Will Cypress rot?

**willsdad03** · 04-30-2012, 12:54 PM

My wife has voluteered me to build a pergola for her. I am thinking about using rough sawn cypress for it. I will be using 4x6's for the corner posts. Will they rot if set in the ground on a gravel bed with concrete poured around them? If so, what could I do to prevent rot but still use the cypress?

**deepwood** · 05-02-2012, 07:04 AM

In my experience, you NEVER pour concrete around a wood post. I don't know about cypress rotting, but as we all know, wood expands and contracts. This will eventually cause the concrete to crack. When the wood shrinks, the concrete stays rigid, a space will form between them, water will get in... it could freeze, etc... There are back-filling methods you can use to ensure the wood will stay put. Before concrete was invented, back-filling a post was the only way to do it! I am not claiming to be an expert on this, so you're going to need to do a little research... However, the bottom of the post needs to be set below the frost line, on a bed of gravel that's a couple inches deep. Then, alternating between layers of gravel and soil, you need to slowly fill and tamp down each layer.
OR, you can use a deck post base bracket to attach the posts to a concrete pad/footer. Then trim around the bracket/bottom of the post to hide it from view, holding the trim above the concrete a quarter inch or so. Hope this helps!

**Timur** · 06-24-2012, 07:24 AM

http://www.vitalwares.ca/

Originally Posted by willsdad03

My wife has voluteered me to build a pergola for her. I am thinking about using rough sawn cypress for it. I will be using 4x6's for the corner posts. Will they rot if set in the ground on a gravel bed with concrete poured around them? If so, what could I do to prevent rot but still use the cypress?

The wood is fairly stable and does not warp or split very much, although available today should not be confused with your grandaddy's cypress. The old growth cypress was rich in resin that made it naturally rot resistant and established a reputation that today's cypress can't live up to. The cypress they are cutting now is much younger and is mostly sapwood.