On Wed, 13 Oct 2010 18:43:00 -0700 (PDT), "hr(bob) "
wrote:

On Oct 13, 7:33*am, Hell Toupee wrote:
On 10/12/2010 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?

I built one back when I was a kid, same problem. I used old window
shades that I pulled off the rollers, then stapled onto the roof and
walls of the house. You could do the same with an inexpensive plastic
tarp.

The OP said it had a flat roof, in his second posting, very bad design
to start with.

The problem is that the OP (me) is incompetent at cutting boards at
other than a right angle, likely because I don't have the equiptment
to do so. I can get the plywood cut at Home Despot but only right
angles. Damn, an old friend's father had a whole woodworking setup in
his basement and could have done this stuff blindfolded. He died a few
years back and my friend rented a truck and took all the machines
cross country and put them into his basement. Maybe if I drew up some
plans I could get him to...

Come to think of it, my roof is pretty much a flat roof and yes, it is
a pain every five years or so. I can't wrap the whole house in a tarp
though. Actually, after those tornadoes just tore through New York
City a few weeks back, lots of homes near me are covered in blue tarp.