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Rickant
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# Posted: 18 Feb 2018 18:28 - Edited by: Rickant
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We have an addition on the cabin that we'd like to finish. I took some pics as how it is done looks odd to me although I am fairly certain that it was done to code. A couple things. One I raised before is insulating the roof. The second thing that I find odd is how it is attached. It is built with a ridge board but I don't see that the peak is tied in?
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ICC
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# Posted: 18 Feb 2018 19:27 - Edited by: ICC
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Unless they used metal straps over the peak on the upper rafter surface there are no collar tie substitutes, nor any collar ties. . I'll bet they never used any straps.
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rockies
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# Posted: 18 Feb 2018 19:49
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Wow, that looks........terrible. It appears that the ridge beam rests against the original exterior siding on the left and sits on top of a 2x4 nailed to the wall (when the beam should go into the wall and rest on a post). The right side of the ridge beam seems to butt up against the post rather than rest on top of it (or does the ridge beam rest on two shorter studs flanked by two longer studs to "lock" it into place)?
I don't know how you are expected to insulate that roof. Cold air will blow up under the edge of the metal roof at the eave and over the top of any batt insulation you put there (never mind having a proper vent space running from eave to ridge over the insulation). There should have been sheathing on top of the rafters with an underlayment on top of that before the metal roofing was applied.
The spacing of your rafters looks like they are 24" on center and you should definitely have joist hangers (Good luck walking across that roof should you ever have to). I think you'll have to cut away the siding below the ridge beam and install a support post down to structure to hold up that end of the beam. You'll also have to remove the metal roofing and install proper OSB or plywood sheathing if you want to insulate properly (and that will require you to look into ridge and eave vents as well).
I think your builder thought you wanted an enclosed unheated space rather than a future heated room because that's basically what you've got.
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ICC
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# Posted: 18 Feb 2018 20:09
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The unanswered question is whether or not the ridge member is supposed to be a ridge board or a ridge beam.
As a ridge board it is unnecessarily large with two layers. IF a ridge board the non-support at either end does not matter so much. The deficiency there would be the total absence of rafter ties across the wall tops and tieing the rafter tails together.
As a ridge beam it is hugely deficient as it has virtually no real support at either end. As rockies points out the outside end does not seem to be supported at all. Maybe a few nails? There does seem to be a good sized column in the outer wall if the ridge is meant to be a beam. However there is no visible means of the beam bearing on the post. Code would be the beam sitting on a post at that end. At the house end a load distributing post and beam setup, to carry the load down and around the window is needed. And that would normally be built back into the house wall or as a free standing load carrying frame outside the wall/siding.
Was this just built; you paid someone for the work? Or was this on a cabin you bought? There may be legal recourse in either case, but that may be more hassle than it is worth.
Insulating is an issue as rockies pointed out. All in all this appears to be a poorly designed and executed effort. Code? No way.
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jtamlin
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# Posted: 18 Feb 2018 21:30
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Ok, let's not panic. It hasn't fallen down yet, and isn't likely going to. I agree the 2x4 scabbed onto the side of the existing cabin isn't ideal but I have seen worse, probably even paid a guy and had worse! Overall it looks overbuilt, not to code, but lots of wood there. The strapping under the tin looks to be 2x4. No problem walking on this roof. Moisture is going to be the problem, moist air from inside will condense on the tin, and voila! Raining inside your cabin! The kids will love it! My advice would be to not finish this right away. Invite a buddy out, preferably a guy who is handy, a contractor type guy. Let him have a look, and reevaluate based on some conversation. Above all don't panic, and don't get bummed out. This is a small bump in the road.
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Rickant
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# Posted: 19 Feb 2018 05:46
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Thanks. It was there when we bought it and has the water pump in the room and seems to have been used as storage. It looks to me that it is a ridge board setup. So I agree missing callar ties for sure. I will have to have someone take a look before doing anything. I’m prett sure that I have a signed off permit in the stacks on paperwork. Regardless it looks odd so I will have someone check it out some time!
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Rickant
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# Posted: 19 Feb 2018 08:21
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Funny enough last year we had tried to buy a property. After a very long drawn out process due to divorcing owners and other circumstances we finally agreed on a price. When went to sign our final offer the roof on the addition had collapsed. The walls had been pushed out and the roof was inside to addition basically collapsed as a unit. It was a shallow roof and it as cathedral inside, so no collar ties, rafter ties, or ceiling joists. We had a lot of snow last year and nobody had cleared it. So I have seen the carnage first hand! Needless to say I will look at rafter ties or ceiling joists. How long can ceiling joists be? Do you just join them like a beam if they are long? I think the room is 14 ft long to the walls of the end of the rafters...
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toyota_mdt_tech
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# Posted: 19 Feb 2018 10:33
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OK, couldnt one just add rafter and collar ties, then it becomes a ridge board and insulate the area at the rafter ties (8 foot ceiling) and add adequate ventilation above?
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Rickant
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# Posted: 19 Feb 2018 11:19
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That’s what I’m hoping. Or ceiling joists .
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toyota_mdt_tech
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# Posted: 19 Feb 2018 14:54 - Edited by: toyota_mdt_tech
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Quoting: Rickant Or ceiling joists
Those are rafter ties, lay them in there, top plate to top plate, slide up against the side of the rafters, 4 nails in each end on the side of the rafter. Collar ties, top 1/3 area, one every 4 feet, but one can certainly do everyone of the rafters (HD)
Then insulate the ceiling and structure issue resolved.
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Rickant
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# Posted: 19 Feb 2018 14:57
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Thanks Toyota, sounds like I have a plan now!
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ICC
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# Posted: 19 Feb 2018 15:46
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Rafter ties and ceiling joists are 2 different things, BUT one can do both jobs if sized and nailed correctly. It's obvious from the pictures that what is needed there are rafter ties, to keep the side walls from bowing out under the weight of the roof loads.
Question: what are your snow loads? The ground snow load for your area will determine how many nails of what size are required to make a secure connection between the rafters and the rafter ties. The pitch of the roof also enters into this as does the spacing of the rafters and ties. Table R802.5.1(9) of the IRC lists the number and diameter of nails needed for different pitches, spacing and snow loads.
Here's a link.
There are many tables there, some will help with determining if you need 2x4 or 2x6; that depends in part on the span distance.
To the question of, can you splice 2x's to make a rafter tie, you can but one piece is better. If the member is just a rafter tie and not holding a ceiling the joint can be anywhere along the length as long as the right nail count is used. The nail count required sometimes means it is better to up the size of the 2x, in order to get all the nails needed into good wood. The splice nail count would be the same as the nail count required for the rafter to rafter tie connection, on both sides of the splice if the splice has butt ends with a scab piece. IF the rafter tie will also be used for mounting a ceiling to, or used to support insulation then any splice must be over a supporting wall or beam. So it is easier in most cases to use a one piece rafter tie.
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Rickant
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# Posted: 19 Feb 2018 16:10
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More great info. How long can a rafter tie be in one piece? Or how long can you get one?
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ICC
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# Posted: 19 Feb 2018 18:13
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A 16 feet 2x4, 6, 8, 10, 12 is easy where I am, 20 ft on special order
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rockies
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# Posted: 19 Feb 2018 20:14 - Edited by: rockies
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What exactly do you hope to finish the room into? You say it has a water pump in there now. Is there any danger of it freezing in winter? Are you planning on living there all year and hope to make it a 4 season utility room or perhaps open it up to the heated interior?
Each option demands different levels of insulation, vapor protection and venting. The ceiling joists would be a better decision than rafter ties since all the insulation could then rest on top of the new lower ceiling and the area above would become an unheated "attic" space.
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Rickant
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# Posted: 20 Feb 2018 05:15 - Edited by: Rickant
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We are hoping to remove the water pump and turn it into a bedroom. Three season.
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neckless
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# Posted: 21 Feb 2018 12:45
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just wondering if the first rafter is lagged to existing over hang
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Rickant
Member
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# Posted: 21 Feb 2018 16:13
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Yeah I wondered the same, will have to check that out
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Rickant
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# Posted: 9 Jun 2018 06:21 - Edited by: Rickant
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@ICC
Re-looking at this after reading the other roof structure thread. So, I looked at the snow load and it is 50psf. I recall 16" oc rafters. We will not use the attic space for living, I suppose it's possible we might want to store some things there, but unlikely. So if i am correct, I could use a 2x8 SS (may need 2x10) (I hAve to remeasure the span) I think it is 14-16ft. Celing joist that will function as a rafter tie with 5 nails at the heel (16d). Nail from the rafter side to the ceiling joist. Do the the filing joists get tie-nailed to the top plates or just nailed to the rafters?
Also, basic question - SS lumber is the lumber stamped as select?
Thanks!
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ICC
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# Posted: 11 Jun 2018 13:52
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50 PSF of snow is a pretty good amount.
SS will be stamped as such, either SS or SEL STR or something along those lines. There are a few websites that describe the grades and some have stamp pictures. Stamps vary from mill to mill but must contain the same information. SS will also be obvious from the price tags and how nice it looks. Not all that common. Typical is #2 with some #1 every so often.
Number of nails at heel joints varies with load of course but also with pitch of the rafters. Table 802.5.1(9) has that info. For roof spans that fall between the listed lengths you can interpolate. EG... if the table spans are 12 ft and 20 ft and 12 ft=4 nails and 20 ft = 6 nails, AND you have 15 foot span use 5 nails.
Ceiling joists / rafter ties are nailed to the top plate according to Table 602.3(1) as well as being nailed to the rafter according to the table in chapter 8.
For attic space NOT used for storage we use a LL of 10 PSF, attics used for storage we use 20 PSF when reading tables or using calculators.
Hope that helps.
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Rickant
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# Posted: 23 Jul 2018 07:22 - Edited by: Rickant
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Hi all... So I am trying to pull together a plan for correcting some issues with this room. There are no signs of problems (although I know there is some poorly executed structure) but we'd ideally like to convert this space into a bedroom. First assumption is that since the roof beam is not supported at either end (serious waste of lumber!) then it becomes a ridge board. Roof load is Carried by 2 walls rather than the beam. I will add ceiling joists to ensure walls don't push out. Correct?
Another issue (I think) that I discovered is the floor framing. So it is framed using 2x6 (in retrospect I eyeballed it so will double check that they aren't 2x8, still either way not ideal). One end is attached to the cabin with joist hangers to a ledger board, other end sIt's on a beam (8x8 I think). Span is about 8 feet. I don't see any other structure so that means the two end walls that carry the load of the roof are sitting on 2x6. The outside 2x6s are doubled, but I assume the outside ones in the pairs are rim joists and dont carry any load? How would I fix is situation ? Sister it with? Since the 2x6 sits on a beam if I use bigger lumber to sister, it wouldn't be able to rest on the beam. 
The room is 8x16 and is part of a Three season cabin. I only bought this place in the fall so don't have much history of it. I suspect this room may have formerly been a screened in porch but that's just a guess.
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Borrego
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# Posted: 23 Jul 2018 11:02
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Quoting: Rickant I will add ceiling joists to ensure walls don't push out. Correct?
Either ceiling joists, collar ties, or posts are needed. Collar ties will give you more headroom, or you could bury posts in a new wall 'sistered' against exis
ting wall(s)
Quoting: Rickant Another issue (I think) that I discovered is the floor framing. So it is framed using 2x6 (in retrospect I eyeballed it so will double check that they aren't 2x8,
2x6 will span that ok if they are 16" OC, but if your real question is the roof load sitting on the outside wall, can you add a post support underneath?
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Rickant
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# Posted: 23 Jul 2018 14:58
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Indeed. I do have room to put a pillar underneath, but do I need one? How do tell if the 2x6 framing is sufficient to carry the load baring wall?
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Rickant
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# Posted: 25 May 2019 08:16
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Finally getting around to installing the rafter ties/ceiling joists. Just to confirm the ceiling joist needs to be nailed from rafter to ceiling joist using 4-5 16d common nails face nailed. They also need to be toe nailed to the top plate using 2-3 8-D common nails? Wanted to confir. That I need to do both the face nail and toe nail. The joists do not have any lapses.
Tha is for the help!
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Rickant
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# Posted: 8 Jun 2019 16:24
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Looking for some help, informed advice. So we are trying to improve the structure of this room by adding the ceiling joists. Having a closer look, I note that the rafters are sitting in the top plate and that there is no birdsmouth on any of them. Each rafter has what seems to be a single 3.5 inch screw going from the rafter to top plate. This is clearly not right. So a couple questions. Do rafters need to have birdsmouths? Could I tie nail 3 8d nails in wa h rafter to the top plate? Is that sufficient?
Hoping this isn’t as bad as it seems.
Help please
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ICC
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# Posted: 8 Jun 2019 22:04
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Am I correct to interpret that to mean the rafter tails were angle cut completely across the depth so there is a flat edge resting on the horizontal wall top plate, but there is simply no birds mouth notch? If so, that is not critical. The flat edge on the top plate is what tranfers the vertical load from rafter to wall; the notch makes it easier for the rafter to be properly positioned when about to be nailed in place.
The screw is a no-no, though. you can use H-1 simpson ties to secure the rafter tails to the wall plates. If swinging a hammer between the rafters is difficult it may be easier to use simpson structural screws.
There could be a problem or two though. The nails or screws that secure the tie to the rafter tail may be too close to the rafter end. That reduces the joint strength. The 2x can split easily. We want the tie joint to give us uplift resistance mainly.
When the rafter is cut with a birdsmouth it overhangs the wall placing the tie 12 inches or more up the length from the end. I install the H-1 ties on the outside of the wall. That makes it possible to lay the ceiling joists on the wall plate and nail the ceiling joists to the rafters. In your case, if the rafter tails end right there at the wall stud outside edge, the H-1's would have to be placed inside the wall. Then the H-1's interfere with the ceiling joists, if the joists are to sit on the wall plate. Maybe raising the ceiling joists an inch or two is necessary? That is permissible but does complicate installing a ceiling if that was in the reno plan.
If you were nailing the rafters to the top plate the recommended code choices are; 3-16d box, or 3-10d common or 4-10d box nails. See IRC chapter 6, table 602.3(1). For the nailing schedule of ceiling joists to rafters, it varies with roof pitch and building width--- see chater 8, table 802.5.1(9)
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Rickant
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# Posted: 9 Jun 2019 05:38
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Thanks, great info. The rafters are longer than the walls so there is a decent over hang. From what I see the rafter is just sitting on the top plate. It is not cut to an angle at that point. So it looks like a 2x10 edge resting on the top plate. No birds mouth, no flat surface. Can you install Simpson ties after the fact? I will try to take a couple pictures.
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Rickant
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# Posted: 9 Jun 2019 05:51
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Here is a couple pics that show the tails of the rafters sitting on the top plate
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Rickant
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# Posted: 9 Jun 2019 05:54
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Note in the first picture I added the nails that you can see. I would use the Simpson ties if I can but I don’t know if they can be used now after the fact?
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ICC
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# Posted: 9 Jun 2019 10:15
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Good grief! I think I would install a ceiling joist, cut long enough to give as much overlap as possible over the wall tops. It might be tricky getting them in there. Then nail the joists to the rafters (or use simpson screws) with at least as many fasteners as the chapter 8 table states. Then toe nail the joists to the wall top plates. Maybe use H-1's on the inside face of the wall top. That is about as good as you can do after the fact, without dismantling the roof.
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