Can I run dust collector PVC piping underground?

[Gary Salisbury]

I am planning to build a new workshop (see attachment) and do not want exposed dust collection pipes. My choices are:

1. To build 6" walls so I can run metal pipes in the walls (higher cost)
2. To build 4" walls and put PVC pipes underground.

Can the latter be done? Since the PVC lines would be underground, I assume there would be no need to ground them.

Has anyone run underground PVC dust collection pipes? Any advice or comments?

Gary in San Diego

[PeterTorresani]

Two of my friends have done so. I kick myself every day

[Jamie Buxton]

A related approach is to put trenches in your slab, build covers for them (from wood or steel), and drop the DC ducting in them later. You also can put electricity or compressed air or water in the trenches, or anything else you want. Trenches give you more flexibility and adaptability than fully-buried stuff.

[Jim Becker]

I'm with Jamie on this. Design "utility" trenches into your floor so that you can have access to your dust collection and electrical facilities over time. They can be covered with a wood or metal lid. The problem with "permanent" installation of things like DC in the floor is that you WILL change things around in your shop over time...and your options will be restricted if the duct is buried in concrete. Further, maintenance, such as clearing clogs is more difficult when you don't have access to the pipe.

BTW, a "2x6" wall will not contain 6" duct anyway unless you fir it out another inch...

[Steven Hardy]

A related approach is to put trenches in your slab, build covers for them (from wood or steel), and drop the DC ducting in them later. You also can put electricity or compressed air or water in the trenches, or anything else you want. Trenches give you more flexibility and adaptability than fully-buried stuff.

I agree . It also gives you a route for other stuff!

[Terry Rasmussen]

After considering going overhead, utility trenches, and PVC under the floor. I decided to go with PVC under the floor for my 22' x 25' workshop. I didn't like the aesthetics of going overhead especially with 10' ceilings, nor did I care for the $$$ the concrete contractor wanted to build the utility trench. I placed the main PVC trunk under the concrete floor. I placed a cleanouts in main trunk under the floor just in case I had any issues as well as future expansion. I placed headers along the walls about 3' above floor so that I don't have to bend over to open gates. It works great.

[Greg Funk]

I buried all my pipes under the slab and would recommend it. Add a few extra ports near the walls if you are concerned about future flexibility. I used spiral pipe rather than PVC. With spiral you have more flexibilty in the size of pipe availalble and I believe the bends have a bigger radius.

I have 6" and 5" and some 4" pipes buried and have never had a clog.

Greg

[Chris Padilla]

Gary,

Is a slab the only route you're considering? If not, you can put in a crawl space that will allow you to place and more easily move DC pipes in the future. Most people prefer a wood floor over concrete to walk on for umpteen hours.

You get one shot to place stuff within a slab so spend lottsa time laying it out and considering all future changes to the best of your ability.

I wouldn't worry about clogs because those can easily be fished out...this is large diameter pipe, clogs will be rare and easy to fish. I worry about future changes and the inflexibility but then that is what flex pipe is for! :)

BTW, I'd go all 6" (either PVC or metal) and then neck down at the tool/spot if necessary.

Were I building my dream shop, I'd put in a crawl space.

[Art Mulder]

I am planning to build a new workshop (see attachment) and do not want exposed dust collection pipes. My choices are:

1. To build 6" walls so I can run metal pipes in the walls (higher cost)
2. To build 4" walls and put PVC pipes underground.

Can the latter be done? Since the PVC lines would be underground, I assume there would be no need to ground them.

Has anyone run underground PVC dust collection pipes? Any advice or comments?

Have you seen the thread from Dave Shively (http://www.sawmillcreek.org/showthread.php?t=72140&highlight=shop+slab)? They aren't PVC, but they are in the slab, and it's a very nice Shop Build thread.

[Greg Peterson]

You don't mention if your DC will be single or cyclone. Only thing I would say is you'll want 6" ducting. 4" will be too restrictive whatever your DC may be.

[Ken Garlock]

A related approach is to put trenches in your slab, build covers for them (from wood or steel), and drop the DC ducting in them later. You also can put electricity or compressed air or water in the trenches, or anything else you want. Trenches give you more flexibility and adaptability than fully-buried stuff.

That is exactly what I did when when I had the shop built. I have 6" PVC and 240v 10ga in the trench. I had some 1/8" diamond plate cut my specs to cover the trench. The trench has a 1" lip on both floor edges that the diamond plate sets in, level with the floor. It runs down the center of my shop and supplies dust collection for my table saw, router table, and jointer. Some day I will add a planer to the list. Each machine is connected to the 6" pipe with 6" sanitary wyes. The trench is not open to the ground on the bottom, but rather is is built as a large indentation in the concrete slab.

My dust collector is a Pentz design kit that I assembled. It has no trouble sucking a block of scrap through the duct. I sometimes just throw a 2 or 3 inch chunk of miter saw cutoff in the pipe just listen to it rattle its way through the pipe form one end of the shop to the collector at the opposite diagonal end. :D

How ever you go with the DC pipe, do use 6" wall studs and insulate between them. The cost of 6" studs over the 4" ones, is small.

[Gary Salisbury]

That is what I really love about Sawmill Creek! Got a problem? Ask a question and there are plenty of helpful people with great ideas!

I hadn't even thought about the trench idea but it might take some critical engineering to implement correctly and I'm concerned about the astetics.

I did think about a crawl space however I wanted to be able to park a car in the shop if ever needed and building it as a garage cuts my taxes in half. I don't know if you can build a garage with a crawl space under???

Thanks also for the info on Dave Shilely's underground dc system. I think this is more along the lines I am looking for. I did not know there was such a thing as PVC coated spiral pipe. Now to find a source.

Gary in San Diego :)

[Jamie Buxton]

I don't know if you can build a garage with a crawl space under???


Yes, you can. In my neighborhood, which is rather hilly, there are several garages with open air underneath.

[Josh Bowman]

After seeing Norm do it in a shop he built on TV, I designed mine the same. Gravity is a good thing! The only issues is this, you have to carefully determine where to put the ports. Mine was simple. I used thin wall 4" PVC and started off with a riser at the proposed wall where the dust collector would be then branched out with 45's to each of the mid floor risers. IE, it looks like a giant chicken foot. What would I do different??!! I talked myself out of running outlets to my radial arm saw at the wall, I figured I would want an overhead pipe. However the underground works so good, I regret that decision.
Don't underestimate 2 things. 1) workers stepping on and breaking the pipes during the pour, I put steaks in every few feet that as they passed them they would pull them out, but it gave them an idea where the pipes were. 2) Pin/steak the pipes down. The whole thing could float up during the pour. I simple used rebar bent into a U and pined the pipes down. They were buried a little in my hard clay and some gravel was put on top, but I still was concerned.
So far I have had no trouble with the system. Some thought could be given to the risers, you could do as I did and let the pipes just come up out of the concrete, but a better way, if you have time is to build access boxes with a lip and cover, so equipment could be rolled over it.
Another thought if you have time to build them is as others have mention is to use trenches. This is going to require some thought for the pour to do right. You'll have to build a box to form the trench and dig down enough to give the slap enough thickness.
Another idea I had....this is for free, is for future expantion of electical, air etc. Would be to run raceways under the concrete. This would simple be the same 4" PVC ran criss cross under the floor, say about 10" grid. We have a building at work that has this and comm cables, electrical, etc run through them. They have access ports (Tees in the case of PVC) that come up to floor level ever few feet and are plated off. I thought very hard about this, however I finally gave into using the attic.

[Ed Labadie]

I buried all my pipes under the slab and would recommend it. Add a few extra ports near the walls if you are concerned about future flexibility. I used spiral pipe rather than PVC. With spiral you have more flexibilty in the size of pipe availalble and I believe the bends have a bigger radius.

I have 6" and 5" and some 4" pipes buried and have never had a clog.

Greg

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

[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/garydsalisbury/woodshops-gary-salisbury/

Gary in Blossom Valley, California
301740

[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.