Question about insulating a floor

[madokie]

I have a craw space under my house and ceramic tile on our front room, how much difference would I see if I was to insulate the space between the floor joist with R 25 fiber glass insulation? and would it be advantageous to put the insulation up against the under side of the floor or put it flush with the underside of the joist thus leaving a 6 inch air space. We have click lock flooring in our dining room and it has a thin foam underlayment and it seems to feel warmer to the touch. I will go lay a thermoter on each and see what the actual difference is.

[Uben]

1. Typically

People use chickenwire to hold the insulation in place. Use 6" batts, staple, then staple up the chickenwire. Should help immensely!

[Warpy]

2. Right, and insulate between the joists, not floating it under them.

Here is a handy dandy how to page: http://www.bpa.gov/energy/n/energy_Tips/weatherization/InsulateFloor.cfm

[madokie]

4. I'll be reading that now to learn how to do it properly

I didn't think to look for a link first before I started asking question, slapping 'self in the forehead, so thanks for that.

[madokie]

3. Thats what I was wanting to hear

I put a thermometer on the floor in the dining room with the wood cliklock flooring and it is registering 60 degrees so I now have it on the ceramic tile floor and it is also showing 60 degrees, so I am not seeing a difference between the two kinds of flooring like I thought I felt on my feet, amazing. I have a solid wood floor in the kitchen so I am going to go see what temp it is. I'm convinced the insulation would have to help, like you say immensely. interesting

I am using the same thermometer for all floors so as to not be a difference in their readings and it is a remote read cooking thermometer with the probe laying flat on the floor with a towel laying on it for insulation.

[bahrbearian]

5. You don't need that much R value insulation

R19 will work just fine, put it up against the flooring, hold it in place with ridge wire (like a coat hanger) cut a 1/4 inch or more longer than the opening in the span between the joist, bend the wire to fit between the joist, push it up against the insulation and release. Put one every 2 feet.

[madokie]

6. That'll save me some money on the insulation and also on the supports

I believe the wire hangers like you suggest are availabe at the large lumber yards. Can't wait to get this job started. kinda' off the question a bit but years ago we lived for a year in a house we rented and I noticed that in one part of the living room it seemed warmer than the rest of the house and I had already been under the house so I knew it wasn't that the floor was insulated, it was the ceiling. Above where I think a recliner was by the owner when they still lived in the house was another layer of 6 inch insulation, just over a spot of about 8 feet square, it made a noticeable difference in the comfort level in that room. So I know more insulation is better.

[OffWithTheirHeads]

7. Ceiling insulation is the most effective

for obvious reasons (heat rises) but wall and floor insulation is important too. Heat travels to cold and it dosnt care which direction the cold is so if underneath the house is cold, you are going to lose heat through the floor. If your ceiling and walls are already well insulated, do the floors, but ceiling and walls first.

As to the correct R value, if you live in Fargo, you will have different needs than San Diego. Check with your local building department for the standards (sometimes requirements) in your area.

After a lifetime in construction, observing and learning from other trades (I'm in heating and air conditioning) I agree with the above poster. The wire (coathanger) method is the easiest installation method I have seen and the one I most often see being used by the pro's.

I'm not a physics major but my guess is that the tile feels colder on your feet than wood is because the tile has a faster heat transfer than wood so your feet feel colder on the tile even though the ambient temp is the same.

[madokie]

8. didn't think of that angle and I think you are right.

to the bare feet the tile feels much colder than the wood while it is pretty much the same temp.

[Magical]

9. Just make sure....

You have no rodent or insect problems...
Make sure their is no way for rodents to get under there...
I know 2 people who recently had to rip out all the insulation because of rodents and insects...
Expensive proposition...
Slippers may be the most cost effective solution depending on where you live.