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-Ra...EAAOSw5cNYg8uR

[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-ROO...8AAOSwnQhXpU0o

[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.