under the floor dust colection

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Forum topic by rf58 posted 02-16-2013 04:10 AM 1650 views 0 times favorited 14 replies Add to Favorites Watch
View rf58's profile


78 posts in 3209 days

02-16-2013 04:10 AM

Topic tags/keywords: under floor heat dust collection electrical outlets question

I need some ideas—-
I will be building a new shop/ garage and have to downsize after 50 years to a garage 24×36
With hot water heat in the floor I would like to put a center island with my saw and work table in it.
HAS ANY ONE DONE this . ANY PRECAUTIONS. or any other ideas on new construction of a shop..

-- rf58, Illinois

14 replies so far

View MonteCristo's profile


2099 posts in 2187 days

#1 posted 02-16-2013 04:36 AM

Sooner or later you will likely get a blockage somewhere in your dust collection lines. You’ll want to be able to unblock the line without resorting to a jackhammer . . .

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View Manitario's profile


2630 posts in 2882 days

#2 posted 02-16-2013 07:00 AM

if you ever get a blockage or want to move around where your machines are….

-- Sometimes the creative process requires foul language. -- Charles Neil

View levan's profile


472 posts in 2978 days

#3 posted 02-16-2013 11:51 AM

Congratulations on the new shop.
I have worked in both, shops with concrete and wood floors. I have to say that wood floors are so much more comfortable to work on. Just easier on the body. If there is anyway to put in wood floors with a crawl space or basement under it for access, I would certainly go that route. A basement also works well for extra storage. It is so nice to have everything under the floor, but I would agree with the others saying you need access.

Best wishes

-- "If you think you can do a thing or think you can't do a thing, you're right". Henry Ford

View Fred Hargis's profile

Fred Hargis

4986 posts in 2492 days

#4 posted 02-16-2013 12:58 PM

Once you put it in concrete it’s there to stay. You will probably be OK with a center location, but it sure makes any changes to the layout tough. Also, if you put in 4” and find you need 6”....well, you’re kinda screwed.

-- Our village hasn't lost it's idiot, he was elected to congress.

View 12strings's profile


434 posts in 2383 days

#5 posted 02-16-2013 01:52 PM

My Father-in-Law just did this very thing…He hasn’t used it yet, though, because the new shop/house is not finished, so the holes are just taped-over right now to keep debris out… BUT, I suspect it is not a horrible idea, and will probalby serve him well once he gets the shop set-up…I trust his judgment because:
-He’s a perfectionist
-He’s built alll the cabinets and trim for 2 houses
-He’s installed all the wiring and plumbing for his new house himself.
-He was a F-16 mechanic for 30 years.
-He framed out the shop himself…
BASICALLY, he knows his stuff when it comes to woodworking, mechanics, building, plumbing, etc…so if he though it was a good idea, it probalby is…I do know he put all the dust-collection holes along the edge of the room, except one in the middle for the Table-saw…same with electrical…an outlet in the middle of the concrete floor for the table-saw. I’m hoping to see the shop take shape once he finishes working on the inside of his new house.

-- I'm strictly hand-tool only...unless the power tool is faster and easier!

View AandCstyle's profile


3052 posts in 2256 days

#6 posted 02-16-2013 03:41 PM

I like the idea in general but have one concern not already mentioned. Dust collectors don’t like 90 degree bends because it significantly decreases air flow. I think you will need a minimum of 4 90* bends to get from the DC to the TS. These can be long sweep elbows (or 2 45 degree elbows separated by a foot or more) which will help, but you will need to dig deep enough below the floor level to accommodate the additional radius. Anyhow, check to see how many CFM you will lose for each bend you need to include. You might also want to include an option for above the table collection. HTH

-- Art

View NotToDay's profile


8 posts in 1925 days

#7 posted 02-16-2013 04:03 PM

Under floor dust collection may be a serious problem for you the difference in temperature between ground temperature that typically is around 60 degrees and humid warm air being drawn through the system may cause condensate to form on the inside of the duct causing the fine dust to collect and plug the system. As far as the in floor heat it is great as long as you don’t try to use it for a few hours at a time once you get the floor warm you will need to keep it at temperature.

-- The faster I go The be-hinder I get

View teejk's profile


1215 posts in 2683 days

#8 posted 02-16-2013 05:36 PM

I wanted to do what you are thinking about but my HVAC consulted with some experts and they told him they had never heard of it being done and advised against it. Clogs and bends were their reasons (all noted above).

I ended up not doing underfloor electrical either (I only had a few days to work, including the radiant tubing). I was coming from very small space and knew however I initially placed the machinery it would probably change as I got used to the new space (I was correct). I think code might dictate that the outlets had to be on a riser (e.g. I couldn’t mount them flush because it was “slab on grade”) and as such I would end up with a live outlet sitting there…as much in the way as an extension cord is. but we have a few sparkies here that can opine there.

Under floor wire chase would be a good idea although you can probably get the same result with a chase above the floor just as well.

I love the radiant heat but it was a PITA to install. It was cold and the tubing was stiff. It took my SWMBO and me 2 full days of backbreaking work (my plumbing guy and my concrete guy hated the staples so the tubing was zip-tied to the re-wire every 18 inches or so…and because suitable zip-ties were only available in 5” lengths, once we were finished with the tubing we had to go back and snip all the tails off otherwise they would pop through the concrete (the picture is “pre-snip”).

We didn’t use an “uncoiler” because my plumber tried a cheap one once and thought it was a bigger job than “man-handling” the coil…500’ rolls of 5/8” that will do everything possible to uncoil itself and leave you swearing…and when at the end of a run the coil has to be flipped without “kinking” the tubing (kinks are a NO NO).

When we were finished and I later did my basement I rented a Rehau un-coiler thinking it couldn’t possibly be as bad as he said…I was correct. I’d suggest you do the same (it will cut your time in half or more). I know part of the problem was the cold weather and the resulting stiffness of the tubing.

View MrRon's profile


4769 posts in 3242 days

#9 posted 02-16-2013 08:57 PM

I’m opposed to putting anything under or in a concrete floor. No expansion is possible. Repairs will require a jackhammer. Why are you opposed to having exposed ductwork, wiring or piping? Maintenance must always be a factor.

View teejk's profile


1215 posts in 2683 days

#10 posted 02-16-2013 10:27 PM

MrRon…with radiant the jackhammer option is very limited (look at my picture above). I don’t even want to drill into it (and my home inspector knew all about it…the basement posts are actually secured to the floor with epoxy in the holes rather than securing them the normal way. As much as I tried to direct the tubing away from the post footings, he knew that all kinds of things can happen in a floor pour/finishing job. The last thing you want is to knick any part of that tubing.

I could envision a sturdy “chase” built below. But it’s going to have 3-4 inches of concrete on top of it (limiting how wide it could be)...I have to wonder whether it would be worth the cost of doing it right.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1947 days

#11 posted 02-16-2013 10:38 PM

have you considered a crawl space so you can access the under floor options. I would think it would be cheaper to frame a floor than pour it plus it would be softer under foot. where I live any thing over 24×24 has to have a footer below the frost line. so I would think poured walls and a framed floor would be the best option for DC, wiring and any changes after the fact

View rf58's profile


78 posts in 3209 days

#12 posted 02-16-2013 11:31 PM

LIKE I JUST TOLD MY wife not much mention of my biggest concern that being MOISTURE. well i’m planning some type of french drain = Post hole with gravel..
AND I DO REALIZE 2- 45 Z VERSES A 90.IS BETTER.planned on that FOR DUST =PVC SEALED using 45 z.. ELECTRIC = UNDERGROUND / BX COATED around it where it comes thru the wood plate with a ground fault . AIR LINE = JURY IS STILL OUT ??? but will have

WHAT I PLAN IS A TROUGH / CHASE ( 10” X 30” x 20” deep ) JUST IN THE CENTER OF MY FLOOR . USING A (PARALLEL BEAM FLAT WAYS ) FOR A BLANK TO COVER IT with holes cut in it( and one to match with no holes ) and room to coil up the electrical and air hose cord beneath it should i want to have a party or someting. .
should be able hit that somewhere. i have BEEN THINKING And DREAMING OF THIS garage for a long time.
this floor thing is just one phase*.. . if things go right it should be done by thanksgiving.
i don’t know how to respond to the individual comments yet but i will find out
thanks again.


-- rf58, Illinois

View mbs's profile


1656 posts in 2939 days

#13 posted 02-17-2013 12:11 AM

Andrew Pitts has DC in his floor but I think it’s the second story portion of his shop. Not sure. You may want to contact him.

I wanted to run my DC in the floor too but the county rejected it. Not sure why. I would like to have an elevated floor made of wood with the DC underneath the flooring but pretty settled in now and won’t be making that dramatic of a change.

Good luck.

-- Sorry the reply is so long. I didn't have time to write a short reply.

View 12strings's profile


434 posts in 2383 days

#14 posted 02-17-2013 06:15 PM

sorry, I don’t know the details…I just know he did it, and he hasn’t tested it yet.

-- I'm strictly hand-tool only...unless the power tool is faster and easier!

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