I want to build a greenhouse over a 12'x12' flat roof
which is part of my house. The current roof is tar and
gravel and needs to be replaced.

I'm going to build a wood floor for the greenhouse, so
the membrane underneath will not bear traffic. Since
greenhouses are damp/wet I need a waterproof membrane.
I'd like a long-term solution, since I'd have to tear
up the floor to replace the membrance underneath.

My first thought was copper sheet, but that sounds
expensive and difficult to install. Anyone got a good
idea for a waterproof membrane under my greenhouse
floor?

Thanx!

"gus" wrote in message
oups.com...
I want to build a greenhouse over a 12'x12' flat roof
which is part of my house. The current roof is tar and
gravel and needs to be replaced.

I'm going to build a wood floor for the greenhouse, so
the membrane underneath will not bear traffic. Since
greenhouses are damp/wet I need a waterproof membrane.
I'd like a long-term solution, since I'd have to tear
up the floor to replace the membrance underneath.

My first thought was copper sheet, but that sounds
expensive and difficult to install. Anyone got a good
idea for a waterproof membrane under my greenhouse
floor?

Thanx!

a roof typically is already waterproof.

will the roof support the weight you're going to put on it?

As I said, the roof needs replacing. The question
is what to use for the replacement, which will be
under the floor of the greenhouse.

gus wrote:
As I said, the roof needs replacing. The question
is what to use for the replacement, which will be
under the floor of the greenhouse.

Can't speak to that but Charles has a very pertinent point. Will your
roof support the weight of the greenhouse? The soil, water, supplies
adds weight in a hurry. I suspect you will need a permit for this.

Harry K