How to backfill after laying waste lines under basement floor

[Dairylander]

I just dug a huge trench in my basement and laid waste lines for a new toilet, shower, etc. Some areas are over 2 feet deep.
Before I re-pour the top four inches of concrete floor, what kind of fill should I use around and above the pipes?

When I excavated I separated the materials, so should I backfill with...
-the dirt
-the dirt and small aggregate
-the small crushed concrete (1/2" to 2")
-the small and bigger chunked concrete (1" to 3")

Or am I being anal retentive and it doesn't much matter?
Just mix it all in and tamp?
It's a small residential house with a low traffic basement bathroom.
Thanks.

[ToUtahNow]

I just dug a huge trench in my basement and laid waste lines for a new toilet, shower, etc. Some areas are over 2 feet deep.
Before I re-pour the top four inches of concrete floor, what kind of fill should I use around and above the pipes?

When I excavated I separated the materials, so should I backfill with...
-the dirt
-the dirt and small aggregate
-the small crushed concrete (1/2" to 2")
-the small and bigger chunked concrete (1" to 3")

Or am I being anal retentive and it doesn't much matter?
Just mix it all in and tamp?
It's a small residential house with a low traffic basement bathroom.
Thanks.

The first 12" should be clean dirt, free of aggregate. After that just be reasonable.

Mark

[drtyhands]

Not even a little bit of sand:p

[swoosh81]

Be sure to tamp it down if you use existing dirt, no need in having your new concrete floor cracking prematurely.
I'd suggest using 2b stone to back fill though.

[gear junkie]

Tell me if this is wrong; lay your pipe on compacted clean dirt, then lay 12" of sand on top. Then backfill as usual. Right or wrong?

[plumberscrack]

What? You guys are hauling dirt out to bring in 12" of sand? Is that a little overkill? I only bring in sand for waterpipe buriel.

[ToUtahNow]

Tell me if this is wrong; lay your pipe on compacted clean dirt, then lay 12" of sand on top. Then backfill as usual. Right or wrong?


While sand is nice neither the UPC or the IPC require sand.

Mark

[Bob D.]

While sand is nice neither the UPC or the IPC require sand.

Mark

No, but they do not preclude its use either I believe.
NSPC* (Not So Popular Code) § 2.6.3 says in part;

"...backfill material shall be sand, gravel, or loose soil that is free of rocks and debris."



* 2006 National Standard Plumbing Code, Section 2.6.3. The NSPC only applies in a handful of states.

[gear junkie]

Reason why I ask is that this is standard Navy practice. Sometimes we don't always do things the right way so I want to know if this is acceptable. Thinking out loud here; How do you achieve compaction rating with dirt placed right on pvc pipe? I know the first lift is 12" but is seems like the pipe could still be damaged when compacting. Since you can't compact sand, there would be at least 18" of soil between the pipe and the packer offering a little more protection.

[ToUtahNow]

There is a slight difference between the UPC and the IPC when it comes to backfilling. The UPC has you backfill 12" in multiple "layers" compacting as you go while the IPC has you backfilling 6" then compacting then another 6" then compacting again.

Mark

[drtyhands]

So I can start chopping at my inspectors now for looking for a minimum of two inches of sand under my soil pipe and 6" on top.I never questioned them after all these years.I've spent 100's of dollars importing sand:mad:

[ToUtahNow]

So I can start chopping at my inspectors now for looking for a minimum of two inches of sand under my soil pipe and 6" on top.I never questioned them after all these years.I've spent 100's of dollars importing sand:mad:

You should always have a code book on your truck so you can ask the inspector to point out his reference when writing a correction. You would be surprised how many inspectors misuse the codes because they don't know them well enough.

As far as the OP's post, imagine digging all of the bathroom drains with 2' deep trenches in the basement. Unless it's a walkout basement you would have to carry all of that dirt out of the basement then carry all of the sand back down. The sand will give him a much better job but at what cost to his back?

Mark