# cutting 4" holes in 10" floor joist



## red_cabby (Jun 21, 2010)

I've read the building code and realize what I'm about to do won't meet code, but I'm weighing my options and would appreciate any advice you can pass my way. I will be moving a second story toilet across 4 joists, the joists are 10" (9 1/2") on 16" centers. Bathtub and shower will remain on untouched joists.

The 4" hole will be much bigger than what code allows, so what I'm looking for is:

1. should I put the holes near the center of the span, or near the ends?
2. how should I add support to these joists? glue/nail 2x10's on each side and then cut the holes, or fabricate metal panels to attach above and below the holes?

Any help or advice would be much appreciated. Of course, if your opinion is that I'm an idiot for cutting joists against code, then plse let me know that as well (better to be told I'm an idiot by strangers, than have my wife point it out when the ceiling starts to sag









Many thanks,
DB


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## Willie T (Jan 29, 2009)

Do you suppose there was actually a reason they put that restriction in the codes? I won't judge your mental state, but I will ask why you would want to violate a requirement meant to keep your house free from problems.

If you heard you shouldn't pour milk in your truck's gas tank, would you ask around to see if you can get away with it?


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## Leah Frances (Jan 13, 2008)

You asked for it.

*Yes, you're an idiot. *

That being said (and only because you asked for a stranger to do it, I saved your wife the effort :wink you have to come up with another plan.


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## stadry (Jun 20, 2009)

you can't get 5gal of wtr into a 4gal bkt,,, seems unanimous so far - you're an idiot from here, too :laughing:


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## red_cabby (Jun 21, 2010)

*ok, something constructive*

Thanks for the "idiot" votes, how bout:

-I only need a 3.5" hole for a toilet
-the joist is 9.5" so according to the attachment I would be very close to meeting code (the size of the 10" joist on the attachment is 9.25", with a 3 1/8" hole allowance; my joist is 9.5" and I want to put a 3.5" hole)...

Given this new info that I rec'd from the Terry Love forum, how would you construction people recommend I beef up my joists?

Many Thanks,
DB


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## stadry (Jun 20, 2009)

ONLY way i'd know is building a ' fitch beam ' - either steel plates OR aircraft grade alum

' close ' doesn't help much 'cept in horseshoes & battle firefights :laughing:


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## Joe Carola (Apr 14, 2006)

red_cabby said:


> Thanks for the "idiot" votes, how bout:
> 
> -I only need a 3.5" hole for a toilet
> -the joist is 9.5" so according to the attachment I would be very close to meeting code (the size of the 10" joist on the attachment is 9.25", with a 3 1/8" hole allowance; my joist is 9.5" and I want to put a 3.5" hole)...
> ...


Why don't you ask your building inspector when you file for the permits.


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## Yoyizit (Jul 11, 2008)

red_cabby said:


> I will be moving a second story toilet across 4 joists, the joists are 10" (9 1/2") on 16" centers. Bathtub and shower will remain on untouched joists.
> 
> The 4" hole will be much bigger than what code allows, so what I'm looking for is:
> 
> I put the holes near the center of the span, or near the ends?


Near the ends, all else being equal. 

Post photos and diagrams of what you want to do, before and after - there may be a way to keep everybody happy. 

Without researching it, one option might be to use a smaller pipe and a sewage pump. Another would be to bolt a steel strap truss structure onto both sides of the existing joists; trusses are mostly empty space and steel is about 20x stronger than wood.

Saying you're not going to meet code is like waving a red flag. (To your credit) you are not a politician or a diplomat or a spin doctor.


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## slickgt1 (Apr 1, 2010)

red_cabby said:


> I've read the building code and realize what I'm about to do won't meet code, but I'm weighing my options and would appreciate any advice you can pass my way. I will be moving a second story toilet across 4 joists, the joists are 10" (9 1/2") on 16" centers. Bathtub and shower will remain on untouched joists.
> 
> The 4" hole will be much bigger than what code allows, so what I'm looking for is:
> 
> ...


I agree, don't just say you are not going to meet code, I am not sure you understand the scope of problems that this can cause. 

Either way post up pics. 

How do you plan on maintaining pitch through the joists? 4 of them at that. Is there no way to move the pipe below the joists and then run up to be between the joists?


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## Michael Thomas (Jan 27, 2008)

Give Metwood a call,* if allowed by your local AHJ*, they may have a engineered joist reinforcement product which will solve your problem.










http://www.metwood.com/products/reinforcer

(For the record, I have no business relationship of any kind with Metwood.)

____________________
I’m paid to be suspicious…


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## Willie T (Jan 29, 2009)

If you can handle the looks of a small 'drop-down' soffit at the edge of your wall, what about running to the wall with the pipe, turning down beneath the joists, then running along the wall to where you need to go. Afterward, box in that wall run with a small soffit.

This way, you cut no joists at all.


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## canadaclub (Oct 19, 2006)

I like that Metwood brace. Maybe not for 4 joists but in one it could save a lot of time.


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## hereslookingatU (Feb 8, 2010)

Hi

Check out 'www.saniflo.com' 
This may get over your problem - only real issue is with noise generated when the pump is running!

Regards


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## bernieb (Mar 20, 2010)

Your new water closet flange and elbo will dictate where pipe will go. If you have a small bathroom and if you have manufactured roof trusses that go from outside wall to outside wall , and if you have the supporting walls on the first floor to support this idea , you may just want to reverse the floor joists in the bathroom area only. I have swung walls from roof trusses many times replacing termite damaged floor joists. As a reminder in moving the comode that far you will need to consider a new vent also as 3 feet is the max from comode opening. Okay boys hammer away as I just may be nuts.


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## Michael Thomas (Jan 27, 2008)

bernieb said:


> I have swung walls from roof trusses many times replacing termite damaged floor joists. As a reminder in moving the comode that far you will need to consider a new vent also as 3 feet is the max from comode opening. Okay boys hammer away as I just may be nuts.


I'm a bit unclear on what you are suggesting, do you have a picture or diagram?

Thanks


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## Yoyizit (Jul 11, 2008)

Michael Thomas said:


> Give Metwood a call,* if allowed by your local AHJ*, they may have a engineered joist reinforcement product which will solve your problem.


May the AHJ, at its discretion, forbid the HO to use this? If so, is the AHJ compelled to say why?


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## jogr (Jul 24, 2007)

You can still comply with code by having a fix engineered. If an engineer signs off on the fix (such as metwood or any other reinforcing) I don't know why an AHJ would not approve it. BTW, don't cut the holes first and then start looking for a fix.


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## xxPaulCPxx (Dec 2, 2006)

You are on the very edge of the limits here, and the big holes go in the center of the span where you loads on the joists are purely across the top and bottom edge. Also, you would need closer to a 10" actual board depth to get that 3.5" hole you desire.

Thinking creatively, since that's what us DIY schmucks do all too well:jester:, consider a couple other options:

1. Instead of PVC, ABS, or cast iron, look at copper tube instead. Yes, it will be pricey, but with a smaller outside diameter it might be the best solution to your problem, in that you might be able to bore smaller holes that will be within the specs of your floor system. Remember though, sewer pipe needs to drop 1/4" every 12" (I think), make sure you are not violating your minimums of top and bottom clearance for that slope through your joists.

2. Instead of cutting holes, cut the joists entirely... and put new load bearing beams across the sides of the new space you are making for your sewer pipe. You would have to take the load path all the way down to the foundation, but that is pretty straightforward, and you would retrofit joist hangers onto those new rim beams to hold the existing joists.


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## rtoni (Jul 18, 2007)

xxPaulCPxx said:


> Thinking creatively, since that's what us DIY schmucks do all too well:jester:, consider a couple other options:
> ..............................
> 
> 2. Instead of cutting holes, cut the joists entirely... and put new load bearing beams across the sides of the new space you are making for your sewer pipe. You would have to take the load path all the way down to the foundation, but that is pretty straightforward, and you would retrofit joist hangers onto those new rim beams to hold the existing joists.


fwiw I used a similar approach re: PaulCP on point # 2 - cut them and add structure to existing to support the new space.

when I bought my house I retrofitted the bathroom and I had similar issue (to move the toilet). I didn't care about running pipe under the joists in my crappy old basement but I didn't want to mess with the connection to existing cast iron stack, etc. so the joists were in the way.

I followed the CMHC wood frame house construction book (i love this book) which details these things in a way even a DIY like me can follow. this was the gist of it in my case - not sure if this was overkill or standard procedure, but it sure worked well here. I hope this makes sense - great diagram in the book but i failed on a quick google around to find similar to link here.

-- cut about 12" right out of the offending joists - 3 of them in my case - enough room for flange, pipe, headers, etc 
-- cut 2 headers to fit between the existing "trimmer" joists (those on each side of and parallel to the ones just cut) - nail these onto the ends of the hanging (tail) joists - one on each side of the opening
-- double up these headers (nail another header piece same size right over the first)
-- nail thru the sides of the existing "trimmer" joists into the ends of the new double headers
-- nail on an additional trimmer joist (same size - i.e. sister it against the existing trimmer joist to double it up)
-- add single / double joist hangers on the ends of the tail / header joist pieces

all materials and joists 2x8 in my case.

The CMHC book describes this as a basic framing technique for floor openings for stairs, etc. - in my case the "opening" was a just space under the subfloor - wide enough to accommodate the flange and the short pipe run across to the old stack. They do recommend getting an engineered solution for a "large" openings but this job was well within the guidelines they used. They also had some threshold where the "doubling up" might not be required, but a bit of overkill in this case was pretty easy to do regardless so I just did it.

The load carries across to wall / beam via the doubled-up trimmer joists - so nothing new underneath or at stack was required to support the change.

it took me a couple hours to complete and floor is now better than how I found it (previous owners had cut part way thru one joist and left it like that - not sure why - old houses full of surprises)

on the other hand, if you have hvac or electrical to contend with that might get in the way (e.g. running through the existing joists that you want to sister) this might not be of much value. others may also see problems with this in your case or in general - just throwing it out there fwiw. good luck...


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## bernieb (Mar 20, 2010)

That's the way to do it ,as xxpaul and itoni says. Besides you couldn't fish a 4 foot pipe if you had a eight inch hole in all the joist. Get a grip!


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