I will be replacing the ceiling joists in my attic renovation. Before I started my demolition, I believed that all the joists were 1x6. It seems that only some are, and I believe that they were installed during construction and not when the attic was originally finished. The are also not on every rafter and I think they may be rafter ties. Would it be bad practice for me to knock out all of the joists at once and replace them with 2x6 material? Or should I remove each rafter tie one at a time and replace as I go? I was hoping to do the former so I could set a ceiling joist at each end of the room and then run a string line to keep everything lined up.

This isn't a recent picture, but gives you an idea of what the walls and ceiling look like: IMG_0068 | Flickr - Photo Sharing!

 

Terminology....rafter or collar ties, not joists, although they will become joists in use. I would replace them with 2x lumber for rigidity and to give you something to nail your ceiling to. Install on every rafter. Replace one or a few at a time to maintain rigidity.

 

Yoinks. After further review, the items in question are collar ties, not rafter ties.

Collar Ties vs. Rafter Ties - InterNACHI

 

To help set and maintain level, you can stretch a couple of strings 2" or so below the bottom edge of your new collar ties and measure up. One or two at a time, as Larry suggested.

 

That's not really going to make installation much easier. I think I may just split the room in half for my replacements. It's not very long.

 

Half's good. Just don't take them all down at once. I'd take them down one at a time and replace them all at once, using the string method to keep them aligned.

 

Ya know what, I took a few down and put a few back up. I decided to use a level to set them in place. It seemed like the string method was going to be a bit more of a pain than I had originally thought. We'll see how it works out. Hopefully it won't bite me in the end.

 

Level in one direction may not be level across the span. Remember you have to install sheetrock on a level surface in both directions. That is why the string method was suggested.

 

Yep Yep. Levelling them one at a time will make for a very wavy inside corner. Use the stringline.

 

Yeah. I took one of the old ones off. Measured from my floor for the height. Placed the joist on the two marks. Secured one end and used the level to secure the other. Then I moved on to the next one. I made sure each end of the next joist was level with the end of the one I had just secured. So far, so good.

I will double check my results before I put the drywall up.

 

Now your ceiling will be level with the floor. Can be good........if the floor is level. String test b4 you sheetrock.

 

UGH! You are not understanding. I measured off the floor for ONE point! I used the level to set the joist level. How else do I set my ceiling height if I don't measure off the floor?

Even if I got the new joists perfect, the rafters are all out of wack. I don't stand a chance to get a crisp line in the drywall. Don't worry, I will be double checking everything so I have a reasonable y flat ceiling.

 

We got what you did... and getting things "perfect" is still possible at this point in the game- you would put those 2 chalk lines parallel with each other... say 32" apart. (so that your top drywall rip will be the same width) If some of the rafters are out of whack and don't touch the line, they would need to be shimmed down (tapered shim) to meet the line before drywall goes on. It's not tough to do, but it's all based on the idea that your eye is going to want to see a nice crisp straight line on the ceiling, not one that's necessarily "level" every which way, although both would be nice.

 

After I put the first 3 or so up with the level, I decided to go to the other end of the room and put a joist up so I could send a string line down. I couldn't go all the way down, so the last two I used a level for. All the others in between, I set to the string. Worked out well.

 

That's exactly what we were suggesting! Glad you got it worked out to your satisfaction, and thanks for the feedback.