The way I do it now has a couple advantages over simply embedding the posts in concrete.
1. I can do the final plumbing and alignment of the posts in the dry and without bracing.
2. In case a post is damaged or does rot, replacement is possible without digging out the embedding concrete.
Here’s my method (for 3-in. and 4-in. posts):
1. Dig a hole about 12 in. diameter and a several inches deeper than the post is to go.
2. Pour crushed gravel into the hole. The top of the gravel should be about where the bottom of the post is to be. (The crushed gravel should be around ¼-in. size, clean and uniform graded for good drainage.)
3. Stick a 6-in. PVC pipe in hole deep enough so that the bottom end is a inch or so into the gravel. (The pipe needs to be far enough into the gravel so its end won’t be displaced during concreting.)
4. Working from an offset line, plumb and align the pipe so that the post will be roughly in the center of the pipe. (Having a level at least six foot long and a 2×4 at least that long makes this step go easier.)
5. Cut the pipe off, either at grade or several inches high to facilitate concreting,
6. Concrete the annular space around the PVC pipe. After the first foot of concrete is in the hole, the plumb and alignment will need to be corrected. After that, assuming reasonable care in placing the concrete, only minor corrections will be needed.
7. Once the concrete has set, drop the post into the empty PVC pipe and fill the annular space around the post with crushed gravel. Start by pouring in a little gravel and then plumb and align the post before pouring in more gravel. Check the plumb and alignment as you continue filling. Working in roughly 6’’ lifts, I use a 1×2 lath to tamp the gravel. Fill to about 1-in. below final grade.
8. Use a good non-shrink mortar to cap the hole. Taper the surface up towards the post for drainage. This cap will go a long way towards keeping water away from the wooden post.
It’s okay to let grass grow in over the concrete, however, the mortar cap should be kept free. Grass, moss or other vegetation growing against the wood will retain water and lead to rot.
The crushed gravel holds the post firmly and assures drainage. Unless the water table is extremely high, the post is going to stay dry.
If a post needs replacement, use a hammer and masonry chisel to break away the mortar cap. Then suck out the gravel with a wet-dry shop vac and lift out the remainder of the post.
×
Get home building tips, offers, and expert advice in your inbox
View Comments
Very clever !
Thanks for posting