Raised Access Flooring in workshop

[Alan Lightstone]

My architects had a really intriguing idea for the floor in my workshop. I've decided that I want the dust collection ducting to run under a false floor in the workshop. Don't need the rehash to over/under debate, this is how I've decided to do things.

I was originally going to go with 2x10 or 2x12 floor joists, with plywood over them, screwed to the joists. Vapor barriers over concrete, etc...

They suggested I go with a raised access floor system. Not sure how many people have had experience with them, but they are commercially used in data centers, car show displays, etc...

Having to just put in the supports every 600mm or 24" and allowing the ducting to go diagonally seems to solve many problems.

Anyone with experience with these? Suggestions?

This will be in coastal Florida, so humidity is 4000 percent, although the workshop will be climate controlled, but not all the time.

Also, how to drill holes to allow ducting to pass through seems more difficult with these than just with plywood? Anyone drilled through these before? (I'm thinking a router and a template). These come in a variety of materials. Most have galvanized metal on the underside. Some are pretty finished surfaces on top, some have composite wood, some have calcium sulphate, among others.

[Bryan Lisowski]

If you have the height, it sounds like a good idea, my only hesitation would be the load bearing capacity. When you make the penetration from underneath, you could probably replace that square with plywood.

[Rob Damon]

They can support CRAC units that weight several thousand pounds depending on the style so weight would not be an issue.

They are not cheap. You-tube has a number of videos on the installs.

[Paul Tubergen]

I have used them in control rooms for process plants as a means to get wires into control equipment. The whole room typically has high heat load reducing the relative humidity and lots of air turnover. I would be a bit concerned about condensation forming under the "cold" floor.

[Alan Lightstone]

I've thought about getting the concrete garage floor sealed with epoxy before applying the floor. Would this be effective in eliminating the moisture transmission from the concrete slab to above?

[Greg R Bradley]

It would not work vey well for very long. The moisture barrier will need to go below the concrete slab. Otherwise any moisture will come through the slab. If you seal it with any of the readily available poly or epoxy coatings, the moisture will simply lift the coating off the concrete, at least in enough area to release the pressure. Basically, the impermeable coating needs to be on the outside. Don't underestimate the force of moisture vapor.

[Bill McNiel]

I've thought about getting the concrete garage floor sealed with epoxy before applying the floor. Would this be effective in eliminating the moisture transmission from the concrete slab to above?

Alan-A poly vapor barrier and 4" of gravel below the slab should take care of "moisture transmission".

[Alan Lightstone]

It would not work very well for very long. The moisture barrier will need to go below the concrete slab. Otherwise any moisture will come through the slab. If you seal it with any of the readily available poly or epoxy coatings, the moisture will simply lift the coating off the concrete, at least in enough area to release the pressure. Basically, the impermeable coating needs to be on the outside. Don't underestimate the force of moisture vapor.
Am I missing something here? My present garage floor is concrete slab that a number of years after installation I had an epoxy coating put on. This is my present workshop. I've never noted any issues of moisture resulting from anything sitting on the floor. And the epoxy coating looks like new. Isn't this what these coatings are made for?

Is this different if a raised access floor is sitting above it? Or is there not an issue.

[Alan Lightstone]

Alan-A poly vapor barrier and 4" of gravel below the slab should take care of "moisture transmission".
Bill, the house is already built, so I can't put any barrier or gravel under the slab.

[Bill Dufour]

Look into used. I live near Silicon valley and I hear there are lots of these flooring systems selling used for cheap as computers get smaller and more spread out. Shipping may be a problem.
I assume you mean the kind with a fixed support structure not the shorter self contained modules like below which are too short for duct work.
Bill

I was surprised how much is on ebay. I assume the different makers are not compatable but you could make some wooden supports if needed to splice different makes together.

http://www.ebay.com/itm/Powerflor-Raised-Access-Floor-For-Computer-Rooms-/122657826229?epid=519248395&hash=item1c8ef9e5b5:g:v6EAAOSw5cNYg8uR

[Bill Dufour]

used tiles look to be cheaper then plywood. I suppose you could lay I joists and place the tiles on top.
Bill

These are in Florida
http://www.ebay.com/itm/COMPUTER-ROOM-RAISED-PANEL-ACCESS-CONCRETE-STEEL-SOLID-FLOOR-TILE-24-x24-/201639705021?hash=item2ef2a9b9bd:g:k78AAOSwnQhXpU0 o

[Mike Heidrick]

Whats the math to determine the size and length ductwork you could drop into a 24" grid?

[Mike Kreinhop]

They can support CRAC units that weight several thousand pounds depending on the style so weight would not be an issue.

I've installed over 50 CRAC units in data centers and mission floors, and we never install them on the raised flooring. The CRAC units and large electrical distribution cabinets are always installed on steel structure at the height of the raised flooring and the flooring is installed around the units. When we have equipment racks that exceed the load rating of the flooring system, we build steel frames that fit under the floor tile and can be adjusted to make contact with the bottom of the floor tile and transfer the load to the concrete floor.

Over the past 40+ years, I've either installed or managed the installation of over 500K square feet of raised flooring at our facilities world-wide. The typical live load is about 1,000 pounds for a tile and four pedestals, which is what a loaded GSA security container weighs. This doesn't mean each tile can support the 1,000 pound load because two adjacent tiles only have six pedestals directly supporting them. Bad things can happen when the flooring fails from overloading.

We no longer install our own raised flooring and prefer to contract it out to the manufacturers. However, we do impose our own restrictions on the flooring installation to meet our requirements. For example, we insist that the entire flooring perimeter is braced with turnbuckles on full tiles and the perimeter edge is filled with cut tiles that do not affect the structural integrity of the flooring system. In my career, I've only seen one flooring system collapse, and it was due to operator error, and not design or installation error.

If I had the option of installing a raised flooring system in my shop, I would do it. The space required to run the ducting and electrical distribution would be less than 12 inches. Cutting openings in the flooring, in my experience, is easy with a saber saw. We used to use large hole saws for the cable management ports, but the saws tend to bind in the tile for less experienced installers, and the torque from the drill can be nasty.

[Alan Lightstone]

I've installed over 50 CRAC units in data centers and mission floors, and we never install them on the raised flooring. The CRAC units and large electrical distribution cabinets are always installed on steel structure at the height of the raised flooring and the flooring is installed around the units. When we have equipment racks that exceed the load rating of the flooring system, we build steel frames that fit under the floor tile and can be adjusted to make contact with the bottom of the floor tile and transfer the load to the concrete floor.

Over the past 40+ years, I've either installed or managed the installation of over 500K square feet of raised flooring at our facilities world-wide. The typical live load is about 1,000 pounds for a tile and four pedestals, which is what a loaded GSA security container weighs. This doesn't mean each tile can support the 1,000 pound load because two adjacent tiles only have six pedestals directly supporting them. Bad things can happen when the flooring fails from overloading.

We no longer install our own raised flooring and prefer to contract it out to the manufacturers. However, we do impose our own restrictions on the flooring installation to meet our requirements. For example, we insist that the entire flooring perimeter is braced with turnbuckles on full tiles and the perimeter edge is filled with cut tiles that do not affect the structural integrity of the flooring system. In my career, I've only seen one flooring system collapse, and it was due to operator error, and not design or installation error.

If I had the option of installing a raised flooring system in my shop, I would do it. The space required to run the ducting and electrical distribution would be less than 12 inches. Cutting openings in the flooring, in my experience, is easy with a saber saw. We used to use large hole saws for the cable management ports, but the saws tend to bind in the tile for less experienced installers, and the torque from the drill can be nasty.

Thanks for the information, Mike. Very interesting.

So a 1200 lb planer, which will sit on several adjacent tiles would be OK? Or not...

[Mike Kreinhop]

Thanks for the information, Mike. Very interesting.

So a 1200 lb planer, which will sit on several adjacent tiles would be OK? Or not...


It might, but it depends on the footprint of the planer, how many load points contact the floor, and how the load is distributed among the points. For example, at one of our sites, we had a large format Xerox copier that weighed 2,200 KG (about 4,800 pounds). The copier was designed so it could be disassembled into major sub-assemblies, each of which would fit through a one-meter wide door. Xerox even made a special transport kit for it that made it possible to move the assemblies.

When we moved out of the facility, we were going to dispose of the copier, but another organization wanted it and made arrangements with Xerox in Ulm to disassemble, transport, reassemble, and commission the system at the new location. The new site had similar construction raised flooring, but no one from the new site gave any consideration to the special precautions we told them about at our site. Because the copier had only four contact points with the floor, and the load was not evenly divided among the points. Two of the contact points substantially exceeded the maximum floor loading, so we had to add extra supports under the floor panels to accommodate the load. Because of the size of the copier, we could not use a steel plate to distribute the load over several floor panels. Fortunately, these were part of the original procurement planning, so the support structure was in place when the copier was delivered to our site.

When Xerox had all of the components delivered to the new site, one of the technicians pulled up a flooring panel to inspect the pedestals and subfloor. Not only were the pedestals and pedestal heads undersized for the load, but the subfloor was an old wooden structure and showed signs of distortion from the previous occupants. I never saw the new location, so I don't know what condition the flooring was in, but the gaining unit decided to scrap the copier because it would be more expensive to renovate the facility than to buy a newer and smaller model.

In addition to determining the floor loading for the end state location, you must also determine the affects on floor loading during transport into the room. I imagine one or two pallet jacks will be used to move the planer around, and these usually have three contact points. In addition to the planer, you have to add the weight of the pallet jack(s) and the personnel operating them as you move along the floor. However, you might be able to use large steel sheets to distribute the load over several floor tiles during movement.

[Alan Lightstone]

Wow, much more to consider then I had expected.

The plan had been to move the equipment into the workshop with a single pallet jack +/- an overhead bridge crane. Once in place, I don't imagine them moving.

Are their systems/materials that can handle larger masses? Are smaller tiles with more supports a sufficient solution?

Really only 4-5 heavy pieces of equipment. Only two above 1000 lbs. I think 1150 lbs max, but unclear how many points of support under those. I had thought of placing them on 4x4's so that they could be moved, if needed, in the future easily with a pallet jack. That would clearly spread out the loads over large contact area.

[Mike Kreinhop]

Alan, everything you want to do is possible and likely easy to accomplish with adequate planning and research. Just make sure the flooring components are rated for the load, or can be augmented as required, the flooring is properly installed and secured, and you have a plan to move and secure the equipment. If I didn't do this as much as I do, I would contract out the moving and placement of the equipment to make sure it was done correctly and safely.

[Greg R Bradley]

Am I missing something here? My present garage floor is concrete slab that a number of years after installation I had an epoxy coating put on. This is my present workshop. I've never noted any issues of moisture resulting from anything sitting on the floor. And the epoxy coating looks like new. Isn't this what these coatings are made for?

Is this different if a raised access floor is sitting above it? Or is there not an issue.
I understood that you were building a shop. I also understood that you had moisture coming through other slabs and were concerned about the new one.
IF you have moisture coming through a slab from below, even epoxy or polyurethane will not stop the moisture movement as the higher pressure water will find a way even lifting the bond from paint to cement. Air conditioning or dehumidifiers can create a problem since you are lowering the vapor pressure above the paint.

I have one building that used to be a shop. We blasted the floor and used two part poly floor sealer before moving in. It was fine for 20 years until that building was converted to a warehouse and air conditioned. Now you can see damage where the ground is occasionally moist underneath after a heavy rainy winter.

I do think we might have a slightly different problem as it is very possible to drop the inside humidity into single digits at times.

To put it simply: IF you have moisture coming up through a slab, you aren't likely to successfully stop it permanently with a coating. Lowering the humidity in the space above will make it fail sooner.

[Brian Tymchak]

Aside from the loading aspects, when I worked in data centers early in my career, my knees and feet took a beating. Maybe things have changed over the last 20 years but back then walking on those data center floors all day was like working on concrete all day.

[Bill McNiel]

Bill, the house is already built, so I can't put any barrier or gravel under the slab.

Alan-
4" of gravel and a vapor barrier have been standard under slabs for a long time throughout the country. It is highly probable that this is the existing condition, especially in a wet state like Florida. But I could be very wrong. Have you experienced any signs of moisture transmission?

Just trying to save you some money - Bill

[Alan Lightstone]

Alan-
4" of gravel and a vapor barrier have been standard under slabs for a long time throughout the country. It is highly probable that this is the existing condition, especially in a wet state like Florida. But I could be very wrong. Have you experienced any signs of moisture transmission?

Just trying to save you some money - Bill
Bill:

Thanks, I very much appreciate the advice. I'm just closing on the house this week, so I don't know if there are any issues of moisture transmission. Hopefully not.

I'll have to ask the architects if there is a vapor barrier under the slab. Hopefully yes.

[BOB LLAMA]

My architects had a really intriguing idea for the floor in my workshop. I've decided that I want the dust collection ducting to run under a false floor in the workshop. Don't need the rehash to over/under debate, this is how I've decided to do things.

I was originally going to go with 2x10 or 2x12 floor joists, with plywood over them, screwed to the joists. Vapor barriers over concrete, etc...

They suggested I go with a raised access floor system. Not sure how many people have had experience with them, but they are commercially used in data centers, car show displays, etc...

Having to just put in the supports every 600mm or 24" and allowing the ducting to go diagonally seems to solve many problems.

Anyone with experience with these? Suggestions?

This will be in coastal Florida, so humidity is 4000 percent, although the workshop will be climate controlled, but not all the time.

Also, how to drill holes to allow ducting to pass through seems more difficult with these than just with plywood? Anyone drilled through these before? (I'm thinking a router and a template). These come in a variety of materials. Most have galvanized metal on the underside. Some are pretty finished surfaces on top, some have composite wood, some have calcium sulphate, among others.


Alan,

It has been many years. There is not much information online about people using raised access flooring in their woodshops. Did you eventually install this?

[Bill Dufour]

When the they remodelled the Berkeley public library they did some work on the floor framing. the night before the books were to be put on the shelves the architect had a fit. He realized they shelves were line loads not spread out. He had to order in steel plates to span between floor beams under each line of shelves. Other wise they would have gone through the floor deck.
Bill D

[Alan Lightstone]

Wow!! A blast from the past.

So yes indeed, I did have a raised access floor installed. I found a company based out of Orlando that installed many of these. I found out that you can buy used ones for a fraction of new, so I took that route. Really couldn't care less how it looked, and with a little cleanup it looks just fine.

Watching installation was fascinating. They just glue steel support posts the floor under each of the four corners of each tile (which is a sandwich of steel, cement, and steel. The supports aren't screwed into the concrete floor, just glued on. Then the tiles all screw down with screws. You use a suction cup to raise each tile if needed (heavy, but not a huge deal with the suction cups).

The floor can hold up insane amounts of weight. All of my commercial equipment is supported with no issues whatsoever.

They cut a number of holes for me with a concrete grinder (if that's the right term), and horizontal, portable bandsaw. I've cut a few holes since then with a grinder.

I have lots of 6" Nordfab ducting underneath it, so essentially all of my long runs of DC ducting are under the floor, with me not tripping on them. I love that.
509938
There can be some minor issues with locating holes for ducting if a machine is sitting partially on a tile (which then can't be lifted unless you move the machine. I found a little prior planning before placing machinery solved all that.

Electrical runs under the tiles too, making that far easier and less expensive than dealing with that on a ceiling or on the walls.

I chose 18" of height for the supports and floor. I have 17 foot ceilings, so that still left me with 15-1/2 foot ceilings which is way more than needed (wish those were lower, but that's what the house had).

Oh, and no moisture issues now for 5 years.

[BOB LLAMA]

Glad to hear that it has worked well for you! Finding used hasn't been easy up here in Ontario, but I'm still looking!

Did you watch the full install? I read that they glue down the supports, let it set, then come back and screw it down. Are there no fasteners at all holding down the supports? Did you try to heed any of the advice in this thread, or just let the contractors do what they do? Mostly asking about perimeter bracing here.

I plan to run ducting and electrical in the RAF. I have a core drill capable of doing 10" holes, so locating them and planning where the holes are shouldn't be a problem, as long as I plan accordingly!

My biggest concern is about concentrations of weight. I've got a wide belt sander that is 2T+. I've already made changes to my plan to reduce the area of RAF in my shop so that this machine sits on concrete, and not the RAF. All other machines are under 1T. Big slabs of wood could bring that number up again. Weight ratings listed online for RAF seem to be hit or miss, but I've found some that say they are rated for 3000lbs, maybe higher if I recall. So overall weight shouldn't be an issue, but all these machines are on feet, which concentrates the weight down to a much smaller point. Was this something that you considered at all? It was mentioned earlier in this thread that steel sub-structures have been built to carry the weight down, but I've also read about just heavier duty custom panels where the feet meet the floor.

With these heavy machines, I don't foresee vibrations being an issue, but have you experienced any?


I was originally thinking my whole shop would be RAF, a big rectangle. Now I've reduced that to a square, leaving space in front and in behind the RAF. But as I plan out this shop, all my duct runs and electrical, run in an F shape, so I can accomplish what I want by running a 2ft a section along one wall, with 2 legs off that into the middle of my shop.

I think it's time I contact a professional haha. I just like to answers all my questions before reaching out, so I can consider all my options. I appreciate your advice here. Information on this topic is hard to come by, your thread has helped me immensely already.

[Alan Lightstone]

Glad to hear that it has worked well for you! Finding used hasn't been easy up here in Ontario, but I'm still looking!

Did you watch the full install? I read that they glue down the supports, let it set, then come back and screw it down. Are there no fasteners at all holding down the supports? Did you try to heed any of the advice in this thread, or just let the contractors do what they do? Mostly asking about perimeter bracing here.

I plan to run ducting and electrical in the RAF. I have a core drill capable of doing 10" holes, so locating them and planning where the holes are shouldn't be a problem, as long as I plan accordingly!

My biggest concern is about concentrations of weight. I've got a wide belt sander that is 2T+. I've already made changes to my plan to reduce the area of RAF in my shop so that this machine sits on concrete, and not the RAF. All other machines are under 1T. Big slabs of wood could bring that number up again. Weight ratings listed online for RAF seem to be hit or miss, but I've found some that say they are rated for 3000lbs, maybe higher if I recall. So overall weight shouldn't be an issue, but all these machines are on feet, which concentrates the weight down to a much smaller point. Was this something that you considered at all? It was mentioned earlier in this thread that steel sub-structures have been built to carry the weight down, but I've also read about just heavier duty custom panels where the feet meet the floor.

With these heavy machines, I don't foresee vibrations being an issue, but have you experienced any?


I was originally thinking my whole shop would be RAF, a big rectangle. Now I've reduced that to a square, leaving space in front and in behind the RAF. But as I plan out this shop, all my duct runs and electrical, run in an F shape, so I can accomplish what I want by running a 2ft a section along one wall, with 2 legs off that into the middle of my shop.

I think it's time I contact a professional haha. I just like to answers all my questions before reaching out, so I can consider all my options. I appreciate your advice here. Information on this topic is hard to come by, your thread has helped me immensely already.
I did watch the full install. And yes, the supports are just glued down. The installers, who do this every day, insisted that screws were not necessary. Five years later, I have not seen a single loose support or tile, so I have no reason to suspect they were incorrect.

The heaviest machine I have is my 27" wide-belt sander, but I have a number of heavy machines on the floor. It may be that the particular tiles I chose can easily support their weight (those steel/cement/steel sandwich tiles). There certainly are tiles that are more decorative, and likely less supportive.

You could place any machine on wood supports to spread the weight out. I initially placed my bandsaw on two 4x4's so that I could move it for final placement with my pallet jack. You could certainly do something like that to spread out the weight. You definitely want to think about tile placement in regards to the ability to lift a tile next to a machine to put ducting/electricity through it, and potentially have access later.

Vibrations have no issue at all.

Time to get a professional. Though they didn't scout out my floor before installation. I just gave them square footage, and spoke about machines, holes for ducting, and weight.

I sing the praises of my raised access floor anytime anyone asks about it. I love not having ducting hanging from the ceiling going down to my machines, or tripping on the floor over them. It's great.

[mike stenson]

The machines we load onto these floors are heavier than most woodworking machines per sq/ft. Things like tape robots are highly sensitive to vibrations and movement. IME, these flooring systems, properly installed, are rock solid.

[BOB LLAMA]

Thank you Alan for your insight, and your update 5 years later.

[George Yetka]

Whats the math to determine the size and length ductwork you could drop into a 24" grid?

The grid system breaks down to do this. I had to put 10' lengths of copper below one a few weeks ago. They are made up of stands glued or anchored to the floor and hollow tube stock that is about 3/4x3/4 in 2' and 4' increments(maybe longer).

The tiles are a bit heavy made of steel and about 2" thick(not solid) they cut them with circular saws/grinders. A hole saw or jig saw can cut them.

As for weight I roll CRAC units at 2000 lbs quite often

[Tom Bender]

Seems like you could just add support legs anywhere you have an extreme load. No need to addd wood on top of the floor.

No doubt the floor has a safety factor in the rating. You might decide to use that (carefully) when moving machinery. Or you could put in temporary extra supports underneath. Or you could use something on top to spread the load.

Cutting holes will compromise the rating for cut tiles.

If you do only part of the floor will you have a big step up in your shop? That sounds like a deal breaker.