On Wed, 13 Oct 2010 12:02:41 -0700 (PDT), Joe wrote:

On Oct 12, 2:31*pm, dgk wrote:
Last year I had a 4*8 outdoor plywood board (pressure treated I think)
cut into appropriate pieces at the local Home Despot and put together
a little house for a few feral cats. I used some polyurethane stain,
caulked the seams, and figured it was pretty waterproof. Yet every
heavy rain the inside was soaked.

I figured that I'd get some of that roofing tarpaper, use the flashing
cement to attach it to the wood, and put some shingles on it. However
I can only buy the tarpaper in large rolls, which is far more than I
would ever need.

So, what's a good way to waterproof a pet house?

It might be easier to redesign the project. Consider using concrete
blocks for walls, plus a sloping piece of Ondura roofing. Anchor
together any way convenient and it should last for years. And zero
maintenance.

Joe

A local guy is doing a workshop on Saturday on how to create a feral
cat house out of styrofoam fish boxes. They only last a year but are
supposed to be warmer than wood and far easier to deal with. Of
course, they need to be screwed onto a wood base or they blow away.

So I got to thinking about just getting one of those 4'*8' foam boards
from Home Despot and slapping one together. But if the tarp works on
the wood then it's even easier.