On Feb 29, 1:37 pm, wrote:

You have a wooden basement with a dirt floor? Most termites don't
normally eat concrete and masonry.

If there were insects that ate concrete, I'd have them.

With a 1/16" gap between the slab and walls, it might have well been a
dirt floor. Didn't slow the termites down one bit. It's all fixed
now, but what a mess.

"JoeSpareBedroom" wrote:

I'm not real keen on removing blocks. The existing slots are in the 2-by
wood which sits on the sill plate.

Furthermore, I'm pretty sure most code requires a minimum distance between the
ground and the house structure if it isn't concrete. Providing a medium that
moisture can follow or that critters can burrow up into the house doesn't strike
me as the best idea.

Given the limited area involved, boxing in the underside of the joists and then
filling them with insulation might be a better alternative...

On 2008-02-29, marson wrote:

The rule about a vapor barrier on the warm side doesn't apply to
floors.

Oh, why is that? Wayne

On Feb 29, 7:55 pm, Wayne Whitney wrote:
On 2008-02-29, marson wrote:

The rule about a vapor barrier on the warm side doesn't apply to
floors.

Oh, why is that? Wayne

Two reasons. First, houses tend to act as chimneys--warm moist air
rises, finds a way out near the top, and thus floors tend to be under
negative pressure--outside air is being pulled in down low. Even if
this isn't the case, most floors are sheathed with plywood which which
has a high enough perm rating to function as an air/vapor barrier. I
have seen a number of floors which were covered on the cold side with
poly and there were no apparent problems, though it would probably be
prudent to use housewrap on the cold side just in case.

I meant to add to this discussion that most foams cannot be exposed in
a crawlspace. they must be covered with a thermal barrier like
drywall.

On 2008-03-01, marson wrote:

Two reasons. First, houses tend to act as chimneys--warm moist air
rises, finds a way out near the top, and thus floors tend to be
under negative pressure--outside air is being pulled in down low.

That's true, but I think water vapor will still diffuse in all directions.

Even if this isn't the case, most floors are sheathed with plywood
which which has a high enough perm rating to function as an
air/vapor barrier.

OK, so there's your vapor barrier on the warm side. :-)

I meant to add to this discussion that most foams cannot be exposed
in a crawlspace. they must be covered with a thermal barrier like
drywall.

Actually, I've wondered about that. Isn't the point of the thermal
barrier to separate the foam from the living space? In that case the
floor plywood would do the job and there wouldn't need to be a thermal
barrier on the underneath.

Cheers, Wayne

On Feb 28, 8:34*am, "JoeSpareBedroom" wrote:
The dining area of my kitchen is built over a crawl space that's enclosed by
cinder blocks like the rest of the house. In the basement, there are two
openings to this crawl space, but they're only 6" high x 18" wide. I assume
they were put there for ventilation purposes, since they're useless for
anything else. The area in question juts out from the main kitchen, and is
12x12 feet.

In winter, the floor is ice cold, so that dining area is useless. I believe
the traditional first step for dealing with this is to lay a plastic vapor
barrier on the soil underneath, followed by fiberglass insulation. The vinyl
flooring needs replacement, so I could also rip up the wood underneath in
that area and have total access to do the work. Replace the sub-floor
afterward, install new vinyl or tile, and it's done.

BUT: Someone suggested an interesting alternative: *When the vinyl flooring
is removed, drill access holes in the sub-floor and pump the space full of
foam. It's already a form of plastic, so it should form its own vapor
barrier. And, it'll insulate. Progress could be checked via the access slots
in the basement. Makes sense, but there's always a "gotcha".

Your thoughts, please.

Pump it in , let it expand, let the floors buckle up 1 ft , Its
termite and Carpenter Ant attractive!!! Have fun!!

marson wrote:

I meant to add to this discussion that most foams cannot be exposed in
a crawlspace. they must be covered with a thermal barrier like
drywall.

Or you can look for an ASTM E-84 fire rated surface foam, which can be exposed,
but not to sunlight or a UV source. A crawlspace would have neither problem...

On Feb 29, 9:26 pm, Wayne Whitney wrote:
On 2008-03-01, marson wrote:

Two reasons. First, houses tend to act as chimneys--warm moist air
rises, finds a way out near the top, and thus floors tend to be
under negative pressure--outside air is being pulled in down low.

That's true, but I think water vapor will still diffuse in all directions.

Even if this isn't the case, most floors are sheathed with plywood
which which has a high enough perm rating to function as an
air/vapor barrier.

OK, so there's your vapor barrier on the warm side. :-)

I meant to add to this discussion that most foams cannot be exposed
in a crawlspace. they must be covered with a thermal barrier like
drywall.

Actually, I've wondered about that. Isn't the point of the thermal
barrier to separate the foam from the living space? In that case the
floor plywood would do the job and there wouldn't need to be a thermal
barrier on the underneath.

Cheers, Wayne

Actually, while there are definitely some gray areas in my mind
concerning vapor barriers and floors, there is no gray area with foam
in crawl spaces and rim joists (including the rim joist where the
ceiling below is drywalled); the foam must be covered by a thermal
barrier. At least according to how the code is interpreted where I
live. I've spent some joyous time grovelling around in a crawl space
screwing OSB onto ICF's per the BI instructions. There are some foams
that meet the flame spread requirements, but not many AFAIK.

On 2008-03-01, marson wrote:

there is no gray area with foam in crawl spaces and rim joists
(including the rim joist where the ceiling below is drywalled); the
foam must be covered by a thermal barrier. At least according to
how the code is interpreted where I live.

Good to know, thanks. Wayne

There are some foams that meet the flame spread requirements, but
not many AFAIK.

One foam I was looking at said: ASTM E-84: FSI 15, SMK 450. That's
presumably flame spread index 15, and a smoke criterion of 450. Do
you know what the flame spread requirements are from the building
code?

Cheers, Wayne

"Wayne Whitney" wrote in message

One foam I was looking at said: ASTM E-84: FSI 15, SMK 450. That's
presumably flame spread index 15, and a smoke criterion of 450. Do
you know what the flame spread requirements are from the building
code?

Cheers, Wayne

That is why they are called out, to show they meet code. Check your local
codes though, in case they differ.

replying to Robert Allison, McStick wrote:
I had a similar idea of filling the entire crawl space with foam, for my 24x16
cabin in Quebec, Canada, where there are no termites. Can you think of any
other objections? Price may be the prohibitive factor.

--
for full context, visit https://www.homeownershub.com/mainte...am-291168-.htm

On Tuesday, November 13, 2018 at 8:14:08 PM UTC-5, McStick wrote:
replying to Robert Allison, McStick wrote:
I had a similar idea of filling the entire crawl space with foam, for my 24x16
cabin in Quebec, Canada, where there are no termites. Can you think of any
other objections? Price may be the prohibitive factor.

--
for full context, visit https://www.homeownershub.com/mainte...am-291168-.htm

Access to water lines, electric lines, maybe HVAC? Ability to move or
add any of those?