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why put gravel under concrete slab on grade

202068Supported Slab on Grade Grade Slab Supported grade slab or slab on grade foundation is chosen when the traditional footings are already framed on site to raise the columns. From the below fig, it is clear that the wall stands on a footing and The grade slab is resting on a layer of gravel

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Slab on Grade or Grade Slab   Types   Construction

Slab on Grade or Grade Slab Types Construction

202068Supported Slab on Grade Grade Slab Supported grade slab or slab on grade foundation is chosen when the traditional footings are already framed on site to raise the columns. From the below fig, it is clear that the wall stands on a footing and The grade slab is resting on a layer of gravel

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Do you need gravel under a concrete slab   Quora

Do you need gravel under a concrete slab Quora

I agree with David Powers and disagree with a statement made by Michael Dillon. Short answer is yes but rather than gravel one should use a material that will suffer compaction such as ABC aggregate base course, crushed concrete, or even depe...

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Importance of Gravel and Sand for Concrete   Hunker

Importance of Gravel and Sand for Concrete Hunker

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 doesnt produce a smooth look or feel but is stronger than a finer grade.

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What is grade slab and what is the difference between

What is grade slab and what is the difference between

Grade Slab Flat concrete structure built on top of the soil at ground level and does not require support from underground footers or foundation walls This grade slab acts as the foundation for a home or building, and provides a stable base for w...

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

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

2020682part question 1 Im building a 2car 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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The Dirt on Below Grade Insulation Insulfoam

The Dirt on Below Grade Insulation Insulfoam

For underslab 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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what do you use under concrete   Everything About

what do you use under concrete Everything About

Hi, I am Mike Day, owner of Days Concrete Floors, Inc. in Maine, where Ive been working with concrete for 30 years now, and this website is where I can share with you all the knowledge and wisdom Ive gained from installing all kinds of decorative concrete, concrete floors, concrete overlays, stained concrete and also fixing cracked or spalled concrete.

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Concrete Floor Problems   Building Science Corporation

Concrete Floor Problems Building Science Corporation

202067Photograph 2 SlabonGrade Done Wrong Note the layer of granular material over the top of the plastic vapor barrier. Liquid phase water will be held by the fines in the granular material creating a reservoir of water that can only dry upwards into the slab leading to

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How to Prepare the Ground Before Pouring Concrete

How to Prepare the Ground Before Pouring Concrete

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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Subgrades Subbases for Concrete Slabs   The

Subgrades Subbases for Concrete Slabs The

Subgrades and Subbases for Concrete Slabs ... then you can put a slab right on top of it without any extra layers. The problems with that are that the soil may not drain well and it can be muddy during construction if it gets wet, it may not compact well, and it can be difficult to get it flat and to the proper grade. ... If the underslab ...

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The Dirt on Below Grade Insulation Insulfoam

The Dirt on Below Grade Insulation Insulfoam

For underslab 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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compacting gravel under a slab   JLC Online Forums

compacting gravel under a slab JLC Online Forums

2004127Re 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 12 slab into something more like a 6 or 8 slab from a structural standpoint.

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Polyethylene Under Concrete Slabs

Polyethylene Under Concrete Slabs

2020672 Reasons Why We Place Poly Under the Insulation Living in a wet, coastal environment in Canada where a large portion of our houses are slab on grade, there are two reasons why we continually choose to place 10mil poly underneath our rigid foam, instead of on top of it. Reason 1 As foam absorbs water its rvalue drops substantially.

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How much gravel under concrete   TractorByNet

How much gravel under concrete TractorByNet

20021126Join Date Jan 2002 Posts 1,569 Location Colorado Tractor 2000 New Holland TC29D with 7308 FEL, and top tilt. 1950 John Deere B. 1940 Farmall A.

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Does anybody use sand as a base before they pour

Does anybody use sand as a base before they pour

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 dont need anything, some need a

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Sand under slab instead of gravel   GreenBuildingTalk

Sand under slab instead of gravel GreenBuildingTalk

201334Id want to know why the sand is so wet in the first place. If its just due to weather exposure and would draindry if under cover, thats one thing. If its due to high water table, I might be inclined to build up the slab area with crushed stone aka gravel in some places before adding the foam and VB.

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Concrete Slab   How to install a slab from start to finish

Concrete Slab How to install a slab from start to finish

A concrete slab is poured right on the ground. It doesnt have a foundation or any concrete walls under it or around it. In Maine we install a lot of slabsongrade for houses and garages. A slab foundation is usually less expensive to install than a full concrete wall foundation with a concrete floor.

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gravel size under concrete slab   strzelnica

gravel size under concrete slab strzelnica

Jan 10, 2005 Re compacting gravel under a slab I was on the ICC site and someone suggested that I use rebar placed in the slab over block or concrete piers and letins on the foundation wall just in case the gravel

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Compact Fill Under Slab   Ask the Builder

Compact Fill Under Slab Ask the Builder

DEAR TOM Uncompacted fill under concrete slabs of any type is a recipe for disaster. The slab could be for an entire home, it might be an exterior patio slab, a front porch slab, a driveway, etc. Concrete is an amazing material, but it has an Achilles heel. CLICK HERE to get FREE FAST BIDS from local concrete slab contractors. Concrete Weakness

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Insulating an outdoor slab   JLC Online Forums

Insulating an outdoor slab JLC Online Forums

2013920Re Insulating an outdoor slab Thanks very much, DGBldr and NW Architect. So, what Im gleaning from your posts is that insulation under a totally exposed concrete slab is useless AND that good reinforcement practice is the best thing I can do, under the circumstances.

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gravel size under concrete slab   strzelnica

gravel size under concrete slab strzelnica

Jan 10, 2005 Re compacting gravel under a slab I was on the ICC site and someone suggested that I use rebar placed in the slab over block or concrete piers and letins on the foundation wall just in case the gravel

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compacting gravel under a slab   JLC Online Forums

compacting gravel under a slab JLC Online Forums

2004127Re 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 12 slab into something more like a 6 or 8 slab from a structural standpoint.

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Slab on grade construction on typical soil   Ecohome

Slab on grade construction on typical soil Ecohome

How to build a slabongrade with a thickened edge on standard soil There are many ways to build a slabongrade or frostprotected shallow foundation, the following is a stepbystep walk though of a thickenededge slab floor we built. XPS or EPS highdensity foam is typically used under concrete slab

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Shouldnt I Have Gravel Under Concrete Footers

Shouldnt I Have Gravel Under Concrete Footers

2012929shouldnt I have gravel under concrete footers Our contractor is telling me that a layer of gravel is not needed under the concrete footers. I called the inspections office in my area and spoke to the lead inspector in my area and he told me the same thing, but couldnt tell me why gravel isnt needed under the poured concrete.

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The Recommended Gravel Base for a Concrete

The Recommended Gravel Base for a Concrete

2019926The 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

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Plastic under concrete floor or not   Speedwake 2 0

Plastic under concrete floor or not Speedwake 2 0

2006122Use a good grade of stone as a base, tamp it real good, and use a good mix of concrete with some wire mesh. Ive never used plastic of any kind under any concrete Ive ever done. Im not sure wat the benefits of using it are, but Im not sure that you want the moisture contained in the concrete

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Under Slab Waterproofing   Building Enclosure

Under Slab Waterproofing Building Enclosure

Waterproofing of the underslab can be as critical to the success of weatherproofing a building as waterproofing belowgrade walls. This oftenoverlooked component has led to a tremendous amount of damage through moisture entry in both liquid and vapor form. Moisture enters the concrete slab at all of the usual suspected areas, such as openings, joints, penetrations and cracks that form over time.

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Subgrade and Subbase for Concrete Slabs   The

Subgrade and Subbase for Concrete Slabs The

202068Subgrade and subbase are the foundation of a concrete slab and play critical role in its performance. According to the ACI Code, the subgrade is a compacted and improved natural soil or brought infill whereas subbase is a layer of gravel placed on the top of the subgrade. Both subgrade and subbase shall be constructed

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Sand under slab on grade   GreenBuildingTalk

Sand under slab on grade GreenBuildingTalk

2009526First off the project is radiant heat for a 4800 slab on grade shop building in North Idaho. The plan and budget has been to use 2 xps, 2 vertical around the perimeter and flat everywhere under the slab. Now Ive seen it recomended in several places fo

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Pea gravel for interior floor slab support

Pea gravel for interior floor slab support

200666RE Pea gravel for interior floor slab support JAE Structural 27 Jan 06 0916 GeoPaveTraffic, one question for you my fear in using pea gravel, or even some sands for that matter, is that with material like this that has uniform gradation, I always sense that there is a difficulty in compacting the material in a way in which it nests into ...

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