The Forestry Forum

Hi,
I plan to make a retaining wall out of white oak posts and pine logs. The posts will go six feet into the ground and six feet out and hold back the pine logs going horizotally. Between the pine logs and the ground being retained i will put pond liner to prevent moisture from the ground rotting the pine logs. All of this is actually going to be located inside of a greenhouse so the pine shouldn't rot as it didn't in another farmer's twenty year old greenhouse. 
   I am wondering if it is necesarry to debark in this application. If the trees are cut and fastened to the posts quickly won't this prevent bugs from entering the wood? And if not will bugs destroy the structural integrity of the wall over time or are bugs usually just a consideration or asthetics?

Welcome to the forum.

I'd suspect bark will/should be removed. Being a greenhouse with other plants, doubt having bugs in the bark or wood will be a good thing.

This project sounds like the perfect scenario and all the makings for rotted pine in your barrier, but if you are convinced it will work for you, then maybe that is not important (or won't happen).

What pine are you going to get?

  Even in rot resistant wood like White Oak, only the heartwood is really rot resistant.  The bark and sapwood will rot within a short period of time if there is any moisture available.
  Saw off the bark and sapwood to know how much post you can expect to be there to hold the wall in place.

If you could get cedar or cypress logs, they would be more rot resistant. But I agree it is best to get rid of the bark and preferably the sapwood on the oak.

My experience is that white oak is about equal to second-growth cypress as far as durability. Eastern white pine generally has more heartwood than yellow pine and is likely to last longer for that reason alone. Yellow pine sapwood will be gone in a few years.

Take the bark off,it will draw bug,s and will wick moisture faster than can shake a stick at. Tim