What is a good economical under floor insulation? (to be installed from under the house--either up between floor joists, or applied to bottom of floor joists)

Anyone have any experience with Tek Foil for this purpose?

this stuff

[This message has been edited by maryjane (edited 05-31-2010).]

I don't know about economics, but the last house i lived in that had a wood first floor ( most are slab out in this area of the country ) it had a water vapor plastic on the wood, then fiberglass batting, then another layer of plastic...

I don't think that insulation has a very high R- value. Is there no way you could use the regular paper backed fiberglass insulation between the joist and then use the bubble wrap insulation to cover and protect the fiberglass? Also, the insulation at the website you linked to is kind of expensive- 8x125 for $450. Ouch! I found this one that has 4x125 (half the width- easier to handle) for $90. http://www.insulation4less....25-ft-500-sq-ft.aspx

I agree with Cooter, Don. We looked into R-13 Poly-Iso foam panels that are easily cut. It is foam insulation with a foil barrier. You'd have to cut it to fit--I assume you have 16" centers--but around here, it is cheap and readily available. I would bet that the Houston craigslist has some. Just a thought.

We have a basement and in my extreme brilliance, I didn't insulate the infloor heat from the upper level floor so we heat the basement as well as the main level. We will definitely install the Poly-Iso panels if we don't unload this house by winter. It will cost us about $550 to insulate 2200 square feet. Poly Iso somes in lesser R-values and I would think you could get by with less in Cleveland and probably pay less than half of what we need.

Under any trailer I have seen, I know not the same, but they are similar. Above ground. They use the pink stuff with like a plastic to keep it in place. Because there is no wood to staple the other backed type insulation to.

I don’t see why you couldn’t just use the backed type insulation. And just staple it to the joists just like you would a regular house with a basement.

Or use the stuff you found as a barrier and staple that to hold the pink stuff up.

My only worry would be insects. Living in the south I know they are a real problem.

Steve

------------------
Technology is great when it works,
and one big pain in the ass when it doesn't.
Detroit iron rules all the rest are just toys.

I realize you fella's in Texas don't have the weather we have here in Canada, but we do know a whole lot about insulation.

First thing is that you probably don't want to insulate the floor unless you have to. You do likely want to put a vapor barrier under it.

You do want to put a skirt around the base and insulate that skirt. Generally a skirt keeps out critters and keeps the wind from blowing under the floor. You can put R20 Styrofoam on the back of the skirt and that will be plenty. The ground temperature cools and heats seasonally. That is a good thing, but the moisture ain't.

If the piers are too tall for a skirt, (too bad if they are) you want an air space between the floor and the vapor barrier. You'll want a flame retardant type insulation. Roxul is a good bat type. You then put your vapor barrier on the bottom of the joists. Again, R20 is plenty. If you have the bucks though, have it spray foamed. That is the best.

Hope this helps

Arn

Don, This may apply. When I built my back porch, I used a steel roof on battens. There was so much radiant heat from the metal it was uncomfortable out there not to mention you couldn't hear yourself scream when it rained. The ceiling is 12-4 with no joist. one layer.
I decided to insulate and used 3/4 blue board set between the rafters halfway. The ceiling surface is 1/4 inch plywood.
This gave me the metal roof, a 3 inch air space, the blue board, a 3 inch space and the 1/4 inch plywood ceiling.
It's quite and cool with no problems since.
The same thing should work with the floor but using the bubble foam rather than the plywood.
You may want to get a price for spray urethane foam, a bit pricey but a supper insulator and will save you money in the long run.

Put the pink insulation between the joists. Dont want to staple it as it compresses it too much. Hold up by running lines of string to hold it in place. Finish by covering the bottom with vapor barrier house wrap.

Cottages and mobile homes have this done up here.

I've seen the spray on insulation on a couple of the TV shows. It is supposed to have a higher R value than regualr insulation. I don't know if they could use it in your application.

quote Originally posted by avengador1: I've seen the spray on insulation on a couple of the TV shows. It is supposed to have a higher R value than regualr insulation. I don't know if they could use it in your application.

Yes, It's also waterproof in case that 100 year flood appears.

Thanks all--but it's not my house. One of the disadvantages of being the youngest member of an aging set of siblings, is you get tasked with a lot of things you'd rather not get tied up with, but that's life--even tho I'm nearly 60 myself. It's my sister's 15 yr old house--no insulation at all under the floor. One of those "Dream Homes" I believe, where the builder builds what ya want and the homeowner builds part of it themselves. It used to be pretty popular around here. In this case, my sister told them she and her hubby would do the underfloor insulation later. Well--later is here--15 yrs later, when they are pushing 65/70 yrs old. They asked me about this stuff this morning instead of using batting, because the house sits about 2' off ground, and they are concerned with bugs-insects and spiders crawling up under the batting and breeding in prolific numbers never before seen in the Northern Hemisphere. So, they are exploring options. The very 1st option they explored and decided on of course--- to contact and then insist upon using--was some nefarious unbonded-under insured non-profit outfit evidently known as "Don's Fencing-Tractor-Electrical-Automotive-Bush Hogging-Dirt Work-Plumbing-Land Managing-Welding-Jack of all Trades/Master of None Company". They found him in the Yellow Pages under "Gullible people so busy helping others they don't have time to take care of their own sheeit".

And of course, the entire house, is completely surrounded by flowerbeds, plants, bushes--all full of old mulch, yard ornaments, etc that I'm pretty sure harbors every insect and spider known to man, as well as Gawd only knows how many damn SNAKES!!

Oh well, I really don't mind---too much. But if Jane posts that Don ran off to his sister's house and seemingly disappeared from the face of the Earth--you'll know what happened. Did I mention SNAKES??

I should have been more clear about the term "economical". They don't want to go to the expense of sprayed in foam, but will spend $ for insulation that both seals and insulates well--a higher R value. Looking at Cooter's link, that R value looks pretty dismal imo.

R Values:
Heat flow down: 7.3
Heat flow up: 2.7
Heat flow horizontal: 3.4

I don't know a lot about insulation, but my idea is to put in batting between the joists (16" centers) and then, if they insist, install this tecfoil on the bottom of the joists to help repel insects and to help keep the wind from pulling the bats out from between the joists. Their original plan was to hold the bats up with staples, then chicken wire on the bottom of the joists. I've done that before, but dang I hate using that chicken wire. Gotta be something better.

Arns--yes, they very much want the floor insulated--the floor gets cold in the bathrooms of that house in winter, even tho we have comparativly mild winters. I know my sister's insurance calls for skirting to be installed to keep gnawing critters like dogs, cats raccoons out, but they never have installed any. Mine calls for it too, but I used lattice because the over riding local code also requires that my skirting be flowthru, or at least breakaway since I am in 100 yr flood plain--otherwise, I wouldn't be able to get federal flood insurance. Then again, grade to bottom of my joists is nearly 5'. My sister is not in the floodplain. She has yet to bring up skirting--maybe she won't, and i won't have to install any behind all those SNAKE harboring plants and bushes.

If I had a choice of crawling in a 2' space pulling bats of itchy fiberglass vs. using rock wool, like Roxul, the choice is an easy one. Both for installation and fire code.

However, if I had a choice of crawling in a 2' space with bugs and critters, vs. installing a skirt, the choice is even easier.

If you have a 2' space, it is really simple to pre-fab 8' sections with blue Styrofoam on the back and just clipping them into place. You don't have to crawl through her prize petunias, or wreck her chrysanthemums. The Styrofoam will ensure a much warmer floor in the winter. Or, you could do the skirt and add some bat insulation under the bathroom and the bedroom. Much smaller job IMHO.

Arn

Well, I say 2', but the joists are of course, sitting on sills, so there is much more room once ya get under there. Almost 1' more.

quote If you have a 2' space, it is really simple to pre-fab 8' sections with blue Styrofoam on the back and just clipping them into place

8' sections of what?

You can use good 1/2" plywood, cover it with siding to match the trailer, and line it with blue Styrofoam. The siding has some rigidity so you could probably get away with 3/8" ply and use clips to clip them together. If you install the ply first and then the siding over top, you can cover the plywood seams. It can look pretty much stock. It will please the insurance company, improve the property value, and insulate very well.

Arn

quote Originally posted by maryjane: "Don's Fencing-Tractor-Electrical-Automotive-Bush Hogging-Dirt Work-Plumbing-Land Managing-Welding-Jack of all Trades/Master of None Company". They found him in the Yellow Pages under "Gullible people so busy helping others they don't have time to take care of their own sheeit". R Values: Heat flow down: 7.3 Heat flow up: 2.7 Heat flow horizontal: 3.4 I don't know a lot about insulation, but my idea is to put in batting between the joists (16" centers) and then, if they insist, install this tecfoil on the bottom of the joists to help repel insects and to help keep the wind from pulling the bats out from between the joists. Their original plan was to hold the bats up with staples, then chicken wire on the bottom of the joists. I've done that before, but dang I hate using that chicken wire. Gotta be something better.

Ya got to watch those fly by night outfits Don, they can be really shady suckers as you well know.

But what you suggested sounds like a good plan to me.

And I am the oldest and get all those crappy jobs for my siblings. The waste products.

Good luck with the snakes. We had a farmer hay our fields and he carried a little 22 pistol for the snakes. When we lived in the south. Although I wouldn’t shoot up, unless of coarse you want to get rid of one of those useless siblings.

Steve

------------------
Technology is great when it works,
and one big pain in the ass when it doesn't.
Detroit iron rules all the rest are just toys.

[This message has been edited by 84fiero123 (edited 05-31-2010).]

At one point in my life, I worked with a company that installed residential heating/air systems into existing homes. Not new houses with plastic underneath or crawl spaces, but OLD houses that you had to dig ditches underneath to run ductwork and cut through concrete floors to set registers in place. There are a few things in life that I hate: clowns (shut up), spiders, snakes and confined spaces. Working with this company covered 3 of my 4 worst fears. I'll make a wooden beak and peck crap with the chickens before I do that work again. My own house has the insulation falling off the floor joist and I just can't bring myself to crawl under there to fix it because I know that there will be snakes, spiders and probably a freakin' clown in the confined space and I will just kill over right there

Don, if it`s the company "Dream Homes" that you are talking about I worked on a framing crew that built for them back in the 80`s.
We mostly worked down south of Houston around the Alvin-Angleton area.
Mike

Yep Mike--that's them. They sold out I think, to someone else--not sure who. Jim Walters maybe.

Thanks all--I'll pass it on. The last time I looked at the blue styro stuff, with foil on one side, it seemed pretty steep imo, considering what it is. I think around $12/ 4x8 sheets, but it would be easy to work with.

Don,
I am not sure what home stores you have in your area, but over here there are a Lowe's and Home Depot pretty close to my house. When I needed some of the blue foam board, I bought the ones with the broke corners and other little damaged spots. I got it for half price and between the 2 stores, we got enough for what we were trying to insulate. Might be worth a shot...

I have some material that I got from my Morton Buildings folks that we used to insulate the inside of the doors in my shop. It's about 3/4" thick, has a very thin metal backing on one side and a kind of dense foam on the other. You can attache it with nails or screws with large fender washers. It's been very durable with the only exception being it's subject to impact damage. That is, if you hit it with the corner of a toolbox or something kind of sharp it will cut through the metal.

If it were me, Don, I'd put fiberglass batt insulation between the joints and then sheet it with the stuff I described and it should be very well insulated. If you use screws it would also be removable for replacement or access to pipes, etc., if you ever had to get to it later.

If you were closer I have about 600 sq ft of the stuff left because when the delievered it the dropped it when it was all banded together and wrecked every corner. I made them give me new materials and they didn't want to even take the old stuff back so it must not be very expensive to buy.

John Stricker

Edited to add:

I think THIS is what I have, if not it's about the same thing in 3/4" thickness.

[This message has been edited by jstricker (edited 05-31-2010).]

Not my house--they get my labor free--they can buy good material for me to work with Cooter, but yeah, we have McCoys Home Center, Lowes, Home Depot etc. Not here in town, but reasonably close by.

Is there any reason (other than a fire hazard from the foam board) NOT to do it this way?



Which way to face the foil--toward the ground or toward the floorjoist?

quote Originally posted by jstricker: I have some material that I got from my Morton Buildings folks that we used to insulate the inside of the doors in my shop. It's about 3/4" thick, has a very thin metal backing on one side and a kind of dense foam on the other. You can attache it with nails or screws with large fender washers. It's been very durable with the only exception being it's subject to impact damage. That is, if you hit it with the corner of a toolbox or something kind of sharp it will cut through the metal. If it were me, Don, I'd put fiberglass batt insulation between the joints and then sheet it with the stuff I described and it should be very well insulated. If you use screws it would also be removable for replacement or access to pipes, etc., if you ever had to get to it later. If you were closer I have about 600 sq ft of the stuff left because when the delievered it the dropped it when it was all banded together and wrecked every corner. I made them give me new materials and they didn't want to even take the old stuff back so it must not be very expensive to buy. John Stricker Edited to add: I think THIS is what I have, if not it's about the same thing in 3/4" thickness.

Interesting--600 sq ft. A long trip--but if i were going that direction anyway........How long can ya hold on to it? Fit in the back of a Silverado?

I'd have to count the sheets to make sure of how much I still have but that's what I remember. Some were damaged so badly we pitched them and I think we used pieces of one. I've been holding on to it for almost 10 years, I don't suppose another year or so will make any difference.

They're either 4X8 or 4X12 sheets so they should lay in the back of the Silverado.

John Stricker

quote Originally posted by maryjane: Interesting--600 sq ft. A long trip--but if i were going that direction anyway........How long can ya hold on to it? Fit in the back of a Silverado?

The foil is a vapor barrier. The vapor barrier goes on the house side, not the outside. So putting foil below your air space and bat is not a good idea. It will hold moisture in the wooden beams. I know I sound like a broken record a bit, but I would use rock wool product, not pink. Critters don't dig in it and it's fire retardant.

Arn