DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   HVAC (
-   -   How to extend HVAC ceiling vent through new soffit? (

NewHomeDIYGuy 02-22-2012 08:36 AM

How to extend HVAC ceiling vent through new soffit?
I framed a new soffit around HVAC ducting in the basement, and I need to somehow now extend the vent in the ducting through the new soffit and upcoming drywall. It looks like a "standard" size vent in the ducting (approx 4" x 10"?), and would need to be extended down ~3" only.

Do any of the big box stores sell something like this that would work or do I need to make something myself out of sheet metal? Big thanks for any help!


ACD22 02-22-2012 09:17 AM

agreif 02-26-2012 11:02 PM


How do you attach that to the HVAC to the trunk if the vent is currently just an opening cut in the main trunk with the vent then screwed in via sheet metal screws? (I was looking for the same thing this weekend, Mike)


NewHomeDIYGuy 02-27-2012 07:25 AM

As agreif said, I have a roughly 10"x6" opening cut into the trunk, with the register that was attached straight to the rectangular trunk via sheet metal screws. Would I have to get a flat ~10"x~6" piece of metal, cut a smaller opening in that, and attach that flat piece to the trunk, and seal the edges?

With the extensions, how do you attach them to the trunk and attach the new register to the extension? Finally tried tackling it this weekend.. Thanks.


agreif 02-27-2012 07:57 AM

I looked at the little take home guide from Menards this morning and found a starting collar 230, that looks like it should work, but it looks like they are just a smaller size than the vent each of us probably has. I would be inclined to seal the hole I have with a piece of metal and then move it over a foot and put this in, but would love to hear about it from someone who knows.

ACD22 02-27-2012 08:00 AM

The fitting I linked to assumed you already had a takeoff from the duct to the register. Since you don't have a takeoff, you need to get one. The big box stores mostly sell takeoffs that are designed to transition to round duct. Guessing that you want to keep the drywall soffit close to the existing duct, you'll need to find a sheet metal supplier in your area or online to get what you need. Check "duct register box" at this site to give you an idea.

NewHomeDIYGuy 02-27-2012 08:12 AM

Thanks ACD that helps a lot. I didn't quite know the terminology so found it hard to find things/understand exactly what I need, when I was fiddling around with different pieces at the local big box store this weekend. The big box store has a limited selection, and for mostly round ducting. I guess I'll have to try someplace locally that sells more variety.

After looking at different things and fiddling around, I see now that the "takeoff" has little "fingers" (that you bend inwards) which are bent into the trunk which hold it on the inside (vs. regular ducting lacks the "fingers"). I didn't quite "get it" but now that makes perfect sense. Thanks!

Edit: Oh ya.. I realize too now (might be the same for you too agreif), it might be easiest to just seal off the old 10"x6" hole made in the trunk (with a metal plate, screws, and tape) and cut a new hole a foot down the trunk. Trying to find a takeoff piece of ducting to fit that largish hole might not be possible, and perhaps it's likely more trouble than it's worth to try and make it work.

NewHomeDIYGuy 02-27-2012 08:35 AM

Are sheet metal suppliers homeowner friendly? I found a couple in my area (United Refrigeration and Johnstone Supply). Would I be best calling them up first or just driving down there and telling them I needed a "duct register box?"

NewHomeDIYGuy 03-01-2012 03:04 PM


You ever get your ducting all finished? Did you have a local supply store with the takoff piece and register box you needed?


Marty S. 03-01-2012 09:23 PM

Guys/gals, Step one- get the measurement from the existing box to the drywall. Step 2- Go to a local HVAC shop that makes their own metal fittings and have them make one up. A simple extension we would knock out in 2 minutes and likely give it to you free of charge.

NewHomeDIYGuy 03-02-2012 07:58 AM


I would gladly pay someone (and it looks like it's fairly straightforward), but what is a "local HVAC shop?" Is that the same as a "sheetmetal supplier?" I'm not sure how to find the local shop via google or the yellow pages. I've tried calling a few local shops (one was a wholesaler), but no luck finding someone short of just calling an HVAC guy and probably paying him a fortune to come out for a service call. Thanks!

Marty S. 03-02-2012 03:59 PM

HVAC = heating,ventilation and air conditioning business. The guys you use to fix the furnace and air or install a new system. Yea you'll pay through the nose to have someone come out and measure for you so call and ask if they make duct. If they do take the measurements to the shop and have it made. If they don't then call another place.

agreif 03-21-2012 11:45 AM

Marty, great point. I'm going to look into that and also see if I can just bend a square piece out of some of the sheets they have at the big boxes and attach accordingly by making some bent flanges off the ends.

ggold 03-21-2012 11:56 AM

send me a picture, I can walk you thru step by step

NewHomeDIYGuy 03-21-2012 12:24 PM

I never posted back, but I got a 10"x3.5" rectangular piece of ducting from the local big box store and made it work. With tin snips, you can cut "fingers" in the metal. Then I attached it via screws and sealed it with that mastic stuff. It's solid and air tight. I only needed to bring it down 3" so it wasn't too difficult. The old opening I sealed up with a piece of sheet metal and mastic. I'll try to post a picture later.

All times are GMT -5. The time now is 07:29 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1