If you’ve ever stood by a window on a cold winter morning, noticing how it stays warmer than a single pane of glass would, you’ve benefitted from insulating glass. Most people know about the glass panes themselves or the seals that keep gas or air trapped between them, but the smaller “other” insulating glass accessories are the unsung heroes of that efficiency. As a supplier specializing in these often-overlooked parts, I field questions all the time from glaziers, architects, and building owners about what we do beyond seals and desiccants, and how to adjust these components when they don’t work as intended. Today, I want to walk you through the most common adjustment methods for other insulating glass accessories, sharing what I’ve learned working with these parts for over a decade—no jargon overload, just real, practical advice that actually works on job sites. Other Insulating Glass Accessories
First, let’s clarify what I mean by “other insulating glass accessories.” When someone orders an insulating glass unit (IGU), the standard components that get the most press are the glass panes, primary and secondary seals, and molecular sieve desiccants. The “other” parts I supply are the small, precision-made elements that hold the IGU together, ensure it aligns with window frames, prevent moisture buildup, and accommodate temperature shifts that would otherwise crack or warp the unit. These include: corner keys, spacer bar inserts, setting blocks, alignment clips, weep system components, and thermal isolator gaskets. Each of these has its own quirks, and adjusting them isn’t one-size-fits-all—what works for a corner key on a residential IGU won’t work for a commercial unit that’s 10 feet wide.
Let’s start with the accessory I get asked about most often: corner keys. These are the small plastic or metal pieces that fit into the ends of aluminum spacer bars, holding the bar’s four sides tight to form a rectangular frame around the gap between the two glass panes. Installers usually put them together in a shop, but sometimes on a job site, a corner key will slip, or the spacer bar will bend just enough that the unit doesn’t fit into the window frame. The adjustment here isn’t just tapping it back in—you have to do it carefully to avoid damaging the seal.
Most people think you just whack the corner key with a mallet, but that’s a mistake. If you use too much force, you’ll crack the glass or puncture the spacer bar, which lets moisture in and ruins the desiccant. My go-to adjustment method for loose or misaligned corner keys is to first run a thin, flathead screwdriver along the seam between the corner key and the spacer bar to loosen any dirt or trapped air. Then, instead of a metal mallet, use a rubber mallet to tap the corner key evenly around its edges, not just the center. If the gap between the glass and the spacer is too wide (meaning the corner key is too loose), I always recommend adding a tiny strip of closed-cell foam tape to the inside of the corner key before tapping it back in. This fills the small gap without compressing the seal, and it’s a trick I learned after a contractor friend of mine had 12 IGUs fail because he over-tightened corner keys that were too loose. For metal corner keys specifically—used in heavy commercial IGUs—you may need to bend the tabs slightly to get a snug fit. I always suggest using a pair of needle-nose pliers, bending only a millimeter at a time, then testing the fit before putting the spacer bar together. Bending too much will make the corner key too tight, which can pull the spacer bar out of alignment when the unit expands in hot weather.
Next up: spacer bar inserts. These are small, plastic or nylon pieces that fit inside hollow aluminum spacer bars, adding rigidity. They’re designed to prevent the spacer bar from bending when the IGU is being lifted or installed, but sometimes they shift during shipping or installation, which can make the spacer bar bow and cause the IGU to sit unevenly in the frame. Adjusting these is simpler than it sounds, but you have to access the spacer bar first—usually by gently prying off a small section of the secondary seal at the edge of the IGU.
Once you have access, slide a small, rigid wire (I use a paperclip straightened out, since it’s thin enough to fit inside the spacer bar without scratching the inner walls) to locate the shifted insert. Most inserts are held in place by friction, so you can usually just push them back into the correct position. If the insert has moved all the way to one end of the spacer bar, you may need to pull it out slightly with the tip of the wire, then re-center it along the length of the bar. A common mistake here is over-adjusting: if the spacer bar is only slightly bowed, you don’t need to reposition the entire insert—just nudge the middle section back to straight. After adjusting, test the spacer bar by running your finger along its length to make sure it’s straight, then re-seal the edge of the IGU with a thin bead of silicone sealant. I always tell my customers to wait 24 hours before installing the IGU to let the sealant cure—rushing that step is why a lot of adjustments end up failing later.
Setting blocks are another accessory that comes up for adjustment all the time. These are small, durable blocks placed at the bottom corners of the IGU, sitting between the glass and the window frame to support the weight of the unit and prevent the glass from touching the frame (which would cause condensation or stress cracks). They seem simple, but if they’re misaligned—too high, too low, or not placed evenly on both sides—the IGU can warp over time, or even crack when the building settles. The adjustment method for setting blocks depends on the type of block you’re using: fixed height vs. adjustable.
For fixed-height setting blocks, which are common in residential installations, the adjustment is all about positioning, not modifying the block itself. First, measure the height of the IGU at both bottom corners with a tape measure. If one side is a quarter-inch lower than the other, that means the setting block on that side is sitting too low. To fix this, you can add a thin shim of EPDM rubber (a material we supply specifically for this) on top of the existing setting block, between the block and the glass. Never add shims under the setting block, because that can make it tilt and put uneven pressure on the glass. For adjustable setting blocks, which are used in larger commercial IGUs that weigh 200 pounds or more, the adjustment is even simpler: most have a small, Phillips-head screw on the side that lets you raise or lower the block by a millimeter or two. I always recommend adjusting in small increments, testing the height after each turn, because you don’t want one side of the IGU to be higher than the other by more than an eighth of an inch. That small difference might not seem like much, but over time it can cause the seal to stretch and break, leading to fogged glass.
Weep system components are another area where adjustments make a big difference. Weep holes are small openings at the bottom of the window frame that let any moisture trapped between the glass panes escape, preventing mold or fog buildup. The “other” accessories here include weep valves, screens, and plugs that keep dirt, insects, and rainwater from getting in while letting moisture out. A lot of times, these components get clogged with dust or construction debris during installation, so the weep system doesn’t work properly. Adjusting them is usually about cleaning, but sometimes you need to reposition them to keep them working.
If the weep hole is clogged, first turn off any sprayers or hoses near the window to avoid pushing water further into the unit. Then, use a soft bristle brush (an old toothbrush works great) to gently scrub the weep valve and screen. If the screen is bent, you can carefully straighten it with a pair of tweezers—just be careful not to tear the mesh, because a torn screen will let bugs and small debris in. Sometimes, the weep valve is pushed too far into the frame, so it’s not aligned with the opening between the glass and the frame. To adjust this, gently pull the valve out a quarter-inch, then use a small amount of silicone to hold it in the correct position so it doesn’t slide back. I always tell contractors to test the weep system after adjusting by spraying a fine mist of water on the outside of the window—if water flows out the bottom weep holes, it’s working. If not, you may need to adjust the valve slightly again.
Last but not least, thermal isolator gaskets. These are thin gaskets placed between the IGU and the window frame to prevent heat transfer and reduce noise. They’re usually made of EPDM or neoprene, and if they’re misaligned or stretched, they can leave gaps that let cold air in in winter and hot air in summer, ruining the energy efficiency of the window. Adjusting thermal isolator gaskets is mostly about repositioning, since they’re flexible enough to work with.
Start by cleaning the frame area where the gasket sits, because dust or old sealant can make the gasket stick unevenly. If the gasket is stretched in one spot, that means the IGU is slightly misaligned in the frame—so adjust the IGU’s position first, then pull the excess gasket gently and trim it with a sharp utility knife if needed. For gaps in the gasket, you can add a small piece of matching gasket material, cutting it to size and pressing it firmly into the gap to create a seal. A common mistake here is using glue to hold the gasket in place—most thermal isolator gaskets don’t need glue, and using too much can damage the material. If you do need to secure a section, use a small amount of silicone sealant made for rubber materials, which won’t eat away at the gasket.
Now, a few general tips that apply to adjusting any of these “other” insulating glass accessories, based on years of working with installers and contractors. First, always check the manufacturer’s guidelines for the IGU you’re working on—even small adjustments can void warranties if done incorrectly. Second, take your time. Rushing an adjustment is how you end up cracking glass or damaging seals, which will lead to callbacks and unhappy customers. Third, keep a spare set of accessories on hand—corner keys, setting blocks, and gaskets are small, so it’s easy to misplace them on a job site.
As a supplier of these components, I’ve seen firsthand how a small adjustment can make a huge difference in the performance of an insulating glass unit. A properly adjusted corner key prevents moisture from getting in, a correctly positioned setting block stops stress cracks, and a aligned weep system keeps glass fog-free for years. If you’re an installer, architect, or building owner who needs more information about adjustment methods, or if you’re looking for high-quality, compatible “other insulating glass accessories” to make these adjustments easier, feel free to reach out. I work with projects of all sizes, from single-family homes to large commercial buildings, and I’m happy to help you find the right parts for your needs or walk you through any specific adjustment you’re working on. Don’t hesitate to connect with us to discuss your project and find solutions that fit your requirements.
Warm Edge Spacer Bar References
- American Architectural Manufacturers Association. (2020). Standard for Insulating Glass Units (IGU) Construction and Performance. AAMA 110-20.
- Glass Association of North America. (2019). Field Adjustment and Maintenance Guide for Insulating Glass. GNA Technical Bulletin 100.
- International Code Council. (2021). Energy Conservation Code Provisions for Window and Glazing Assemblies. ICC 125-21.
- EPDM Rubber Manufacturers Association. (2020). Best Practices for Thermal Gasket Installation and Adjustment in Window Assemblies. RMA Technical Paper 45.
Renqiu City Xinjian Metal Products Co., Ltd.
Renqiu City Xinjian Metal Products Co., Ltd. is one of the most professional insulating glass accessories manufacturers and suppliers in China. With abundant experience, we warmly welcome you to wholesale customized insulating glass accessories from our factory. If you have any enquiry about free sample, please feel free to email us.
Address: Caicun Dajie Village, Changfeng Town, Renqiu City, Hebei Province China
E-mail: melody@xinjianmetal.com
WebSite: https://www.xjglassspacer.com/
