# Cutting floor joists?



## hroark2112 (Apr 16, 2011)

I don't do a ton of new construction. I prefer service. That being said, I'm doing a few houses for a contractor I trust. 

Back to back bathrooms, cast iron tubs, vanity sinks. Anyone have any photos of the right way to cut these joists without compromising them too much??

Thanks!!.


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## UN1TED-WE-PLUMB (Oct 3, 2012)

Around here we need 2" of meat left on top and bottom of hole. Other than that...have at it!!


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## justme (Jul 4, 2012)

I'm not a residential plumber by trade but I do a few house's a year . I have always been told to follow the manufacturer's guidelines which is usually you can drill the center third of the joist . Basically divide the beam into thirds and you can only drill the center third of the beam. But I would recommend finding out the specs from the beam manufacturer.


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## MacMech (Sep 15, 2011)

http://www.anthonyforest.com/powerjoist.shtml

Might help there are some Pdfs to look at that show where to drill holes


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## Gettinit (May 9, 2012)

justme said:


> I'm not a residential plumber by trade but I do a few house's a year . I have always been told to follow the manufacturer's guidelines which is usually you can drill the center third of the joist . Basically divide the beam into thirds and you can only drill the center third of the beam. But I would recommend finding out the specs from the beam manufacturer.


:blink:


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## OldSchool (Jan 30, 2010)

Up here they are called TGI 

All depends how deep the joist are ... Normally 5 ft from a bearing point ...

Joist should come with detailed drawings where you can cut and drill


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## Will (Jun 6, 2010)

You can't cut the top or bottom flange of the TJI joist. They are not much different than any other framing. Drill the center.


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## Will (Jun 6, 2010)

.

http://www.woodbywy.com/literature/TJ-4000.pdf


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## beachplumber (Feb 7, 2010)

Specific tgi manufacturer. Different size holrs will have different placement


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## justme (Jul 4, 2012)

Gettinit said:


> :blink:


What's the :blink: about lol


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## Gettinit (May 9, 2012)

justme said:


> What's the :blink: about lol


Not sure about what percentage is but you are not supposed to touch the middle of the span. You are not supposed to drill anything but the laminated part of the tgi and I believe you are supposed to stay two inches from where it rests on the block wall. 

I agree with needing to check with every manufacturer. 

I could be wrong though.


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## Will (Jun 6, 2010)

Y'all are driving me nuts with your "TGI" commits. Its "TJI". Stainds for Trus Joist I-Beam.


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## plumberdad70 (Sep 29, 2012)

Thank you will!!!!!!! Lol


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## OldSchool (Jan 30, 2010)

Will said:


> Y'all are driving me nuts with your "TGI" commits. Its "TJI". Stainds for Trus Joist I-Beam.


Lmao ... Is that all it took 

We are plumbers not carpenters


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## Will (Jun 6, 2010)

Feel better now...lol


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## OldSchool (Jan 30, 2010)

Will said:


> Feel better now...lol


You should have been a carpenter


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## plbgbiz (Aug 27, 2010)

OldSchool said:


> You should have been a carpenter


He should have been a tool collector...oh wait... :laughing: 

That's why he keeps getting bigger trucks.


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## Will (Jun 6, 2010)

OldSchool said:


> You should have been a carpenter


I could of been a hell of a framer, but I would have been a lousy carpenter. I don't do finesse work.


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## Gettinit (May 9, 2012)

Will said:


> Y'all are driving me nuts with your "TGI" commits. Its "TJI". Stainds for Trus Joist I-Beam.


Whatever they are I like them. Don't need the chainsaw anymore, just a razor knife. :laughing:


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## OldSchool (Jan 30, 2010)

Will said:


> I could of been a hell of a framer, but I would have been a lousy carpenter. I don't do finesse work.


Dam that's like saying you can rough in but can't set the fixtures


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## RealLivePlumber (Jun 22, 2008)

TJI, Weyerhouser, and Boise Cascade are the prominent manufacturers of wooden I beam style floor joists. 

They are very different when it comes to cutting, notching and boring.

Get the exact literature from the manufacturer and follow the rules EXACTLEY. (Be very aware that there are different models of the same size i joist.) The framing inspector will. 

In general, you are not allowed any holes near end, mid, or cantaliever bearing. Usually 3 1/2' to 5'. But it varies greatly. You must have minimum areas between holes. DO NOT cut or drill the flanges.

Surprisingly, you are allowed to bore a hole the size of the entire web, towards the center of the span, but there are other considerations, including other holes in the joist.

You are also allowed to offset a joist to allow for pipes, usually 3" on center.


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## Will (Jun 6, 2010)

OldSchool said:


> Dam that's like saying you can rough in but can't set the fixtures


Theres a pretty big difference between building cabinets than setting fixtures, but yeah I'm definitely better at rough ins and top outs, than finals.


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## OldSchool (Jan 30, 2010)

Will said:


> Theres a pretty big difference between building cabinets than setting fixtures, but yeah I'm definitely better at rough ins and top outs, than finals.


Both are carpenters ...

I guess they have their speciality


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## Plumbus (Aug 4, 2008)

Yesterday Will couldn't spell carpenter, now he are one.


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## RealLivePlumber (Jun 22, 2008)

Gettinit said:


> Not sure about what percentage is but you are not supposed to touch the middle of the span. You are not supposed to drill anything but the laminated part of the tgi and I believe you are supposed to stay two inches from where it rests on the block wall.
> 
> I agree with needing to check with every manufacturer.
> 
> I could be wrong though.


You are allowed a full size hole the same size as the web, in the center of the span. Not so much near bearing. Smaller holes are a few feet from bearing.


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## Will (Jun 6, 2010)

Plumbus said:


> Yesterday Will couldn't spell carpenter, now he are one.


Im at the mercy of the spell check. On the smart phone it aint so good....


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## gear junkie (Jun 20, 2008)

Sometimes it's easier and more structually sound to drill a couple extra studs or joists and feed through the outside or in a room then do a bunch of notching.


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## ironandfire (Oct 9, 2008)

Will said:


> Y'all are driving me nuts with your "TGI" commits. Its "TJI". Stainds for Trus Joist I-Beam.


That was hilarious.


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## cbeck (Mar 7, 2012)

Joist lit should be in the permit box


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## leakfree (Apr 3, 2011)

If you look over the joists you'll usually find a pamphlet attached to one or two of them with all of the spec's for them.It is possible to cut the top of the joist,but a structural engineer has to supply a drawing and plans for the gusset that gets added to the joist after it is cut ( had an apprentice cut one once).


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