# Drilling Dryer Vent Hole Through Floor Joist



## Nealtw (Jun 22, 2017)

A 2 ply floor joist may be considered a beam and likely should be considered as carrying a load.
I would like to see a sketch of the layout of the bathroom.
What is the ceiling height in the bathroom?
Do you have a path for the bathroom ceiling fan duct?


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## chandler48 (Jun 5, 2017)

You don't want to denigrate the viability of the joist by drilling through it. Eating over half of the joist will weaken it. You, likewise don't want to go down and then back up. You will be forming a ptrap and moist air will condensate and fill the hose, eventually stopping the air flow. Straight out, down and straight out are the best options. Going up also presents backwash of lint, so you will have to anticipate that and put a tee cleanout in the end.


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## l008com (Mar 7, 2015)

chandler48 said:


> You don't want to denigrate the viability of the joist by drilling through it. Eating over half of the joist will weaken it. You, likewise don't want to go down and then back up. You will be forming a ptrap and moist air will condensate and fill the hose, eventually stopping the air flow. Straight out, down and straight out are the best options. Going up also presents backwash of lint, so you will have to anticipate that and put a tee cleanout in the end.


Down and straight out is preferred but the only way I can do that is by drilling a hole in the joist.


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## HenryMac (Sep 12, 2018)

Is this an electric dryer?

Are you aware that you can use an indoor dryer vent kit? Makes a lot of sense in the winter, not so much in the summer.

https://www.amazon.com/BetterVent-I...=2025&creative=165953&creativeASIN=B00Q4X2FSM

As for drilling a hole, 2-3/8" is the max. allowable diameter for a 2x8 floor joist and that's only if you aren't near the midspan of the joist.


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## Yodaman (Mar 9, 2015)

Make your lateral move into the next stud bay before you go down thru the floor.


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## l008com (Mar 7, 2015)

Yodaman said:


> Make your lateral move into the next stud bay before you go down thru the floor.


That's not possible. I'd have a dryer hose coming out of the wall of the bedroom and going down into a hole in the floor. The only bay the vent could possibly come down into is this "wrong" one. I'll try to sketch out a floor plan so it makes more sense, but me no draw good....


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## Nealtw (Jun 22, 2017)

l008com said:


> That's not possible. I'd have a dryer hose coming out of the wall of the bedroom and going down into a hole in the floor. The only bay the vent could possibly come down into is this "wrong" one. I'll try to sketch out a floor plan so it makes more sense, but me no draw good....


We build drops and boxes for those kind of things all the time. Could you cheat the corner of the bedroom with a 8x8 box floor to ceiling?


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## l008com (Mar 7, 2015)

Ok it's visual aide time.

First, the floorplan. The orange lines are the floor joists. And the big one at the bottom is the centerbeam. I can't see any possible way to make it so the vent comes down in any bay but the bay that is blocked by sewer pipes. 

Next, a photo of this side of the bathroom, with blue square where the washer and dryer go.

Then a view of the bathroom from the basement. The blue squares are approximate because it's hard to draw accurately. 

And last, a view looking down the bays, towards the back wall of the house. The washer and dryer would be above this and facing towards our left.

So the "idea" has evolved from sistering a short 3rd 2x8, lagging it in place, and drilling through all three... from that, to sandwiching three strips of half inch plywood, liquid nailed and bolted in place, about 6' long, then drilling the hole through all that material. I know this is still not ideal and I'm not saying that I'm actually going to go through with it. But I would prefer to do it that way, given the alternatives.


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## chandler48 (Jun 5, 2017)

Why not come down and turn laterally with the joists and exit through the sill? It only appears to be less than 8 feet.


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## l008com (Mar 7, 2015)

chandler48 said:


> Why not come down and turn laterally with the joists and exit through the sill? It only appears to be less than 8 feet.


Because the sewer pipes block the bay the vent comes down in to. That's the whole problem, unless i'm not understanding your suggestion.


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## chandler48 (Jun 5, 2017)

I understand. OK, plan B. Since your walls are opened up, why not a rear exit from the dryer into the wall cavity, turn right and exit out the exterior wall? You can buy wall pans to accomplish this since you probably only have 3 1/2". https://www.homedepot.com/p/Dundas-...ace-Saver-Aluminum-Dryer-Duct-UD48S/202449700


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## l008com (Mar 7, 2015)

Turning right goes into the rest of the house. I'd have to turn left and I'd hit that same sewer pipe and vent.


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## Yodaman (Mar 9, 2015)

Take another look ti see if it is possible to squeeze the dryer line past the drain. A 4" alum. dryer vent can collapse a bit into a oval if needed. Might want to pick up 2' length and try to position it in there. 

I really would avoid popping a 4" hole, mid way thru a 8" floor joist. Not a good plan.


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## Brian Famous (Feb 4, 2019)

So you already have that blue wire dropping down, what 3" below the beam? Is an extra 1" really going to be that inconvenient? 
Though that will still result in your vent going down and then back up to go out unless you're going through concrete...

So, looking at your picture, the joist to the left of the beam looks to be about 12" from the double, while the rest look to be 16" on center. I might think about seeing if that single joist can be moved over enough (2-4") to accommodate the vent going past the sewage drain pipe. At most, that joist would still only be 16" from the double beam, which should still be able to carry the load without issue.

A lot of work for a stupid dryer vent? Yes.
Compromising structural integrity? No.


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## Nealtw (Jun 22, 2017)

l008com said:


> Turning right goes into the rest of the house. I'd have to turn left and I'd hit that same sewer pipe and vent.


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## LawnGuyLandSparky (Nov 18, 2007)

How about going up? Run a shallow bulkhead along the ceiling of the bathroom and laundry closet. It'll be well above the toilet and vanity.


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## Domo (Nov 9, 2018)

Get a stacked washer and dryer.

Put the dryer on top of the washer.

Turn the washer so it faces the entry door to the bathroom.
You will have your choice of bay to go into the basement. See the picture.

As an alternative, you would use 1/2 the existing closet from the room to the left -


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## 3onthetree (Dec 7, 2018)

The alternatives mentioned are all viable. If you still want to keep that layout and bore thru the double joist, you definitely don't want to compromise a structural joist that much, even if it would still stay up there in practice. But . . . . . .

I edited your plan to match the picture. There is about an 8" space between D/EE. C is cut for the toilet and just hanging there which makes B/D 24"o.c. (the end support in purple is not continuous across from B/D nor is B or D a double joist).

It seems that boring thru EE could be thought of as moot, because if EE didn't exist you'd then have 20"o.c spacing between D/F. If you are not comfortable with 20" then add another joist between EE/F to reduce it.


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## l008com (Mar 7, 2015)

3onthetree said:


> The alternatives mentioned are all viable. If you still want to keep that layout and bore thru the double joist, you definitely don't want to compromise a structural joist that much, even if it would still stay up there in practice. But . . . . . .
> 
> I edited your plan to match the picture. There is about an 8" space between D/EE. C is cut for the toilet and just hanging there which makes B/D 24"o.c. (the end support in purple is not continuous across from B/D nor is B or D a double joist).
> 
> It seems that boring thru EE could be thought of as moot, because if EE didn't exist you'd then have 20"o.c spacing between D/F. If you are not comfortable with 20" then add another joist between EE/F to reduce it.


It looks from these pictures that your drawing is correct, but in fact the purple piece at the end of beam C does go all the way from beam B to beam D. Theres an extra piece of wood in there, but that part is built correctly, even though it doesn't quite look it from this angle.


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## chandler48 (Jun 5, 2017)

I think Neal hinted at the solution in post 8. Build a "plenum" box with a take off collar going up into the hole in the floor, and deep enough to allow another collar to take off laterally from below the joists. It will help with condensation and won't form a ptrap as the moisture will be drying as the air passes over it.


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## l008com (Mar 7, 2015)

chandler48 said:


> I think Neal hinted at the solution in post 8. Build a "plenum" box with a take off collar going up into the hole in the floor, and deep enough to allow another collar to take off laterally from below the joists. It will help with condensation and won't form a ptrap as the moisture will be drying as the air passes over it.


Do you have a photo maybe because I'm not following you.


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## l008com (Mar 7, 2015)

As an entirely alternate thought.... although someone did mention something similar.... those periscope things convert the 4" tube into 2x6 tube, then back. Does anyone sell 2x6 dryer ducting? With 90°*bends? I would need a flat bend and a thin bend, and then a straight line 2x6 to 4" conversion piece. But with all of that, I'd be able to get through the studs with a 2 1/8" slot instead of the big old hole. And still have no low spots or sketchy sections.


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## Yodaman (Mar 9, 2015)

Those telescopic vents reduce flow dramatically, clog rapidly, and increase fire risk.


Have you looked at switching the tub and washer & dryer locations?


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## chandler48 (Jun 5, 2017)

Picture? No, that's why I made a rudimentary drawing in Paint. It was an idea, not something you can buy off the shelf. You may need to have a HVAC person build it for you. As Yoda mentioned, those reducing boxes restrict the flow, and you don't want to cut a hole close to half the size of the joist. Going under without creating a ptrap would be your best bet.


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## SPS-1 (Oct 21, 2008)

Nealtw said:


> We build drops and boxes for those kind of things all the time. Could you cheat the corner of the bedroom with a 8x8 box floor to ceiling?



Sounds like a good idea.


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## huesmann (Aug 18, 2011)

Totally unrelated to the issue at hand, but you should move your door from outside the W/D area to between the sink and bathtub, opening to the left as you enter.


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## Brian Famous (Feb 4, 2019)

huesmann said:


> Totally unrelated to the issue at hand, but you should move your door from outside the W/D area to between the sink and bathtub, opening to the left as you enter.


I'd agree to separate the laundry from the facilities... But I'd probably out for pocket or barn doors for both... But that's well outside the question


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## 3onthetree (Dec 7, 2018)

The OP hasn't said, but I think the room next to the bath is the kitchen. A chase there might not work. There is zero room to squeeze by the stack. I'm not understanding where the option of plenum-style box would go and what that solves beyond a 90d Elbow travelling below the joists.




l008com said:


> Does anyone sell 2x6 dryer ducting? With 90°*bends? I would need a flat bend and a thin bend, and then a straight line 2x6 to 4" conversion piece. But with all of that, I'd be able to get through the studs with a 2 1/8" slot instead of the big old hole. And still have no low spots or sketchy sections.


If you use a wall box the outlet is an oval-ish shape, requiring the 4" duct to be squeezed to mount to it anyway (oddly they are not designed to take a 6" standard oval transition). But keeping that line squeezed either thru the bore hole or between something else doesn't help anywhere that I can see (unless I'm missing something). I haven't seen any special 4" shapes.



I'm still going on the double joist is not doing much (its not supporting the stair, no bearing wall, no big chase), looks as if it was done just for the change in o.c. spacing. So bore your opening and put another joist next to the dryer line and your overall joist spacing will still be about 12" to 13"ish.


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## carpdad (Oct 11, 2010)

https://www.metwood.com/joist-reinforcers/


Sorry didn't read all posts. How about something like this? Search such for double joists. Double joists are sometimes auto reaction to a wall above, just for the dead load. Possibly you don't need much of a reinforcement. Maybe just a double post next to the hole? Or if you brace that non load bearing wall, 1/2" ply, bottom to top plate and the studs, that wall should hold itself up.


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## Hidyi (Sep 26, 2014)

LawnGuyLandSparky said:


> How about going up? Run a shallow bulkhead along the ceiling of the bathroom and laundry closet. It'll be well above the toilet and vanity.


Good idea, I agree. Sounds like the most practical solution to build a soffit at the top of the wall and running the dryer exhaust to the exterior above the toilet/vanity and clearing in front of the vent pipe.


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## Calson (Jan 23, 2019)

Another option is to build a 6" high platform for the washer and dryer to sit on and have the space below it to run the vent to the next bay.


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## snic (Sep 16, 2018)

Some of the ideas mentioned so far involve long duct runs (such as venting up through the attic) or a portion of duct with smaller diameter. Or a convoluted "up and over" duct run with several bends. All of these would also reduce air flow.

A potential solution is to install a dyer booster fan:

https://www.hvacquick.com/products/residential/Dryer-boosting

Dryers' in-built fans are simply not strong enough to push the air through long or constricted ducts. As a result, the air speed is slow, and that's why lint builds up in the duct. These fans greatly increase airflow and prevent the lint build-up. Not only do they eliminate a fire hazard, but they decrease drying time (and energy expense) by a LOT if you have long ducts.

I've installed two of them in different houses, which both had absurdly long ducts (probably 25 or 30 ft). They have worked flawlessly.


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## RobbD (Sep 4, 2018)

I an ahtnkful that I live on the first floor on a concrete slab. Our dryer vent attached to a molded ffitting and directs straight through the outside wall.






OTOH, our over the range hood vents straight up through the upper cabinet and into the closed soffit, maing one elbow turn and strignt out the sidewall/


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## HotRodx10 (Aug 24, 2017)

Calson beat me to the option I was going to suggest - put the washer and dryer (or just the dryer) up on a box, so that the vent can run back under it to an open joist bay. If 6" is too much, you can get it to about 4-1/2" using 1/2" plywood or 7/16" OSB for the top of the box. Just line up the walls of the box with where the weight of the dryer rests (the feet).


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## snic (Sep 16, 2018)

HotRodx10 said:


> Calson beat me to the option I was going to suggest - put the washer and dryer (or just the dryer) up on a box, so that the vent can run back under it to an open joist bay. If 6" is too much, you can get it to about 4-1/2" using 1/2" plywood or 7/16" OSB for the top of the box. Just line up the walls of the box with where the weight of the dryer rests (the feet).


This is a great idea - except I'd make the platform higher than 6". Front-loading washers (and dryers) often have an optional riser that you can buy (for a lot of money) to raise the appliances up by a foot or two. The idea is that you then don't have to stoop so much to transfer your laundry. Why not just build your own riser?

You could either get a front-loading washer and build the box for both washer and dryer, or a top-loading washer and build the box only for the dryer. Either way, you make it easier to do your laundry, solve your duct routing problem, and probably save some money over the cost of the insanely expensive risers (at least the ones I saw a few years ago), assuming you're doing this construction yourself.

(Here's an example of a riser that comes with a front-load washer or matching dryer:

https://www.pcrichard.com/Whirlpool/Whirlpool-Front-Loading-4-3-Cubic-Foot-Washer/WFW862CHC.pcrp

See the Accessories on the right - the "washer/dryer pedestal" costs $250 each, and raises the machine up by 15".)


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## HotRodx10 (Aug 24, 2017)

Agreed snic. I thought it would be a given that the box could be higher, if it was more convenient. Most of the older models (and some new ones) have the controls on top at the back. While getting the clothes out may be easier with the dryer up higher, it may put the controls out of the reach of short people. For some of us, it's already hard enough to get the kids to help with the laundry...


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## daxinarian (Jul 9, 2008)

Connecting dryer ducting to a dryer on top of a box is orders of magnitude easier. You can make all the connections with the dryer in it’s final location so you can use rigid ducts instead of flexible ducts, so you also have less airflow restriction.


Sent from my iPhone using Tapatalk


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## huesmann (Aug 18, 2011)

The "box" is commonly known as a pedestal base.

The trick thing would be to stack a front-load washer above a dryer with a swing-down door. That way you could just haul your damp clothes out of the washer and drop them down on the dryer door, and shove them directly into the dryer—a minimum of bending over!


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## Nealtw (Jun 22, 2017)

huesmann said:


> The "box" is commonly known as a pedestal base.
> 
> The trick thing would be to stack a front-load washer above a dryer with a swing-down door. That way you could just haul your damp clothes out of the washer and drop them down on the dryer door, and shove them directly into the dryer—a minimum of bending over!


I think you want the heavy one on the bottom.


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## huesmann (Aug 18, 2011)

A guy can dream, can't he?


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## 3onthetree (Dec 7, 2018)

huesmann said:


> A guy can dream, can't he?


You still talking about washers/dryers, or "heavy one on the bottom" about something _else_? :devil3:


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