Fun with SketchUp - 20x30 virtual cabin

[troy]

As I continue to dream about living the dream, I've been having fun with sketchup!  For those who don't know and are wanting to learn, there are some awesome tutorials out there that will help you build just about everything from stairs to roof trusses.  Neat thing about Sketch-Up, is that you can stretch boards, you can cut more than once, and there's absolutely no waste to budget for!

Progress is slow, but I intend to do a compelete 20x30 cabin in Sketch-Up (complete with terrain and even plumbing/electric.  It'll be one heck of a model when/if I can complete it!

For now, I just have the bones.  I really like how I can let a barge rafter float in midair with no support



The floor and roof trusses are representative.  Someone on the forum posted a truss calculator he's working on, which I used to create the roof trusses.  Pretty cool stuff.

The stairs were created with the help of a great series on YouTube called Stairmathter.  It took more than a few attempts, but I ended up with stairs that look to be about as good as they can get.

One of the questions I have, is when building the floors, does it have to have a 'ribbon' going around?  I'm thinking that the sheathing could just be attached directly to the ends of the trusses.  I guess that would be a question answered by the engineer designing the trusses, but I'd like to make my model as accurate as possible.

[rick91351]

Looks good Troy but running it on a continuous loop can be sort of distracting to us ADD - Dyslexic types - I claim both. 

By ribbon going around are you referring to the truss blocking?  I think it is also referred to as roll blocking.



Interesting you bring up a topic I have been going to post and that is waste.  I read on here all the time people concerned about waste of lumber.  I feel other than OSB sheeting from cutting out windows and door ways - and trimming the ends of a walls.  This OSB waste might be captured to use on a garden shed or a wood shed.  As far as lumber - there is no waste by the time you get all your blocking in the framing.  Plumbing will require blocking.  Some electrical requires blocking.  Sheetrock requires blocking or nailers.   Most times you are scouring the job site at the end for a few more 12" 2X4 and 6's.  All that to say do not over plan and cut yourself short.  The house we are just  finishing up - 2200 sq ft and our scrap pile was about four wheelbarrow loads of board ends nothing much longer than ten inches.  Well except for those pieces that you scab a couple 2Xs together and nailed so good there is no tearing them apart.      I was also lucky on my build the lumber yard owner brought up a nice sized pile of culls that he had.  He said it was on the house.  We went through a lot of that for blocking.  But I went very extreme to buy everything through him.  (That he wanted to handle.)  Some stuff he just does not handle enough of to want to mess with such as wonder board or large gauge wire.     

[troy]

Hah.. yeah, I hear you on the loop.  I tried to pick a speed that wasn't too fast.  Guess I missed the mark.  Next one I do, I'll slow it down a bit more, add a long pause before looping, and stop it after a few cycles.  Odd that [ESC] doesn't stop animations anymore (at least not in Firefox).  There is an addon called SuperStop that fixes this behavior.

I'm not really thinking waste... that was just an emphasis on something I kept hearing in a YouTube series talking about using SketchUp, where there really is a board stretcher.

As for my question, yeah... ribbon, blocking, whatever.  I just looked it up.  Rim Board is what I'm thinking of.  Wondering exactly what it's purpose is, other than sealing up the space.  If it's to provide a nailing surface for sheathing, wouldn't this be solved by putting your joists on 16" centers directly in line with your studs?  For sealing up the space, wouldn't the sheathing take care of this?  If it's structural, what are the properties it provides?

I'm not actually ready to put the sheathing up yet, but isn't sheathing alone adequate?

[akwoodchuck]

Yeah I'd say you need it....adds shear resistance to your floor diaphragm when the subfloor is nailed to it properly....your subfloor looks like it's running the wrong way btw.....

[Don_P]

You've drawn open web floor trusses, typically they do have a let in 2x4 ribbon at the top outside edge standing upright. The bottom chord extends to the outside edge of the mudsill (don't see one), then stand up 2 vertical 2x4's, the outer one is 2" shorter than the 2 inner ones, then the top chord extends over the inner 2 vertical studs. This leaves the notch for the 2x4 ribbon. Then the wall sheathing extends over the mudsill, attaches to the floor truss ends and the ribbon and on up the wall. These are not made to hang a deck ledger off of unless it is noted in the truss drawings, that's one of those really bad days at a framing inspection if it catches you unawares... or so I've heard  .  When stick framing the rimjoist is part of the lateral stability (anti-roll) of the floor system. As the depth to thickness ratio of the joists changes the blocking and end restraint requirements also change... somewhere in the floor chapter of the IRC, holler if you can't find it. For an engineered floor system the designer/ supplier engineers all of this and hands you an assembly diagram.. at the head of your stair opening there is probably a double LVL that the trusses die into. And yup, the floor sheathing needs to rotate 90 degrees. I'm a big fan of skp, you're doing awesome 

[troy]

Don (and woodchuck),

I know I've seen pics (probably on this site) showing the joist/rim assembly, but I'm not finding any at the moment.

For the open web truss (which I think I would prefer for ease of mechanical/electrical/plumbing access, I used the one Menard's sells (no Menard's near us that I know of).



I'm not going to pretend to follow what you described (yet), but here's what would seem to work with this specific truss.  This also shows the mudsill better after moving it to it's own layer (it was included with the foundation):



(yeah, yeah... I still need to notch in the solid web on the ends)

I'm not going to get too anal about it unless someone wants to point me to some actual specs/measurements for an open web truss for a 20' span.  Then I'll build an accurate model (might even include the steel plates).



Speaking of the subfloor, if I'm using T&G, I'm losing about 1/4" per seam.  With 4 seams, I lose about 1" total on the width.  If I'm 1/2" shy on both edges, will it pass muster?  Can this space be filled or would it be better to take a page from MountainDon's playbook and build a few inches shy on the width?  How does this translate to a CMU foundation/basement wall, would I have to build 8" shy of a full 20' width?

PS: Don, I'd love to come down (I'm up in Pulaski) and see any projects you might have going on... can't promise I can help you do anything other than take a break, but I'd love to pick an experienced brain sometime.

[Don_P]

Cool, swing on by sometime, pm me your email and I'll send a map. I'm actually making occasional tuesday runs up to B-burg in the reefer beefer truck if you're near 81.

The joist you have pictured is a stock trimmable end joist, I've never used them and don't know what the end attachments are for them. For the engineered ones the 2x4 you have drawn flat is up on edge, I'll try to find an old sheet. Gotta run to Boone right now, more later. And yes I make each of those, things like the mudsill, a component and stick it on its own layer.

[mwhutch]

Our floor trusses were engineered 20' long, and they are like Don_P says have a let in for a 2x4 on its side at the top. They were very comparably priced to the stock trimmable trusses you have pictured, except they have a larger space in the center for a mechanical chase(runs the whole 32' length).

[troy]

Yeah, on the trusses, those were the only off the shelf versions I found.  Good enough for a model, but when/if I actually build, I'm sure I'll go the full route with a truss company and go from there.

Same thing with my roof trusses.  I used the calculator Madeek posted (very cool tool by the way).  I have no idea what some of the variables are, but again, the truss design it spit out for me is perfectly suitable for a model.  At least until Madeek updates his calculator to spit out a Gambrel Attic Truss.   



Mostly, I just want to build a virtual cabin to explore what's possible.  I've actually started a few different cabins of various sizes and styles.  One challenging thing I've been thinking about, is how to bump a stairwell out of the 20x30 footprint to give me access to a basement and 2 floors above.

Here, for example, the 8x9'4" stairwell looks like it would be big enough for a very comfortable set of stacked, split stairs.  I think the transition from the CMU to framed wall would be easy enough, giving a pretty nice plant shelf or something, but I'm (almost) completely lost on what the 8' span would look like.  Not sure if there's a prescriptive way to deal with this, or if it would take an engineer to figure out a solution.  Not only do I have to span the basement walls, but I'll also have the same span to deal with at the 2nd floor and roof (though I want the roof to extend down over the last half of the top flight).



I'm also not sure I fully understand the IRC with regards to stairs.  For a few different reasons, I want my basement to have 9' ceilings, which means that the total rise from the basement will be about a foot more than the total rise to the 2nd floor, but will have about the same total run.  This means that the rise per step will be different, and I'm just not sure that it would pass an inspector.

Anyways, I'm having fun with it and that's all that matters.  As my skills build, I'd be happy to create some tutorials on how to do certain things, or possibly even collaborate on a model.

[Don_P]

To me that is one of the great untapped possibilities with sketchup on forums, the ability to pass around the file and collaborate on design. I've tried it with a couple of clients but could never get any of them up to speed as far as drawing but I've gotten several to the point where they could manipulate the 3d model enough to look around and see things better than a static 2d sketch, which I think is helpful. You can develop pretty good contours from google earth and include terrain in the model. For passing a model to me, I'm still stuck with skp8 until I get a faster internet signal hooked up, I haven't been able to update since then.

Generally with stairs I like to keep rise/run very similar from floor to floor, if total height is different I can usually run one set out a step or two further.

For things like the bumpout structural framing, develop the plan as far as you can and ask for critique... we aren't shy  .

[Erin]

This means that the rise per step will be different, and I'm just not sure that it would pass an inspector.

I could be completely wrong on this, but I THINK if you have a distinct change of direction, a landing, a change of floors, etc, you can have a change of riser heights. 

[troy]

That would make sense. I think I was letting myself get confused by some of the discussion here.  The landing does indeed seem to terminate the flight.  So a U-shaped stack for 3 floors would technically be 4 flights separated by 3 landings.  The OCD part of me would still like to have complete symmetry, but with the desire to have a deeper basement, I don't think I'll get perfect symmetry on the stairs.

[Don_P]

That is correct according to code, a "flight" runs from landing to landing and we reset our stride with the new flight, but... don't change rise/run within a set of stairs between floors. In the real world we don't reset that well and believe it or not we set our stride on stairs to within small fractions of an inch, it doesn't take much to cause falls.

[MountainDon]

We certainly don't reset well.. New York City Subway stair youtube video.  One step higher than the others. 

http://www.youtube.com/watch?v=ap-22FjgoE4

[Erin]

don't change rise/run within a set of stairs between floors.

Of course this means in the same flight.  Ie, no "reset" from a few strides across a landing. 


My grandpa had a flight of stairs down to the basement where he goofed at the bottom and the bottom rise was nearly an inch shorter than the rest of the flight. 
I knew it was there, and it would still get me every time!   

Consequently, every time we ever built stairs, (including just last fall when he helped me install the set for our deck that I'd already built) my dad would give the lecture that "even the ancient Greeks knew the importance of a regular stride when it comes to stairs.  Do you remember those stairs that Grandpa built...?"    lol