Expert: Jamie Yocono - 6/12/2005

Question
Hello

I have 2 large wood poles that support a little roof in my deck.  They developed very large splits (cracks)  Can I fill these with regular paintable caulking or, real strength, do I need to fill with wood puty only?    Caulking is easier to work with (for me ).

Thanks   Gabe  

Answer
Hi Gabe,

While this question is somewhat out of my area of expertise (I build custom furniture) I do have something to share with you.

The reason those cracks developed in your posts is because moisture is leaving the wood quickly, and when the wood can't react to that quickly enough, well- as they say- split happens. It's also called checking, and it's totally a moisture related problem.

Now if the posts have been there a while, perhaps they've been drying out over time, and then the wood just finally hits the point that it can't shrink anymore without something giving. That's what causes the cracks.

What you want to ensure is that water/moisture can't reenter those cracks, so if it were me, I would want to seal those areas (deep into the cracks) with some sort of a sealer. I would recommend spar varnish, which is very moisture resistant. Because of the nature (depth) of the cracks, I would consider spraying the varnish inside of them. You know those little extension nozzles that come with a can of WD-40? You might fool around with that on the varnish spray can; see if that nozzle will hold the tiny tube. That way, you can insert the tube into any deep crack and make sure it's getting a good coat of varnish.

For cosmetics, you can use wood filler, but frankly, I think it will shrink away and fall out over time. Better yet- as you suggested- a flexible caulk, like a silicone caulk, will both keep the cracks sealed, and make them look better. That should solve your problem, but I think I would try to get some varnish deep into those cracks first before you caulk them, just to be sure.

Good luck, I hope this helps. Feel free to write back with any other questions you might have after reading this.

Jamie Yocono
Wood It Is! Custom Cabinetry
www.wooditis.com
Las Vegas, NV