# Deck Joist Unevenness - Sand or Plane?



## ShatpestJim (May 8, 2018)

I've gotten past my uneven deck post problem from a week ago. I've actually gotten my new deck to the point where we are almost ready to start laying decking. I just need to install my hurricane ties (and wait for my Trex to arrive). Considering that this is my first deck-building project, everything went surprisingly well.

The only problem is that one of my three beams was very slightly higher than the other two (apparently). Where the 2x6 joists end on that one side (12 ft wide), I have several joists whose ends do not match up perfectly with the 2x8 ribbon board. The worst one is nearly 1/4" taller; several others are more like 1/8"-3/16". I definitely want to try to correct this before I start laying Trex. 

What is my best bet - sanding or planing? I've been doing a lot of checking online and people seem pretty evenly split. I do not own a belt sander. But I was thinking about buying a cheap one at Harbor Freight for $35 and getting some 50 grit belts for it. Then again, Harbor sells an electric planer for a few dollars more (still less than $40). I've read that it is best not to sand PT because of the toxicity. What will be easiest and/or do the best job? The deck is 16' long so I have eleven joists to do. I'm thinking that this would be a lot of sanding. I have never used an electric wood plane before, but I am leaning in that direction. Oddly, when I went to assemble the frame, my two end joists mated up perfectly.


----------



## Marson (Jan 26, 2018)

Is it too late to reset the joists? I would typically line up the top of the joists, even if involved notching the bottom where they sit in a joist hangar. And why are they uneven? Treated lumber is typically swollen and will shrink back to it's original dimension when it dries. 



Otherwise, definitely a power planer would be the way to go IMO.


----------



## SPS-1 (Oct 21, 2008)

Sanding is for smoothing wood. If you have any significant amount of material to remove, planning would be a much faster process. Don't even need a power plane --- a hand plane will do it too.

I also would be worried about the toxic dust.


----------



## de-nagorg (Feb 23, 2014)

Sanding, cutting, plane-ing, anything that is done to shape PT will remove a layer of treatment, and might cause that spot to prematurely rot before another spot.

As suggested re-set these offending joists.

And always " Crown up."

This will insure a virtual sag free deck.

Look each joist over for any sign of a bow this indicates it's crown, also look at the growth rings, and overall condition of the joist, assemble with all crowns in the same direction "up".

After resetting, you might find all are within an eighth of an inch or better.

Good choice of TREX, it is forgiving of slight variances, and is a long lasting product.

I have TREX on my deck for 25+ years now and it still looks great.


ED


----------



## ShatpestJim (May 8, 2018)

Thanks, Marson & SPS-1!

Again, I am a newbie and this is the first project like this that I have undertaken. So far, the project has turned out about 95% to my satisfaction. I'm actually rather proud of it. 

As I mentioned in my original post, when I attached my end joists to the ribbon boards, all four corners matched up beautifully. I got my diagonals square to within 1/8". I was thrilled. Then when I went to set my joists, I noticed that, on the one side, they weren't dead even with the top of the ribbon. I made sure that all of my lumber was installed crown up. So it is possible (I guess) that that one beam is bowed a little more than the other two. But there's only one joist that is really bad - about 1/4". The others are less. A couple of the joists I probably wouldn't even mess with. But I figure that if I am going to plane the problem joists, I'll get them all perfect.

But thanks again very much for the responses - I greatly appreciate them!


----------



## Mike Milam (Mar 3, 2017)

Well, if it's just the one and it's not a great big job to remove, take the offending joist back and get a straighter one. Personally, I would plane it.


----------



## ShatpestJim (May 8, 2018)

It involves most of the joists (7 of 11), not just one. This is what led me to believe that the beam on that side may have been slightly taller than the other two. I was really meticulous about getting my posts lined up and level parallel to the beams; a little less so across. But it is very strange to me that, as I mentioned, my end joists lined up almost perfectly with both rim joists (or are they called ribbon boards? I've seen both terms used). I didn't notice a problem until I started hanging the inside joists.


----------



## de-nagorg (Feb 23, 2014)

Is it possible that the offending joists, hangers are a bit off in being the same distance from the edge? 

May be just a RCH high.


ED


----------



## Nealtw (Jun 22, 2017)

Treated lumber is usually wet and not all the same. If all the hangers were level, expect all to dry to the same level.
Mills do not cut a variety of lumber and all are about the same moisture when they are cut. If when all is dry and there is a high one, you crawl under and lower the hanger.


----------



## ShatpestJim (May 8, 2018)

I'm sure not the expert. That's why I posted here. But I am 90 percent certain that it is the beam that is causing the problem. After reading some of the responses, I went out today and popped the nails out of the hanger on the worst one to see if I could get the end of the joist to go down any farther. It is in there rather snugly, but I tapped it with a mallet both left and right then downward just to make sure that it wasn't hanging up on something. It is hanging up - on the beam.

Perhaps the beam is a bit more "crowned" than normal, I can't tell. But as I mentioned, when I constructed the frame, the end joists and the rim joists snugged up to one another almost perfectly - level as well as nice and square. But it seems that the two worst ones are near the middle - in other words, joists #5 & #8 out of eleven. The beam seated on the three posts nicely when I set it in place. So it is not as though the middle post was taller than the other two. I would have noticed that and corrected it.

Short of disassembling everything and removing the flashing from the dual-2x8 beam to check for level, I am inclined to go with the $38 electric planer from Harbor Freight. Even if I were to take it all apart, I'm not sure if I could do anything about it. It's a little worse than I originally thought; the two worst ones are about 5/16" high. A couple of others are about 3/16". The rest are 1/8" or less.


----------



## Nealtw (Jun 22, 2017)

Beam, 2 or 3 ply 2x? If you laminated them together did the crown line up on them and how many nails did you use to laminate them?


----------



## ShatpestJim (May 8, 2018)

Nealtw said:


> Beam, 2 or 3 ply 2x? If you laminated them together did the crown line up on them and how many nails did you use to laminate them?


2-ply, Neal. 2x8's. They seemed to mate up really nicely. I did the recommended sets of three nails (12d 3.25") every 16 inches on alternating sides nailed in opposite directions.

I went through every piece of lumber before I started, noted crowns, and marked each piece with an up arrow using a magic marker.

I just posted a photo to my album if anyone is interested in seeing. Joist #4 is in the foreground. #5 and #8 are the worst ones.


----------



## Nealtw (Jun 22, 2017)

ShatpestJim said:


> 2-ply, Neal. 2x8's. They seemed to mate up really nicely. I did the recommended sets of three nails (12d 3.25") every 16 inches on alternating sides nailed in opposite directions.
> 
> I went through every piece of lumber before I started, noted crowns, and marked each piece with an up arrow using a magic marker.
> 
> I just posted a photo to my album if anyone is interested in seeing. Joist #4 is in the foreground. #5 and #8 are the worst ones.


 Feel the top they can be drying art different rates and strange things can happen while joists dry, crowns can disappear or get more pronounced. Sometimes they just get ugly and I have changed out joists on occasion.


----------



## ChuckF. (Aug 25, 2013)

Hard to tell without pictures, but I would want to see if I could move the joists that are low, up to meet the highest one. Easiest way to do that is to pound wedges between the bottom of the hanger and the joist, if you used hangers.

If you are planning to use some kind of flashing on the top of all the joists, there's opportunity there as well to add some height.


----------



## mathmonger (Dec 27, 2012)

I recently had to change out a few boards, but the new boards were a little thicker than the old ones. There wasn't really room to work a plane in that little 6 inch wide hole where I had taken the old board out. So I put a 36 grit disc on a grinder and hogged out a little material from the bottom of the new boards. Maybe not the prettiest solution, but it worked.


----------



## Marson (Jan 26, 2018)

Ok, so the beam has a hump in it. Nail a small 2x block on the top of the joists on either end of the beam, and pull a mason's string between the blocks over the beam. Then go along with a third 2x block and get a visual of how low the ends are. That is if they are dead on, your third block will just slide under the string. Then cut some shims from treated, and shim those end joists up so they are as high as the highest joist. Then go along and check the rest, shimming if you have to. It's more accurate, faster, and you won't have to buy a Harbor Freight power planer.


----------



## ShatpestJim (May 8, 2018)

The $38 electric planer from Harbor Freight did the trick. That just might be the best forty bucks that I've ever spent. I have uploaded before and after photos to my album. 

Ready to put some Trex down now. As soon as it arrives.

Thanks to everyone for your responses. The assistance is greatly appreciated.


----------



## Mike Milam (Mar 3, 2017)

mathmonger said:


> I recently had to change out a few boards, but the new boards were a little thicker than the old ones. There wasn't really room to work a plane in that little 6 inch wide hole where I had taken the old board out. So I put a 36 grit disc on a grinder and hogged out a little material from the bottom of the new boards. Maybe not the prettiest solution, but it worked.


I did that on one joist in my deck when I built it. Dimensional lumber is always dimensionally the same.


----------

