Hi,
Im renovating a workshop and have to replace 4 joists. One end will
sil just below ground level, in eatch essentially and I am worried that
it will rot. I have located treated joists 3x8x144 inches and am
planning on cementing them in.
Is there any other way? Something else I should be doing? Will this be
enough or is there a damp proof product, plastic sheeting / foam /
something else?
Any advice would be really appreciated!
Mike
Mike, years ago they used to make a "below grade rated" treated wood
that was a genuine Wolmanized product. It was rated to be used in your
application, and for decking on boat docks, etc.
Haven't seen that stuff in years, and they probably don't even make it
anymore with today's EPA requirements. But if you could find that, it
should last a long time.
But today's treated lumber is rarely more than a low pressure dip of
green wood in a pool of mildly preservative liquid. It is better than
nothing, but that would be where I would leave it.
I have seen some pretty good preservation from some of the old
buildings I have worked on. In some areas where the wood structure was
going to flood, they put creosote treated wood (think telephone poles
and railroad ties) that had been sawn into rough boards into the wet
areas, but scabbed them onto regular wood. In other words, the wet
area was scabbed, not the whole piece.
Alternately, when I was a kid we used to put a 1/4" or so layer of
roofing tar on fence posts when we replacing posts. We figured out how
deep they fence post would go, then went about 6" higher with the tar.
That worked great. But it was a fence.
But the real solution is what Joe said. Regrade your terrain to get
the joists out of the dirt/water exposure. You need to get the
moisture from the dirt and water away from the wood. No wood will ever
last a long time sitting in dirt.
Robert
On 8 May 2006 02:30:20 -0700, "Mike" <[email protected]> wrote:
>Hi,
>
>Im renovating a workshop and have to replace 4 joists. One end will
>sil just below ground level, in eatch essentially and I am worried that
>it will rot. I have located treated joists 3x8x144 inches and am
>planning on cementing them in.
>
>Is there any other way? Something else I should be doing? Will this be
>enough or is there a damp proof product, plastic sheeting / foam /
>something else?
>
>Any advice would be really appreciated!
>
>Mike
I did some work in a very old house and recall that a portion of the
back corner was below grade. This resulted in rotting of the sil and
the ends of the joists.
One solution was to change the entire grade of the back yard - very
expensive.
In this case the contractor dug down -about 4 feet- all around the
affected area outside. They filled about 2-3 feet of the hole starting
with 2" stone on the bottom and ending with pea stone. They covered
this with about 12" of loam watering it down to allow seepage.
The idea was to create efficient drainage so that the top-soil would
never be saturated.
If you can adjust the grade outside without a huge earth moving effort
that might be ideal. If not this approach is better than doing
nothing.
In any event, the pressure treated will last quite a long time even
exposed to constant moisture.