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Industrial Structure Information Blog

Visiting an Old Mezzanine Supported Modular Office

mezzainine supported modular office from 1997

After almost 20 years of service this modular office is holding up great

Occasionally, I’m asked about how well our modular offices hold up over the years if they are designed so that they can be reconfigured in the future as your needs change. Surely, after general wear and tear they will want to just order a new building anyway, no? Well, I recently had the opportunity to visit an old customer of ours. Over the years, we’ve provided them with a number of mezzanines, catwalks, and modular offices. Several of the modular offices have been disassembled, modified, and reinstalled in different locations. While there, I got an opportunity to look at this old tank platform mezzanine and A-wall 300 modular office we provided them with back in 1997. The steel decking has started to bend up a little at the seam in a couple areas, but after almost twenty years of service the mezzanine and modular office were in excellent condition. If the customer wanted to, it would still be a simple task to disassemble the modular office and put it up again in a new location, possibly with a few modifications. The components are all still compatible with what we provide today. The only design change is that the I-splines used to connect the panels in the A-wall 300 modular building system are now typically painted to match the panels as opposed to the same color as the framing on the windows and doors. So yes, these modular buildings are built to last.

Steel Fixed Ladder Handrail Options

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Does my ladder need a handrail?

Almost all ladders will have an extension at the top, with the only exceptions being ladders accessing roof hatches, manholes, floor doors, or anything else that closes over the top of the ladder. If you are exiting the ladder to the side or going to an offset platform due to the 30’ maximum climbing distance between ladders, you will need to add four more rungs above the platform. Those rungs are only to be used for hand-hold only, to give you something to grab onto to safely exit the ladder.

Side step ladder platform for climbs over 30′ in length

If the ladder is going up to a wall, to a roof, or to a mezzanine, then you will need extensions on the ladder for the “walk-through” exit of the ladder.

We have three different designs of walk-through handrails and I’ll go into the details on each of them below.

Steel ladder handrail options

The first design, the “8” shape, is our standard ladder design. This is the most commonly used handrail setup as it allows for the top of the walk-through to mount to the landing surface, providing the greatest rigidity at the handrail. It also makes installation easy, as there are no questions where the top rung mounts; it is always installed properly meeting the top of the landing surface as required by code.

In cases of short parapets or locations where you cannot have the walk-through handrail anchor to or even set upon the roof you would use the second “P” profile, our “self supported walk-through handrail”. This handrail design works well when there is a parapet under 14” high that the handrail mounting pads would not line up with. It is not a necessity to use the “P” shaped handrail in those instances. Many installers still prefer the “8” layout for the added cross brace back to the ladder. When installing a ladder with our self-supported walk-through handrail, be sure to install properly, with the top rung level with the top of your roof. There is no foot pad at the top to ensure this is done, so installation just requires a check to be sure of compliance.

The last ladder handrail design is our “customer supplied walk-through handrail”. This is used in instances where the installation location has existing railing and handrails that they want to weld the walk-through handrail to. This is useful in locations where space is minimal and existing site conditions allow for field welding to existing rails.

Not shown is our step across platform, which is essentially a crossover used when site conditions require the ladder rung to be more than 12” away from the landing surface as required by OSHA standards. Most commonly, this is used on locations with gutters that are more than 5” off the face of the climbing side of the wall.

OSHA 1910.27(d)(3)

“Ladder extensions.” The side rails of through or side-step ladder extensions shall extend 3 1/2 feet above parapets and landings. For through ladder extensions, the rungs shall be omitted from the extension and shall have not less than 18 nor more than 24 inches clearance between rails. For side-step or offset fixed ladder sections, at landings, the side rails and rungs shall be carried to the next regular rung beyond or above the 3 1/2 feet minimum (fig. D-10).

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

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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.

Stair tread adhesives

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By Jared @ Floormatstore.com

Winter is coming… and it’s time to shift from tackling outdoor projects to indoor ones. At the floormat-store.com division, that tends to mean a spike in stair tread inquiries. Installing indoor rubber and vinyl stair treads is a great cold weather project. What most customers forget to consider when attempting a stair tread project when it gets cold though, is the adhesive.

Rubber and vinyl flooring adhesives have minimum temperatures usually around 65°F. If the temperature of the room you’re installing in isn’t at or above the minimum, you’ll be waiting a long time for the adhesive to set. Every year, we get a few customers calling with the complaint that the adhesive they received was a bad batch. So far, every time, it wasn’t the adhesive’s fault. The installer failed to read the instructions thoroughly enough to catch that temperature warning. Usually, it’s an unfinished basement or the few steps that lead from the garage to the house, but with the kids out of school over Thanksgiving and winter break, cold stair wells in schools are a common application, too. Most adhesives also need around 24 hours to set in ideal situations, so leave that heat on for a day (or two) after you finish.

Musson #300 water based contact adhesive with 0 VOCs. Great for indoor stair tread installations

While keeping the temperature in mind, you’ll also want to consider that a lot of adhesive options require a well ventilated area. In summer that’s easy – just open some windows and doors and wear a mask. As it gets cold outside though, leaving those open isn’t an option. So make sure to get a low VOC adhesive that will work for the application. The last thing you want is to pass out from the fumes while installing stair treads – ouch! A water-based contact adhesive, like Musson’s #300, works for both rubber and vinyl treads, risers and tiles, going over concrete, wood, terrazzo, metal and marble – and typically have 0 VOCs. That safely covers just about any application.

Best of luck and stay safe with your projects.

-Jared @ www.floormatstore.com

Ladder Modification to Meet OSHA standards

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control_tower_ladder We recently were called out to look at a ladder that did not meet OSHA standards (1910.27) for clearance on the back side of the ladder. The ladder also had two angles of climb as shown in the above photo. When climbing up the ladder, the concrete walk was too close to the ladder for you to safely grasp the rung and also to put your foot on the rung while climbing. The ladder was accessing the top of the traffic control tower at an airport, and as such, we had to work around a variety of factors to ensure a proper replacement or modification of the ladder could take place without interrupting operations. As the install location was at an airport, the use of a crane to bring a replacement ladder to location would have been a logistical nightmare. We decided that whatever the solution was, it was to be brought up from the inside of the tower.

Our first option was to remove the ladder and replace it with a 90 degree ladder. That is the most common fixed ladder type. There were, however, issues with supplying a replacement ladder. First off, the concrete walk and rail were extended beyond the top of the tower. This meant that our replacement ladder would need to be very far from the structure in order to give us the required 7” clearance behind the ladder at the concrete walk location. That is not a deal breaker, but holding so far off the structure would have also required an extra-long crossover to reach the tower roof. OSHA allows the ladder to have a maximum 12” step across at the top of the ladder. As the ladder has to stand 7” off of the wall (or the furthest obstruction off the wall) you can get by without a step across platform if the obstruction is 5” or under (5+7=12). The replacement ladder would have been very large. Ordinarily, this too can be dealt with by using our modular line. Our Modular Fixed Ladders come in pieces no larger than 7’L. Each ladder section bolts to the next one and has a pair of standoff brackets before and after the splice.

We could not accommodate additional standoff brackets required by the modular design so we would have needed to weld each splice together. Again, this was not a deal breaker either, but it did make this option less economical than other options.

We decided that it was more economical to modify the existing ladder. The top of the ladder was already angled at an 81 degree angle. In the field we ran a laser down the ladder from the top to see where we would land if we kept that same angle throughout the climbing run. By cutting the ladder at the bend, and then cutting each of the lower standoff brackets, we were able to gain close to a foot of clearance at the concrete landing, well within the acceptable tolerances of OSHA’s standards. This option was not without its challenges though. As the ladder was going to be sticking off the wall even further than before, we were concerned about having a stable climb.

Here is the original ladder with the standoff brackets back to the structure.

We added cross bracing across the two standoff brackets to stiffen the ladder up with the extended bracket length. After modifying the ladder, the bottom rung was still within the 14” allowed by ANSI A14.3, so no additional ladder rungs were required. Each welded location was then sanded down to remove any sharp edges or burrs and painted with a rust inhibiting primer. The end user was going to have their maintenance department repaint the ladder after completion of the work to help cut down on costs.

The ladder modification was completed at budget and within the scheduled time. Most importantly, the customer now had safe access to their roof. If you have a unique situation like this, give us a call. We can help you come up with the solution that fits your site requirements and budget, too.

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.

Do I Need a Swing Gate on My Fixed Ladder?

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Walk-thru fixed ladder with safety cage

Do you need a ladder gate at your ladder opening in your railing? According to OSHA 1910.28(b)(3)(iv)“Each employee is protected from falling into a ladderway floor hole or ladderway platform hole by a guardrail system and toeboards erected on all exposed sides, except at the entrance to the hole, where a self-closing gate or an offset must be used.”

This means that every ladder opening needs to be either (a) Offset so that a person cannot walk (or fall) directly into the opening or (b) Protected by a ladder safety gate. It is an easy either/or. The most common ladder installation locations are not offset and as such require safety gates. Below you will see some photos of ladders and top view sketches clarifying why each of their orientations either do or do not require a gate. Note: ladder chains do not meet OSHA standards.

Another seemingly redundant standard from OSHA further increases the areas requiring gates is 1910.29(b)(13) and 1910.29(b)(13)(i): When guardrail systems are used around holes that serve as points of access (such as ladderways), the guardrail system opening: (1910.29(b)(13)(i) has a self closing gate that slides or swings away from the hole, and is equipped with a top rail and midrail or equivalent intermediate member(…).

This standard opens up gate requirements to manhole covers, roof hatches and other similar systems that would remain open while accessed.

Now that we know what the code requirement is, it is time to review a few common ladder mounting orientations to discuss where they fall under the code.

Fixed ladder mounted to side of platform

The above fixed ladder is mounted onto the side of the platform. Work is performed further down the platform but it is possible to fall directly down the ladder opening. This location is not offset and as such would require a swing gate. See the below top view sketch for clarification.

Top view sketch of side mounted fixed ladderway opening

You can walk directly to the ladder opening from where work is/can be expected to be performed and as such, a safety gate is required at the ladder opening.

Fixed ladder with offset landing platform

The above ladder accesses a platform and then turns to access the main walkway. This ladder is offset and would not require a swing gate at the opening.

Top view sketch of offset mounted fixed ladderway opening

As you can see above, if someone fell while at the main walkway they would fall onto the ladder landing surface, they would not fall down the ladder opening. If the ladder was rotated to the left side of the landing it would require a safety gate because then the ladder opening would no longer be offset.

Ladderway opening on side of catwalk

Above is a very common ladder mount position. This one can be tricky until you lay it out from the top view. From first glance it looks like because the ladder is off to the side that it would be offset from the normal flow of traffic, but if you fell at that point of the catwalk there would be no guarding to protect you. A swing gate is a requirement at this location.

Top view sketch of catwalk side mounted fixed ladderway opening

As you can see from the above sketch, there is a single direction of travel to the ladder from the catwalk. This is not offset. It would be a single direction fall into the ladder opening and as such, a ladder safety gate is required to protect your employees when a ladder is installed in the above orientation.

Most areas are not offset. A good rule of thumb is that if you can fall into the ladder opening with a single direction fall, then you are not offset. The only example above that didn’t need a gate was the second ladder location. With that orientation, you would fall onto the ladder landing and then hit the rear railing, not fall through the ladder opening.

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.

Stay safe everyone!

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We received a sobering message from a customer looking at our caged fixed ladders today:

“My dad fell off of the roof to his death in June while trying to come down the ladder he had rested on the side of the building. I believe his foot got caught in the rope. If he had had one of these ladders this would not have happened.”

Stay safe out there everyone. I know that the above was just a random accident but if there is the chance that you can prevent those, especially after hearing about what can happen, why wouldn’t you? Taking precautions and doing things the safe and right way may take a little longer or cost a little more, but going home to our loved ones at the end of the day is worth any price.

Our sincere condolences are with this customer and their family and hopefully sharing this story will cause someone else to take a moment to look around and make sure they are taking all necessary safety precautions. If you are unsure if you are doing something right, ask someone.

With a little help we can all make it home safe tonight.