Hiding dust collection in a poured concrete floor


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My first concern would be obstructions/something getting sucked in you don't want. I have a weaker system, but occasionally have accidentally sucked up things I didn't mean to, such as the remote I use to turn the dust collector on and off...<_<

In some cases, things can get sucked into the pipe which the system is not able to fully bring to the other end. With an  overhead system you can always open things up to clear the obstruction. With a more powerful blower, this might not be an issue.

The next concern is flexibility. Overhead systems are certainly more adaptable if you ever change tools or layout. 

Finally, depending on your location/ground water table, it might be a place for water intrusion. 

 

 

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nrl  ? National Rugby League ?

I could understand routing a couple ducts under the slab out to a tablesaw or other tool centrally located where the vertical pipe would be in the way.  But all the drawbacks listed above make imbedding the whole network of pipes unwise.  Not being able to rearrange machines being the biggest.  Also consider resale of the property. A recessed box in the slab that could be capped if the duct s no longer used would be smart. An outlet for the tool might be nice as well, in conduit so changes or maintenance is possible. 

Also check into local code issues. Insurance companies look for any reason to deny claims. An un-permitted building or code violation could circle around and bite you.

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Hello All,

I'm a first-time poster who has been lurking and learning from you all for over a year now.  I am currently slowly turning a portion of an existing storage shed into a workshop.  the shop will be 24' x 20' with provisions for an external dust collection, compressor room and possibly a 10' x 10' finish room.  Because it had a dirt floor I took the opportunity to form a service chase through the centre of the shop.  It is 12" x 12" and will allow me to run 220v, 110v and a dust collection main to my major tools.  Dust collection for secondary tools will all run along the walls.  if the next owner has other plans he can just cap the trench.  It will be a slow, probably never-ending process but I am excited to get going on this project!

 

 

shop trench.jpg

trench cover.jpg

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3 minutes ago, RJS said:

Hello All,

I'm a first-time poster who has been lurking and learning from you all for over a year now.  I am currently slowly turning a portion of an existing storage shed into a workshop.  the shop will be 24' x 20' with provisions for an external dust collection, compressor room and possibly a 10' x 10' finish room.  Because it had a dirt floor I took the opportunity to form a service chase through the centre of the shop.  It is 12" x 12" and will allow me to run 220v, 110v and a dust collection main to my major tools.  Dust collection for secondary tools will all run along the walls.  if the next owner has other plans he can just cap the trench.  It will be a slow, probably never-ending process but I am excited to get going on this project!

 

 

shop trench.jpg

trench cover.jpg

That is a great solution, allowing continuous access to the ductwork and being able to run power in the same. Certainly where the power goes, dust collection is likely to follow!

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The other thing I wonder about pouring the concrete over the duct work is the strength of the concrete over the duct work itself because the concrete won't be as thick there as the rest of the floor.  

I have heard of people pouring the floor and then installing joist and wood flooring over it and installing the ductwork under the wooden floor.  This also would make the duct work some what excessable if needed in the future.

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15 minutes ago, Chet said:

The other thing I wonder about pouring the concrete over the duct work is the strength of the concrete over the duct work itself because the concrete won't be as thick there as the rest of the floor.  

 

 

The duct work would be in a ditch just like plumbing under the slab so so slab thickness wouldn't be affected. Someone else was worried about things getting lodged in the ductwork the fix for that concern would be putting clean outs at the end of runs just like they do for plumbing waste lines. also why would you need to ground a under slab duct it would be covered in dirt that is already grounded. If you are using PVC or ABS pipe and you use the proper cement for all your connections ground water would not be a factor. they bury plumbing waste pipes everyday and crap doesn't leak out and ground water doesn't leak in. I wanted to do this very thing when building my shop and it wasn't any of those reasons I didn't I was under a time constraint and just needed to get the slab poured so I could get my equipment out of storage and into my new shop.

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37 minutes ago, higtron said:

 

The duct work would be in a ditch just like plumbing under the slab so so slab thickness wouldn't be affected. Someone else was worried about things getting lodged in the ductwork the fix for that concern would be putting clean outs at the end of runs just like they do for plumbing waste lines. also why would you need to ground a under slab duct it would be covered in dirt that is already grounded. If you are using PVC or ABS pipe and you use the proper cement for all your connections ground water would not be a factor. they bury plumbing waste pipes everyday and crap doesn't leak out and ground water doesn't leak in. I wanted to do this very thing when building my shop and it wasn't any of those reasons I didn't I was under a time constraint and just needed to get the slab poured so I could get my equipment out of storage and into my new shop.

Construction is very regional. The practices you describe are not universal. Some places worry about things like frost heave, while others worry about things like shrink and swell of soils. No one said this couldn't be done, we are just pointing out some concerns to keep in mind. The clean outs are a good suggestion, though they do increase the overall complexity of the thing, which as you said, costs time and/or money.

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1 hour ago, Isaac said:

Construction is very regional. The practices you describe are not universal. Some places worry about things like frost heave, while others worry about things like shrink and swell of soils. No one said this couldn't be done, we are just pointing out some concerns to keep in mind. The clean outs are a good suggestion, though they do increase the overall complexity of the thing, which as you said, costs time and/or money.

Good, thoughts...most of them wrong. Monolithic slabs are often bedded in a thick enough bed of flexible subsoil (read sand or sand gravel) that will abosorb the movement of the slab and pipes with it. I know extremely few soils that will allow a slab construction, that are unsuited for plumbing beneath. If a slab passes code, the plumbing for ground floor is underneath. 

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3 minutes ago, C Shaffer said:

Good, thoughts...most of them wrong. Monolithic slabs are often bedded in a thick enough bed of flexible subsoil (read sand or sand gravel) that will abosorb the movement of the slab and pipes with it. I know extremely few souls that will allow a slab construction, that are unsuited for plumbing beneath. If a slab passes code, the plumbing for ground floor is underneath. 

Sorry for the confusion, I'm not concerned about the duct breaking from movement, those were just intended as examples of differences in construction practices. My original concern, as noted above, was groundwater intrusion. And again, I'm not saying it can't be done, I'm just pointing out things to address in the construction, which is what the poster requested. 

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3 minutes ago, Isaac said:

Sorry for the confusion, I'm not concerned about the duct breaking from movement, those were just intended as examples of differences in construction practices. My original concern, as noted above, was groundwater intrusion. And again, I'm not saying it can't be done, I'm just pointing out things to address in the construction, which is what the poster requested. 

In the water table is one place a slab will fail code. FWIW, PVC cement is a chemical weld and water proof, and pipes through a slab are buffered by expansion sleeves and can be caulked. 

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10 minutes ago, C Shaffer said:

In the water table is one place a slab will fail code. FWIW, PVC cement is a chemical weld and water proof, and pipes through a slab are buffered by expansion sleeves and can be caulked. 

Yeah, in my work I look at failures in buildings, from design, construction, maintenance, or accident. Certainly not only plumbing problems, but water intrusion is a big issue that I deal with. Awhile back I saw a modern church, with classrooms and such around the sanctuary,. They had under slab heat/cooling ductwork (24" diameter or so). It ran around the perimeter of the building, located just inside the foundation walls. Water was intruding into the ductwork. Not to the point of flooding up into the actual occupied space, but it had filled the lower couple inches of the ducts at some points. As you can imagine, having standing, dirty water in your conditioned air ducts is a bad outbreak of legionaries disease or similar condition waiting to happen.

Of course I also see many instances of slabs which have water that floods up during big rain events, with common sources of intrusion being joints/cracks in the foundation walls and slabs, and at floor drains. Sometimes the intrusion comes up through the drain, during a back up, but sometimes it comes around the drain (Which can be from poor construction or from lack of maintenance, ie. aged and cracked caulking sealant).

 

 

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Alain Vallencourt used under-slab ducts for the DC is his shop in Canada. He seems to manage with a fairly small collector, unless he has upgraded since the shop was built.

Here is a link to the build videos, its a pretty nice shop.

Building the shop: https://www.youtube.com/playlist?list=PLx8vGrJfGrEys9u-msnqdMH86FXHnjROP

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