Destroyed Concrete Floor

[danski0224]

What the hell are you talking about? I've only put in 100 - 150 foundations as a carpenter. If you can't get the top of the foundation level, you better find another career.

Oh, so that's why when I look at where the mudsill meets the top of the foundation, in some places I see daylight and others I don't see daylight...

Must be different kinds of levels out there...

 

[volleyball]

I would also consider putting a vertical piece of insulation along the edge. Like along the block or between the posts. I did this in my shop and I really think it helps keep the cold from working under the edge of the slab.

Is 6 inches think enough concrete for under the lift?

Sent from my SCH-I605 using Tapatalk

For footings for a conditioned space a vertical 4' piece of insulation is required where I live. I have a space that will never be heated, which means I don't have plans yet, that I put the foam around and under the slab. While it is open to the outside, it doesn't feel as cold to stand on that I'm sure it would if it wasn't. The foam also is a moisture barrier which allows the concrete to cure slower, keeps the concrete from absorbing moisture, freezing and thawing. More help in it not cracking.
I bet in the near future anyone who is doing concrete where cold and moisture is not scarce, will be doing this defacto. Just as caulking and insulation goes in as the framing goes up, not just much later when you cannot get to many voids.

 

[danski0224]

Foam under the concrete? What is that for I have never heard of that?

Insulation. Makes a big difference.

Also acts as a vapor barrier.

Parts of a concrete floor had foam insulation on a job I was on, and whan the temperature changed, you could tell where the foam was- no condensation on the concrete.

You don't want the white stuff, you want the extruded pink (or comparable) foam. You can buy it in 25 and 50 PSI grades.

 

[ADSR]

You don't want the white stuff, you want the extruded pink (or comparable) foam. You can buy it in 25 and 50 PSI grades.

Misinformation right there. EPS (Expanded Polystyrene Insulation) is industry standard for this application. The pink has a higher R-value at 3 times the cost.

4x8x2" white - R value 7.5 @ 16 dollars a sheet.

4x8x2" pink R value 10.0 @ 65 dollars a sheet.

Do the math. An extra 2.5 R value is not worth the extra 50 dollars a sheet.

 

[volleyball]

I got off size sheets from a local distributor. They sell massive amounts as fill for projects as it is cheaper to transport and as effective. If they put it under commercial buildings, it will hold up in a residential garage.

 

[danski0224]

Misinformation right there. EPS (Expanded Polystyrene Insulation) is industry standard for this application. The pink has a higher R-value at 3 times the cost.

4x8x2" white - R value 7.5 @ 16 dollars a sheet.

4x8x2" pink R value 10.0 @ 65 dollars a sheet.

Do the math. An extra 2.5 R value is not worth the extra 50 dollars a sheet.

2" thick 4' x 8' sheets of pink or blue foam is nowhere near $65 a sheet in my area- even in Canadian money. About the only thing close to that price in my neck of the woods is 4" thick sheets of icynene foam used on commercial roofs- and I suspect that if you buy a couple hundred thousand square feet of it or so, the price will come down a bit.

I have *never* seen anything but extruded pink or blue foam used under concrete (residential or commercial) in my area. I'm not wasting time to look it up in the IRC code book.

No personal experience with ICF's.

 

[Alexztt]

With the foam do i only put one layer down or multiples. Just like the vapor barrier which is just plastic sheets right? How much and thickness do I need.

 

[ADSR]

With the foam do i only put one layer down or multiples. Just like the vapor barrier which is just plastic sheets right? How much and thickness do I need.

I'd go with a minimum of 2" R-7.5. After the foam i put a poly vapor barrier over the foam.

 

[Alexztt]

O so the vapor barrier goes over the foam? So a plastic sheet is not the vapor barrier?

 

[volleyball]

I went with base. plastic, foam, concrete. This keeps most ground water out and it can drain if any water gets in there.
I did mine with 1" board stacked with offset seams. I don't think it matters.

 

[ADSR]

vapor barrier goes on the warm side of the insulation. But i'm not so sure it matters much in this case.

 

[volleyball]

That is for any insulation that would hold or degrade by the moisture. This is the one time to do it "backwards". I live on a hill and not at the top. I have mini flows underground.

 

[FORMUD]

2" thick 4' x 8' sheets of pink or blue foam is nowhere near $65 a sheet in my area- even in Canadian money. About the only thing close to that price in my neck of the woods is 4" thick sheets of icynene foam used on commercial roofs- and I suspect that if you buy a couple hundred thousand square feet of it or so, the price will come down a bit.

I have *never* seen anything but extruded pink or blue foam used under concrete (residential or commercial) in my area. I'm not wasting time to look it up in the IRC code book.

No personal experience with ICF's.

I sell 2" x 4' x 8' pink board ( Owens Corning - Foamuler ) 25 PSI for about $34.00 a sheet....Blue board ( Dow ) cost a few dollars more per sheet and the green board ( Pactive ) is about the same price as the pink. Most of the white board is cheaper but it has to be thicker to have the same R-valve and I think they have a higher water absorbent rate. Theres also a 40 and a 60 PSI ( High density board ) out there....But your talking a higher price.

 

[iagsxr]

Last fall I got 2" pink from Menards for $25/sheet. There was a local building supplier that was like $28. Home Depot was low $30s.

 

[Alexztt]

I am confused does the vapor barrier go under or over the insulation and what is it made of?

 

[iagsxr]

Vapor barrier's just plastic sheeting.

Today's the first time I've ever heard of the insulation being below it.

 

[ADSR]

Vapor barrier's just plastic sheeting.

Today's the first time I've ever heard of the insulation being below it.

It's code here to put it on the warm side.

 

[Alexztt]

So typically it is below and how thick should the plastic be?

 

[ConCretin]

So typically it is below and how thick should the plastic be?

There is some debate about whether the insulation or vapor barrier should be on top. Some think the vapor barrier should be on top to prevent water from pooling in the voids around the insulation.

Many, including myself believe that any such water will migrate out just fine and that protecting the integrity of the vapor barrier is more important and put it below the insulation. This is especially true with radiant installs where you want to attach the tubing to the insulation.

Keep in mind, vapor barriers under slabs are very different from those in walls so it makes no difference which is the warm side.

As to thickness, I'd do a minimum of 10 mil poly and make sure you tape the seams. If you think you might want to install a floor covering such as epoxy at some point, step up to a 15 mil product such as Stegowrap.

 

[danski0224]

I am confused does the vapor barrier go under or over the insulation and what is it made of?

A vapor barrier can be latex paint, vinyl wallpaper, Kraft paper or any one of several types of synthetic material- including plastic sheeting. The synthetic material can have a layer of aluminum bonded for zero permeability.

This is one company from a Google search that offers many different kinds of "plastic sheeting" with different properties: http://www.globalplasticsheeting.com/

Vapor barrier type and placement is dictated by climate zone.

Someone in Georgia USA will have different vapor barrier requirements and location of the vapor barrier than someone in New Jersey USA. Our Canadian neighbors also have different requirements.

*Your* best bet is to first figure out what Climate Zone you are located in (Google also works for that ) and then go here ( http://www.buildingscience.com/index_html ) and start reading, rather than take advice from random people here that (1) aren't qualified and (2) don't live in your area and (3) "the way we have done it for years" isn't always right.

A primer on vapor barriers in walls: http://www.buildingscience.com/docu...por-barriers/?searchterm=vapor barrier zone 5

A primer on vapor barriers and concrete floors: http://www.buildingscience.com/docu...r-problems/?searchterm="vapor barrier"+ floor

The rest is on you. Read up.

 

[ConCretin]

danski0224, I feel I should clarify something. You have included a lot of information on vapor barriers but it could be confusing because you combined under-slab vapor barriers and vapor barriers in walls and ceilings. The OP has a slab issue and much of the information you suggested isn't relevant to his issue.

Under slab vapor barriers are designed solely to stop moisture intrusion from the soils underneath. They have nothing to do with keeping warm, moist air from reaching the dewpoint and condensing, which is a vapor barriers purpose in heated structures. Under slab vapor barriers are almost exclusively plastic membranes and their selection has little to do with geography or the other criteria you mention.

It was an informative post - just a little of topic. Sorry to be so picky but there is a lot of confusion out there about under slab vapor barriers and I want people to be clear.

By the way, I am qualified, I don't need to live in his area to give him this particular piece of advice and the way I've done it for years is the right way. If everyone heeded that bit of counsel, we'd have have a lot less to talk about on GJ. Cheers.

 

[danski0224]

danski0224, I feel I should clarify something. You have included a lot of information on vapor barriers but it could be confusing because you combined under-slab vapor barriers and vapor barriers in walls and ceilings. The OP has a slab issue and much of the information you suggested isn't relevant to his issue.

Under slab vapor barriers are designed solely to stop moisture intrusion from the soils underneath. They have nothing to do with keeping warm, moist air from reaching the dewpoint and condensing, which is a vapor barriers purpose in heated structures. Under slab vapor barriers are almost exclusively plastic membranes and their selection has little to do with geography or the other criteria you mention.

It was an informative post - just a little of topic. Sorry to be so picky but there is a lot of confusion out there about under slab vapor barriers and I want people to be clear.

By the way, I am qualified, I don't need to live in his area to give him this particular piece of advice and the way I've done it for years is the right way. If everyone heeded that bit of counsel, we'd have have a lot less to talk about on GJ. Cheers.

Well, the whole thread has gone off topic. What's new? At least it hasn't gone political yet...

I just double checked my post, and I did specify "walls" and "floors". I wasn't confused.

In any event, those that choose to read the information will probably learn something, and those that choose to ignore it won't. Obviously, those that already know it can be excused

 

[Justanoldguy]

If everyone heeded that bit of counsel, we'd have have a lot less to talk about on GJ. Cheers.

True, and we could all have more time in the garage building our Hot Rods..

 

[Alexztt]

I think i am going to put it under the insulation it feels like the way to go. What kinds of questions should I ask any contractor that comes to give me an estimate? Things I should look out for.

 

[Alexztt]

danski0224, I feel I should clarify something. You have included a lot of information on vapor barriers but it could be confusing because you combined under-slab vapor barriers and vapor barriers in walls and ceilings. The OP has a slab issue and much of the information you suggested isn't relevant to his issue.

Under slab vapor barriers are designed solely to stop moisture intrusion from the soils underneath. They have nothing to do with keeping warm, moist air from reaching the dewpoint and condensing, which is a vapor barriers purpose in heated structures. Under slab vapor barriers are almost exclusively plastic membranes and their selection has little to do with geography or the other criteria you mention.

It was an informative post - just a little of topic. Sorry to be so picky but there is a lot of confusion out there about under slab vapor barriers and I want people to be clear.

By the way, I am qualified, I don't need to live in his area to give him this particular piece of advice and the way I've done it for years is the right way. If everyone heeded that bit of counsel, we'd have have a lot less to talk about on GJ. Cheers.

I have no doubt of qualifications and was hoping for your input, I am still reading your undergroud garage build. Thanks to all for there guidance so far.

 

[volleyball]

I think you need to figure out as much detail as you can, tell them what you want with those details and they can give you a better estimate. If you are going to do part of the work, be sure to let them know.
Do you need to account for a future lift? Can you put a drain in? What about pitch.
The foam you want is XPS, you will want a 4' vertical piece around the perimeter and 2" under the slab. You may want to source the stuff as a lot of contractors won't be familiar with it.
I suggest you break up a section and excavate down a foot to see what you have. That will help you and the contractor better estimate what you need to do. You have plenty of time as you don't want to pour until May or so.
A power trowel finish will make a better, harder, smoother, straighter surface.

 

[rburke65]

If you are going to remove the entire floor, you might want to conceder radiant floor heat. Don't know if you have heat now or not, but just giving you something else to keep you awake at night. Between the folks here and you.....you,ll be able to come through this. Good luck.

 

[Alexztt]

I am still a little confused about this 4 foot vertical piece is it necessary and what does it do exactly?

 

[ADSR]

I am still a little confused about this 4 foot vertical piece is it necessary and what does it do exactly?

thermal break

 

[volleyball]

Yeah, limits the frost outside the perimeter from freezing what is under your slab. Also water intrusion. dry soil doesn't heave as much.