DG over moisture barrier

Jonathan Cartwright · 03-21-2008, 06:01 AM

Inspected the crawlspace of a 2007 built home. There is a sump and drain in the center of the crawlspace - drain is supposed to terminate at a drainage ditch adjacent to this neighborhood. Most of the homes in this small neighborhood have these drains however a few do not.

My question is why is the entire crawlspace covered with 2 to 4 inches of decomposed granite (DG) on top of the moisture barrier? Does this have anything to do with the drain system? The few homes without the drains have no DG in the crawlspace.

Similar Threads:

**Raymond Wand** · 03-21-2008, 06:47 AM

Yes it appears so. The holes in the plastic liner have holes in them within inches of the top.

**Jerry Peck** · 03-21-2008, 11:53 AM

Originally Posted by Jonathan Cartwright

decomposed granite (DG)

I know I could do a Google search and probably find out, but ...

... I'll be the dumb one and ask:

What to heck if "decomposed granite"? I didn't know granite "decomposed"????

**Gunnar Alquist** · 03-21-2008, 04:40 PM

Jerry,

Hard to believe, but granite does crumble and eventually fall apart into particles resembling crushed sand. Presumably a part of the erosion/weather process. Here in CA, we have Joshua Tree National Monument and Yosemite, at both of which the ground is covered with DG in many areas.

Around here, DG is used a lot for garden walkways. It is spread it out, watered and compacted with a tamper or weighted roller. Makes an attractive and durable walkway that you can roll a wheelbarrow on.

I guess I sound like an ad for the DG marketing counsel.

**Jerry Peck** · 03-21-2008, 05:23 PM

Originally Posted by Gunnar Alquist

Jerry,

Hard to believe, but granite does crumble and eventually fall apart into particles resembling crushed sand.

No, that is not hard to believe, I've seen it, but ... the granite is not "decomposed" is it? Isn't it then just 'crushed granite'?

It is the "decomposed" part which I'm not getting. Wood "decomposes", but does "rock"?

**Gunnar Alquist** · 03-21-2008, 08:21 PM

JP,

I guess it is just what it is called, rather than what it is. Like ironwood is not really iron or Grape Nuts are not made from grapes or nuts.

**Rick Hurst** · 03-21-2008, 08:31 PM

I don't even want to know then where butter comes from.

Jonathan Cartwright · 03-22-2008, 02:08 PM

Now that we have thoroughly explored the regional lingo of DG and gravel based breakfast cereal does anyone have any ideas as to why the whole crawlspace would be covered with the stuff???

I have seen gravel placed around sumps in the crawls to prevent excessive soil from washing in and clogging the pump however I have never seen this type of application throughout the crawlspace.