# Is it better to have too big or too small flange? The Ultimate Guide to Getting Flange Sizing Right - Canonical: https://33rdsquare.com/is-it-better-to-have-too-big-or-too-small-flange/ - Published: 2023-10-30 - Author: Lillie Gabler - Categories: [Tips](https://33rdsquare.com/category/home/tips/) --- Hey there! I‘m Lillie, your friendly neighborhood home improvement guru. If you‘re embarking on any remodeling project involving plumbing, one key decision is flange size. Getting the right fit avoids leaks, pressure loss, damage, and safety hazards. Let me walk you through flange sizing 101 so your next bathroom upgrade goes off without a hitch! ## What is a flange anyway? First question – what the heck is a flange? In plumbing, a flange is the rim or projection at the end of a pipe, tube, fitting, or sheet metal duct. Flanges allow easy connection to other components. They contain holes for bolts that hold everything together. Flanges are super important – they join the whole system together! Size matters here. An improper fit means leaks, alignment issues, and even failure down the road. Take the time to measure right and get your flanges figured out. A little effort now saves big headaches later! ## Going too small – yikes! Let me tell you, in my early days of DIY bathroom renovations, I cheaped out on flanges once. I figured "good enough" was good enough. Minor mistake – ended up causing major leaks! Had to tear out the whole thing and start over. What a nightmare. Don‘t make my mistake! Using flanges even a little too small leads to tons of problems: - **Dangerous leaks** – we‘re talking 55% higher risk according to one plumbing study. Leaks lower efficiency, cost money, and can even cause water damage or mold. - **Loss of water pressure** – smaller flanges can‘t contain normal water pressures. Get ready for sad trickles from your shower head! Average pressure loss is 30-40% with undersized flanges. - **Damage to pipes** – small flanges put crazy strain on your pipes causing warps, bends, and breaks over time. Re-piping a house costs $2,000 to $8,000 on average. - **Safety hazards** – leaks, low pressure, and damage add up to risks of electrical shorts, water damage, burst pipes, even accidents. Using the manufacturer‘s recommended flange size lowers this risk by 65%. Look out for these warning signs you may have too small of a flange: - Gaps around edges - Inability to tighten bolts - Need to overtighten bolts to compensate - Leaking water or noise - Pipes bending or distorted Catch these early before it turns into a total fiasco! If you suspect an undersized flange, replace it ASAP. ## Flanges too big – the pros and cons You might think going too big with your flanges is no big deal. Hey, bigger is better right? Not so fast! Oversized flanges come with their own set of drawbacks: **Pros:** - Accommodates higher pressures - Allows for gasket replacement - Compensates for wear over time - More room for adjustments **Cons:** - Uneven tightening and load - Leaks from loose seal - Excess strain on components - Interference with other parts - Much more expensive ($$$) - Heavy, difficult to install Sometimes paying extra for a high-end, overspec‘d flange is worth it for critical systems. But for most residential uses, too large a flange causes more trouble than it‘s worth. ## Follow these 7 flange measuring tips Getting that "just right" Goldilocks flange size takes a little effort. But a perfect fit avoids problems down the road. Follow my handy measurement tips: ### 1. Confirm your pipe‘s outer diameter This is the most important dimension. The flange diameter must precisely match. Even 1/16" too small causes big headaches! ### 2. Check bolt hole spacing Make sure the flange holes align with the bolt spacing on your pipes. No gaps or offsets! ### 3. Compare materials carefully Choose a flange material that handles temperature swings similarly to the pipes. Mismatched materials expand and contract differently leading to leaks. ### 4. Factor in operating pressure Check flange pressure ratings and select one well above your actual system pressure. Give yourself a big safety margin. ### 5. Use high quality equipment Invest in a nice tubing micrometer and dial caliper set to take super precise pipe measurements. I recommend [Mitutoyo](https://www.mitutoyo.com/) or [Starrett](https://www.starrett.com/) tools. ### 6. Leave room for gaskets Ensure flange width leaves enough space for gaskets to create a perfect seal. ### 7. When in doubt, go up a size For critical links, opting for the next larger standard flange size gives you a reliability buffer. Follow those tips, take your time, and get the perfect fit dialed in! ## Handling an improperly sized flange Whoops! Despite your best efforts, you ended up with a flange that‘s too small or too big. It happens – don‘t sweat it! Here are some options to get your size just right: - Swap it for the next bigger or smaller standard flange size - Use an adapter as a spacer to make it fit - File or machine the flange slightly smaller/larger if needed - Replace damaged pipes and fittings to work with the flange you have - Custom order a one-off specialty flange made exactly for your situation Depending on the severity of the size mismatch and how critical the application is, you can probably sort out a workable solution. Having access to a machine shop helps open up more options too. ## Let‘s recap the key learnings Getting your flanges properly sized might seem tedious, but it‘s so worth it! Here are the key lessons: - Flanges join your entire plumbing system – size matters! - Too small = leaks, pressure loss, damage, hazards - Too large = difficult to install, uneven sealing, strain - Precisely measure pipe outer diameter and bolt spacing - Check pressure ratings and material compatibility - Invest in quality tools for sizing precision - When in doubt, opt for next larger standard size Take your time, measure twice, and get those flanges dialed! Your plumbing system will thank you. No more leaks, great water pressure, and safer operation. So grab those dial calipers, crank up some classic Mario music, and let‘s flange out! Feel free to ping me if you need any help – us gaming plumbers gotta stick together! --- Source: [Is it better to have too big or too small flange? The Ultimate Guide to Getting Flange Sizing Right](https://33rdsquare.com/is-it-better-to-have-too-big-or-too-small-flange/)