Floor Insualtion

[pioneergal]

We are trying to stay one or two steps ahead with our plans for future phases while working on whatever our present phase may be.

Someone may have already started a thread in Re: to this subject but if so I have overlooked it.

Before long we will be looking at our options for floor insulation.

We have 24" clearance between the ground and the bottom of the floor joist.

One person suggested  rolls of R-13 batting as an option as long as we stapled the brown paper faced side up .

If we should choose to use this how would one keep the batting from falling or being destroyed by the elements or animals?

Do we have other choices of insulation that would be easier to install and give us a good R - rating?

Pioneergal in North Central Texas......45 minutes from CowTown.

[peg_688]

  Gal   Use as thick a insulation as will fit in the joist bay . Buy unfaced insulation or call a insulation company in your area .
  
   Where I live you can buy from installers , installed insulation for just about the price of the material generally .   Your place may to to far out , off the beaten path.

  I'd use typar/ tyveck stapled to the under side of the joist after they or you installed the batts.  If your area critters are more determined you could put some 1/4 wire mesh on after that .

  The typar will protect and let moisture out .

 Good luck , PEG  

[dorothyinak]

Pioneer gal,
I think you are just one small step behind where we are....we just got our insulation and subfloor done this past weekend......

We used the typar fabric stuff on top of our beams before we layed the joists....I guess you do want this layer to be permiable for water.  We are up off the ground a bit too, and we plan on putting some visqueen down on the ground (if it ever stops raining!!) and then putting some treated plywood skirting around as a barrier to animals and to create an area around our sonotubes that is a little warmer than the ambient temp. outside.

We used R-38 insulation (might be overkill, but were in AK) in between the joists....it didn't quite fill the entire 12 inches or so that our joist depth is, but the way the unfaced battens are cut, friction pretty much held the fluffy stuff up off the typar, so there is a little gap underneath it before the typar begins.  I don't know what kind of R-value insulation you might need there.....

Good luck!  Glad someone else is around the same point we are!  

[rdzone]

Just a quick note on insulating the floor before the roof is up.  I had a friend spend a weekend insulating and forgot to put the tarp back over the deck.  Wouldn't you know it rained and all of his hard work got drenched.   He paid for fiberglass insulation twice!  A hard lesson to learn.

[bil2054]

I'm not there yet, but one of the ideas  under consideration is to use hardboard, masonite, something like that, under the joists, and pouring in cellulose, with a six mil poly vapor barrier on top of the joists.  The less I have to do with itchy fibreglass, the better I like it!  I have read elsewhere in this forum (I think )  a caution against the fibreglass that comes bagged in a poly vapor barrier.

[jraabe]

Billy Bob:

You can do what you suggest for the cellulose insulation. You should have all the wiring and plumbing done before filling from the top. You could use peg board and Tyvek on the bottom.

You don't really need poly on the top if you use plywood or OSB subflooring as it will be the vapor barrier.

This works best in a small house that can then be quickly brought out of the weather. If the subfloor is soaked all bets are off.

[bil2054]

Thanks, John.
Guess it would be easier to "screw and glue" without the poly!

I plan on the Builder's Cottage, which should dry in pretty quick.  Plus I'll be building in a part of Arizona where rain is kinda rare!

[n74tg]

If your house is being built over a walled-in crawlspace (as oppossed to piers open to the weather) I think I would consider insulating the crawlspace walls just so I wouldn't have to insulate the joist spaces under the floor.  BuildingScience.com has lots to say about the subject.  

I am building over a crawlspace in Hot Springs, AR and will definately insulate the walls rather than each joist.

[jraabe]

This is a good suggestion for climates where the soil temp is moderate (IE: not in permafrost  ).

I've done this in my house (1983) and had no moisture problems. It sure is easier to work on things when there is no insulation in the joist cavity.

[bil2054]

That's a good idea, and one I have considered.  I was thinking, at 5200 ft altitude and temps down into the teens at times, I might best do the joists.  But if it works, I'm for it!  
I don't think the pier foundation is a problem, since I planned on cripple walls anyway.  Just have to insulate them.  I think that, plus insulation on the ground under the building, (that Scandinavian trick), might do it.  I reckon I could always blow the cellulose in later if I needed more, eh?

[pioneergal]

            
Thanks to everyone that took the time to read and respond to my insulation question.

While surfing the web on the topic I found this site and its product.

I was wondering if anyone has heard of or used this product.
                              
            

http://www.astrofoil.net/index2.astrofoil.radiant.barrier.html


   ASTROFOIL  REFLECTIVE  INSULATION






 

[Amanda_931]

I saw the same site you did.  No R-values claimed, I noticed.

But I used it or something similar to patch the ceiling of a house once.  It surely did help.  But then tissue paper would have been better than those great big holes in the ceiling right under a black roof.

they did swear it was great under a concrete slab.  

Of course I've been thinking I want PAHS where whatever you want in the way of insulation, underfloor isn't it.  (Passive Annual Heat Storage--it does include cooling!  also see AGS--annualized geothermal storage.)

But I kind of doubt I'll get PAHS on my flat, badly drained field up the hill.

[jraabe]

Reflective insulations have a checked past and a suspect future. They have seldom lived up to the hype and the calculated R-values they are supposed to impart.

To be effective, radiant (reflective) barriers must work across a true dead air space where there are no convection currents. Then the reflective surface must stay shiny and clean for the life of the house or the dust covered mirror does nothing. Both of those conditions are very hard to meet in the real world.

I would not suggest using such insulations in floors or walls. Radiant barrier insulations are used with some frequency for reducing attic temps in high heat areas such a FL and the SE. I don't know if long term testing has justified the cost in even those areas.

[glenn-k]

Stupid question time.

If it's dark, how does a reflective barrier know that it is supposed to reflect.  Seems to me it would only be effective on an outside surface.

Just going from the old saying, "They all look the same in the dark."

[Okie_Bob]

Other than the cost, what would be wrong with having Icynene blown in after all plumbing, electrical and other utilities are complete? I plan to use it myself but, only as the last step afer all else is complete.
I've used Icynene already and love it.
Okie Bob

[bil2054]

Lol, Glenn; I think that remark, 'They all look the same..' is a paraphrase from Ben Franklin's "Advice to a young man...'.  Very funny, VERY sexist.(What in the 18th cent. wasn't?)

To the point, what the radiant barrier is  reflecting is energy down in the infra-red end of the spectrum, which we can't see.  The reason it must be kept clean is: dust, etc., in contact with the nice shiny surface is not reflective; it absorbs the heat energy and gives it up through conduction.

[glenn-k]

Thanks, Billy Bob.  I knew it came from somewhere-- Probably my unwittingly accepting some unknown to me person's sexist philosophy in the past nearly got me in trouble in the present.  Garsh, I'm so embarrassed --really red faced--- can hardly stand to live with myself :-/  I should not have misunderestimated (thanks for that word GWB) the connotations attached to some phrase that somehow just got stuck in my mind.

Thanks for the explanation also.  I've always been interested in how things work in the dark.