How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tim H. Your Own Question
Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
Type Your HVAC Question Here...
Tim H. is online now
A new question is answered every 9 seconds

I have a some rectangular wall duct running from basement to

This answer was rated:

I have a some rectangular wall duct running from basement to second floor. How many support brackets should this have in the wall, and should it be screwed or affixed to the floor or opening on second floor?

Tim H. :

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Thanks for the opportunity to help!

Tim H. :

Hello there

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.
I switched to the Q and A mode either to allow you to make some checks or because it appeared you were offline. In this mode, you can post questions and I'll reply. Please allow for some delay in my responses as we come and go on this site. I check my questions frequently, however, so please be patient. Please do not hit "relist" as this will slow things down.
Rectangular duct should be supported every 2 feet. If it is running vertically up through the wall, it is best to support with L brackets to the wall stud. It does not have to be supported right where it passes through the floor. Let me know if you have any additional questions.
Customer: replied 3 years ago.

So a duct tied to a stud or framing with brackets within 2 feet of the end and it should be fine? I couldn't remember if the final end of a run was typically screwed into the floor or what.


I was planning on putting 2 1/4 X 10" duct into a 2X4 wall due to the stud size and a joist in the basement that seems to be in the way of using a 12".


How do they rate or compare a 2 1/4 X 10 to other duct options for flow, is it the equivilent of a 5" or even less? Possibly I could use a 12 but I don't know how to accomodate the joist in the basement that is squeezing me down to the 10" option.





Well, you would also want to have L brackets right at the end of the run for sure. When you say screwed into the floor, are we talking a vertical run up through a wall? Or a horizontal run down in the basement ceiling?
If you are using the 2 1/4 " x 10" for a single supply or even 2, you should be fine.
Customer: replied 3 years ago.

I was referring to screwing it to the floor (at the floor where it protrudes) or directly below the floor. Maybe it's not neccesary, as long as I can get close to the end with some brackets.


I would probably be able to attach L brackets withing 10 inches from where it terminates into a floor register.


This is a supplemental run for a cold room that did have 3 uninsulated walls and a stairway to a loft where all the heat rises. I've insulated 2 of the 3 walls, so I'm hoping that adding a supplemental run (even if it's just a 2 1/4 X 10) will be helpful.


I wouldn't fasten right at the floor because if there is any vibration from the blower in the unit, it would be transferred to the floor.
Customer: replied 3 years ago.

Do you think the size of this run (10 X 2 1/4) is worth the time for the heat it would add?


I've never run a complete duct before, is the best process to place the first piece through the floor and secure it with L brackets (in the wall). Then build on that (I have wall access) down to the basement where the supply and stack boot are waiting and then cut the final rectangular piece for length and put the indents in it for the boot ?



Yes, I think it would make a difference. And as far as the best way to install, you could start with the piece through the floor and work backwards from there to your main trunk line.
Customer: replied 3 years ago.

Ah OK, so it's not typical that you would do you supply line taking off from the furnace all the way to the bootstack. Stop, and build down the rectangular, cutting off the excess and hopefully get the bootstack to connect with the rectangular then.



Yes, you could work either way, from the piece through the floor and back to your trunk line and also up to the point where your wall register will attach. You will need to have the floor piece sticking down into the basement to attach the rest of the ductwork.
Tim H. and other HVAC Specialists are ready to help you