Building Process Video 9: Vapor Barrier and Sand

We add a vapor barrier and 2 inches of sand to our underslab prep.

Category:

Howto & Style

Tags:

• construction
• owner
• builder
• building
• process
• concrete
• home

[imthupertherial]

They called for the sand on the plans? Wow architects are dumb... I'm not even out of college yet and they already give me headaches!

[conmanumber1]

BACK AGAIN.... THE WEEDMESH OR WEEDMAT CLOTH IS TO STOP THE WEIGHT AND EFFECTS OF GRAVITY OF GRAVEL OR HARDFILL SETTLING BELOW SURFACE OF SUB BASE......BASICALLY INCREASING SURFACE AREA.

ON HARDFILL I STARTED USING PEAGRAVEL AS IT DOES NOT SETTLE LIKE SAND AND SITS LIKE BIRDSHOT...AGAIN ON PEAGRAVEL I STABILISE TOP 3 INCH WITH CEMENT AND SAND....CARL G

[conmanumber1]

HI AGN FRM N.Z.

THE COMMON PRACTICE IS 1 OR 2 INCH SAND OVER THE COMPACTED HARDFILL AND SAND THEN POLY AND REINFORCING MESH CHAIRS AND REINFORCING ON TOP.

I PRIOR TO PUTTING DOWN HARDFILL LAY DOWN A WEEDMAT TYPE MESH OVER CLAY OR SUB BASE THEN FILL WITH HARDFILL (MIXTURE OF CLAY, SAND AND GRAVEL OR JUST SAND AND GRAVEL) PRIOR TO COMPACTION I STABILISE TOP 2 TO 3 INCH FILL WITH CEMENT, DAMPENED THEN COMPACTED HARD UNTILL PLATE COMPACTOR BOUNCES ON SURFACE. THEN YA DONE.

[Suamere]

There shouldn't be problems with "avoid using sand." Sand should only be used in basic slabs where there is no vapor barrier. The sand will actually be a hinderance on top of a vapor barrier, since the plastic won't allow any drainage at all. On top of that, you are immediately filling the sand with water when you pour concrete on top of it, with no way to get out because of the plastic. When using a vapor barrier, do not ever use plastic. Control Joints to manage cracking if needed.

[areyouinthevibe]

you have to put a vapor barrier to avoid moisture to come across the concrete

[carlamyjohnson]

hi, im building in spain using slab foundations, only i dont think they have any sort of vapour barrier, is this a must?? iv watch the videos you have uploaded and find them very very informative.  i have just come back from holiday in Vegas, fantastic place.