Installing Post Anchors

Intro

Installing post anchors utilizes many of the same methods you employed when you initially laid out the site -- measuring, squaring, lining things up. This time, however, everything needs to line up as precisely as possible -- and that's where adjustable post anchors come in. Unlike fixed anchors, adjustable models allow you to correct as much as a 1/2-inch discrepancy in any direction if you have made an error when placing footings or J-bolts.

You'll find adjustable post anchors at your home center in a number of configurations and with a varying number of pieces, but all of them do the same job. A bottom plate is made with an opening that allows lateral movement in all directions, a clamping plate holds the bottom plate in place under the pressure of a nut and washer, and a pedestal raises the post off the surface of the footing to allow water to drain away.

Before you get out the measuring tape to square things up, install all the anchors loosely on the footings, then line them up using the techniques shown here.

Prestart Checklist

Time
About five minutes to initially fasten each anchor. Allow three hours to place the anchors for a 12x16-foot deck.

Tools
Socket wrench and socket, tape measure; hammer drill and speed square for drilling epoxied holes

Skills
Tightening nuts, drilling with hammer drill, measuring

Prep
Install footings

Materials
Post anchors, mason's line, threaded rods or all-thread for epoxied studs

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Step 1

Set the base of the anchor, the pressure plate, and the washer over the threads of the J-bolt. Start the nut on the threads and tighten it finger-tight. You should be able to move the anchor with moderate pressure. Install all the anchors before moving on to the next step.

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Step 2

Start with the footings opposite and parallel to the house. Set a long straight 2x4 across the front edges of the anchors. Measuring from the house to the front edge of the 2x4, line up the anchors so all of them are an equal distance from the house. Tighten each nut about one-half turn more.

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Step 3

On the batterboard crosspiece next to the house, mark to the outside of the centerline at one-half the thickness of a post. This mark represents the outside edge of the post. Mark the corner crosspiece at the same point, and restring the lines. Drop a plumb bob from the line at the outside corner, and adjust the anchor so its edge lines up with the point of the plumb bob. Measure the diagonals, and adjust the anchors until the diagonals are equal.

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Step 4

Tighten each anchor nut firmly with a ratchet handle and socket. When the nut feels secure, tighten it one-quarter turn more so the anchor can't move. Don't strip the J-bolt threads. Measure the diagonals again to make sure the anchors are still in line.

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What If... You want to install threaded studs? Step 1

Threaded studs are an alternative to J-bolts and you can install them after the footings have cured. Using a hammer drill, drill a hole 1/8 to 3/16 inch larger than the stud diameter and to a depth that will leave 1 inch of threads exposed.

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What If... You want to install threaded studs? Step 2

Mark the top of the stud with a 1-inch piece of tape (which will also keep the threads clean). Then blow the dust out of the hole with a shop vacuum. Using a quick-set epoxy syringe, inject epoxy into the hole and push the threaded stud into the hole immediately. If a small amount of epoxy doesn't issue from the hole, pull out the stud and inject more epoxy.

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What If... You want to install threaded studs? Step 3

Plumb the exposed end of the stud with a speed square and let the epoxy cure for the length of time specified by the manufacturer. When the epoxy has cured, measure the height of the threads. If more than 1 inch protrudes from the hole, thread on the nut until its top face is an inch above the concrete. Cut the stud with a hacksaw and remove the nut.

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