Register Extensions - Oh yea, talk dirty to me

Register extensions are the just about the sexiest thing involved with finishing your basement on your own.

They are the quintessential basement finishing task. A cross road of ingenuity, problem solving and buying a ridiculous tool. Not to mention the fact that you literally have to buy a sheet of metal. How awesome is that!

register extension diagram for basement finishing

Excuse my crude diagram - You can either use an existing hole in the HVAC line or cut yo' self a new one. Either way, you'll need to build a register extension.

Background on Register Extensions

A.k.a ,what the hell am I talking about. I'm talking about HVAC baby. I'm talking about the metal "ducts" that bring hot and cold air to your basement and the rest of your house.

Registers is just the fancy way of saying "those metal grates that cover the hole in the floor where your heating and air conditioning come from."

When you're finishing your basement, in most cases, you will need to "extend"  the length of an existing air register. Or maybe even cut a hole for a new one.  Either way, you can mail me a thank you card letter later, 'cause I'm about to tell you exactly how to do it.

Sheet Metal and Bending Stuff

Holy crap it took me forever to figure out that NO ONE SELLS PRE-MADE REGISTER EXTENSIONS!  You have to make them yourself.  Sorry to have to ALL CAPS yell at you about that, but it was really frustrating.  You'll need three things to make yours:

  1. A sheet of metal
  2. A pair of metal snips  (aka scissors for sheet metal)
  3. A metal bending tool
my basement register

Here's a picture of one of my register extensions. I put some tape on the outside to ensure all the air stayed within the HVAC line.

The basic idea is that you have to make a rectangle  out of the sheet metal.

The height of that rectangle will be the distance that you need to make up from the current register to the edge of the drywall.  Typically this will be about the width of a 2 x 4 plus the width of your drywall.

Be sure you review my kick-ass diagram at the top of this post.

You'll need to add an extra 1/2 inch to the height so you can create some "tabs".  This is where the bending tool comes into play. Snip the corners of your metal rectangle and then bend the edges. These will then go inside your HVAC line to hold it in place. Oh, also don't forget to add the width of the drywall to the height of your metal extension box.

metal snips with red handle for finishing your basement

My Dad gave me these. I had just helped him move and he was tired. I think they were 'thank you' metal snips.

Metal Bending Tool (see pic above)
Honestly, I've only used the metal bending tool this one time. Just haven't had a lot of metal to bend and I'm not sure that's ever going to change.

I'd suggesting asking to borrow one, but I'm pretty sure your friends wouldn't even know what you're talking about.  If you can figure out another way to bend metal, go for it (and let me know what it is in the comments below).   Metal bending tool on Amazon.

Sheet Metal
You can get the sheet metal at home depot. They really only had one thickness and one or two sizes.

I'll try to head over to the D-Po to get a picture of where they store it but I think it's near the sheet wood products (makes sense right?)

Metal Snips
If you don't have any metal snips you'll need to buy some. Every household worth it's salt should have a set of "snips". I use mine about once a year, but when I need them they are super handy. Metal Snips on Amazon

Tips for Bleeding Less

Wear gloves - Thick leather work gloves, not those pansy cotton mittens you wear out in the snow. The sheet metal edges are razor-sharp and like an angry prisoner they will "cut you".

I was going to link to a set of gloves on Amazon but the ones I use have been passed down from my wife's Dad after like 20 years of service. I just don't know what brand they are. Anybody have a good leather glove recommendation?

Seal It - Use duct tape to seal the tabs to the HVAC mainline so none of your conditioned air sneaks into the empty drywalled space. What you see in my picture is not the best option. I used Gorilla tape, which is amazing stuff, but not the best in the long term for ducts.

Pre Frame Support - Frame in some 2 x 4's near the register so you have something to screw the register into. Don't get lazy and skip this part like I did.  Or your register will get loose and fall out... like mine did.

basement finishing jason 205I'm not going to sugar coat it, this is kind of an all day job.  For a pro this probably takes 30 minutes but for joe-joes like you and me, it's a bit of a show at first.

Don't worry though, you CAN do it. In the end it will look and work perfectly and you'll be one step closer to your finished basement.

Cheers - Jason

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Questions and Comments

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  1. Brandon says

    Good insight on this easily over-looked aspect! What about creating new supply runs in the basement? Did you have to do any of that?

    • says

      Brandon - Not yet. It's super cold here in NOVA right now, about 20 degrees. The basement is cooler than normal but still very usable. That's with only two register extensions. There's another main line I can tap into if I wanted to add two more extensions. I don't anticipate ever having to create a new run. In the summer it's super nice, very cool. My basement is a walk up, so almost entirely underground - that helps.

      Another reason I LOVE BASEMENTS! - Jason

  2. K says

    Thanks for the incredibly informative site Jason. One of the books I was reading, in addition to your handy dandy site, mentioned duct tape as being phased out in favor of heat resistant foil tape.

  3. Steve says

    Another good post and great writing. First, the pros now go to a metal fabrication shop and just tell them what they need. Second, like brother K says, duct tape ain't duct tape no mo :-).

    I'll be asking my former HVAC friend if I can just order from the metal fab shop, too :-) All the same, it is a bit of fun to bend metal--just don't tell my cous who is a member of the sheet metal workers union, so we don't have to prove blood is thicker than water, though skin is still softer than sheet metal, especially mine.

    • Jamie says

      Ahh!! No no no!!! The Pro's Make their own sheet metal. Custom fabrication baby!! Sorry, licensed Sheet Metal Worker here. Only the 'pretend pros' pick them up at the shop!

      • Adam S says

        Un-licensed ex-duct monkey here. Yes, pros make duct themselves as needed, except in new construction. And your estimate of 30 minutes to do this step is way off... it's probably more like 5.

        Yes, don't use duct tape. Foil tape or duct sealant (goopy gray "paint") please. Duct sealant is the best, and you can seal up your other duct seams on the existing duct-work while it's exposed.

        I never personally owned a sheet metal folder, although they do make nice bends. You can do the same with simply a straight edge and hammer. Draw a line on the metal where you want the bend, then overhang the metal along your line (on a sturdy table, concrete ledge/step, etc.). Work your way back and forth with a hammer until you get a 90 degree bend. Do it slowly and it'll turn out great. It wont be as pretty as using a bending tool, but nobody will see the finished duct anyway (and you won't buy a single-use tool)! You could alternatively use sheet metal hand seamer, but that's just as much as a specialty tool you'll never use again.

        Oh, and as far as gloves go, I prefer the nitrile-coated gloves. Much better for gripping slick sheet metal (vs. leather) all while keeping sharp metal corners outside your bloodstream.

        • says

          Never owned a sheet metal folder! WHAT IN THE... JK, yes, I guess you could fold it on a table. Yes, no one will see the fold. But I guess I'm more on the Apple side of the world, even though no one sees it, I know it's there. Lurking behind the drywall. Haunting me. A slightly non-crisp metal duct fold. - Jason

    • says

      Good question. It's actually zinc plated steel. Here's a link to the description on the HD website. This is pretty much what I bought. You can see in the product overview that it can be used for duct work. Have fun bending steel! You're officially a superman bad ass. - Jason

  4. Dan says

    If you install registers for direct air into the basement, do you then have to install return-air vents in cavities of the exterior walls? Thanks! Great site.

  5. Matthew says

    You can get a really nice bend by using a couple pieces of scrap 1x4. Just sandwich the metal between two pieces and bend away, use a clamp to hold them together better if you want.

    • says

      Matthew - Yup. Probably would work just fine. I "may" have been a bit excited about buying exotic tools at the time. Still, no regrets, my sheet metal bends are amazingly accurate. - Jason

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