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Setting Barn Posts for Glulam Frame and Ensuring They do not Rot

Postby odacunha » Sun Nov 08, 2015 10:02 am

Hello all,
I'm planning a glulam barn frame to go up in place of an old, crumbling, partly collapsed oak frame.

During my planning phase I've been investigating the best way of setting the posts. I've seen many instances where suggestions are:
1. dig a 1m deep hole
2. place 4-6" gravel in the bottom.
3. install and plumb post; pour in concrete and allow to set.

No issue with that; nice clear instructions. My concern is that the wood will take up the concrete's water and start wood rot.

I was thinking of either:
1. wrapping bottom 1m of post in fibreglass or;
2. painting bottom 1m of post in resin roof repair such as Everbuild Evercryl.

Anyone come up with a better solution?

Any and all advice appreciated.
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Postby katoosh525 » Wed Nov 18, 2015 11:28 am

Yes, use this stuff: ... xy-sealer/
It's expensive, but will offer more rot protection for your money than anything else you will find. If you were to put the Evercryl or fibreglass wrappers around the wood, you will find that they:
Don't bind particularly well to the wood long term
Don't move particularly well with the timber, which encourages their separation from the outer fibres of the wood.
Given the cost of trying to sort out a rotten glue lam frame later, I would have no hesitation in using CPES here.
There is a whole wealth of evidence out there from the wooden boat community, see here for a bit:
CPES will penetrate into the timber, and will make the bottom of the glu lam beams effectively impermeable to liquid water. This will allow the beams to breathe normally, and thus you will not offer the ideal conditions for rot to begin.
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Postby odacunha » Thu Nov 19, 2015 5:48 pm

Thanks Katoosh. I think that'll do the job just fine. Shame I'll need to take out another mortgage, but I want it to last my lifetime so I'll be doing it the right way.
Thanks again.
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