How to Drill Accurate Holes for Deck Post Bolts

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I show how to drill accurate holes in a 6×6 deck post to install 1/2 inch bolts in the Simpson Strong-Tie PBS66HDG Standoff Post Base. This project is continued from How to Install a 6×6 Wood Deck Post. Also see the project introduction which explains the sagging wood deck problem.

How to Drill Accurate Holes for Deck Post Bolts

I didn’t think I could freehand drill a 1/2 inch hole through the 6×6 inch deck post to install bolts in the Simpson Strong-Tie Standoff Post Base, so I’d fastened the post with Simpson Strong-Tie SD #10 x 1-1/2 structural wood screws as temporary solution.

Wolfcraft Drill Guide

My solution was to buy a Wolfcraft Drill Guide Attachment from Amazon.com. For a $30 tool it did really well. I used the combination square to check the drill guide was set at 90 degree and set a 3/8 inch spade wood bit in the chuck to drill a pilot hole:

Wolfcraft Drill Guide Attachment Model 452504 for Bolt Holes in Deck Post Simpson Strong-Tie Standoff Post Base PBS66HDG

Wolfcraft Drill Guide Attachment Model 452504 for Bolt Holes in Deck Post Simpson Strong-Tie Standoff Post Base PBS66HDG


The Wolfcraft drill guide has a raised base that fits over the Simpson Strong-Tie standoff post base. I recommend using wood spade bit to drill the pilot hole because a twist bit will pull too aggressively into the wood and bind. By contrast the spade bit doesn’t pull itself into the wood and gives you more control. I drilled a the smaller 3/8 inch pilot hole in case the hole alignment was a bit off so I could make corrections when drilling the 1/2 inch hole. The Wolfcraft drill guide stroke was a little short and didn’t the drill bit didn’t make it all the way through the deck post. After drilling this hole, I moved to the opposite side and completed the hole. Tip: The drill guide stop (blue knob by my left thumb) on the guide bar can be removed for a longer stroke:

Install 6x6 Deck Post - Drill Bolt Holes with Wolfcraft Drill Guide

Install 6×6 Deck Post – Drill Bolt Holes with Wolfcraft Drill Guide

Success! An accurate hole drilled through the post to the other side of the Simpson Strong-Tie standoff post base!

Simpson Strong-Tie Standoff Post Base - Drill Pilot Holes in Deck Post for Bolts

Simpson Strong-Tie Standoff Post Base – Drill Pilot Holes in Deck Post for Bolts

After drilling the 3/8 inch pilot holes through the deck post, I enlarged the holes with a twist bit by drilling from opposite sides of the post. Not sure why I didn’t think to use my 12 inch long twist bit here:

Through Holes for Bolts Drilled in 6x6 Deck Post

Through Holes for Bolts Drilled in 6×6 Deck Post

Pipe cleaners were used to swab a generous amount of Copper-Green Brown Wood Preservative (10% copper naphthenate) inside the drill holes as required by the deck building code:

Treat Deck Post Bolt Holes with Copper Naphthenate Wood Preservative

Treat Deck Post Bolt Holes with Copper Naphthenate Wood Preservative

I used about 1.5 gallons of Copper-Green Brown while rebuilding the deck.


Bolt the 6×6 Deck Post to the Simpson Strong-Tie Standoff Post Base

The deck post must be fastened with 1/2 inch bolts with washers and nuts to comply with the Georgia Amendments Prescriptive Deck Details based on the 2012 International Residential Code. The first galvanized bolt is being tightened:

Fasten 6x6 Deck Post to Simpson Strong-Tie Standoff Post Base with 8 inch Bolts

Fasten 6×6 Deck Post to Simpson Strong-Tie Standoff Post Base with 8 inch Bolts

The two 1/2 inch by 8 inch long galvanized bolts with washers installed. Recall the bottom end of the post is a bit darker than the redwood stain toner because I had brushed on a coat of the Copper-Green Brown wood preservative before mounting the post. I’ll leave the SD #10 screws in the bracket because removing the screws would leave holes:

6x6 Deck Post Fastened with Bolts to Simpson Strong-Tie Standoff Post Base PBS66HDG

6×6 Deck Post Fastened with Bolts to Simpson Strong-Tie Standoff Post Base PBS66HDG

I installed a 2nd nut on the bolts to serve as a lock nut. The 2nd nut is optional but will prevent the nuts from loosening as the pressure treated post dries:

6x6 Deck Post Bolted to Simpson Strong-Tie Standoff Post Base PBS66HDG

6×6 Deck Post Bolted to Simpson Strong-Tie Standoff Post Base PBS66HDG

Side view of the bolted deck post:

Simpson Strong-Tie Standoff Post Base PBS66HDG with Bolts

Simpson Strong-Tie Standoff Post Base PBS66HDG with Bolts

In the next updates, I’ll install the lateral support 2×6 knee braces, rebuild the deck rail and replace the improper installed deck boards.

Most people will want to install the beam-post knee braces next. I choose to rebuild the deck railing first because it was unsafe after removing several 4×4 guard posts.

This project is continued in How to Build a Code Compliant Deck Railing.

Thanks for reading,

Bob Jackson

 

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4 Comments

  1. Steve March 15, 2015 at 11:44 am - Reply

    Wonderful review of the drill guide. I’m going to do the same.

    One question… you mentioned a copper preservative and you are using galvanized bolts. I’ve read that those two are corrosive together and can cause structural failure of the bolts.

    Before I do it, I was wondering if you had heard that or taken it into consideration.

    • Bob Jackson March 15, 2015 at 3:31 pm - Reply

      Good question!

      Galvanic corrosion between dissimilar metals isn’t a problem with copper naphthenate wood preservatives according to the USDA Forest Products Laboratory publication “Types of Wood Preservatives” report:

      “Copper naphthenate treatments do not significantly increase the corrosion of metal fasteners relative to untreated wood.”

      Recall that Copper-Green Brown Wood Treatment is a 10% copper naphthenate solution.

      Thanks,
      Bob

  2. James September 20, 2015 at 8:41 pm - Reply

    Hi Bob,

    Was there a way to secure the guide to the post so it wouldn’t move while drilling? If not, how did you keep it in place?

    James

    • Bob Jackson September 20, 2015 at 9:34 pm - Reply

      The important thing is to get your upper body directly behind the drill guide. I sat down on the cement patio for better alignment and pressed the drill base firmly against the post so the rubber feet will grip. Notice in this photo the drill guide base at the 4 o’clock position is against stand-off post base to further limit drifting.

      The guide also worked well when drilling pilot holes for deck post knee braces while standing on a ladder.

      I haven’t tried it but you could fasten the guide with wood screws set in the four holes in the base. Two wood screws should do it.

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