Hello all,
i noticed some houses in the owner builder forum have the post set in concrete in the ground.
if i was to do this, would it be better to pour the footing with rebar then place the 6x6 on top with a sonatube surround and fill above grade to protect the wood?
Quote from: astidham on January 25, 2010, 12:55:13 PM
Hello all,
i noticed some houses in the owner builder forum have the post set in concrete in the ground.
if i was to do this, would it be better to pour the footing with rebar then place the 6x6 on top with a sonatube surround and fill above grade to protect the wood?
Moisture is the great killer of wood. Even PT wood over time will go bad exposed to enough of it. There are different grades of PT as well and you would want to make sure that you have the grade intended for that use. At the least I would slope the concrete from the post to the ground to make sure that the water will run off. Then come back later and apply a bead of caulk(exterior) at that intersection of the post and concrete.
Here is a newer concept that would work good in this application but again you will either need to extend the sleeve to where water will not run into the sleeve. Perhaps caulking will work here as well.
http://www.plasti-sleeve.com/plastisleeve.html
I am not a believer in pouring concrete around wood posts. Once the footer is poured place the post and backfill and tamp the material dug out of the hole. Build the ground up so it slopes away from the posts. Using tar to coat the 8-10 inches of wood that will be above and below ground level will help prolong their life even if they are PT.
There are three (or more) grades of PT wood. It goes by the amount of preservative in the wood. First is above ground (approx .25 pcf, pounds per cubic foot), then ground contact (.40), in ground (.60) and even more for in water.....
Quote from: Redoverfarm on January 25, 2010, 01:06:28 PM
Here is a newer concept that would work good in this application but again you will either need to extend the sleeve to where water will not run into the sleeve. Perhaps caulking will work here as well.
http://www.plasti-sleeve.com/plastisleeve.html
Pole barn builders will use those sleeves "for an extra charge", which surprised me. Doesn't look like an expensive enough product to warrant additional costs, but maybe it is.
I would certainly use it, though.
I can see where they would work ok providing that you cover the top of the sleeve if exposed. With a pole barn it will mostly be shielded with the sheeting. I think I would still caulk the top of the tuibes if they were in a doorway or where water could be blown into the opening.
I did have a neighbor build a barn and used the sleeves. You have to allow more drying time to the concrete. It seems that the plastic will not let the water out to cure the concrete as fast.
Its alot easier to replace a wooden post thats sitting on a bracket then to replace a post sitting 2-3 feet down in concrete.
I wrapped three poles in plastic in a relatively dry area. They were not pressure treated but they rotted off in three years. Poles without plastic do better than that.
John has mentioned using soil cement around the posts - it draws water away as the ground dries and makes the post much more solid. Use appx 5 to 7% Portland cement mixed with the soil to firm it up.
In engineered post frame construction this is all part of the lateral restraint of the building for wind. In a code foundation the continuous footing and foundation walls perform this function. A post sitting on a footing and bolted to a girder has essentially zero lateral bracing. This needs to be considered and some form of sway bracing incorporated in the design.
Ever notice posts always rot off right at ground level? Rot requires oxygen, what you plant the post in below that level really doesn't matter rotwise.
Thank you all!
Is there a way to perserve the section of post above ground?
and will clay soil Accelerate rot?
i really want to build this right, so thank all of you for your help and expertise.
Foundation grade treated should take care of it. From the surface down to about 6 or so inches below is where the active layer is.
Here is a link to a lamp post question. I was also going to suggest the asphalt sealer. I sometimes use Henry's 107 - water based asphalt emulsion -available at HD and other places.
http://www.thisoldhouse.com/toh/asktoh/question/0,,637257,00.html
Here is another crazy idea if you are into workinj with steel.
Use some steel box tubinj for posts if you are in termite land or other harsh conditions.
I hope to insert a pic of a roujh sketch I made. I have not tested this so you are on your own. It is just a sujjestion for those that like to play with steel.
Bruce
(https://i778.photobucket.com/albums/yy62/the_troglodyte/brucepost.jpg)