I have a springhouse sitting atop a mostly buried, 14' X 14' open-top
concrete cistern. The plywood flooring is rotted and needs to be
replaced. Though the cistern has some vents below the floor level,
the underside of the floor is essentially a high-humidity environment.
What is the best material or construction to use for this floor?
Things I have considered:

1) pressure-treated plywood (rejected, since this sits just over our
drinking water),

2) Marine-grade plywood (very expensive)

3) exterior-grade plywood, installed over a vapor barrier (6 mil poly sheeting?)

What will work best?

Thanks,

Kelly

On Fri, 19 May 2006 20:17:08 +0000 (UTC),
(Kelly E Jones) wrote:

I have a springhouse sitting atop a mostly buried, 14' X 14' open-top
concrete cistern. The plywood flooring is rotted and needs to be
replaced. Though the cistern has some vents below the floor level,
the underside of the floor is essentially a high-humidity environment.
What is the best material or construction to use for this floor?
Things I have considered:

1) pressure-treated plywood (rejected, since this sits just over our
drinking water),

2) Marine-grade plywood (very expensive)

3) exterior-grade plywood, installed over a vapor barrier (6 mil poly sheeting?)

What will work best?



Concrete planks.

In article ,
Goedjn wrote:
On Fri, 19 May 2006 20:17:08 +0000 (UTC),
(Kelly E Jones) wrote:

I have a springhouse sitting atop a mostly buried, 14' X 14' open-top
concrete cistern. The plywood flooring is rotted and needs to be
replaced. Though the cistern has some vents below the floor level,
the underside of the floor is essentially a high-humidity environment.
What is the best material or construction to use for this floor?
Things I have considered:

1) pressure-treated plywood (rejected, since this sits just over our
drinking water),

2) Marine-grade plywood (very expensive)

3) exterior-grade plywood, installed over a vapor barrier (6 mil poly sheeting?)

What will work best?



Concrete planks.

Never heard of them before, but they sound promising. But, I imagine
they weigh significantly more than plywood. WOuldn't I need to beef
up the joists, as well?

Kelly

Kelly E Jones wrote:
I have a springhouse sitting atop a mostly buried, 14' X 14' open-top
concrete cistern. The plywood flooring is rotted and needs to be
replaced. Though the cistern has some vents below the floor level,
the underside of the floor is essentially a high-humidity environment.
What is the best material or construction to use for this floor?
Things I have considered:

1) pressure-treated plywood (rejected, since this sits just over our
drinking water),

2) Marine-grade plywood (very expensive)

3) exterior-grade plywood, installed over a vapor barrier (6 mil poly sheeting?)

What will work best?

Thanks,

Kelly
Does it need to be plywood? Could you do it like a deck and use 5/4 or
2x deck boards? If you don't want the spaces then how about tongue and
grove planks? They are available in Mahogany, fir and pine. You could
maybe even route some PT pine decking to fit together T&G.

Mahogany T&G is not too expensive around here (relatively speaking) and
is used on exterior porches. (Think Victorians, etc)

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Concrete planks.

Never heard of them before, but they sound promising. But, I imagine
they weigh significantly more than plywood. WOuldn't I need to beef
up the joists, as well?


They ARE the joists. I was talking about those 2' wide,
8" deep, hollow-core pre-stressed concrete planks that
come in lengths up to 40' It would be a stupidly
expensive way to solve the problem, but it would
be permanantly solved.