Wood has a stronger compression yeild strength then tensile, I put crown side down.

 

I've been taught when framing a deck to put whatever crown in the lumber down unless its a radical crown then cut one surface straight and put the straight cut up. Is that what you all do it?
N.Pattie

The only time I've ever seen crown down is when there is a cantilever over 2'. Typically, crown goes up otherwise you're building in a pre-existing sag in the joists. Gravity will take some, if not all, of the crown out when the weight of the decking is added.

Now, about that avatar....

 

Yup crown up here too. Unless like lone said its a cantilever or a special situation.




Dave

 

I started as a framer & was taught to crown everything up, studs in walls, ceiling joist, & rafters. So I always crown the joist up, never heard of crowns down. Any board with a bad crown I will pop a line end to end & cut it.

What's the logic with crowning joist down because it's a deck?

 

Any floor has always been crown up. If it's an extreme crown it goes back to the yard. I order extras so they can be culled as I'm using them. Some of them can be cut for bridging, but if it's extreme it's tough to get a 90 on them.

 

Unless this is some kind of a jersey joke the crown always goes up. J.

 

Unless this is some kind of a jersey joke the crown always goes up. J.

Seriously, I've been on projects that had roof load and second floor load on 28" cantilevers. It was common practice to crown upside down in that scenario.

 

Crown up.
Have you been back to look at
your decks later on?

 

Crown up.
Have you been back to look at
your decks later on?

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.

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.
Its more noticeable with composites if they are screwed from the expose face.
Once we use a hidden system it doesn't show.
12" centers don't help it just seems to get worst.
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.

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.

 

Loneframer has it right on the money :thumbsup:

 

Ditto, crown up. And I have never even switched that for a cantilever.

 

Can't believe this is even debatable. Crown UP unless an unusual cantilever. We have been instructed by engineers to reverse it in unusual circumstances. I have seen 16' joists that started out with a 1/4" crown, weather to a 3/4" crown. Imagine if that was crowned down with a heavy table above it.

 

Crown up.

 

i'm speechless

 

Dont 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.

 

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

 

Uncalled for jab retracted, sorry Patti.

 

Ok NP. and that's N. PATTIE

 

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.

 

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.

 

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

Why?

 

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.

 

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.

 

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.

 

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

 

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.

 

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:

 

OK folks, move along. Nothing to see here.:blink::blink::blink:

 

Neo=Epic Beard Man???

http://www.youtube.com/watch?v=wF6W3206l70

 

Crown up.
This may have been the first thing I learned.

 

Can someone tell me why glue lams usually come with a crown, and they say to put it up? Must be a mistake, right.

By the way, "The Epic Beardman" is from my area and I 've seen many clips of this confrontation. It was great. I'm not sure if it was mentioned, but earlier, he was at a ball game and became unruly. The cops had to use a stun gun on him. There are video's of that as well.

 

Yet another YouTubian reference
that was lost on me...:cheesygri