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Industrial Structure Information Blog

Author Archives: Derick

Putting a Window and a Through the Wall Air Conditioner in the Same Panel of a Modular Building

Non progressive modular building system with a through the wall HVAC

The existing modular building with a through the wall HVAC, before modifications.

Modular building systems are designed to be relatively easy to modify should the need arise. This past summer we put in this 10′ by 11′ odd shaped modular building to serve as a control booth at a steel plant here in Ohio. All the panels had a window in them, aside from a small panel on the end which held a through the wall heat/cool air conditioner. After everything was installed, the workers who operate the control booth determined that they wanted to add a window to that panel as well, and move the air conditioner above the window. Unfortunately, modular wall panels are not generally designed to support a through the wall air conditioner when placed above a window. We could, however, modify it to put the air conditioner below the window.

non progressive modular wall system dissassembly

Removing the modular building wall panel to make the modifications

Depending on the modular building system used, there are a couple of different ways to go about making the modifications. In this particular case, with it being a non-progressive modular building system with steel skinned panels, we reused the existing materials, and made the modification directly to the panel. We shipped the customer a new custom width window to fit inside the narrow panel, and some new trim for the framed HVAC opening as the customer decided to put in a heavier duty air conditioner while we were doing the modifications. All the other components were reused from the existing.

Modular wall system with window and HVAC in the same panel

After the modifications the wall panel now has a new window and HVAC below

The modifications were fairly quick and easy. When the installers arrived, they disassembled that section of the building to remove the panel in question. They then cut the modular building panel to fit the new window and air conditioner. Afterwards, it was simply a case of putting it back together. All said and done, it took two guys about half a day to complete the modifications.

Minimizing the Thickness of a Mezzanine Deck

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W16x31 primary framing member with 4”x14” long tab side mounted to the column

A mezzanine deck thickness between the bottom of the primary framing member and the top of deck.

There are many times when the thickness of a mezzanine needs to be minimized due to various height restrictions. The tightest we could normally provide a storage mezzanine would be one foot between the clearance height underneath and the top of deck. In order to do this though, there are several things we need to consider.

First, we need to consider where the mezzanine is going. Mezzanines in highly seismic regions, such as the Pacific coast, typically require larger and heavier beams than those installed in regions with minimal seismic activity, such as here in northeastern Ohio. This doesn’t necessarily mean that we won’t be able to get the deck thickness down to a foot, but it does make it more difficult.

Next, we’ll want to look at our general design and column layout. The positioning of the columns can greatly affect the size of the beams required and, in turn, the thickness of the mezzanine. What are the required column spans for the project? Typically we like to keep our column spans under 20 feet on center for economic concerns. Longer spans require bigger beams. Often if we’re trying to minimize the deck thickness we might need to go with even shorter spans. We’ll also want to avoid a cantilevered deck if possible, as that too can require a larger beam than normal.

Another thing to consider is bracing on the deck. Generally we have a moment connection between the columns and our framing members by trimming back the wide flange I-beam and bolting it directly to the side of the column without requiring knee bracing. While trying to minimize the thickness of the mezzanine, we might ask you if we can use “tabs”. These are typically 14” long by 4” high pieces of angle that we attach below the primary framing members at the columns. This is particularly important when trying to keep the thickness of the mezzanine to just a foot, as there just isn’t enough beam to make a good solid connection. We might be able to provide a mezzanine with 7’ clear and an 8’ top of deck, but at the columns above the baseplates you’ll have a piece of angle coming 4” off of that 7’.

The final thing to consider is price. Minimizing the thickness of the mezzanine will increase the price. The beams might be smaller, but they are heavier. We might need to use more columns than usual. We might have to replace all “C” section secondary framing members with structural steel beams. All this extra steel adds to the cost. On average, most of the mezzanines we provide have a deck thickness of 1’3” or 1’5”. If the extra couple inches are critical then by all means go for it, but if not, it is usually not worth the added cost.

Using Modular Building Materials to Build a Control Room in a Steel Plant

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Steel plant control room constructed of non-progressive modular building system

The shiny new control room made using modular building materials.

We recently received some photos back of a modular building we provided a customer that I thought would be nice to share with you. The customer has a steel plant here in Ohio, and was looking to replace and expand upon an existing steel constructed control room pulpit on their mill floor.

Looking inside the odd shaped modular building control booth

The irregular shaped control panel dictated the pentagonal shape of the building.

The new control room was roughly 10’ long x 11’ wide x 9’ high, but due to the shape of one of their existing control panels, the room needed to be pentagonal with a diagonal wall. The wall panels were made of 24 ga painted steel with a 3” thick polystyrene core. The customer wanted the building to stand out and requested we paint everything safety yellow.

For this project we used a more traditional progressive building system where the wall panels were separated by wiring chases as opposed to our non-progressive A-wall system. While this system does not offer the uniform sound barrier that the A-wall system offers and has more pieces required to install, it did offer them some advantages. Due to the overall design of this project, it was less expensive for the customer. If something were to happen to one of the panels that would require it to be replaced, they would not need to disassemble as much to replace it as the progressive system allows them to remove an individual panel without needing to start at the corner. The customer also has several other control rooms in their facility of this same design. They’re very pleased with them and wanted to maintain compatibility through their plant.

Exposed recessed beam in ceiling plenum of modular building control room

With the control room ready for electrical installation, you can clearly see the beam used in the ceiling plenum to provide the customer with a 25 PSF “walking load” for the roof deck.

Using a steel beam in the ceiling plenum, and some heavier gage reinforced wiring chases underneath, we were able to also provide the customer with a 25 PSF “walking load” capacity for their roof deck. For one more special little touch, we were able to provide the customer with some cabinets that would fit above their windows to store their notebooks and such.

The bright safety yellow control room really stands out.

Their existing control room was torn down on Saturday, and the new modular building was put up on Sunday, ready for their electricians to wire in the control panels. The customer was really pleased with how quickly the transition went.

Finishes of modular building wall panels

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When starting out on a project, it’s important to pick the right material. Painted mild steel rusts when used outdoors. Wood products swell when soaked. Stainless steel is expensive. You need to compare the properties of the material against the environment in which it will be utilized.

Modular wall systems are a versatile piece of equipment used in a number of different environments and applications. Because of this, we offer a number of different types of finishes on the panels so that we can meet the different requirements of the project.

Modular building panels with a vinyl finish

6 mil. vinyl, Class A fire rated, stipple textured vinyl. Bone and white are standard.

Bone vinyl over gypsum A-wall building panel

The vast majority of the modular buildings we provide feature a vinyl finish to the panels. It serves as our best, and most cost effective, general all-purpose finish, offering you a clean finish to the panel so that you don’t need to paint the walls in the field. Being covered in vinyl also allows you to clean them with a damp sponge if the walls get dirty. One common application where we would use vinyl clad panels would be in an office space.

Modular building panels with a painted steel finish

Embossed, 24 gauge, galvanized, painted steel. Almond and white are standard. Smooth also available.

Almond painted steel over gypsum A-wall modular building panel

Another common option that we offer is to finish the panels with painted steel sheets, which can be applied to the inside of the panel, the outside of the panel, or both. Most commonly this is used in equipment enclosures where we are concerned that something might pierce the walls. The steel sheet acts as a layer of armor helping to prevent shrapnel from puncturing the system. The steel sheets also offer an additional benefit important in many equipment enclosures. Our typical wall panels consisting of two sheets of ½” gypsum board separated by polystyrene studs generally offer an STC of 32. The additional mass of the steel helps minimize the ability of sound to be transmitted through the walls. For each side of the wall that is clad in steel the STC rating increases roughly by one.

Fiberglass reinforced plastic modular building panel finish

Pebble textured, Class C fire rated, Fiberglass Reinforced Plastic. Khaki and white are standard. Smooth and Class A also available.

Khaki FRP clad gypsum modular wall panel

The third most common finish that we offer is fiberglass reinforced plastic (or FRP). FRP is our most durable modular wall panel finish. It holds up exceptionally well to various scrapes and abrasions, and the FRP is a more water resistant finish as well. One of the most common applications where we’ll use an FRP wall panel finish would be for bathroom walls.

Using a Pallet Gate to Protect a Second Story Doorway Opening

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Second story double doorway used for pallet access from below

Second story doorway opening with snap chains

We are often contacted by customers looking for a pallet gate to use in an atypical application. Most commonly they have a second story that has been closed off with walls and a set of double doors through which they load pallets from below. We recently received some photos back from a happy customer out in British Columbia for whom we provided a solution for just such a case.

The customer wanted something more substantial than the snap chains across the door frame to guard the opening when the doors were open. In order to assist them with this, we provided them with a customized self closing pallet gate.

A: The clear opening width of the doorway. B: From the second story floor to the bottom of the door frame. C: From the second story floor to the top of the door frame

The required dimensions to properly fit a pallet gate on a door framed opening

The gates on the self closing pallet gate need to freely swing inward and clear the existing doors. The clear opening with on their doorway was 6’. In order to save the customer some money we used our standard hoops for a 5’ clear opening width gate. The overall width is approximately 5’6”, leaving about a 3” gap on either side when centered on their doorway. If necessary, we could have gone with a custom width, but remember, the largest self closing pallet gate we can provide has a 6’ clear opening (approximately 6’6” overall) width.

Outside view from the bottom of pallet gate mounted around a door frame

Wall mounted self closing pallet gate being used to guard a second story doorway.

As the gate wasn’t being mounted in the usual fashion to industrial handrail to the sides, we provided special angle brackets and longer columns to fix the gate to the wall above and below the door frame. If the floor extended beyond the doorway, we could have gone with the angle bracket above and the typical floor mount brackets to mount it to the deck below.

Inside view of the second story doorway opening being protected by the self closing pallet gate

With this gate in place, when the customer opens their doors, the opening is still protected with industrial use handrail. Their fork truck driver just needs to push the pallet against the bumpered gates which will open as they load the pallet into position on the second story. When the customer pulls the pallet away from the landing area, the spring loaded hinges will automatically close the gate, once again protecting the door opening until the customer closes their doors.

Mezzanine Deck Surfaces: Roof Deck with Steel Plate

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Let’s continue on with our discussion on the advantages and disadvantages of the various types of deck surfaces we offer on our mezzanines. First we talked about corrugated roof deck with resindek. We mentioned that it was an extremely versatile and cost effective solid deck type, but that as a wood composite material it doesn’t perform well in environments where it is prone to getting wet. Next we talked about open bar grating: an open steel deck surface that excels in outdoor/wash down environments as it allows water, snow, and debris to fall through. While texture in the bar grating provides a very grippy surface, it makes it very difficult to move pallets across and there are times when you don’t want materials to fall through the deck. Today we’re going to talk about a mezzanine deck surface that combines features of both of these — corrugated roof deck with steel plate.

Like roof deck and resindek, roof deck with steel plate is a solid deck surface composed of two layers. The strength of the deck comes from the corrugated roof deck. The steel plate is there to provide a flat surface to walk across. Typically we use a smooth plate which allows for easy transport of pallets, carts and other rolling materials. Every once in a while though, where this is not the plan, we’ll go with a steel plate that has a raised texture to it, providing a better grip. It’s a very strong and durable deck surface, and being a steel deck, it holds up in potentially wet environments. In particularly wet environments you’ll want to seam weld the deck and set up a drainage system so the water doesn’t get trapped in the corrugation.

The biggest disadvantage of roof deck with steel plate is its cost, which is comparable to open bar grating. Many of the applications that call for a closed deck mezzanine would be equitably serviced by resindek as it would by steel plate. The resindek would have the advantage, though, as it is significantly less expensive. Unless it’s in a potentially wet environment or being installed in a location where no wood is allowed, you might as well save your money and go with the resindek.

Mezzanine Deck Types: Open Bar Grating

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Painted 19W4 open bar grating on an observation catwalk

Open bar grating deck surface on an observation platform.

Let’s continue our exploration into the different types of decking used on our mezzanines. Last time we talked about corrugated roof deck with resindek. We mentioned that as a wood composite material it can swell if soaked, so it is not the ideal deck type for wet environments. Today we’re going to talk about one deck type that excels in wet environments: open bar grating.

The typical grating that we use is a 19W4 bar grating. It’s made by taking steel bearing bars placed 1-3/16” on center and joining them together by welding wire rod cross beams perpendicular to the bearing bars every 4” creating an open grid. The grating typically has either a painted or galvanized finish depending on the application.

Galvanized serrated 19W4 open bar grating on a mezzanine deck

Serrated and galvanized open bar grating on a landing bound for the outdoors.

Galvanized and serrated open bar grating is an ideal deck solution for outdoor applications.Open bar grating has many advantages as a decking material. It is very strong and durable, and the grated surface provides excellent traction. For particularly slick locations, such as oil factories or outdoors in icy environments, we offer a serrated version for even better grip. As an open decking surface it easily allows water, air, and light to pass through the system. This is why it is a particularly popular decking material for outdoor applications.

There is one common misconception about the open bar grating that I would like to note though. We are often asked to put open bar grating in sprinkled environments, with the customer thinking that they will not need to add sprinkler lines below the platform. Unfortunately this is not the case. The decking and framing of the mezzanine system occlude the area below enough (even before factoring in the materials on top of the platform) that your fire inspector will still require you to sprinkle below the deck if it is sprinkled above.

Oddly enough, open bar grating’s strengths are also its weaknesses. As a fabricated steel material, it is significantly more expensive than the resindek. The grated surface makes it extremely difficult to roll pallets and such around on top without adding something like a layer of plywood in order to provide it with a smooth surface to roll across. And as an open, porous material it allows things to flow through it, such as fingers, heels, dropped hardware (i.e. nuts, bolts, screws), or spilled material.

Tempered Safety Glass Windows

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This past week I had a customer who had a slight misunderstanding of what tempered safety glass was, so I thought I’d take a minute to discuss just what tempered glass is and the safety features it provides.

Tempered (or toughened) glass is a type of safety glass in which chemical or thermal treatments are used to strengthen it so that it is harder to break then standard glass. Tempering compresses the outer surfaces and puts the inner surfaces of the glass into tension. When broken, these forces cause the glass to crumble into granular chunks as opposed to larger sharp edged pieces, and are much less likely to cut you. This is why auto manufactures use tempered safety glass in the side and rear windows of cars.

If you’ve ever had a broken side window on your car, you’ve seen how when tempered safety glass breaks it shatters into hundreds of small grainy pieces all over the inside of your car. If you’ve broken your windshield though, you can see a spider web of cracks throughout the window, but it typically stays in its frame as opposed to filling the car with pieces of glass. Auto manufactures do something different with the windshields. They use laminated safety glass.

If the goal is to keep your modular building‘s window in its frame if it breaks, you’ll need to look at either wired glass or laminated glass.

Mezzanine Deck Types: Corrugated Roof Deck with Resindek

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I thought it might be a good idea to begin a little series in which we discuss some of the different mezzanine deck types available. To start things off, let’s talk about our most commonly used mezzanine deck type: the corrugated roof deck topped with resindek.

Corrugated roof deck, painted reflective white, as viewed from below.

As the name implies, roof decks with resindek is a two-layered mezzanine deck surface. The structural component of the mezzanine deck is provided by a 1-1/2” corrugated steel roof deck. The gauge of the roof deck used varies depending on the loads the mezzanine deck is designed to support. The underside of the roof deck is painted white to help reflect light under the mezzanine deck. The corrugation of the roof deck doesn’t offer a very useable deck surface, so it needs to be skinned with a second material — in this case, resindek.

Unfinished Resindek mezzanine deck surface

Resindek is a wood composite material specifically designed to provide a durable and affordable mezzanine deck surface. There are different grades of resindek depending on the loads the mezzanine deck is designed to support. Most commonly we will use an unfinished ¾” Resindek LD material which is designed to accommodate a combined pallet and pallet jack load of up to 2000 lbs. If we’re designing the mezzanine to support heavier loads, varieties are available for all the way up to an 8000 lb max load. It provides a smooth surface to roll your pallets across, both on and between panels, and doesn’t peel layers like plywood can.

Corrugated roof deck with resindek is easily our most popular mezzanine deck surface, largely due to its significant price advantage over other deck types. There are, however, some situations where it would not be the best option. As a wood based material, resindek can swell when it gets wet. During installation you leave a gap between panels about the width of a nickel to accommodate some swelling, but if the deck will be in a wet environment it is not the recommended tool for the job. In our next segment, we’ll talk about another deck type that would work better for wet environments.

What makes a mezzanine gate a mezzanine safety gate?

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We offer a number of different varieties of gates to provide fall protection on your mezzanines at your pallet access locations, but only some of them are labeled as safety gates. Aren’t they all safety gates? While all our mezzanine pallet gates are designed to protect your personal safety while working on elevated platforms, the gates are designed to meet different standards.

Having only a single layer of gates, the self closing pallet gate is not considered a true mezzanine safety gate.

Gates, such as our self closing pallet gate, horizontal sliding mezzanine gate, or vertical sliding mezzanine gate, help keep your employees safe while working on elevated platforms, but are not considered true safety gates. They are all single gate systems designed to meet the federal OSHA safety railing requirements for dimensions and loading. This means that they have a 42” hand rail, a 21” mid-rail, a 4” high toe board, and can hold back 200 lbs. of pressure. Because they are single gated systems, when the gate is open, you have a potential exposed opening on your mezzanine. When using a single gate system, we recommend that you mark out a 6’ bubble around the opening, train your employees to remain behind that line when the gate is open, and post signage reminding them of this at the location.

Many of these single gate systems have some additional safety features built into their design. The self closing pallet gate was designed so that instead of needing to open the gate to lift a pallet to the deck, you can lift the pallet up and push it against the bumpers of the closed gate. As you load the pallet the spring loaded doors will open up just enough to fit the pallet, keeping the sides closed off. When you then pull the pallet all the way through from the top, the gate closes itself. The controls for a manual horizontal mezzanine gate are all located behind your existing handrail so your personnel will always be behind OSHA hand rail while opening and closing the gate. Even better, the horizontal mezzanine gate and vertical mezzanine gates are both available in electric operated versions. This allows us to add additional safety features such as strobe warning lights and adjustable timers so the gates will close after a predetermined period of time if your employees forget to shut them. With both control boxes being field wired, you can place them in a location within view of, but away from, the opening.

Having both a front and back gate, the dual interlocked vertical mezzanine safety gate is an example of a true safety gate

True mezzanine safety gates have both a front and back gate, and are designed to meet the voluntary ANSI MH28.3-2009 standard (Section 6.4.3) in addition to the OSHA safety railing requirements for dimensions and loading. Operating like an airlock, the double gated system allows access to the pallet for the fork truck down below or your personnel above, while keeping a line of guard rail between your employees and the edge of the mezzanine. The pivoting mezzanine safety gate, double drop horizontal mezzanine safety gate and the dual interlocked vertical mezzanine safety gate are all examples of true safety gates. If your facility is following the ANSI standards and wants to put a mezzanine safety gate in a pallet opening, make sure it is a double gated system.