"mm" wrote in message
...
Same friend who is getting a new roof, I looked at her home.

She has a deck held up by 6x6 posts. There is a 10 or 12 foot span
that sags and needs another post in the middle.

I could use a 6"x6"x8', but I'm not sure how to keep it from going
further into the ground in a few years, or even tomorrow. I could pour
redi-crete around the base, but I don't see how that would do more
than slow its sinking. (I would use a jackpost to lift up the deck
to put the new post in.)

(snip)

It ain't a fencepost. On a deck, wood and dirt should never touch. You need
a proper footer, sized for the frostline in your area, and the weight that
will be supported. Same store that sells deck parts will have the plastic
cone things to form up footers. Just bury them as indicated, fill with
concrete, and with whatever bolts local code calls for to hold the metal or
plastic spacer plate the post actually sits on. Same concept as a carport
post or centerline beam post in a basement. If the existing posts are in the
dirt, you may as well fix them too, while you have the jack there and are
mixing concrete. You can probably saw them off and reuse them, so the cost
will mainly be time.

Might I recommend one of they DIY deck books at the big box, or Google for a
deck building web site? The pictures will show what I am talking about much
more clearly.

aem sends...