Concrete pier blocks don’t have any way to mechanically connect to the wood deck posts.

How to use concrete pier block with wood cap. My preference, for a variety of reasons, is to use precast deck pier blocks buried down to compacted soil rather than dig and pour concrete footings. Embed the pier an inch or two into the top of the concrete, keeping it above ground so that your posts are protected from contact with the soil and possible rot. Whether you're building a freestanding deck, walkway, shed, or other exterior structure, the versatile camo block is the right foundation for the job.

The pier will be held firmly in.