paqman

Framing around heating duct

Hey everyone, I'm framing a couple bedrooms in my basement, and I've got a question regarding framing around a heating duct. It's a rectangular duct, going perpendicular to the floor joists. Below is a diagram of the layout of the bedrooms. The heating duct is represented by the pink box.


Anyway, the question I have is that the bedroom on the left is going to have pocket doors for the closet, and I just bought one of those prebuilt pocket door frames. The pocket door frame has to sit underneath the duct, and it comes pretty darn close. It is about 1 and 1/4" inches from the duct. I hadn't decided how close I wanted to frame around it yet so I was wondering if that's too close. Also, that would not allow for any 2x4's on top of it directly under the duct. I would frame over the top of it further out where it is not under the duct, but I was wondering if this would work out ok. It's just going to be a partition wall, not load bearing. Here's the door frame under the duct to give you an idea:


And here's a closeup with the tape measure to give an idea of how close it is:


Out to the left where it is not under the duct, I would be adding some sort of header above it, but would it be ok the way it is under the duct? It would obviously connect to the rest of the frame I plan on building around the duct.

chandler

Assuming you will be attaching the dead end of the pocket door to framework, as well as the free end, as you state, you won't have a problem. Just make sure it is supported at the end of the duct work and fastened along the wall at the back. Now, you have to let us know what type ceiling you are installing, since you obviously don't want to install it directly to the ductwork.

Nashkat1

I would drop 2X4 cripples on each side of the duct and use 1X4s for the flat spans. I think they'd be OK for that short distance, especially with 1/2" or thinner rock. Dont forget to use short screws!

Others may differ...

paqman

True, I will have framing attached to both ends, so there won't be any ends hanging out there. The ceiling will be 1/2" sheetrock, but you're right, it won't be attached directly to the ductwork, I'm going to framing around the ductwork using 2x2's, to attach the dry wall to. Here's a quick draw-up. This is a cross cut looking directly down the duct, not top down like my other drawing. This frame will go the length of the duct work. Only where the pocket door frame is will the frame be interrupted to allow for the pocket door. Sheetrock all around.

I would drop 2X4 cripples on each side of the duct and use 1X4s for the flat spans. I think they'd be OK for that short distance, especially with 1/2" or thinner rock. Dont forget to use short screws!

Ah yes, of course short screws! Wouldn't want to puncture the ductwork. I guess I really also wanted to make sure that it's ok to have my framework that close to the duct. Not sure if there's some fire code or something like that.

chip wolff

You can have the framing touching the ductwork if you want. Look at the top of the duct, It's probably tight to the floor joists. Just make sure you run the heat for a while before you hang the DW to make sure you didn't create any vibration issues

chip wolff

make sure you support the right side of your pocket door frame and the header above it so its not flapping around. You can brace it to your ductwork framing.

paqman

Awesome guys thanks, that's a relief. I was afraid I would have to rearrange that wall, but now I can do it the way I wanted.

You can have the framing touching the ductwork if you want. Look at the top of the duct, It's probably tight to the floor joists. Just make sure you run the heat for a while before you hang the DW to make sure you didn't create any vibration issues

Vibration issues, hadn't thought of that. Maybe that's a good reason to not have it touching just in case. But it's good to know I can be really close.

make sure you support the right side of your pocket door frame and the header above it so its not flapping around. You can brace it to your ductwork framing.

Yes, both sides will be attached to my 2x4 framing with cripple studs over it where possible. It will be solid.

Now another question relating to the heating duct. I plan on just cutting a vent into each room directly from the duct, putting vents in the ceiling right under the duct. So with my frame going around the duct so tight, can I just drop one of these in and call it a day? (i only post that one cause it's the closest product I can find on Home Depot's site to what I think would do it. Is there a better product suited for my vents?

Thanks again, your replies are golden.

chip wolff

can I just drop one of these in and call it a day?

You can use any number of things. Just make sure your grill can open and close so you can regulate the flow of air.

paqman

Yeah, I'll use a standard vent cover that can open and close.

Nashkat1

I plan on just cutting a vent into each room directly from the duct, putting vents in the ceiling right under the duct. So with my frame going around the duct so tight, can I just drop one of these in and call it a day?

Sure, but I would cut them into the side rather than the bottom for better air flow. Maybe two per room. You'll need to make the seam air tight. Also, be sure to provide a path for return air to leave each room even when the doors are closed. BTW, where's the return intake for this level?

paqman

Dang, I replied to your post a while ago, but it didn't go through for some reason. Anyway, a guy I was talking to actually said I should cut it in from the top of the duct. Would that be even better than the side? Also he said I should run it across the room and have it come down on the side with the exterior wall, so as to create some sort of temperature "barrier". Is that true also?

Also, there is no return air intake on this level, as none of it is finished yet. I hadn't planned on putting one. Do I need to for just these two bedrooms? And if so, do I just put it anywhere else in the unfinished portion, or does the intake have to be in one of the finished bedrooms?

chandler

Top or side, won't make much difference, just not from the end. On our remodels, we usually run the flex across to dump either at a window or door for barrier purposes. Our HVAC pros can probably chime in better on this. I'll alert one to check this thread. They may have more questions regarding your return as well, so grab hold.

hvactechfw

In order to best condition the space, the registers should be located on an outside wall. It looks like each room has a window, so I would put the register above the window if at all possible.

You must add a return either 1 common for the whole basement or 1 per each conditioned space. If you do not do this you will put the basement into a positive pressure and the above grade living space into a negative pressure. If you do not add a return at all in the basement it will not condition the space properly.

paqman

Top or side, won't make much difference, just not from the end. On our remodels, we usually run the flex across to dump either at a window or door for barrier purposes.

Yes, it would be pretty easy to run a flex duct to the exterior wall, luckily the joists are going that way.

In order to best condition the space, the registers should be located on an outside wall. It looks like each room has a window, so I would put the register above the window if at all possible.

You must add a return either 1 common for the whole basement or 1 per each conditioned space. If you do not do this you will put the basement into a positive pressure and the above grade living space into a negative pressure. If you do not add a return at all in the basement it will not condition the space properly.

Ok so I did a little research on that and negative/positive pressure, so here's my question then. If these two bedrooms are the only space in the basement that is finished, can I still have have a return somewhere else in the basement? I suspect they would still have a negative pressure if the bedroom doors were closed right? But putting a return register in each room would prove difficult because the return air duct does not go through those rooms, so i would have to run a duct perpendicular to the joists, and I can't cut holes that big in the joists. I thought I could put a common return in the unfinished portion of the basement, and put vents in their doors to equalize the pressure, but in essence, wouldn't I then waste energy trying to heat the rest of the basement with their rooms, cause it would be sucking the warm air out of their bedrooms into the rest of the unfinished, uninsulated space?

When I get a sec, I'll post up a diagram of the current layout of the ducts, but in the mean time, here's a picture of our furnace the ducts coming out, and some mystery duct coming out of the top of it. Is that a return duct? I know it's not blowing air. Just not sure what it's for.

paqman

So here's a mock-up of the current duct layout in the basement. Blue is return, pink is supply. Furnace is in the middle. I've marked where that mystery duct is. The return goes up and is two returns upstairs for the main area, one in the hallway, and one in the master bedroom. You can see that the duct downstairs stops just before the one bedroom, so I suppose I could cut into the end of it and put a return for that bedroom, but I'm really not sure. I will finish insulating and building the rest of the basement, but that'll be at least 2 or 3 years out. So not sure how to do it in the mean time. Here's the diagram:


I forgot to mention, there is another supply duct going perpendicular from the one in the drawing, starting on the left hand side of the left most room, and going downwards in the drawing, but it goes between the joists, using the joists, as sides I suppose.
Edit: I lied, that one's a return. Also, sorry, this thread started out as framing, but now probably belongs in the hvac section. :-)

Nashkat1

What if you extended the return to run next to the supply through the first bedroom into the second? The HVAC experts may have a comment on this too. We'll see...

paqman

Could do that but that would just close in the rooms more as I would have this massive ceiling drop where the duct is. However, after thinking about it, if I did just put a return in the unfiniahed area for the basement in general, then put some vents in the bottom of the bedroom doors or something, I guess that would effectively just pull cold air out of the rooms when heating. And the summer shouldn't be a huge deal cause its always cooler down there anyway.

Mikedel

For reference, using your diagram in post 15, if I read it correctly, you have in the "top row", left to right: "unfinished" area, bedroom (1), closets, bedroom (2).
Could you : install a return vent/duct through the wall between BR 1 and the unfinished space, connected to the return duct in the "unfinished" room.
Then, run some sort of vent/duct through the closets, connecting BR 2 to BR 1. With this-the return air would flow from BR2 to BR1 to furnace.
I'm not sure how well this set up would function, but the hvac pros can/will address that, I hope!
Good luck with your project.

paqman

I have actually thought about doing that and am curious what the hvac pros would say. I would predict that they would say that in a closet the vent would get blocked or restricted, causing negative pressure in Br 2. But still not a bad idea. I could even build a mini duct in the closet going to the walls of the room so it doesn't get blocked. But again, I think cold air returns should be down low and this setup wild work better with them up higher.

Mikedel

I have actually thought about doing that and am curious what the hvac pros would say. I would predict that they would say that in a closet the vent would get blocked or restricted, causing negative pressure in Br 2. But still not a bad idea. I could even build a mini duct in the closet going to the walls of the room so it doesn't get blocked. But again, I think cold air returns should be down low and this setup wild work better with them up higher.

I agree, I was thinking more along the lines of duct(s) connecting BR2 to BR1 that pass through the closet, rather than just vents into/out of the closet. Also, high vs low would be your choice, but it is worth a thought, of course with the input from the hvac guys!.

paqman

I don't know how I missed this, but I just noticed that there is a supply duct running off the main duct (the pink one in my diagram), going to the upstairs, and it is running up to the exterior wall of bedroom 2. It's right above the window in that room. Would it be bad to cut a vent right out of that one? The reason I didn't notice it is because the ceiling has already been insulated. Now that I look at it, the insulation is bulging quite noticeably inbetween those joists. :-) I wouldn't have the luxury of that for bedroom 1, but could I do that, or would that cause problems upstairs?

Edit: I lie, there is the exact same duct running across the ceiling in bedroom 1, going upstairs, right over the window. Man, it's really tempting to just cut right into those ducts. I just need to know if it's frowned upon or not.

hvactechfw

you can do that, but expect diminished air flow at both upstairs and downstairs registers.

paqman

True, but if I were to cut in and run new duct from the main supply line right there would I not have the same diminished flow? Or does that simply diminish air flow from the whole system in smaller amounts?

I'm not sure what kind of science explains this Crap lol.

I guess it would be best to run a new duct to each room from the main supply, then it would spread the loss over the whole system, while giving more air to those cold rooms because they're first in the line.

hvactechfw

You figured it out on your own... good job.

paqman

Ok, another question. You guys are taking me through this step by step lol. The question of clearance over the door. With my frame going under the air duct, if I build the bottom of the frame to just go straight to the wall, it comes to about an inch over the rough frame of the three doors on that wall. Which puts the drywall about a half inch over the rough opening. That doesn't leave much room to put any sort of molding over the door or anything. Should I frame around the duct in a u shape and go back up to the ceiling on the back of it, so then there would be regular height over the door? Will this make my drywall guy hate me? Or is he going to hate me either way?

As you can see from the photo below, I could raise the frame up by maybe 1/2 to 3/4 inch, by putting another board on top of the frame, but that's about it. This shot also gives you a bit of an idea how much space is behind the duct on the door side of the wall (the 13 inches is all the way to the wall, not to the board like it looks in the photo):


Here's a picture of what the clearance would be over the rough opening (the board there is just set in place, not nailed):


And here's a wide shot:

mrkurtz

Your Cad/drawing program

Sorry this is not a message to help you, but I was very impressed by your plan sketching/drawings. Is this a program that is available?
Thanks,

mrkurtz