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justplumducky 09-30-2010 11:06 PM

Dryer duct hole thru band joist & floor joist
I'm relocating a washer and dryer to the basement (this coming Tuesday, Oct. 5th, 2010), and the only option for the dryer duct (4") seems to be thru a floor joist and band joist (that's what a plumber called it...the band joist - the outer 2" x whatever it measures)'s probably a 2 x 10 just like the floor joist?

The floor joist is a 2x10 also (I assume) (it measures 1-1/2" x 9" actual, or very close to that.

These two joists are about 8" apart, on center (on centers?)

I was told that a 4-1/8" hole in the band joist (the outer one) would be ok, because it sets on a bottom plate and the bottom plate sets directly on the foundation (basement wall). However he recommended doubling up the 2x10 floor joist before drilling the 4-1/8" hole in that one.

By that, he meant slapping a piece of 2x10 (probably about 24" inches wide or more? (I'm guessing) onto the existing floor joist for reinforcement before drilling the 4-1/8" hole.

All that sound ok? If so, would the following be the best way to go about it?:

A 4-1/8" hole saw through the band joist, drilled from the outside of the home. Then, the hole saw with a right angle drill, through the doubled up floor joist, from the inside of course. Except, the doubling up on the 2x10 would make it an actual 3" thick x 9" joist and the hole saw is only good for 1-3'/4" depth.

So, I should drill the reinforcement 2x10 first, then hold it up against the floor joist and mark it for drilling the second hole? Or go ahead and fasten the reinforcement piece of 2x10 onto the floor joist, then drill thru the reinforcement piece until it digs into the floor joist (and marks it for me). Then, remove the reinforcement piece and drill thru the floor joist....

...or just remove the drilled out plug from the reinforcement piece, while it's still fastened to the floor joist, then continue drilling thru the floor joist with the right angle drill? Never used a right angle drill before (my friend is bringing one over).

Grateful for any help.

DexterII 10-01-2010 09:24 AM

Let's assume for now that the band or rim joist is not an issue, as I tend to agree. As for the floor joist, I suspect that whoever suggested "doubling it" meant doubling the entire joist, not just scabbing 2' onto it, and even in that case, it seems like a lot of material to remove. So, before going that route, is there any way that you can either extend the run at the dryer, and drop into the basement on the outside of the affected joist, or that you could turn 90 degrees, once you go through the floor, and run it between the joists to one of the band or rim joists? I can see your predicament, as I have encountered similar situations, but, so far anyway, have been able to come up with an alternative to cutting a 4" hole in a joist.

Ron6519 10-01-2010 02:30 PM

You can't cut out a 4" diameter hole in any 2x? floor joist.

steveel 10-01-2010 03:02 PM

I'm dealing with something similar. In my old house, the first joist in from the band joist has a notch nearly all the way thru for an old furnace duct. It's been like that forever, and prior owners have just lived with the dip in the floor along that wall. Since I am fixing a lot of bigger problems under a structural engineer's watchful eye anyway, I asked him what I could do about the notch. He suggested cutting and removing the notched section of that joist completely, and adding a double-header (two 2x10s nailed together) perpindicular on each side of the duct. They'll perch on the foundation and tie into the band joist, and extend into the face of the 2nd joist from the band joist. The cut joist will attach to the midpoint of the headers forming a sort of "T". We'll use off the shelf "joist hangers" for all of the connections.

Your mileage may vary.

Michael Thomas 10-01-2010 06:47 PM

If the local AHJ will approve it, you may be able to use a Metwood HR-10 joist reinforcer:

gregzoll 10-01-2010 08:19 PM

Mine has been that way for over 50 years, and have not had any problems with the exhaust going through the rim joist. Majority of the homes have the exhaust going through the Rim joist with no doubling on it. IF contractors thought that it would be a problem with basement laundry, they would have had the architect factor it in.

steveel 10-01-2010 08:36 PM


Originally Posted by gregzoll (Post 510068)
Majority of the homes have the exhaust going through the Rim joist with no doubling on it.

I wasn't talking about doubling the rim joist, but instead doing something to catch the floor load of the joist that would be compromised. My engineer suggested a pair of double headers perpindicular to the compromised joist, to span from rim to the next joist in. I didn't know about the Metwood thing Michael mentioned. That's a great tip, thanks.

gregzoll 10-01-2010 08:42 PM

How close is the joist that is being planned to get taken to war? Take a picture of it, with a tape measure and post. Possible that you may be able to box around it. May want to go a different direction that you run between the joists, not through one, otherwise as mentioned you will need to box around to strengthen.

justplumducky 10-03-2010 11:46 AM

Steveel, this what your structural engineer recommended? (pic below). For all others (thx so much for your replies), haven't had a chance to take a pic yet - not my house. Probably go over there in just a while, then post a pic.

The First Floor Joist is 8" on centers from the Rim Joist, but it's not sitting on the foundation wall - about a 1-1/2" (close to that) above it. The Rim Joist is sitting on what might be called a bottom plate (?), which sits on the foundation.

2nd Floor Joist was about 16" on centers from the 1st Floor Joist.

This pic is slightly inaccurate - it's showing the headers (double-up 2x10's ) butting up to the bottom plate, instead of butting up to the rim joist.
http://microlightstore.comfloorjoists.jpgI've edited this post, because I just realized that I wouldn't be able to get at both sides of the joist hanger hardware that attaches to the rim joist. The pic below is looking from the basement at the outside wall and the 1st floor joist sitting just above the foundation wall. The rim joist is behind the 1st floor joist
Could I toe-in the headers to the rim joist? And toe-in the 1st joist from the rim joist, to the headers? Pic below shows what I mean, if that's not the correct expression? Bottom plate is not shown in pic below. If I can do that, what screws should I use?

steveel 10-03-2010 01:17 PM

Since it's not your house, I assume you're not getting paid and so it is up to the HO to figure this out (perhaps with your help). If you are getting paid, then I assume you have any required license and insurance and will send the rest of us a consulting fee.

Assuming you're helping a friend, I think your friend should go talk to their inspector to find out if (a) they need a mech permit to do the drier duct in the first place and (b) if the joist reinforcer posted by Michael Thomas will be acceptable, and if not then what they want to see where the duct passes that joist.

To answer your question, for MY house with the EXISTING compromised joist, yes that's the concept the engineer mentioned during a walk thru last week. I don't have the final report yet. If you go that route, again HO needs to talk to inspectors first, since theres a good chance they will need a building permit to alter the floor framing.

Ron6519 10-03-2010 03:14 PM

"I'm relocating a washer and dryer to the basement (this coming Tuesday, Oct. 5th, 2010), and the only option for the dryer duct (4") seems to be thru a floor joist and band joist "
I find it hard to believe you cannot vent the dryer without going through a joist. There have to be other simpler options.

del schisler 10-03-2010 04:24 PM


Originally Posted by Ron6519 (Post 510827)
"I'm relocating a washer and dryer to the basement (this coming Tuesday, Oct. 5th, 2010), and the only option for the dryer duct (4") seems to be thru a floor joist and band joist "
I find it hard to believe you cannot vent the dryer without going through a joist. There have to be other simpler options.

Do you have a window close by?? Take the window out and build a vent their ? Or make it 1/2vent and 1/2 window ??

justplumducky 10-05-2010 12:31 PM

Thank you del and Ron, Dexter and Gregz.

The work was planned for today, but have delayed it, temporarily.

Would rather not do the window thing and the only other option I see is going thru the wall adjacent to the one in question here, which leads to the garage. Don't like the idea of a vent pipe in the garage, then going outside, and that would also result in too many elbows, which would also be a prohibiting distance of run for the vent pipe, according to manufacturer's instructions.

Everywhere else is either the same problem (the floor joist 8 inches away from the band (rim) joist (which makes the band joist inaccessible, because both are just an inch and a half, or so, above the concrete wall, and any other option is too far away for maximum distance of run for the vent pipe. Prefer not to have a booster fan in the vent pipe run.

Along the same line of support technology as the Metwood Joist Reinforcer (thank you Michael Thomas), what would you think about something similar, like a steel plate 1/8" thick or more (Metwood is light-guage steel according to their webpage)... 6 inches of steel on either side of the 4" drilled hole in the plate and 2-1/2" of steel on top & bottom of the hole (accessible vertical height of the joist is 9") ...all one solid piece of steel, with 4 inch hole... ?

This 4" hole is not very far from the load-bearing joist (mentioned above) that is common to the garage wall. Maybe a couple of feet - will be going back to measure this distance (and get pic) next week. Also will get the distance for the other side of the 4" hole (horizontal distance to the I-beam that goes across middle of the basement (there's only one of those I-beams).

I apologize for no pic yet - probably next week.

In the mean time, whaddya think about the steel plate? I would drill the plate in the same fashion (locations) as Metwood has drilled theirs - the one with the hole in the center/see link below to Metwood slide show (no holes directly above/below the hole, which I'm guessing would be critical stress areas not to be penetrated).

If you want to see some pics (slide show) of different applications of the Metwood Joint Reinforcer:

Thank you all so much for your help.

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