Victoria cottage questions.

[Oly Pen]

Well I'll start by saying hello.   I've been lurking for a while now and figured it was time to say hi.
I have a couple questions in regards to victoria's cottage. I have not ordered the plans yet so I'm sorry if some of the answers are in there. The location for the cabin is in Mason county, Washington. (I'm just outside of Belfair for those of you familiar with the area.) It will be a 16x24 rectangle, nothing fancy, with maybe one shed dormer in/over the loft. The upstaire will be like the full loft in victoria's plans but without the study-sitting room. So here are my two biggest questions as of now.

1) #2 douglas 2x10 @12oc with deflection limit of L/480 the max span is 16'5. So does than mean I can do without a center beam and those I-joist things and have full span 2x10 joist? I thinking 4 piers spaced 8' apart on each 24' wall. Triple 2x10 running across the four piers with the 2x10x16' joists for the subfloor.

2)What serves as the rafter ties if I were to balloon frame the outside walls with 10' studs and set the loft at 7'6? Does the loft act as enough of a tie?  Collar ties will be used to avoid the hastle of setting a beam and tracing the load, but how do I get around no rafter ties? I understand the a35 simpson bracket can be used to reinforce the connection between rafterd an top plate but is this sufficient?  I plan on using rafter ties in the open section of the house.
Thanks in advance.

[John Raabe]

There is a very simple 16' structural plan as part of the Victoria plans (these are not complete permit ready working drawings). I can share what I used and you can see if you have enough info to build what you're planning.

The pier and beam foundation has 6x12 DF beams spaced a max of 7' between piers. You could make up a composite beam from 4- 2x12s. I have both I-joists and standard 2x10 DF joists spanning the 16' width 16" o/c. The walls are 2x6 balloon framed 12' studs at 16" o/c. The loft floor can be adjusted to provide up to a 5' high sidewall in the loft. The roof can be built with trusses engineered to local snow loads or framed with a collar tie to provide a 7'-6 or 8' ceiling. Be sure to use a hardware connection between the roof framing and the walls on each side.

[Don_P]

Hi Oly Pen 
A rafter tie is required by building code to prevent the rafter bottoms from spreading unless the roof is engineered. The rafter tie in the code is required to be in the lower third of roof height. A collar tie in the upper third of roof height or straps over the ridge are required for either a ridgeboard or ridgebeam to restrain uplift. With a dormer a ridgebeam is probably worth reconsidering.

[Oly Pen]

Is a ridge beam required when there's a 3' half wall in the loft. If there's a partial wall, the floor joist can't act as rafter ties but they do tie the walls together, which are connected to the rafters.

[MountainDon]

The loft floor joists do connect the walls together but also leave that stub sticking up to where the rafters will be fastened. The rafter thrust will act on that stub trying to bend it outwards. If the stud is notched on the inside for a ledger that weakens the stud as far as the outward bending force. If snow or wind loads are high that force can be substantial.

As Don_P pointed out code calls for a rafter tie and a collar tie (or metal strap). There is usually good reason for code required structural requirements. That's not to say that anything that does not meet code will fall down. But it should give some pause when contemplating design. That is my opinion.

[John Raabe]

The easy way to insure that code is satisfied is to frame your roof with trusses built by a local company. They will engineer it for local loads and it will have no outward thrust on the wall. You can then platform frame your 1/2 walls instead of balloon framing if you want. Trusses can be designed in many configurations. Take you cross section sketch in to see what they could do. There should be no cost for this service.