grain with a wax based sealer (Anchorseal is a common brand used). The end grain of a piece of wood is the exposed capillaries of the wood. Water will run out/dry out very quickly from the ends if not sealed. This will lead to uneven drying/shrinking. Sealing those ends stops water from leaving allowing drying to only occur from the sides of the timber. Water will dry from the sides much more slowly and evenly. Slowing the drying and making it more even will allow the timber to shrink more uniformly and therefore reduce the internal stresses that lead to checking. When working with green wood, always seal the end grain, whether it's the end of the log, or the end grain within the mortice you just finished cutting.