Best Way to Fix Rafters

quicksandfarmer · Jan 25, 2014

Measure the height of each rafter. Subtract the height of the highest one from all of the others. For each rafter (except the highest), rip a piece of 2x the length of the rafter to the calculated difference. Tack it in place with a couple of siding nails, the purlins will hold it once they are attached. For example, let's say the highest rafter is 6.25 inches. If another one is 6.0 inches, then you rip a slice of 2x that is 0.25 inches thick. I do this all the time to even out old walls where the studs are uneven dimensions. With a table saw it hardly takes any time.

As others have noted, lumber is never perfectly straight, so this just gets you to where you would have been if all the pieces were the same width to begin with.

Following Eddie's suggestion, if I were building something with the bottom of the roof exposed where I cared about the appearance, I would use tongue and groove 2x6's for the sheathing. You can get them with a v-groove on one side, which I would face down. A coat of urethane and it looks like a finished ceiling. Wouldn't really add much cost.

ray66v · Jan 26, 2014

I am not sure if it is necessary to do anything here.

You don't just have inconsistent size to deal with, you also have the natural crowns, bows, and twists in wood working against you. And even if you could get it perfectly flat, it probably won't stay that way over time.

I would use a straight edge to determine the high spots. Carefully mark them, and roughly reduce them using a 9" disc grinder with a 16 or 24 grit carbide disc. Then, finish and carefully fine tune them with a power planer.

I have found a disc grinder to be very effective for removing softer materials quickly, and it seems to be a completely overlooked option in construction.

ustmd · Jan 26, 2014

Hiya,

Thanks for all of the info and advice. To make a long story short, it was easier to replace them all of with boards that were closer in size. With dome more detailed measurements, I discovered that I was more than 1/2" out between the high board and the low board. Almost every one would have to be adjusted.

Luckily, I can still use the boards from the rafters elsewhere in the project (one advantage of buying materials as you go).

I will post more pictures as I get further along. Unfortunately, work and weather are working against me on this project.

lostcause · Jan 26, 2014

metal roofing has some great advantages over shingles, but you have encountered what i see as the biggest drawback: it's not visually forgiving to framing variations. i've seen some older roofs redone in metal that really made the sag show. i'm an architectural tab shingle man for those ones. they help hide the sag that can come with age

ETpilot · Jan 27, 2014

A little off topic. I opened OP pictures and both opened upside down on my iPad. On another forum I posted pictures and both thumbnails posted upside down. Not sure why. Anyone know why this happens and how to fix? Thanks.