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DaJTCHA
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# Posted: 30 Apr 2012 23:16 - Edited by: DaJTCHA
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Would you please take a look at my latest video, about half way through I'll visit the loft.
www.troutcampretreat.blogspot.com
You'll notice the roof rafters are 2X6, 16OC and built in a salt box roof style. The "short roof wall" is 8' long which sits on the top of the 2X4" wall top plate with a birds mouth notch. The "long roof wall" is 12' and follows the same routine at the other side. The roof is fairly steep and the actual angle is 85%.
The loft floor is constructed of 2X8's 16OC that are actually mounted underneath the wall's top plate and affixed to the stud with horizontally driven ringed shanked nails. Then underneath those floor joists on either wall, I've run a 2X8' beam to support either end and affixed the beam to the studs. Sort of a hybrid balloon frame type construction. The reason I mention this is that with this type of second floor construction, I find it hard to believe that the walls will be pushed out by the load of the roof because each joist is tied into each stud of the either walls.
With that said, do you think I should install collar ties at the top of the roof rafters where they meet the ridge peak beam?
Thank you for your expertise, there is a reason I directed this thread to you as I value your input.
Thank you!
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MtnDon
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# Posted: 1 May 2012 00:43 - Edited by: MtnDon
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First, collar ties, located up snug near the peak (or at least in the upper third) serve to hold the rafter points together. They can be a boon if and when the winds pick up to high numbers. Their sole duty is to hold the peak framing together at times like that.
A rafter tie holds the lower ends of the rafters together and hold the wall tops, keeps the wall tops from spreading. Technically rafter ties should be on top of the wall top plates, not below the top plates. In your case though, as I can not see any stub of a wall stud sticking up above the loft floor you should be fine. The very steeply pitched side of the roof will have very little horizontal component to the force on the wall. The other roof half is still fairly steep.
The important thing is you do not have a stub of a wall stud sticking up a couple feet or more as many have done. That stub, what is referred to as a kneewall by most, can be a problem area. You don't appear to have that problem.
The greater the length of that knee, the greater the possibility of horizontal outward forces from the rafters causing a stud to split, especially if the studs have been notched to inset a ledger. So I'd say you are alright.
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DaJTCHA
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# Posted: 1 May 2012 00:50
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Thank you. I'll throw some collar ties up there to shore things up. I have a bunch of 1/2" plywood left over that I'll glue and screw.
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MtnDon
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# Posted: 1 May 2012 01:05
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How many nails were used to secure the loft joists to each wall stud and the rafter bottoms to the wall plate? Three 16D common nails (not box nails which are what most air nails are. If box type add a couple) on the steep side would do for both while the shallower pitch should have (maybe) 4 for each. The loft floor joists are face nailed into the studs? If the nails pass through the stud clinching them over greatly increases their holding strength. Ditto on rafters.
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MtnDon
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# Posted: 1 May 2012 01:54
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But to answer the question about collar ties. They would be a good idea. If the finish roofing was not yet installed there are metal straps that can be nailed over the rafters from the outside or over the sheathing at the rafters on the outside. Max spacing of 4 feet.
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DaJTCHA
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# Posted: 1 May 2012 10:34
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The loft floor joists are faced nailed through the joist end and into the vertical stud where they meet against one another. The beam that is jammed up underneath the floor joists is secured with two lag screws through the beam and into the stud (X 14 = 28 lags each side).
I've used 3.5" ring shanked hot dipped galvanized nails shot out of my PCable pneumatic nail gun and each board (rafter end and the floor joists) has at least 3-4 toe nailed in each of them.
Thanks for thinking this through even more and bringing up your ???'s and concerns. I appreciate it!
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