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.
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)
4" foam foil face is good....... or larger.
or 2 layers of 4" depending on R value desired.....
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).
If the space under tha tfloor is not to be finished and used as a room,
would it be possible for him to reinstall fiberglass, but then "drop"
small-diameter wire mesh by nailing soem sort of "spacers" to every 4th (or
so) joist, and then nail the mesh/hardware cloth to the "spacers"? It
seems to me that would keep the fiberglass out of the reach of the rats.
It'd be expensive, but less so than rat damage (and rat-related stress).
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.
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
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.
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. :)
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).
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
I love my radiant bathroom floor. I have to fight the urge to lie
down on the warm tile...sometimes I even win. ;)
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.
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.
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:
I agree with all of the above except cutting down on drafts unless a
spray foam or ridged sealed in place. Loose fill, glass or mineral
wool do not stop air flow and normally will not even slow it down.
I have a thing about payback. What is the pay back on the boat,
plasma TV, SUV, 6,000 sq ft house for one person, vacation, going out
to dinner, remodeling the kitchen and the list goes on.
We are brain washed by marketing that we can spend thousands on a SUV
but when it comes to making our homes comfortable and energy efficient
we will not do it unless it has a payback better than we can get in
out investments. I'm not saying we should give up all those other
things just put the energy efficiency of our homes on the top of the
list, not the bottom.
If I was into betting man I bet on much higher prices of energy.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.