[deckman22]

Uncalled for jab retracted, sorry Patti.

 

[Static Design]

See...most of us here have the understanding of Newton's Law of Gravity. If you put something in crown down, gravity will make it worse. If you put it up, gravity helps draw it down some. Over time, your deck is going to sag way more than the rest of the planet that puts it crown up.

That's not entirely true, yes gravity does affect material behavior but if you read on in Newtons little law you will see that there is an equal but opposite force acting against gravity called a "normal force" this is why gravity doesn't smash you like a pancake through the earth and keeps things in equilibrium.

I put crown down, after many deck examination and building them also I found that here in KY the wood splits far less and looks/last a whole lot longer in this area. When the cup is up then screwed down the fibers in the wood are pulled in a tensile force causing them to split. From what I seen it starts to get really noticeable around the 3 year mark of the decks life.

This is an on going debate and probably will continue but I do cup side down. I maybe completely wrong but I like debates when I get free time. :laughing:

 

[Warren]

The cupping issue is separate from the crown issue. There is no mechanical force when determining which side of the crown should go up or down. As for the cupping, we have had that debate on jobsites many times. Our best compromise was to just put the best looking face up. If the wood is very cupped, we don't use it. My own deck was built with pt pine 15 years ago. It has been painted a few times but no boards have ever been replaced. It is about due, but after three years I think it was still doing pretty well.

 

[Static Design]

Im not saying the deck is not functional or the deck boards need to be replace after 3 years, I am saying that is when I found a noticeable difference between up or down.

 

[SC sawdaddy]

I've never even considered putting the crown down.
I can only think of one thing to say about it.

Why?

 

[Joe Carola]

I've never built one with the crowns up, but as all of us know every once in a while someone puts one in with the crown up.

No, everyone always puts the crown up and maybe once in a while one puts the crown down. You are the first person that I have ever heard in almost 27 years of framing say that they put the crowns down on floor joists. I've heard homeowners doing that.

Since when does a crown in a floor joists go down? This is framing 101. A deck joist/floor joists/ceiling joist/rafter crown is always up.

Now I always reinspect the project we build. I found that when the crown is up or the crown is a serious amount, you can see a hump or sag in the deck surface.

Since your crowning the joists before you put them i(in your case down) you should never use the ones with a bad crown to start. Order extra joist for that reason and toss the bad ones aside. Why in the world would you use a joist that has a bad crown whether your framing a deck or house that will haunt you in the end?

Its more noticeable with composites if they are screwed from the expose face.

Again, why are you using bad lumber from the start? Don't tell me that you had to and won't go buy a good piece if you ordered exact. That';s no excuse. If I ordered the exact amount of lumber and one or two were bad, I would go to the lumberyard and buy two more. That's my problem that I have to waste my time and go get two more. It's better than having a problem like you have with a finished product. What happens if the HO didn't want to see a big hump like your describing? Will you tell them that it's a bad joists and you couldn't do nothing about it? What happens if they ask you if you could've bought a good joist, what would you say?

I find the best way to is to keep the surface real flat so those deck drainage spaces keep looking optically straight, is to crown down and cut serious crowns out.

That or buy good joists. PT lumber most of the time has some bad crowns, that's why you over order and don't use bad joists.

I realize most of you have been taught something else but I haven't always had the advantage of learning from another. I had been thrown in this business by necessity, no chance or time to learn. It was sink or swim.

Here's your chance to learn. You always frame deck joists/floor joist/ceiling joists/rafters up.

 

[TDG]

Don't use really bad humped up lumber for the joists

Crown up, use a power planer on the ones that show.


If you crown down just how do you cut out the serious ones??? That would be like trying to cut out a hole.


I am not understanding how 12'' on center makes it worst. J.

John what makes it look wavy is the fact that the joist are not even.
By adding more joist you increase your changes of making more out of even joist. Hope that helps.

When we have a 2x10 or 2x8 with a strong crown we can cut either side the hump side or the sagged side to make it straighter. We always cut the sagged side being we might locate this altered cut joist next to a sagged one and it conforms better. we chaulk a line on the sagged side and cut off material that nature put out passed my chaulked line.

Now to try and get the sags out of my forehead and neck areas that's a whole new thing

 

[TDG]

No, everyone always puts the crown up and maybe once in a while one puts the crown down. You are the first person that I have ever heard in almost 27 years of framing say that they put the crowns down on floor joists. I've heard homeowners doing that.

Since when does a crown in a floor joists go down? This is framing 101. A deck joist/floor joists/ceiling joist/rafter crown is always up.




Since your crowning the joists before you put them i(in your case down) you should never use the ones with a bad crown to start. Order extra joist for that reason and toss the bad ones aside. Why in the world would you use a joist that has a bad crown whether your framing a deck or house that will haunt you in the end?



Again, why are you using bad lumber from the start? Don't tell me that you had to and won't go buy a good piece if you ordered exact. That';s no excuse. If I ordered the exact amount of lumber and one or two were bad, I would go to the lumberyard and buy two more. That's my problem that I have to waste my time and go get two more. It's better than having a problem like you have with a finished product. What happens if the HO didn't want to see a big hump like your describing? Will you tell them that it's a bad joists and you couldn't do nothing about it? What happens if they ask you if you could've bought a good joist, what would you say?




That or buy good joists. PT lumber most of the time has some bad crowns, that's why you over order and don't use bad joists.



Here's your chance to learn. You always frame deck joists/floor joist/ceiling joists/rafters up.

Joe I don't know where you purchase your materials but the crowns of floor joist is not a determine factor of quality. Sure if a 10 foot 2x8 has a 3/4" twist in it or bow you'd be in your rights to not accept it. But price and quality of lumber is mostly by grading. Then again certain mills get a better growth.

I'll say it just one more time This is a cosmetic issue only.
If you have straight or minimal crowns down your deck surface will be more uniform and even.

Just imagine if one joist wanted to, during the curing critical, bow up about 3/4" you just might have a problem, or you just might be a red-neck to borrow Foxworthy line. If it was crowning down it wouldn't be a noticable.

 

[Tinstaafl]

Just imagine if one joist wanted to, during the curing critical, bow up about 3/4" you just might have a problem, or you just might be a red-neck to borrow Foxworthy line. If it was crowning down it wouldn't be a noticable.

It might want to, but it would be fighting long odds to do so. :no:

You have a couple of hundred years' collective experience in this thread telling you that you're mistaken. Might not hurt to rethink things a bit. :thumbsup:

 

[Kent Whitten]

That's not entirely true, yes gravity does affect material behavior but if you read on in Newtons little law you will see that there is an equal but opposite force acting against gravity called a "normal force" this is why gravity doesn't smash you like a pancake through the earth and keeps things in equilibrium.

I put crown down, after many deck examination and building them also I found that here in KY the wood splits far less and looks/last a whole lot longer in this area. When the cup is up then screwed down the fibers in the wood are pulled in a tensile force causing them to split. From what I seen it starts to get really noticeable around the 3 year mark of the decks life.

This is an on going debate and probably will continue but I do cup side down. I maybe completely wrong but I like debates when I get free time. :laughing:

AFAIK, we are talking about JOISTS, not deck boards. Your picture is of deck boards. And that terminology would be called cupping, not crowning. And yes, the cup side is down, but not because of gravity.

This is seriously the most ridiculous debate I have partaken in.

 

[Ayerzee]

Crown up...think about it, when it's loaded the joist is going to deflect downwards. I always thought of it similar to something like a prestressed concrete beam and when it is loaded it while flatten out (But when it's not loaded it bows upwards). They also do this on flatbed trailers, sometimes the beams are bowed up quite a bit and you can see that when they're not holding any weight.

 

[Warren]

Let me just say that I don't build many decks. I think I know what she is referring too though. I have seen decks built with the composite decking that do tend to wave with every crown. Maybe they are a little less noticeable if you crown upside down? Structurally that is a bad idea. Gravity has a way of taking over. We were told a long time ago that sometimes you may have to plane the crown down a little. Its certainly a pain but if your just talking cosmetics, sounds like an option. You could also try what another guy I know suggests. He says why not "grade" the crowns with a 1, 2, or 3 and put the slight crowns near each other, while never having a 1 and a 3 next to each other. There are some things that we have to make the best of. It is nice that you care enough to want to make it look nice. I guess a good illustration would be drywall hung on each side of a wall with the studs crowned. The side with the crown is probably more obvious to the eye.

 

[Joe Carola]

Joe I don't know where you purchase your materials but the crowns of floor joist is not a determine factor of quality.

Crowning the floor joists up are the way you are supposed to build, period! Just use common sense if your not going to follow the way you are supposed to build. The joist is carrying a load that can possibly push the joist down. The joists will deflect after time anyway. If the crown is up, it might push the crown down a little. If the joists are already crowned down they will have a bigger dip in them after time.

So your just framing decks the wrong way for cosmetic reasons and not structural reasons. The crowns should be up and that's the correct way to frame. No other way to say it.

I'll say it just one more time This is a cosmetic issue only.
If you have straight or minimal crowns down your deck surface will be more uniform and even.

Again, you frame decks the wrong way for cosmetic reasons. This means that every single framing in the Country should frame all floor joists with the crown down and so that oak floors should look good cosmetically.

Can't even believe this is a discussion. This is something a DIY'er does.

 

[John Hyatt]

This is pretty silly but one more time.

Pick your joists,install crown up, power plane any humps out of tolerance trying to cut them even with a worm drive wont work near as well. This is standared know how for any real Carpenter with a few dings in his hammer.

Ghesssssssssss JonMon.

 

[TDG]

Uncalled for jab retracted, sorry Patti.

Ok NP. and that's N. PATTIE

 

[loneframer]

This isn't a matter of loads on a deck. Most deck failures have nothing to do with crowning wood joist members and the same goes for wood roofs. Crowning surely wont stop that any clasp.
This is a cosmetic issue. Crowning wood joist in deck construction isn't going to prevent deck failures. You can't use that as an excuse. LOL

Sorry if I misrepresented myself, but I don't recall anywhere in my posts having said that you are doing anything wrong. I merely stated my opinion and my methods. I crown deck joists up, so that the floor doesn't start out with a built-in sag. The only time I have ever crowned joists down is in the case of a loaded cantilever, again, in an attempt to resist gravity.

Crowning in either direction will result in unsatisfactory conditions if the crowns are not consistant. I crown every piece of lumber that goes into a build, not everybody does. I do what I do because it makes things better for me when I move into the next phase of the job. I know the benefits that come with neat, organized and deliberate construction tecniques. That's why, after almost 25 years in the trade, I continue to do it my way.:thumbsup:

 

[Birch]

I've heard tell; "If it's all wrong, it's alright”, cause at least it’s all the same. :laughing: :shifty:

 

[D.Foster]

Up and Out,...First Day stuff....Unless you are using 2' joists then who cares:laughing:
The situation mentioned by loneframer and others, i've never had but,
makes sense.

 

[curapa]

This reminds me of an newbie employee I had that wondered why I did something a certain way and then had a "better way" to suggest :no:.

This is a silly debate. The crown goes up, plain and simple. :thumbsup:

 

[neolitic]

That's not entirely true, yes gravity does affect material behavior but if you read on in Newtons little law you will see that there is an equal but opposite force acting against gravity called a "normal force" this is why gravity doesn't smash you like a pancake through the earth and keeps things in equilibrium.

I put crown down, after many deck examination and building them also I found that here in KY the wood splits far less and looks/last a whole lot longer in this area. When the cup is up then screwed down the fibers in the wood are pulled in a tensile force causing them to split. From what I seen it starts to get really noticeable around the 3 year mark of the decks life.

This is an on going debate and probably will continue but I do cup side down. I maybe completely wrong but I like debates when I get free time. :laughing:

AFAIK, we are talking about JOISTS, not deck boards. Your picture is of deck boards. And that terminology would be called cupping, not crowning. And yes, the cup side is down, but not because of gravity.

This is seriously the most ridiculous debate I have partaken in.

X2 joist have crowns,
deck boards have cup,
and the grain pattern is upside down
on both your deck boards....:shifty: