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Home > Archive > Building and Construction > April 2008 > Best Floor Insulation?
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Best Floor Insulation?
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| When I built my house I insulated the the floor with R19 fiberglass batts.
Rodents have - over the years - torn must of it down. I want to insulate
once more and never again after that. What would be a better way to go?
My floor joists are 2x10's.
Thanks,
RO
--
Robert Olin
Bob's Water & Septic LLC
jolin@whidbey.net
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| jloomis 2008-04-03, 3:25 am |
| Tough job.....solid insulation........cutting and installing.......
I used a sawzall mounted on a plywood board.......with blade sticking up to
cut rigid insulation.
Worked great with less dust......
screw the fence to the plywood for cut measures....push it through.....use a
rough blade.....(wood blade)
install tightly.........
4" foam foil face is good....... or larger.
or 2 layers of 4" depending on R value desired.....
jloomis
"RO" <jolin@whidbey.net> wrote in message
news:8-ydncZWuZMtxmnanZ2dnUVZ_qygnZ2d@whidbeytel.com...
> When I built my house I insulated the the floor with R19 fiberglass batts.
> Rodents have - over the years - torn must of it down. I want to insulate
> once more and never again after that. What would be a better way to go?
> My floor joists are 2x10's.
>
> Thanks,
> RO
>
> --
> Robert Olin
> Bob's Water & Septic LLC
> jolin@whidbey.net
>
>
>
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| hogheavenfarm 2008-04-03, 9:25 am |
| Rodents will chew into foam as well. In some cases I think tey like it
better, it tunnels easier. At least you will be able to hear them
though. Maybe you could wire screen over it? Would be expensive but it
would last. By the way, solid foam is quite expensive also. You will
need 2" foam to equal R19, and 3" foam would be better, but much more
expensive. I don't know how it compares to building up layers of
thinner foam (R5 or R10).
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| PeterD 2008-04-03, 9:25 am |
| On Wed, 2 Apr 2008 21:43:15 -0700, "jloomis" <jloomis@ocean.net>
wrote:
>Tough job.....solid insulation........cutting and installing.......
What kind of solid insulation? Foam? If so cutting is easily done with
a hot wire cutter.
>I used a sawzall mounted on a plywood board.......with blade sticking up to
>cut rigid insulation.
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| S. Barker 2008-04-03, 9:25 am |
| WHY? Heat travels up. Are you trying to prevent ground heat from entering
the house?
s
"RO" <jolin@whidbey.net> wrote in message
news:8-ydncZWuZMtxmnanZ2dnUVZ_qygnZ2d@whidbeytel.com...
> When I built my house I insulated the the floor with R19 fiberglass batts.
> Rodents have - over the years - torn must of it down. I want to insulate
> once more and never again after that. What would be a better way to go?
> My floor joists are 2x10's.
>
> Thanks,
> RO
>
> --
> Robert Olin
> Bob's Water & Septic LLC
> jolin@whidbey.net
>
>
>
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| RicodJour 2008-04-03, 9:25 am |
| On Apr 3, 9:29 am, "S. Barker" <ichasetra...@coldmail.com> wrote:
> WHY? Heat travels up. Are you trying to prevent ground heat from entering
> the house?
That is not true. Hot air rises due to convection but heat radiates
in all directions.
R
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| S. Barker 2008-04-03, 9:25 am |
| Yes, but insulating a floor never pays back. It's a waste of time and
money.
s
"RicodJour" <ricodjour@worldemail.com> wrote in message
news:a7198b83-2d46-4121-9d27-a464eab5cdb4@i12g2000prf.googlegroups.com...
> On Apr 3, 9:29 am, "S. Barker" <ichasetra...@coldmail.com> wrote:
>
> That is not true. Hot air rises due to convection but heat radiates
> in all directions.
>
> R
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| S. Barker wrote:
> Yes, but insulating a floor never pays back. It's a waste of time and
> money.
That's simply a false over-generalization.
hAdT knows no difference between down and up or sideways...
--
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| RicodJour 2008-04-03, 1:25 pm |
| On Apr 3, 10:10 am, "S. Barker" <ichasetra...@coldmail.com> wrote:
> Yes, but insulating a floor never pays back. It's a waste of time and
> money.
Based on what time and energy cost assumptions are you basing that
particular gross generalization? I'd imagine that floor insulation
life would be on the order of several decades, and unless you've got a
Mr. Fusion cranking away to keep you warm, I doubt that energy costs
are going to go down in the foreseeable future. There's also the
issue of comfort. A warmer floor is more pleasant to walk, keeps your
whole body warmer, regardless of time and money invested, and cuts
down on drafts - a major source of heat loss and discomfort.
R
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| PeterD 2008-04-03, 1:25 pm |
| On Thu, 3 Apr 2008 09:10:30 -0500, "S. Barker"
<ichasetrains@coldmail.com> wrote:
>Yes, but insulating a floor never pays back. It's a waste of time and
>money.
>
>s
>
You clearly don't live in a cold climate, do you? 'Pays back' is
meaningless, an ice-cold floor in winter is not. But, even still it
will pay back, just as any reasonable insulation job will do.
>"RicodJour" <ricodjour@worldemail.com> wrote in message
>
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| S. Barker 2008-04-03, 1:25 pm |
| BUT, only one thing wrong with this statement about the cold floor.
Insulating the floor will not make it warmer, 'cause the 'cold' does not
come from below. The only way to make a floor warmer is to put heat UNDER
it. Heat rises, cold falls. can't change that.
s
"RicodJour" <ricodjour@worldemail.com> wrote in message
news:e1a2070d-0a46-4901-be80-73a4844e7bbb@c19g2000prf.googlegroups.com...
> On Apr 3, 10:10 am, "S. Barker" <ichasetra...@coldmail.com> wrote:
>
> Based on what time and energy cost assumptions are you basing that
> particular gross generalization? I'd imagine that floor insulation
> life would be on the order of several decades, and unless you've got a
> Mr. Fusion cranking away to keep you warm, I doubt that energy costs
> are going to go down in the foreseeable future. There's also the
> issue of comfort. A warmer floor is more pleasant to walk, keeps your
> whole body warmer, regardless of time and money invested, and cuts
> down on drafts - a major source of heat loss and discomfort.
>
> R
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| S. Barker 2008-04-03, 1:25 pm |
| Some would not consider where i live a cold climate. It's probably not
compared to other parts of the country. I live in kansas near the mo state
line south of KC. It's more than cold enough for me. I hate cold.
s
"PeterD" <peter2@hipson.net> wrote in message
news:ta3av3tjb234dsu1cfsupo2r6e5ptqhh0d@4ax.com...[color=darkred]
>
> You clearly don't live in a cold climate, do you? 'Pays back' is
> meaningless, an ice-cold floor in winter is not. But, even still it
> will pay back, just as any reasonable insulation job will do.
>
>
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| S. Barker wrote:
> BUT, only one thing wrong with this statement about the cold floor.
> Insulating the floor will not make it warmer, 'cause the 'cold' does not
> come from below. The only way to make a floor warmer is to put heat UNDER
> it. Heat rises, cold falls. can't change that.
....
Except it isn't so...warm, _still_ air rises, not heat.
Heat conduction is independent of anything except h, A, and dT and knows
nothing of direction--at a given delta-T, the same amount of heat is
conducted out a wall or ceiling of the same area and w/ the same overall
effective heat transfer coefficient and temperature differential. And
the temperature differential is dominated by the effective k which is
insulation value.
--
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| Wayne Whitney 2008-04-03, 1:25 pm |
| On 2008-04-03, S. Barker <ichasetrains@coldmail.com> wrote:
> Insulating the floor will not make it warmer, 'cause the 'cold' does
> not come from below.
For a floor separating a conditioned area above from an unconditioned
area below, the floor temperature will be determined by equilibrium.
That is, in the steady state, the rate of heat loss to the cold space
below will equal to the rate of heat gain from the warm space above.
If at some point, the heat loss to the cold space below is higher, the
floor temperature will fall, which reduces the heat loss to below
(smaller temperature difference) and increases the heat gain from
above (larger temperature difference). Eventually the two rates
balance and you have equilibrium.
Conversely, if the heat loss to the cold space below is lower, the
floor temperature will rise, as the floor absorbs more heat from the
heated space, until again the two rates balance. So if you reduce the
rate of heat loss to the space below, by insulating the floor, you
raise the floor temperature.
> Heat rises, cold falls. can't change that.
That's simply false. Heat can be transferred by 3 mechanisms:
convection (movement of air), conduction (touching objects) and
radiation (infrared radiation all things emit). For convection, yes,
hot air rises and cold air falls. But conduction and radiation don't
care about gravity at all.
Cheers, Wayne
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| RicodJour 2008-04-03, 1:25 pm |
| On Apr 3, 1:15 pm, "S. Barker" <ichasetra...@coldmail.com> wrote:
> BUT, only one thing wrong with this statement about the cold floor.
> Insulating the floor will not make it warmer, 'cause the 'cold' does not
> come from below. The only way to make a floor warmer is to put heat UNDER
> it. Heat rises, cold falls. can't change that.
Besides the fact that you're completely wrong, you shouldn't argue
points you don't really understand. It's even worse to give advice
based on those errors in comprehension. Maybe this will help you
understand heat transfer a bit better:
http://www.diynetwork.com/diy/cda/a...L-PRINT,00.html
R
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| RicodJour 2008-04-03, 1:25 pm |
| On Apr 3, 1:19 pm, dpb <n...@non.net> wrote:
> S. Barker wrote:
>
> Except it isn't so...warm, _still_ air rises, not heat.
Why do you say that it's only still warm air that rises? Any body of
warm air rises and induces convection - sailors have been relying on
it for millenia. Since convection is a more efficient heat transfer
mechanism, it seems a bit misleading to say that heat doesn't rise.
R
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| RicodJour wrote:
> On Apr 3, 1:19 pm, dpb <n...@non.net> wrote:
>
> Why do you say that it's only still warm air that rises? Any body of
> warm air rises and induces convection - sailors have been relying on
> it for millenia. Since convection is a more efficient heat transfer
> mechanism, it seems a bit misleading to say that heat doesn't rise.
Because in a circulating system the circulation pattern is generally
stronger than the convective force...
But the point is it isn't "the heat" that is rising, it is that warmer
air is less dense and hence does tend to rise. But, as the assertion
made here again is also misleading at best, it's important to note that
it isn't "heat" that's moving somehow magically out the ceiling that
leads to the perception that floor heat loss is somehow magically different.
--
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| dpb wrote:[color=darkred]
> RicodJour wrote:
....[color=darkred]
And, I didn't say "only", I simply emphasized "still" owing to the
effect as noted earlier being most significant when forced convection
isn't in play.
And, of course, while convection is effective in heat transport within
the room, once it gets to the wall/ceiling/floor surface, except for
undesirable leakage paths it becomes a conduction problem for the most part.
Hence, except for the probably relatively small (in general) temperature
difference in a well-regulated room between the ceiling and floor the
heat loss is pretty much dependent on how cold the other side is and the
effectiveness of the insulation.
Of course, there's the sensitivity of bare skin to hard floorings issue,
too, that is a localized heat transfer effect, particularly to bare feet. 
--
--
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| RicodJour 2008-04-03, 5:25 pm |
| On Apr 3, 3:13 pm, dpb <n...@non.net> wrote:
> dpb wrote:
>
>
>
> And, I didn't say "only", I simply emphasized "still" owing to the
> effect as noted earlier being most significant when forced convection
> isn't in play.
I'm not a big fan of forced hot air heating, and at least in my area
the predominant heating systems are hydronic and steam radiators
(which, of course, are really convectors).
> And, of course, while convection is effective in heat transport within
> the room, once it gets to the wall/ceiling/floor surface, except for
> undesirable leakage paths it becomes a conduction problem for the most part.
>
> Hence, except for the probably relatively small (in general) temperature
> difference in a well-regulated room between the ceiling and floor the
> heat loss is pretty much dependent on how cold the other side is and the
> effectiveness of the insulation.
All you have to do is calculate the location of the dew point
temperature to graphically determine that an insulated floor is
warmer. The only time it wouldn't be warmer is if there's no heat in
the house and there's no sun. Luckily that excludes most of our
planet.
> Of course, there's the sensitivity of bare skin to hard floorings issue,
> too, that is a localized heat transfer effect, particularly to bare feet.
I love my radiant bathroom floor. I have to fight the urge to lie
down on the warm tile...sometimes I even win. ;)
R
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| Roscoe P Pendoscoe 2008-04-03, 5:25 pm |
| On Wed, 2 Apr 2008 21:23:16 -0700, "RO" <jolin@whidbey.net> wrote:
>When I built my house I insulated the the floor with R19 fiberglass batts.
>Rodents have - over the years - torn must of it down. I want to insulate
>once more and never again after that. What would be a better way to go?
>My floor joists are 2x10's.
>
>Thanks,
>RO
Well them must be some active little devils to tear down fiberglass.
The first thing I personally would do is seal up all the access those
creatures have found to get in.
They do not like steel wool. Use that when you plug crevices/holes
then good sealant.
Are they interested in any edibles other than insulation?
Knowledge is like money, the less you talk about it
the more people assume you have.
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