Just finished installing some rafters on a simple gable roof and we stupidly installed the ridge with the crown down. Much as I hate to backtrack, I’m thinking we really should make it right before proceeding further (it may mean the sawzall since the rafters were nailed off–I’m hoping we might get away with keeping the birdsmouths fastened to the walls and just tacking the unfastened rafters together while we flip the ridge crown up and reinstall).
Since I don’t have any experience framing roofs, I just wanted to check with some of you pros and see if I’m making too big a deal out of it. This is a toolshed, not a house–a little rough is OK, but I don’t want to be looking at a sagging roofline in ten years. The pitch is 12:12, span wall-to-wall is 12 feet, rafters are 2×6 24″ o.c., ridge is 2×8. Roof will be strapped with 1×6 and galvalume (Max-rib) on top of that. Little or no snow should stick on it.
The crown’s not too bad, but if you sight down the ridge you can see a slight dip. I’d guess maybe a half inch or so total, maybe 3/4.
Opinions? I’m ready to fix this, but time is short, I’m anxious to get a roof on, and I don’t want to be unecessarily fussy.
Replies
How many rafters do you have nailed in and how bad is the crown?
If you crowned the ridge before you put it up, and decided it was acceptable, I'm sure it'll be fine upside down, especially on a tool shed.
1/2" - 3/4" in how many feet of lenght? If it's aournd 10 or 12' or more, I say leave it. Shouldn't get any worse as long as you have ceiling joists that are parralel to and nailed to the rafters which in turn are tieying the opposite wall cap plates together.
Edited 11/13/2005 6:00 pm ET by Matt
A shed huh? Can you see the crown from the ground? Even if you can notice it just a bit, I'd say leave it. Minor things like that often look worse to you because you've been staring at it and thinking about it for however many days you've been working on the shed. Anyone else would never notice and you'll probably forget about it by the time the thing is finished. If it sticks out like a big red azz from the ground a 10' away or so, I'd say fix it.... but if only you can see it when you really look for it.... leave it alone.
Thanks for replies all.Ridge is 24' long--the piece in question is only 14 feet--runs from the gable end to the 8th set of rafters.I don't really notice it from the ground. To be honest, if it remains stable over time it's not going to bother me. If it starts to sag a little more over the years, I'll kick myself for not dealing with it when I had the chance. I don't have enough experience with these things to know if it'll sag or not.Would collar ties be smart? Basically the space is going to be used for storing lumber, I was planning on running 2x6 joists across at each rafter.All rafters are nailed in.
Edited 11/13/2005 7:49 pm ET by Megunticook
If your roof is designed and framed properly you don't have a thing to worry about.
Ridgelines sag because a wall has blown out... not because of a bad ridge. You can frame a roof with no ridgeboard at all and have it stay put for years and years. Does your frame have wall ties or ceiling joists connecting one wall to another.... forming the other leg of an "A"?
Collar ties go in the upper third of the roof and won't do anything to help with a sagging ridge or bowed walls. "Wall ties" or ceiling joists in the lower third will stop your walls from blowing out and prevent your ridge from sagging.
If your ridge sags in the future..... it wasn't because of the direction you crowned it.
Ah, I feel better already.Where the ridge board dips a bit, the rafters in that spot stand a bit proud of the ridgeboard top, so I suppose since they're what'll be supporting the roof the dip won't show in the exterior.At this point I've only installed 1 joist tying the walls together in the center. The walls run perfectly straight, checked with string lines. I was planning on installing more joists, probably at every rafter (24" o.c.). Can I leave a few out to permit easier access to the open "loft" or would that risk having the walls bow out?Should I not bother with collar ties then? I hear differing opinions on that one.
You should only need two, maybe three collar ties. I have a roof much bigger roof than that (12/12 and 25' between walls) and it's only got a collar tie every 4 feet (it was engineered for NC).
MERC.
If he's looking to prevent future sagging, wouldn't rafter ties be in order as opposed to collar ties? I always thought that collar ties were to prevent the roof from opening up in the event of high winds (as in the rafters coming loos from the ridge & opening outward not rafters coming loose from the top plate of the wall.
I can't tell if their are ceiling joists from the picture, but if the rafters are tied to the ceiling joists, it should be fine the way it is.
Not sure what, if any, is the distinction between "collar ties" and "rafter ties". I've always considered any kind of tie on the upper third of rafters essentially useless, unless you have an open building and live in a tornado zone. And even then I think it only assures that your roof will be blown away as one piece instead of blown apart into little pieces.
I think the most important thing is to keep the walls from spreading. And the best way to do that is some kind of tie as low down as possible on the rafters (that is what I call a collar tie).
I think the original poster is interested in leaving out some of the ceiling joists (which would be collar ties) so he can have reasonable access to the moderately useful storage above. With the two gable end walls, I think he can split the remaining space up with two or three collar ties/ceiling joists, though he would probably want more for storage purposes.
MERC.
upper third = collar tie
lower third = rafter tie
That's the way I understand it too.
I wouldnt agree that only three collars ties are necessary. That puts them at every 6'.
Everyother rafter is code here in Michigan.
I would agree that only 3 "wall ties" are needed. I call them wall ties because they sit on the wall and tie the walls together and keep them from spreading. I don't agree that wall ties are okay on the bottom third of the rafters though. I suppose they work somewhat okay there, but they do tend to sag the rafter. I know that from experience.
blue
If it was sagged, and your rafters fall with it......the wall line might be bowed out-how much, can't say. If the walls are spread, cut loose the nails on the rafters/ridge, pull the walls in straight, add the joists and renail the rafters up above the sag (straight ridge as far as the rafters are concerned).
Then again, it is a shed.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time
I often tell my clients: everyone's roof is perfectly flat except for your own....
Don't sweat it, and when you have some time for a slow walk, look closely at everyone else's roofs.
You'll feel much better.
I work with a guy that we still call Crown Down Brown. He made that mistake only once.
If you make sure it wont sag more, then relax.
OK, just for the hell of it I'm posting a shot. Anybody see the dip in the ridge?
If not, I guess I shouldn't be too worried.
View Image
If it's on the right, then I see it........or guessed good.
You said your walls are straight and the couple rafters run high on the sagged ridge, so add your joists and roof it.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time
If it's on the right, then I see it........or guessed good
Well I guess it's not too obvious...low point in the dip is 5th rafter from the left. Runs from about 3-7. Of course the camera lens distorts things a tad, so it's kind of hard to judge by a photo.
In any case, the consensus seems to be don't worry about, just proceed with the job--which is just what I was hoping to hear.
In the picture I don;t see any joists that are parallel to the rafters, that go from the top plate of one exterior wall to the top plate of the opposing exterior wall. I got the impression from what you wrote a couple of posts ago that you are going to add ceiling joists? If you do add those joists, then your ridge is a non-structural ridge board. Nothing to worry about, as the joists will keep the walls from spreading.If you're not going to add those joists, then the load of the roof will eventually cause your exterior walls to spread and your ridge to sag. With your ridge board being two pieces (I took from a previous post that you used two pieces, one 14' and one 10'), it's not structural, crown up or crown down.With no joists, to prevent that spread and sag you'd need a structural ridge OR you'd need to add the rafter ties that the boys were yapping about in previous posts.
Go ahead and install the collar ties on every other pair of rafters. Shove the collar tie all the way up to the bottom of the ridge, meaning that they would essentially be scraps of wood around 16" long. You probably have that much trash laying around unless the DW has been around :helping" :-) the cost/work is so little, I say why not? They will not hurt.
As far as leaving out ceiling joists, I'd put as many of them in as possible, and the ones toward the center are more important than the ones near the gable ends.
BTW - Most people put the ceiling joists in first so they have a place to stand while they are installing the rafters...
PS: no gable end overhangs (barge boards)? Not one of my favorite looks... not to mention weather protection...
Edited 11/14/2005 7:45 pm ET by Matt
BTW - Most people put the ceiling joists in first so they have a place to stand while they are installing the rafters...
Good point, next time I'll do it that way.
PS: no gable end overhangs (barge boards)? Not one of my favorite looks... not to mention weather protection...
I agree. Gable ends will have 18" overhang to match eaves. The reason there aren't any rafter tails in the photo is because on that side I'm building a 6:12 shed roof off the side to store firewood beneath.
Edited 11/14/2005 9:03 pm ET by Megunticook
Can't see it from my house. Just kidding, Looks good, you are not building a piano.
;-)
Leave it be.