floors

[woodmills1]

the post on the barn floor has had quite the discussion on what goes under concrete floors. any one have insulation under theirs. if so is there some right way to place it? i will be placing much concrete over the next three years, and have trowled in the past. two of the five buildings in my plan could benifit from insulation. the 2000 sq ft barn i hand trowled at my recently departed domicile was on 6 inces of sand and, I used left over rewire from the boston harbour out fall tunnel. it did fine, but i am looking to do my homework on insulation. thanks in advance.

James "woody" Mills

 

[njrqs]

Ooh

Now I really am learning about the good ole USA.

Hear in Australia, I have not heard about insulation under concrete. Concrete seems a good insulator by itself.

Our coldrooms have insulation under their slabs.

Does it get that cold over there? - What about the walls??

<font color=blue>Neil from OZ.</font color=blue> /w3tcompact/icons/smile.gif

 

[HalseyGreen]

I've helped to set up for a pour of two heated garages, use 2" foam next to the block wall and again coming out 2' from the wall. I was told that this keeps the concrete from conducting the cold in from the outside. I have noticed that the slab in both stay warm from the wood stoves, and that's nice when working on your back laying on the floor. Sounds good to me and its an inexpensive addition.

 

[Youare]

About 20 years ago a friend of the family built a house here in Hew Hampshire. He was going to heat his home with radiant panel electric heat. He contacted Public Service of New Hampshire for suggestions on the most efficient method of insulating the whole house. They suggested insulation under the concrete floor for the basement as well as insulation on the outside of the foundation walls footing to sill.

As far as I know the ground under the floor was prepared in the usual manner, plastic sheet spread out, a layer of high density styrofoam board was placed on the plastic, then the reinforcing wire spaced on top of this and the floor was poured. This seemed to make a difference his floor was not as cold as my basemnet floor with about the same amount of heat in the cellar.

PSHN may still have some publications reguarding insulating cement floors for electric heat.

Randy

 

[RichNJ]

I used insulation under the house, garage and breezeway concrete slabs. Here's the basics:

1. Used Celotex polyisocyanurate foam core rigid insulation. The poly core has fiberglass fibers for added strength. Each piece is 4x8ft by 2 in thick. You can get many different thicknesses. There is a foil layer on each side. R value of about 7/inch. Used foil tape to seal seams between sheets.
2. The house slab is 1 foot thick. We have no footings. The basement walls are keyed into a notch in the edge of the concrete slab. The slab acts as a thermal energy storage mass for solar heat. Starting from the bottom: 6 to 12 inches crushed stone, vapor barrier, 2 staggered layers of rigid insulation (4"total), concrete. Bought so much it came on 2 tractor trailer loads directly from the factory.
3. The breezeway between the house and garage is a haunched slab. 1 foot thick at the edges and 6 inches thick for the rest. 2 foot of crushed stone under slab. Floating slab is not attached to either the house or garage. Use 4 inches of insulation (leftover from house). Put tubing attached to wire mesh for future hydronic heat if the breezeway is ever enclosed.
4. Garage slab is 5 inches thick with cruched stone layer, vapor barrier, 2 inches insulation, vapor barrier again, wire mesh, hydronic tubing, wire mesh again, concrete. Conventional footings with concete blocks to just above grade. 1 inch insulation between blocks and edge of slab. Slab is not attached to blocks. Backfilled around blocks with crushed stone to avoid settling and therefore cracked slab.

The vapor barriers were from 2 different companies but in both cases they are made to withstand the abuse of pouring concrete and do not breakdown from chemical interaction with the concrete as conventional poly sheeting does. I don't recall the names now but I'll look them up for anyone who wants the info.

 

[rdln]

I have been researching this and found this to be helpful

http://www.owenscorning.com/comminsul/applications.asp?Application=67

this along with communication with concrete batch plant people
have convinced me that 15psi polystyrene rigid foam board is
dense enough for basement slabs and garage slabs.

The question not yet answered is when they talk about 40psi
and higher density foam. they say it is for heavy loads but they
dont say what constitutes heavy.

I can imagine using a four caster floor jack (which probably doesnt
have a total of a sq. inch of contact with floor) to jack up a truck
and cracking the slab as my insulation compresses./w3tcompact/icons/shocked.gif

Concrete has some bridging affect when a load is placed upon it.
What I would like to find is a table showing loads on top of floor,
floor thickness, strength and reinforcing methods and the resulting
load that is put on the base below the floor.

When pricing the 40psi board, I find that the price doubles, it is a special
order and a minimum quantity is required which is 10x as much as I would need.

 

[toddwulf]

I've been researching Radiant Floor Heating for our new house and attached is a description with diagrams in MS Word format that may be helpful. You can find this at the following website:

www.radiantdesigninstitute.com

'98 NH 1920 4x4

 

[beenthere]

If you place insulation (rigid foam) under the concrete, be sure to protect it from getting concrete under it when the concrete is poured. I helped a friend pour his, and the blast of concrete coming down the chute got under the foam, lifted it, and made one $#@* of a mess. Lay reinforcing mesh on top of the foam board and be careful when pouring. It works great if cold ground is under the floor. I believe it is very important to also insulate at the perimeter (even a few feet out from the edge of the floor and down the foundation walls) of the floor to keep the heat from the floor from disappating and trying to heat the outside ground and air.