Can I run dust collector PVC piping underground?

[Greg Funk]

I would not use galvanized steel duct under the cement. Over time it will rust out. I worked in an office that had the hvac ducting done this way. It rusted out and would fill up with water. Not a good thing.

Ed

When they lay the pipes they put plastic poly in a trench then put the pipes in and then sprayed polyurethane foam around them. We have them in our house as well. I haven't seen any signs of water in the pipes.

Edit: my shop is also at ground level not in the basement so I don't have any issues with high water table.

Greg

[Gary Salisbury]

What is the purpose of the polyurethane spray foam around the pipes? Insulation? Are you in a cold zone? I wonder if it would be needed here in Southern California where it never freezes?

Gary in San Diego

[Greg Funk]

What is the purpose of the polyurethane spray foam around the pipes? Insulation? Are you in a cold zone? I wonder if it would be needed here in Southern California where it never freezes?

Gary in San Diego

Gary,

I have to admit I'm not 100% sure why they sprayed the insulation around the pipes. In our house the pipes are just used to exchange fresh air into the house. We don't have air conditioning. Air is sucked out of the house through a heat exchanger and fresh air is brought in and warmed up by the outgoing air. I suppose the insulation prevents the fresh air from getting cooled by the ground. It may also help protect the pipes before the slab is poured. The insulation was strong enough to walk on.

Greg

[Jim Becker]

The foam around the metal pipe serves to reduce condensation from temps dropping and as a close moisture barrier as well as providing additional structural support around it as weight goes over during the pour.

[Chris Padilla]

The insulation was strong enough to walk on.

Greg

Sounds most definately like a closed-cell foam (as opposed to an open-cell foam, that you can easily rip chunks out with your hand) that gets pretty stiff when cured.

[Gary Salisbury]

Well here we are, six years later and I am just now building my dream shop. Life kind of got in the way but I just broke ground last week on the project. If you are interested, you can take a peek here:

http://www.pinterest.com/garydsalisbury/

or more specifically here:

http://www.pinterest.com/garydsalisb...ary-salisbury/

Gary in Blossom Valley, California
Rock & me.jpg

[roger wiegand]

Having moved from a concrete floor shop to one with a wood floor a couple of years ago, I would never go back. Much more pleasant to stand and work on. I laid down a moisture barrier on the concrete slab, sleepers, plywood subfloor and then hardwood flooring on top (got "mixed domestic hardwoods" from the flooring mill, dirt cheap and a very interesting floor for a shop). I ran power under the floor, but didn't have enough overhead clearance to make it tall enough to accommodate dust collection.

Having occasionally had to take my overhead piping apart to clear jams, the idea of having DC pipes buried in concrete would really give me second thoughts. After a while I learned not to try to suck up long stringy strands from turning.