Best Way to Fix Rafters

[ustmd]

So I am building an outdoor "kitchen"--really a shade and rain structure for the grill. I am using rough cut Western Red Cedar--some purchased new, some reused from other projects.

I am putting a metal roof on part of the structure and that is where I made a rookie mistake. The rafters are 2 x 6. After I got them up, toe nailed in and hurricane clips installed, I realized that the rafters vary +/- 3/16 to 1/4" in width. The differences are enough that if I just put the roof up "as is" the wavy roof line will, to paraphrase my mother, stick out like a women of questionable virtue in a house of worship.

So here is my question, do I take the rafters down and rip them to the same width or just try to shim the purlins to correct for the unevenness?

Taking the rafters down, means pulling the galvanized, ring shank that I used for the toe nails and taking off the hurricane clips. NOrmally not an issue, but since this is cedar, it is pretty soft and most likely the rafters wold take a beating.

Shimming the purlins, means keeping all of the purlins level in two planes (across the rafters for each purlin and from purlin to purlin) which may mean its own set hassles. This is my first time installing purlins, so this may be a normal situation

Thoughts, feedback? Which way would you go?

Here a few pictures of the current build.

 

[Raspy]

Could you just plane the higher ones to match the rest, with a power planer. I'm assuming you mean they are too high, rather than too thick, in other words the "6" dimension varies. Taking them down seems like a lot of work and a lot of damage.

 

[smstonypoint]

Shimming the purlins, means keeping all of the purlins level in two planes (across the rafters for each purlin and from purlin to purlin) which may mean its own set hassles. This is my first time installing purlins, so this may be a normal situation

I am no expert, but I would try the shimming route. It seems to me that you could use string lines to maintain level without too much hassle.

Steve

 

[mehig]

I would lay purlins across the top and simply notch out the rafters so the purlins are straight and level

 

[BuilderML]

When working with regular 2x lumber the crown alone will be beyond 1/4" in height some times. In your case forget taking them down. Do like listed above plane down the high spots and/or shim the low spots. If your thinking taking them down to run them on the table saw which will give you the same result as just taking the planer to them without having to remove them. You could also find your two lowest rafters and use that to set your height and notch the high ones to set your purlins. By no means do you need to make them exact to each other. Lay a straight edge across all of them to see how bad they really are and adjust from there, some of the ones you measure thicker may not be that bad due to the crown of others. Start at the top with your straight edge and work your way down. You have a few options to "blend" everything in.
Have fun.

 

[EddieWalker]

I would get a straight edge on top of the rafters and either notch, sand or shave them in place, depending on how far I needed to go.

Seems like kind of a shame to have to see the underside of the metal through the purlins with that nice cedar you are using. Have you considered a wood ceiling and then laying 30 pound felt paper on it and installing the metal on top? I did one where I just put 2x8's across my rafters as tight as I could get them, then plywood on top of the 2x8's with screws going through the plywood, into the 2x8's. Then I shingled the roof. The final result was very nice from below and above.

Eddie

 

[EddieWalker]

I would get a straight edge on top of the rafters and either notch, sand or shave them in place, depending on how far I needed to go.

Seems like kind of a shame to have to see the underside of the metal through the purlins with that nice cedar you are using. Have you considered a wood ceiling and then laying 30 pound felt paper on it and installing the metal on top? I did one where I just put 2x8's across my rafters as tight as I could get them, then plywood on top of the 2x8's with screws going through the plywood, into the 2x8's. Then I shingled the roof. The final result was very nice from below and above.

Eddie

 

[Eyecatcher]

I'd just go ahead and put the metal on. I don't think you'll notice that small difference from the ground. If you do, you're pretty picky. Women of questionable virtue need church too!!!

 

[paulwestski]

3x on the notching
Standard procedure
When ever you cut rafters you should cut the first one, test it and then use it for the pattern.
Always keep the pattern flush with the top of the rafters.

 

[HillStreet]

Use a string line across the peak and across the eave on each side. Mark heights to the string line, then use a chalk line on the high rafters peak to eave. Either power plane or use a sawzall to remove the higher ones.

 

[quicksandfarmer]

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]

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]

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]

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]

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.

 

[bobhaub]

Same thing here, but on an XP desktop. First time that's ever happened to me.

A little off topic. I opened OP pictures and both opened upside down on my iPad.