Once you’ve installed the ledger, you can now install the outermost joists at the either end of the ledger.
The outer joists should cover the exposed end of the ledger. Have someone support the furthest end of the joist in a more of less level position and nail the joist into the ledger using 3 or 4 16d (penny) HDG (double hot dipped galvanized) nails. To ensure that the joist is a right angle to the ledger, place a framing square at the intersection of the joist and the ledger and make sure it is at 90 degrees angle. Then drive a temporary 2 x 4 stake into the ground that will hold the joist level (check with a 4’ – 8’ level) and at that right angle. Nail the joist to the stake.
For an accurate measure, use a 3 – 4 – 5 triangle. Repeat with the other outer joist.
Note: The outer joist should be as straight as possible. Choose two that is straightest to install at either end of the ledger. As you look down the joists you will notice that they have a small bow, or crown. No piece of wood is ever perfectly straight.
To remedy this, this crown should always point up toward the sky when you install the joist. This is called “crowning a joist”. Over time the bow will settle down if gravity is working with it. So be sure to crown your joists before installing.
Locating the foundation pier holes
With the two outer joists in place you now have a clear outline of the edges of the deck. From this outline you can locate all your foundation pier holes. Check your plans to determine the exact locations.
Example: your plans call for two holes, the centers of which are exactly 11 from the wall and 2’ in from the outer edges of the sides of the deck.
1. Measure out along each of the two outer joists 11’ from the wall, mark the joists, drive nails at those points.
2. Draw a string from joist to joist between the two nails.
3. Then measure 2’ from the outside edges of the joists along the string and mark the string. Allow extra measurements if there are decorative band joists to be added over the two side joists just installed
4. These marks on the string locate the centers of the two pier holes.
5. Transfer these marks to the ground with a plumb bob.
6. Drive in two small stakes and Then mark out for the radius of the pier holes and begin digging.
NOTE: The location of the pier block holes depends on a couple of factors, such as code enforcement and design. Be sure you know where you want the supports before you start to dig.
Size does matter.
The diameter and depth of the hole is usually about 16”, but there may be a need to check with the local code. Depth distances are normally between 12” – 60”. Frost level in the area may play a role as well (the colder the climate, the deeper the hole).
Once diameter and depth has been determined dig good, straight (not sloping) holes. Dig until you hit stable undisturbed soil that will not settle.
NEVER backfill a hole with loose dirt before pouring concrete. This compacts and causes settling.
Next step is to mix up some concrete, pour it in the hole, drop a pier block in the fresh concrete, level and align it, and continue.
Tip: Keep the concrete damp while hardening for a stronger pour. This can be done by sprinkling water on the pour as it dries or by laying wet cloths across the top.
Follow the instructions as to the proper mix. Pour the concrete in the hole within an inch or so of the top and smooth it out with a piece of 2 x 4 or a trowel until it is relatively level. You can now place the pier blocks.
Pier blocks serve as a transition from the posts supporting the girder to the concrete foundation footings.
The most common type is simply a small truncated concrete pyramid on top of which the wooden post sits (See Figure A).
The weight of the deck keeps the post in contact with the pier block. Often metal fasteners are used in areas where there are earthquakes (Figure B). They are embedded in the fresh concrete and the posts are bolted to them. This prevents the posts from shaking off the pier blocks in a quake.
Back to building your deck
1. Fill the hole with concrete, making sure the concrete leveled and smooth.
2. Then drop the pier block into the fresh concrete and work it down until at least 3” – 4” of the base of the block are embedded.
3. Make sure that the pier block is properly aligned and that they are level.
4. To check alignment, drop a plumb bob from the marks on your string that you have made earlier. The tip of the plumb bob should be centered to the pier blocks.
5. To check level, use a small torpedo level, placing it in both directions as well as diagonally across the top of the pier blocks until the tops are level. Tap and move the blocks around to make any needed adjustments.
6. Once you’ve done your checking and re-alignments (if needed) allow the concrete to harden, which can take anywhere from 2 to 24 hours.
7. You can then begin building the girders and posts.
Tip: Keep the concrete damp while hardening for a stronger pour by sprinkling water on the pour as it dries or by laying wet cloths across the top.