# Countersinking Hex Bolts into Pergola Beam a Good Idea?



## captainjz16 (Jul 9, 2013)

I am getting ready to build a 12x12 pergola with a 14x14 overhang in rough cut western red cedar and I want the finished product to be as clean as possible. Here's what I'm using:

Posts: 6x6s
Beams: 2x10s

The tops of the posts will be notched 1" to allow for half of the beam to sit on the post.

Here's the Question: If I've got 2" of beam, then 4" of post and then 2" of beam, that's 8" to go through with a hex bolt. how deep into the 2x10 beam can I countersink without compromising the integrity of the board? Ideally, I want to be able to countersink then place a plug in each hole to hide all the hardware. I think I'd have to go in at least 1", and I'm worried about that being too much. 

Thanks for the replies!


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## cabinetman (Jul 5, 2007)

captainjz16 said:


> The tops of the posts will be notched 1" to allow for half of the beam to sit on the post.
> 
> Here's the Question: If I've got 2" of beam, then 4" of post and then 2" of beam, that's 8" to go through with a hex bolt. how deep into the 2x10 beam can I countersink without compromising the integrity of the board? Ideally, I want to be able to countersink then place a plug in each hole to hide all the hardware. I think I'd have to go in at least 1", and I'm worried about that being too much.
> 
> Thanks for the replies!


Can you do a rough drawing showing the orientation of the pieces?








 







.


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## woodchuck1954 (Nov 11, 2008)

Using carriage bolts will not need countersinking and leave an acceptable finish. If you want to blend to wood color, spray paint the heads, prior to installation, if the whole thing is painted, paint after installation. I would use stainless steel hardware, otherwise galvanized and cedar combined, will result in black staining.

woodchuck1954
"A Legend in his own Mind"


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## Crusader (Jan 14, 2013)

I guess you could always use all thread, something like 3/8 should be plenty stout enough to tie both sides together. 

Use a forstner bit http://www.leevalley.com/US/wood/page.aspx?p=63566&cat=1,180,42240,63566 and a plug cutter http://www.leevalley.com/US/wood/page.aspx?p=42292&cat=1,180,42288

Anyway that's my hair brained idea for the night:thumbsup:


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## FrankC (Aug 24, 2012)

Looking at your drawing the post will support the beams, the bolts are only holding them in position, 1" of material should be fine.


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