Our why put gravel under concrete slab on grade

The Dirt on BelowGrade 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.

Ask the Builder | Concrete slab needs quality self ...

I’d put a great crosslaminated vapor barrier on top of the gravel before you pour the slab in the garage. This will keep water vapor from rusting tools and causing havoc in the garage in the ...

Vapor barriers under concrete slabs Stego Industries

mance of the concrete slab. Why use vapor barriers? Vapor barriers are traditionally ... Vapor barriers under concrete slabs Should the concrete be placed directly on the vapor barrier? By Bruce A. Suprenant ... most commercial slabongrade concretes are placed with a water c e m e n t ratio of to Also, the amount ...

Gravel Or Sand Building Construction DIY Chatroom ...

Jul 11, 2010· Wouldn't the under a patio slab keep the water from draining, if the slab was poured on the leveled subgrade for a patio? And possibly freeze easier if the slab is covered with snow that melts into the porous concrete slab during the day pooling there to freeze at night?

Insulating a slab on grade Fine Homebuilding

In climate zones 4 and 5, the code requires certain slabs (belowgrade slabs that are less than 12 in. below grade) to have R10 vertical insulation at the slab perimeter, extending downward from the top of the slab to a depth of at least 2 ft.

Soil Under Slab No Crushed Stone Used Building ...

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

Code Requirements for Concrete Slabs on Grade EVstudio

In addition, you need a base course of 4″ of clean, 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. There needs to be a vapor retarder at least 6 mil between the base course and the slab.

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. ...

why put gravel under concrete slab on grade

why put gravel under concrete slab on grade why sand under concrete? ... I'm preparing to pour a finish concrete foor, slab on grade. I'm preparing to pour a finish concrete foor, slab on grade. The structural plans call for" compacted gravel base, ...

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

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 lot of help. From American Concrete Institute ACI360R10 Guide to Design of SlabsonGround Design of Slabsupport system General "After subgrade soils have been classified, the general range of K values can ...

Concrete Slab Foundation Process Best Practices YouTube

Apr 29, 2016· The most common foundation in the South is a Slab On Grade. In this video Matt will give you an overview of the process as well as some Best Practice tips you can use on your ...

Vapor Barriers under Concrete Floor Slabs: Friend or Foe?

Before one can make the best decision regarding whether or not to place a vapor barrier under a concrete floor slabongrade, it is important to understand the sources of moisture, how it moves through the slab, and how it adversely affects certain floor coverings, adhesives, and coatings.

Polyethylene Under Concrete Slabs GreenBuildingAdvisor

It doesn't really matter very much whether the PEX is near the bottom of the slab, in the middle of the slab, or at the top of the slab, as long as there is plenty of insulation under the slab. 3. Don't worry if the concrete contractors put a few holes in the poly.

Structural fill below slab on grade Foundation ...

Sep 20, 2007· My concrete sub says that without sand or some other "absorbing" material below the concrete, the slab will only cure from above. (uneven curing) He suggests 4" of 5/8" compacted gravel, 2" insulation board, vapor barrier, 4" sand, then wire mesh.

Sand under slab instead of gravel GreenBuildingTalk ...

Mar 04, 2013· I have used as much as 5' of sand under a slab. The sand was dry, contained by block walls and compacted. Never a problem. My guess is that if the sand is quite wet there is a chance of some settlement when the sand drains.

Placing a Concrete Foundation on Rigid Foam Insulation ...

Compacting the gravel base for the foundation slab. On top of this base goes the radon mitigation system, the slab foam insulation layer, the vapor barrier, and then the concrete slabongrade. ... it has become common to place a layer of insulation under a slab on grade…

Why Put gravel under concrete? Google Groups

May 06, 2010· I wish you had asked him for a better clarification. Coarse gravel, like 57 stone, under a slab is used as a capillary break to prevent ground moisture wicking up through the concrete.

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 lowwatercontent concrete mix, a blotter layer is unnecessary.

compacting gravel under a slab JLCOnline Forums

Dec 07, 2004· That would put the top of the block about 2 and a half to three feet above the original grade. So I would need about 2 and a half to three feet of gravel fill beneath the slab. ... but hopefully they'll be no "oozing" of concrete into the gravel under this slab. I'll have a layer of thick poly ontop of the gravel then a layer of 2 inch rigid ...

Concrete Floor Problems | Building Science Corporation

Figure 1: SlabonGrade 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 ...

Concrete Foundation Three Types of Concrete Foundations ...

Slabongrade foundation As the name suggests, a slab is a single layer of concrete, several inches thick. The slab is poured thicker at the edges, to form an …

why is it important to have gravel under a concrete slab ...

Mar 24, 2010· For the best answers, search on this site https:///avT7K I would suggest using 6" of compacted sand and 4' of concrete. It is necessary to have the original concrete floor broken if not it should be broken to allow any trapped moisture to drain to the sub grade under the original floor.

Concrete Slab How to install a slab from start to finish

A concrete slab is poured right on the ground. It doesn't have a foundation or any concrete walls under it or around it. In Maine we install a lot of slabs for houses and garages.

why sand under concrete? | Fine Homebuilding | Breaktime

I'm preparing to pour a finish concrete foor, slab on grade. The structural plans call for 4" compacted gravel base, insultarp vapor barrier, 2" of sand and 4" of concrete.

Why you need gravel under slab YouTube

Feb 06, 2013· Built up water level outside foundation wall pushing water between floor and wall. With proper waterproofing the water makes it to the weeping tile and out to pump.

How to Pour a Slab on Clay Soil | Home Guides | SF Gate

1. Clear and level the area where you plan to pour the concrete slab. If the clay soil is very soft, excavate the soil to a depth of several inches and mix in gravel to create a firmer base for ...

Concrete slab specs sand or no sand? | Fine Homebuilding ...

The plastic goes over any sand or peagravel used under a slab. Both provide a drainage plane beneath the slab and a cushion for expansion,contraction, etc. Sand is also less likely to cause the poly to get ripped, puntured, or torn than gravel under the slab.

gravel stone size for concrete slab – Grinding Mill China

why put gravel under concrete slab on grade Network What lies below your concrete slab is critical to a successful job... may include granular materials such as sand, gravel, or crushed stone... » …

Concrete Forms and Pouring a Concrete Slab | The Family ...

Pouring Concrete Form and Pour a Concrete Slab. ... Look for a supplier under “Sand and Gravel” in the yellow pages. Ask what your supplier recommends for fill under slabs. We used crushed concrete, which compacts and drains well. ... straight and well braced. Have at least two contractorgrade wheelbarrows on hand and three or four strong ...

Proper Subgrade Prep| Concrete Construction Magazine ...

With slabongrade 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. ... Contractors often ask how to backfill foundation walls for an area that will end up under concrete …

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

gravel under concrete slab? is it absolutely required? up vote 4 down vote favorite. ... I could put gravel in, say 2" and " of concrete over that. ... but my crete is still only a little cheaper, and it will be a thinner slab. I could put gravel in, say 2" and " of concrete over that or just full " of crete or I could do lot of gravel ...

CIP 29 Vapor Retarders Under Slabs on Grade

CIP 29 Vapor Retarders Under Slabs on Grade WHAT are Vapor Retarders? Vapor retarders are materials that will minimize the transmission of water vapor from the subslab support system into a concrete slab. Vapor retarders are typically ... Under Concrete Slabs, ASTM, West Conshohocken, PA. 5. Slabs on Grade, Concrete Craftsman Series CCS ...

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.