Concrete Foundation - Three Types of Concrete Foundations ...

The slab normally rests on a bed of crushed gravel to improve drainage. Casting a wire mesh in the concrete reduces the chance of cracking. A slab on grade is suitable in areas where the ground doesn't freeze, but it can also be adapted with insulation to prevent it from being affected by the frost heaves. (see below) In summary: Slab on grade ...

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Pouring a concrete slab: Prepare the Ground & Drainage ...

Jul 28, 2016· Pouring a concrete slab foundation: Prepare the Ground & Drainage. ... Measuring Grade for a Backyard Rink with a line level. - Duration: 8:58.

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Insulating a slab on grade foundation - Fine Homebuilding

Martin Holladay explains insulating a slab on grade in the Energy Smart Details department. Insulating a slab on grade depends on at least four factors: the climate, the type of foundation, whether the slab includes hydronic tubing for radiant heat, and the severity of the local termite problem.

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Choosing Best Gravel For Concrete Pad - Concrete & Paving ...

Jan 06, 2008· for concrete deck or slab - prolly should tamp it. Nobody ever does though. If you don't tamp it - at least wait a week or so before you pour. It WILL settle within that time. ... Choosing Best Gravel For Concrete Pad I couldn't make any sense of the 57 and 67 explanation. OK, the explanation I can understand, by why not name them 39 and 16?

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gravel under concrete slab? is it absolutely required ...

Its about 3.75 cu yards of crete, or like $400 It will cost $100 for gravel to fill in 2", but my crete is still only a little cheaper, and it will be a thinner slab. I could put gravel in, say 2" and 3.5" of concrete over that or just full 5.5" of crete or I could do lot of gravel and a 2" top coat over that with a bunch of steel and fibers,

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why put gravel under concrete slab on grade

Sep 05, 2010· ""the only thing under the concrete is ground")" ----- usually they excavate down to the footing depth on the whole basement, then back-fill dirt (or gravel) to bring the sub-grade up so the slab is sitting on the footing (with the v.b. under and covering the end of the slab).

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Subgrades & Subbases for Concrete Slabs - The Concrete Network

Apr 28, 2014· Concrete may seem strong, but after many years, elements, and pressure, it will eventually crack. So in order to make your concrete last as long as your money that went into it, adding a layer of crushed stone under a slab of concrete will increase the life of your investment. Here are 3 reasons why a layer of crushed stone is important to the life of your concrete:

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Structural fill below slab on grade - Foundation ...

Sep 20, 2007· Ahh, the old vapor barrier under slab-on-grade debate. The best article I have ever read on this is entitled "Where to place the vapor retarder" by Suprenant and Malisch (I can't remember the magazine, but I think it was Aberdeen's Magazine of Concrete Construction).

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Does anybody use sand as a base before they pour concrete ...

Concrete cracks no matter what you do, that is why you see regular spaces groves or lines in sidewalks, its a control joint to allow cracking to occur there rather than where it wants. Otherwise, what is under a slab depends on the ground you are pouring the slab on, some soils don't need anything, some need a …

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Code Requirements for Concrete Slabs on Grade - EVstudio

Mar 27, 2018· Code Requirements for Concrete Slabs on Grade. ... lays out a series of requirements for pouring a concrete slab on grade. Its more than just forms and pouring concrete! ... graded sand, gravel, crushed stone or slag under 2″ when the slab is below grade unless the existing soil is exempted by the soils report.

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Why Put gravel under concrete? (2019 UPDATE)

May 06, 2010· I want to pour a driveway section in front of the garage and was told by a guy at the concrete company (who came to measure the amount needed), that I need to put gravel under the concrete. WHY? I should mention that I always put lots of small to medium sized rocks under concrete to save on the amount of concrete needed.

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Better Garage Floors| Concrete Construction Magazine

If you're installing rigid foam under the slab, put the vapor barrier on top of the foam. Don't place a sand or gravel blotter layer on top of the vapor barrier. There was a time when that practice was recommended to reduce curling in the slab, but if you're using the proper low-water-content concrete mix, a …

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Foundation: Compacting sand and clay under our slab on ...

Feb 03, 2012· Here is how we compacted the fill and sand inside the foundation walls. We backfilled some clay before adding sand. The video shows clearly how to tell clay from soil. Organic matter is not ...

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How much gravel under a slab? - tractorbynet.com

Sep 10, 2002· Figure gravel and sand at or about twenty five hundred pounds a yard. I have a bud who has a fleet of trucks hauling sand and gravel. He's told me to figure a ten yard load will cover four inches five hundred square feet. I've heard some of the cities now are getting away from wanting cushion sand under a slab while others still demand it.

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Why Put gravel under concrete? (2019 UPDATE)

May 06, 2010· I have poured many small sidewalks and shed floors and never put gravel under the concrete. I want to pour a driveway section in front of the garage and was told by a guy at the concrete company (who came to measure the amount needed), that I need to put gravel under the concrete.

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Concrete Floor Problems | Building Science Corporation

May 26, 2008· Figure 1: Slab-on-Grade Done Right —Concrete slab is isolated from ground contact with sheet polyethylene. Note that the polyethylene extends under the grade beam and upwards to grade. Latex paint over the exposed portion of the slab prevents liquid phase water from being absorbed by the concrete—but allows vapor phase water to leave the ...

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Should vapor barrier in slab be under 4 in. of gravel or ...

May 03, 2011· 2-part question: 1) I'm building a 2-car garage with upstairs apartment in zone 4, 26' x 28'. getting different opinions on whether the vapor barrier -6ml plastic- should be under the 4'' of gravel or on top of the gravel directly under slab? Some are saying it is not good to pour concrete right on plastic, although this seems to be the most common way to do it.

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How important is gravel under a concrete sidewalk? (Home ...

How important is gravel under a concrete sidewalk? I got an estimate from a company on your list to replace my old, beat-up concrete sidewalk. When they dug up the old sidewalk, there was no gravel underneath, and they wanted several hundred more dollars to dig out some of the dirt and put in a gravel bed - is this necessary?

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How to Prepare the Ground Before Pouring Concrete Slab ...

Determine the proper depth by establishing the height of the concrete slab. Add 2 inches to the depth for gravel if the soil is normally moist or has a high concentration of clay. Most concrete slabs will sit 1 to 2 inches higher than the dirt and 2 to 3 inches below the surface of the dirt, making the needed depth of the hole 3 to 5 inches.

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Importance of Gravel and Sand for Concrete | Hunker

Apr 12, 2018· Smaller gravel particles equals a "fine" grade of concrete. Use the fine aggregate for concrete slabs or other smooth surfaces. A "coarse" aggregate means using larger pieces of gravel. Coarse concrete is helpful for sturdier projects. Concrete with a coarse aggregate doesn't produce a smooth look or feel but is stronger than a finer grade.

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How to Pack Down Rock Before Pouring Concrete | Home ...

Gravel is especially important in clay soil because it doesn't drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains. Gravel allows ...

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Vapor Retarders Under Slabs on Grade — What, why, & how ...

ASTM E1643, Standard Practice for Installation of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs, ASTM, West Conshohocken, PA. Slabs on Grade, Concrete Craftsman Series – CCS-1, 2nd edition, American Concrete Institute, Farmington Hills, MI.

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Pea gravel for interior floor slab support - Geotechnical ...

Jun 06, 2006· Recently, a local builder used pea gravel up to 6 inches in thickness above the vapor retarder and under a post-tensioned slab. The builder used the increased pea gravel thickness to help re-establish grade due to winter construction conditions. The local builder believes the pea gravel to be "self-compacting" which is not correct.

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Sand under slab instead of gravel - GreenBuildingTalk ...

Mar 04, 2013· I'd want to know why the sand is so wet in the first place. If it's just due to weather exposure and would drain/dry if under cover, that's one thing. If it's due to high water table, I might be inclined to build up the slab area with crushed stone (aka "gravel…

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Proper Subgrade Prep| Concrete Construction Magazine

Sep 20, 2007· With slab-on-grade foundations, an alternative to native soil material may be used to restore grade. These imported fills may include granular materials such as sand, gravel, or crushed stone. These high-strength and permeable materials offer low compressibility, which is ideal for a …

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compacting gravel under a slab - JLC-Online Forums

Dec 07, 2004· Re: compacting gravel under a slab Tucker: With 2 to 3 feet of rock, I fail to see why you need either poly or insulation under the slab, I think I would opt for the "oozing" and the thickening effect of the "waffle" bottom, I would think that structurally it turns a 3 1/2" slab into something more like a 6 or 8" slab from a structural standpoint.

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Gravel under Concrete Slab | Pilots of America

Jun 28, 2016· For the Civil Engineers out there. Does anyone know of any real reason to spend the money to put gravel under a concrete slab? I have always just graded the dirt under the slab so it drains off to the sides or bottom same as the concrete slab will drain, compacted it and called it good.

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The Dirt on Below-Grade Insulation | Insulfoam

Aug 14, 2014· For under-slab applications, the rigid foam insulation typically should be installed over a gravel base, with a poly vapor diffusion retarder between the gravel and insulation. Additional insulation is applied along the edges of the slab, because that is a primary surface for heat loss.

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Slab-on-Grade Vapor Barrier - JLC-Online Forums

Feb 10, 2006· Re: Slab-on-Grade Vapor Barrier We put the vapor barrier under the concrete. First we level the pad with Item four and compact, then put a 4 inch layer of 3/4 stone, compact again, then the foam and plastic, then place the concrete. But I don't see what difference it would make if you swithched the foam and the VB positions.

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The Recommended Gravel Base for a Concrete Driveway

The strength and durability of a concrete driveway are not only determined by the type of concrete mix but also by base or sub-base over which it's poured. A layer of gravel placed between the ...

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