stone veneer over pressure treated posts
Hi. This is my first time using this tool to find answers to issues I am encountering with a new house build.
I have a covered verandah of poured concrete 8x10. To support the cover, my contractor used 6x6 pressure treated posts. I wanted these finished as they were quite unattractive as is so I had a stone mason cover them with stone veneer. The posts at 6 inches square were not substantial enough, asthetically speaking, so I nailed 2 x8's to them to build them out. Next I covered them with tyvek house wrap and then nailed metal lath over the tyvek. This was the substrate the masons mortared the 0ne inch thickness stone veneer to. It lasted one winter and now each post has a crack down the west (outward facing side) almost the entire length of the post.Tell me what went wrong.As much as I can live with the crack, I can picture it getting bigger with each passing freeze and thaw cycle through the cold season (mid western Ontario). Any ideas, suggestions, comments will be most appreciated. Thanks.
This is fairly common, especially on posts with 4 corners close together. The problem most likely is that the Tyvek isn't keeping water away from the wood. Cultured stone is absorbant, like a sponge, and takes in and can store more than enough water to saturate the wood material behind it. Tyvek works well under some cladding, not so well though directly under thin adhered masonry. Odd's are the wood is swelling under the Tyvek, and considering the stone veneer has little flexibility, it's telegraghing through to the surface.
For more info, google "solar driven moisture - masonry"..........
My preferred method of achieving a column like this is a little different, but then again I live in Florida.
From a pressure treated 2 by structure I use 5/8" exterior plywood covered in your preferred moisture barrier and sealed. Cover all surfaces with expanded metal sheathing, overlapping at any joints and also around corners, nail every 6"or so with galvanized round headed nails
I use Thin-set as a bonding agent and working from the bottom apply your exterior stone veneer to all four surfaces as you move up the column. Force the Thin-set into the expanded metal sheathing thick enough to cover all area at the back of stone veneer. Next fill all joints with manufactures recommendation of mortar or grout
This has always worked well for me in Florida.
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