Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 03-18-2012, 04:14 PM   #1
Member
 
Join Date: Oct 2011
Location: US
Posts: 48
Share |
Question

Splitting a 6" duct


I'm finishing a bedroom in my basement. Directly above is the kitchen, which has a duct run to it and a small vent built into the cabinets. I need a register boot for the new bedroom window, which is pretty close to the existing 6" duct pipe. Unfortunately the basement ceiling is quite low, and they already ran the 6" duct right through the floor joists, which seems like not a great idea given the heavy kitchen right above. I would like to avoid cutting more huge holes into the joists for another run, and given the low ceiling height I'd like to avoid adding more soffits as well. So, I was wondering if I could put a 6" T piece in and split that supply duct to add my register boot for the new bedroom.

Also, how many supplies should I add for my basement? My basement has 5 windows, so I thought 1 for each window, plus one for the half bath (which has no window), plus one return close to the stairs. It's about 900 sq ft I'm adding. I'm in Utah, if that matters, so we heat in the winter and cool in the summer.

Thanks for any comments/suggestions.

TomU is offline   Reply With Quote
Old 03-18-2012, 04:29 PM   #2
MarginallyQualified
 
Join Date: Dec 2011
Location: Winston-Salem NC
Posts: 3,647
Default

Splitting a 6" duct


Quote:
Originally Posted by TomU View Post
...they already ran the 6" duct right through the floor joists
...I would like to avoid cutting more huge holes into the joists
...I'd like to avoid adding more soffits as well.
http://www.youtube.com/watch?v=OagFI...eature=related

Quote:
Thanks for any comments/suggestions.
1) fix the joist with the duct running through it
1a) remove that piece of duct
2) go back and do that right
2a) include provision for the new work

TarheelTerp is offline   Reply With Quote
Old 03-18-2012, 04:42 PM   #3
Member
 
Join Date: Oct 2011
Location: US
Posts: 48
Default

Splitting a 6" duct


Quote:
Originally Posted by TarheelTerp View Post
1) fix the joist with the duct running through it
1a) remove that piece of duct
2) go back and do that right
2a) include provision for the new work
Why should I remove the existing duct? The only way to fix the existing joists would be to probably add new ones, which doesn't appear to be an easy undertaking given the room is already framed. It is a brand new home I would assume it's up to code, even though I don't really like the idea of ducts going through the joists. But it's already done.

I was merely wondering if I can split an existing 6" duct, or if I should avoid that at all cost and somehow run a dedicated 6" duct and add a soffit.
TomU is offline   Reply With Quote
Old 03-18-2012, 04:57 PM   #4
Member
 
Join Date: Nov 2011
Location: Hartfield VA
Posts: 25,542
Default

Splitting a 6" duct


Easy or do it right? Floor joist should never ever be cut to run duct work!
Not a big deal or a hard job to go back and redo this the way it should have been done in the first place.
joecaption is online now   Reply With Quote
Old 03-18-2012, 05:42 PM   #5
Part of the Clover Leaf
 
Join Date: May 2011
Location: NW Burbs of Detroit Mi.
Posts: 1,107
Default

Splitting a 6" duct


What he said.

Cut a joist, collapse a house.

Don't laugh, it happens. When you consider most joist are 7' 1/2" and you are taking a a larger than six inch bite out of it ..well...it seems obvious to me that youe weaken the structure.

Didn't that occur to you?
hvac5646 is offline   Reply With Quote
Old 03-18-2012, 05:50 PM   #6
Member
 
Join Date: Oct 2011
Location: US
Posts: 48
Default

Splitting a 6" duct


The total height of these joists (made by i-level) are 12", and they span about 10'. I do know that it's not a good idea and they should have done it correctly in the first place, but unfortunately the damage has already been done. The floor appears to be stable otherwise, and I haven't observed any sagging whatsoever. Since it's a kitchen, there won't be more weight added (other than people walking in there). I just figure that yeah it's not ideal, but I don't want to go through the hassle of ripping the ducts out and somehow adding new joists. Given that room was already framed, I'd probably have to rip out the framing in order to be able to get any new joists in there.

I'm certainly not going to cut more holes into it, that's for sure. Which is why I wonder if it's ok to add a T connection to the 6" duct and split it to supply the bedroom underneath.
TomU is offline   Reply With Quote
Old 03-18-2012, 06:01 PM   #7
Part of the Clover Leaf
 
Join Date: May 2011
Location: NW Burbs of Detroit Mi.
Posts: 1,107
Default

Splitting a 6" duct


that is small conciliation...tweleve inch will still weaken... and that you knew that but did it anyway shows poor judgment on your part.

I can't help you...maybe somebody can.
hvac5646 is offline   Reply With Quote
Old 03-18-2012, 06:21 PM   #8
Member
 
Join Date: Oct 2011
Location: US
Posts: 48
Default

Splitting a 6" duct


OK, so I did some research. They used TJI-210 joists with 11 7/8" depth from ilevel, and their spec is here: http://www.woodbywy.com/literature/TJ-4500.pdf

If I understand the specifications regarding holes on page 11 correctly, the manufacturer allows round holes up to 8 7/8" in size for these joists. I'm not an expert at this, but it appears that - although not ideal - they stayed within specification.
TomU is offline   Reply With Quote
Old 03-18-2012, 06:51 PM   #9
Part of the Clover Leaf
 
Join Date: May 2011
Location: NW Burbs of Detroit Mi.
Posts: 1,107
Default

Splitting a 6" duct


Tell that to your local building inspector and see if he agrees.

Mfg specs are overly optimistic...that's why it is against code to cut joists and run duct thru them.
hvac5646 is offline   Reply With Quote
Old 03-18-2012, 08:08 PM   #10
30 year tech
 
hvac122's Avatar
 
Join Date: Dec 2007
Location: Lincoln, Nebraska
Posts: 427
Default

Splitting a 6" duct


Most TGI'S it is OK to cut a duct run through. Usually you need to stay a certain distance from the end. As long as they followed the manufactures instructions you should be fine.
As far as using a tee you will lose airflow designed for the kitchen so it is not a good idea. Run a separate supply and return.
hvac122 is offline   Reply With Quote
Old 03-18-2012, 08:34 PM   #11
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,371
Default

Splitting a 6" duct


Its allowed by inspectors here, an done quite often.

Teeing into that 6" won't get you enough heat for that bedroom..
beenthere is offline   Reply With Quote
Old 03-18-2012, 08:39 PM   #12
Member
 
Join Date: Oct 2011
Location: US
Posts: 48
Default

Splitting a 6" duct


Quote:
Originally Posted by hvac122 View Post
Most TGI'S it is OK to cut a duct run through. Usually you need to stay a certain distance from the end. As long as they followed the manufactures instructions you should be fine.
Yeah, I checked the specifications against the document I linked in a previous post, and they followed these. Plus the hole is well below the maximum hole size that the manufacturer appears to allow.

Quote:
Originally Posted by hvac122 View Post
As far as using a tee you will lose airflow designed for the kitchen so it is not a good idea.
Quote:
Originally Posted by beenthere View Post
Teeing into that 6" won't get you enough heat for that bedroom..
I was afraid that that was going to be the answer to my question. I guess I'll have to figure out how to run it there and box it in.

Thanks
TomU is offline   Reply With Quote
Old 03-19-2012, 08:46 AM   #13
Part of the Clover Leaf
 
Join Date: May 2011
Location: NW Burbs of Detroit Mi.
Posts: 1,107
Default

Splitting a 6" duct


Quote:
Originally Posted by beenthere View Post
Its allowed by inspectors here, an done quite often.

Teeing into that 6" won't get you enough heat for that bedroom..
Beenthere you have some very lax code enforcement where u are.

Our local guy would be all over that. We have seen engineered lumber fail on three occasions and killed several people in a shopping mall. It was supposed to be able to take the load of a steel girder. Since than no engineered-lumber is allowed where traditionally a girder would be used.

I drilled out a joists to run pipe thru...in another community....they threatened me..said if I did it again I would have to pay a structural engineer to certify the integrity of the joist or pay for installation of a new one.

Local authorities do not have to accept a certain procedure or material if it is not conducive to the health and welfare/safety of the local community.

Our guys have chosen not to allow drilled joists or engineered lumber.

Some opinions on this thread differ from mine...but I am quoting what is not allowed in mine and several communities across the country.

Check your local building authority before cutting up a joist.
hvac5646 is offline   Reply With Quote
Old 03-19-2012, 03:26 PM   #14
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,371
Default

Splitting a 6" duct


Quote:
Originally Posted by hvac5646 View Post
Beenthere you have some very lax code enforcement where u are.

Our local guy would be all over that. We have seen engineered lumber fail on three occasions and killed several people in a shopping mall. It was supposed to be able to take the load of a steel girder. Since than no engineered-lumber is allowed where traditionally a girder would be used.

I drilled out a joists to run pipe thru...in another community....they threatened me..said if I did it again I would have to pay a structural engineer to certify the integrity of the joist or pay for installation of a new one.

Local authorities do not have to accept a certain procedure or material if it is not conducive to the health and welfare/safety of the local community.

Our guys have chosen not to allow drilled joists or engineered lumber.

Some opinions on this thread differ from mine...but I am quoting what is not allowed in mine and several communities across the country.

Check your local building authority before cutting up a joist.
Its common and allowed in most areas across the country. That I found out from other forum sites.

Its allowed in the OP's area, or it would have been shot down on rough inspection.

Strange thing about your engineered beam not being allowed. Wood is safer as a support then steel in a fire. It was proven by the navy over 70 years ago. So that failure, was probably incorrect engineering, not a fault of using the wood.

we have laxed code enforcement in many areas. And very strict in others.
beenthere is offline   Reply With Quote
Old 03-19-2012, 03:48 PM   #15
Part of the Clover Leaf
 
Join Date: May 2011
Location: NW Burbs of Detroit Mi.
Posts: 1,107
Default

Splitting a 6" duct


Quote:
Originally Posted by beenthere View Post
Its common and allowed in most areas across the country. That I found out from other forum sites.

Its allowed in the OP's area, or it would have been shot down on rough inspection.

Strange thing about your engineered beam not being allowed. Wood is safer as a support then steel in a fire. It was proven by the navy over 70 years ago. So that failure, was probably incorrect engineering, not a fault of using the wood.

we have laxed code enforcement in many areas. And very strict in others.
The city lost all faith in it after the mall accident....the mfg pleaded their case before a committee...somebody dropped the ball in quality control ...the material was disallowed from then on and is still banned. And drilling out a joist is still not allowed in several surrounding communities.

personally I' did not know whether it was a banned material in the OPs area or not.

I was responding with the zeal that me and the city feel for drilling joists.
That is why I told him some one else can help him.

I think it is a bad practice and should be banned nationally. .


Last edited by hvac5646; 03-19-2012 at 03:54 PM.
hvac5646 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Planning on New duct work..any feedback... kilosos2 HVAC 28 01-26-2011 09:21 AM
6" round duct vs. oval independentpete HVAC 1 11-17-2010 04:41 PM
Splitting duct to a new bathroom nalishaw HVAC 4 10-31-2009 01:22 PM
Splitting HVAC flex duct dphens HVAC 16 08-19-2009 02:47 PM
replacing rectangular duct with 6" pipes peso HVAC 4 06-05-2008 08:43 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.