Vapor Barrier Question

[fritz]

I know I probably missed this somewhere.  But on the little house or similar, with a post and pier foundation, after you lay the vapor barrier, if you keep the crawlspace open -- or concealed by lattice, what is the effect of sideways rain and or melting show that leaves water on the vapor barrier?

Is it a concern?

A fully enclosed crawlspace wouldn't have this problem.

[glenn kangiser]

The concern I would have is just that if it gets in there it will get back out.  Even houses on flat areas need drainage away from the house.  That would apply to any water that got under onto the vapor barrier also.  It should be made to drain away by proper grading including away from under the house.  

[jraabe]

Yes, in an open to the air vented pier foundation you can expect some short term water, snow and such. It will be like what happens on an open porch. In some heavy snow climates you would be better off to wrap the house with mill board or metal skirting to control drifting snow or driven rain.

In most mild climates this will evaporate and not be a long term problem.

Glenn is right about drainage. Water and air should always be able to flow downhill away from the house. Don't build in a hollow.  

PS - on my own house I have a sealed and insulated crawlspace with no vents to the outside. There has not been any moisture or as much as a spider in the crawlspace for 24 years. (Well, one broken pipe now that I think of it.   --- but that wasn't the fault of the foundation system.)

[fritz]

Thanks on the grading reminder -- and the "water on an open patio" analogy.  Now I picture it.  

I have begun getting rafters in place and have someone local to sheath and roof the dog trot.  I now plan to be out of the weather by late July.  More photos later as I progress.