flagstone patio next to house - plastic under it or not?

My 1917 farmhouse had a patio poured at the exact same height as the room it adjoined. This allowed water to seep under the exterior wall and wet the drywall and insulation.
We just has the patio removed. The new patio is going to be about 3 inches lower. We are going to use those flagstone-looking squares (18") from Lowes/Home Depot. These will be set on a bed of sand with either sand or maybe marble chips in-between.
We are lucky that the room adjoining the patio has a tile floor that serves to seal out the moisture that seeps up through the concrete. I will put some kind of sealer on the newly-exposed raw edge as well. What I'm debating now is whether or not to put plastic sheeting under the flagstone. The concrete patio was 6-8" thick so the ground is very compressed. They used a backhoe to remove the big pieces of concrete and the ruts held water for 3 days (but it has rained -alot- here in the East).
I will do all of the appropriate sloping so the plastic will have a chance to drain at one end. I just can't visualize whether the plastic would help or hinder moisture (not water) sponging it's way to the concrete under that room.
Thoughts?
Thanks!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Lyne writes:

What for? In any case, it won't last. Polyethylene doesn't take weather.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dig out, slope bottom away from house, lay down heavy landscape fabric, fill with sand or finely crushed stone, lay stones.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

fill
Agreed - I laid plastic down one time many years ago over some loamy clay soil. The plastic held in the moisture which allowed the ground below the stone to swell. One helluva mess! Eric is right on target.
Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mark Ransley wrote:

Why? for What? Now who in the hell are you talking at, you stupid fuck? Will you ever use any usenet accepted protocol, or will you always be just a webtv shit stain?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.