14x24 Cabin help with pics?

[mand0092]

I started building my cabin 2 months ago and have been working nights after my day job. I started with 2 rows of 5 footings each  12"x48" in dimension. I reinforced the footings with Rebar and used wetset concrete for anchor attachements.






I then doubled up green treated 2x12's for beams that span over each footing for a total length of 24' running parallel to eachother.




Connected the ends and squared/leveled the beams. I attached the floor joists with hurricane ties 16" on center using 2x10's. we went with a little stronger lumber because we were spanning roughly 11'6" between the beams and wanted to be safe than sorry.



We have a 1' cantilever on either end that is now boxed in with the rim joists. I've installed the joist hangers on the ends, have squared everything up and everything is level. this weekend I'll be nailing in all the blocking between the joists and firming everything up.



Im hoping to install the underlayment plywood, insulation and subflooring this weekend.

Does anyone know how I can upload pictures? I would like to show you my progress and see if anyone has any suggestions before I get to far along.

[alex trent]

In the Forum News section on the home page, right below this section in the index you will find "Photo Bucket Tips"..it is about the 6th one down on the list.

Looks formidable, but just follow along and you will be able to upload easily.

[Redoverfarm]

I started building my cabin 2 months ago and have been working nights after my day job. I started with 2 rows of 5 footings each  12"x48" in dimension. I reinforced the footings with Rebar and used wetset concrete for anchor attachements. I then doubled up green treated 2x12's for beams that span over each footing for a total length of 24' running parallel to eachother. Connected the ends and squared/leveled the beams. I attached the floor joists with hurricane ties 16" on center using 2x10's. we went with a little stronger lumber because we were spanning roughly 11'6" between the beams and wanted to be safe than sorry. We have a 1' cantilever on either end that is now boxed in with the rim joists. I've installed the joist hangers on the ends, have squared everything up and everything is level. this weekend I'll be nailing in all the blocking between the joists and firming everything up.

Im hoping to install the underlayment plywood, insulation and subflooring this weekend.

Does anyone know how I can upload pictures? I would like to show you my progress and see if anyone has any suggestions before I get to far along.

.  Just a word of caution.  If it is going to be sometime before you are able to get a roof on and dried in you might consider a waterproof subfloor such as Advantex.  Even with that there is a possibility that your insulation will get wet in spots. Without it alot will get wet. If you have the room to get under the crawlspace later that would be a better choice.  Not sure what area you are in but winter has a tendency to slow construction down in certain areas.

[mand0092]

Alextrent, thank you for your help with the pictures! I have uploaded them and hopefully I did it right. Redoverfarm, thank you for the suggestion. I was thinking the same thing, although it's going to be very difficult getting under the cabin afterwards..I was thinking of putting a vapor barrier under the subflooring and a tarp over the top, covering it from moisture. I like your idea of advantex. I haven't heard of that and will look into it either way.

Thanks guys!

[Squirl]

Tips.

The beam joints don't break over posts.  It is normally good practice, and required by code.

Extremely close to the ground.  No room for later plumbing.

[mand0092]

Squirl,

Thank you for your tips. I'm not planning on having plumbing out to the cabin for a few years but you're right it is fairly close to the ground....about 4". If plumbing is added I'll have to make a channel or something. The beams are doubled up..I used 1- 10' and 1-14' on one side and 1-10 and 1-14' on the other side of each beam. then slide them together and connected them with many 4"x1/2 galv carriage bolts. I was told doubling the 2x12's adds significantly more load barring capability and the seem wouldn't need to be centered on the footing as both beams are dirrectly on the footings? Let me know if this is wrong cause I'd rather make changes now (even though it would suck) than later.

thanks

[Squirl]

Yes, 2-2x12s is stronger than 1-2x12.

More nails are better than fewer carriage bolts.  More surface area and contact between the two boards.  It distributes the weight of any load over a broader surface of the wood too, rather than concentrated in a few spots.  IIRC, Code for beams and headers is every 16" along each edge.

I don't know who told you that.  I would say to fix it.  You have two beams cantilevered and jointed in between the same center posts on each side of the building.  I would say maybe leave it if they weren't all between the same two posts, but I still wouldn't recommend it.

What are your piers spaced at?

[CjAl]

Squirl is right. the joint where two boards are butted together have to be over a pier.  it looks like that inner board isn't even butted togther but has a gap between it. You essentially have no support (or very little) between the two piers where the butt is. the 2x12's will eventually start to split at the nails from the stress of trying to bend. a few nails are not strong enough to support a house

[Squirl]

I was told doubling the 2x12's adds significantly more load barring capability and the seem wouldn't need to be centered on the footing as both beams are dirrectly on the footings?

Sizing and load bearing capacity are dependent upon span and width.  The information is out there and free on the web.  I did a quick walkthrough of the charts.
http://countryplans.com/smf/index.php?topic=10511.0

I did the math, and I would estimate that you have around 5.5 ft span.  Some factors that come into play is how many floors (loft?) and ground snow load.


Also, installing insulation now is dependent on type.  Any that can retain water such as rock wool, fiberglass, or cellulose is generally not installed before the building is dried in.  I have noticed what seams to be a large consensus from many members who did this and regretted it.  I'll let other weigh in on that because I have not done it. 

[MountainDon]

Squirl and CjAl are correct on the joints in the built up beams. IRC states the joints have to meet over the support. You wouldn't be the first person to do what you have, but it is not the best idea, even if there is no inspection. It is your call of course.

A beam built to fulfill IRC specs pretty much only uses the nails to hold the pieces together. It does not add much/any real strength. Carriage bolts are not recognized by the IRC as fasteners for beams or other structural purposes. A machine bolt is different; they have threads at only the end and a full diameter shank for most/all of the length where it passes through the members. The carriage bolt with threads full length are weaker, size for size, than a machine bolt. Machine bolts should be used with a large washer under the head and the nut, and not tightened so much as to crush the wood fibers.


There have been some folks who have been lucky with insulation installed in a floor before the structure was dried in. Others have not. Once again, your call.


Regarding the height off the ground. According to the IRC the floor joists should be PT wood when less than 18 inches off the ground; beams PT when less than 12 inches off the ground. Yet again, your call.  PT wood must also use the correct nail, correct coating, so the chemicals in the wood don't corrode the nail severely. (Mentioned just in case you were not aware or readers looking for ideas were not aware.)

[Don_P]

It looks like you could pull the bolts in the splice area, drop a 2x12x~6' inside that would cover the splice and bear on the piers on each side, then refasten the splice to the inner ply. Not ideal and I wouldn't suggest it to someone who was asking before doing it, but as they say "you are here". I'd count on digging under an end and insulating later. Once you're under there it looks like there is adequate room to move around, got to be more than under my Honda  .

[LightningBG]

Just so everyone is on the same page, this is what the current layout is of the beams.  They are all butted tight.  In the picture with the gap, that beam hadn't been secured yet. 

Inspector said if the the seams are within a foot of the pier, they are fine, but they'll probably get changed either way, which I'm pretty sure will weaken it, but will meet code.



All of the wood shown in the pictures is pressure treated and proper fasteners were used.

[LightningBG]

So, if these boards were spliced in (red), code would be met, correct?  (Would also seem counter productive IMO, since there would now be 2 seams in close proximity on the center pier).

[Squirl]

Changed names?

LightningBG

Interesting inspector. 

I originally thought both were spliced in between the same two posts.  I see I was incorrect on that.  Code still requires all joints to be over a post.

Yes, the second drawing would be to code.  Normally people try to avoid the both of the same splices over the same post.  It is still stronger than your current set up.

The first picture the one side of the board is within 1 foot of the post, but the other side is unsupported by 4 ft.  The weight of this then relies more on the bearing capacity of the single 2x12.

The further you go out from a point unsupported the greater the mechanical advantage. (leverage)

[Don_P]

Hold on, if the inspector was ok with it and if the splice is near the inflection point leave it as is, the inspector is quite right and he approved it.

[LightningBG]

Changed names?

LightningBG

I'm the one providing the tools for said project (but I'm no professional carpenter, that's for sure)

[Squirl]

I believe Don_P is a professional carpenter or engineer.  Calculating inflection points is beyond my understanding in building.  All I know simple framing and code descriptions.

[Don_P]

Just an old carpenter.
I'm attaching a table of bending moment diagrams of uniformly loaded continous beams over varying numbers of piers.

The graph is showing the coefficients to multiply the bending moments by in the various sections of the continuous beam. Basically the diagram is showing the bending stresses in a continuous beam.  Notice that the stress in positive and negative directions is greatest at roughly midspan and in the negative direction over the posts.



Now look at the diagram, off the post and slightly inboard of the quarter point of span the bending force (leverage thats stressing the beam in bending) passes through zero bending stress. The inflection point, or the point of contraflexure. If you connect a splice to a continuous section at that point, is it a bad thing? A timberframe splice joint in a long sill or beam is off the post generally around or over the brace. Did the old timers understand that stress wave in the diagram above? 

Canadian code does, or did, allow built up beams with splices at roughly the quarter points of span.

There is more down that path, but I just drug us way off track. I think you're fine. To build to prescriptive (easy to show compliance) the codebook calls for splices over posts. It keeps things simple, I don't disagree, but this works within its limits.

[LightningBG]

Don, thanks for the table.  Very useful.  We'll see what the inspector says.  Mand0092 went out and measured the joints and they are about 18" off the piers.  We are sending a message to the inspector and see what he has to say, then we'll do whatever is needed per his request.

[mand0092]

The inspector said that 18" from a pier is to much and he will not sign off on it. I will be picking up more lumber tonight (treated) and replacing the beams to meet code (gotta love being a rookie and taking 1 step forward and 2 steps back).

[NM_Shooter]

Don't despair!  You won't regret the fix.  Make your foundation and floor right, everything else depends on it. 

BTW, you know that you can also work during daylight hours?  Yeah, I didn't know either for quite awhile.  I framed my walls up in the dark or in my garage.   

[mand0092]

So I worked all day Saturday...tried to jack up the beams and found out quickly that the beams wouldn't hold the suspended weight if I was going to be replacing sections. I removed all of the hurricaine ties and anything attaching the joists from the beams. Moved the whole section of joists off in 2 pieces so I could get to 1 beam at a time. needless to say, this is turning out to be a Sh*tShow, but it will be worth it when it's supported correctly and back in shape. Definately frustrating to take so many steps back and spending what would have been the decking money on more lumber for the beams. After I get the beams replaced I'll send some more pics. Could be a while though

[Squirl]

Sorry I forgot to warn you before.  It is about the crawl space height.  I can't tell from the picture, but you need 18" of height between the bottom of the floor joist and the finished grade of the crawl space for ICC code.  Your 2x12 should be a good start, but I can't tell if your piers are 6" up.  If the inspector said he would not pass the beams, it makes me worry a little more about how much of a stickler he may be. You also need a 2 ft wide access to the crawlspace through the floor or the outside for ICC code.  Because the footprint is so small, most people go through the outside.

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_4_sec008_par003.htm

[mand0092]

Squirl,

Thanks for the heads up..now I don't regret taking off the joists, freeing up the beams. There is definately not 6" of clearance under the beams. What would you suggest I do? Should I take a 4x6 post and cut it up? placing  a 1' 4x6 piece on the footing? the reason I need to go with a 4x6 is because my wet anchors are 4" in width. if I do that, I could place the beams (after completed) on top of the blocks and that would give me 18".

Would that be a good idea?
Thank you for your help!

[Squirl]

A 6"-8" 4x6 should probably work.  From what I've read, the shorter may be better, less leverage I believe. It would be just tall enough to pass code and get a good bracket connection.  Simpson makes post brackets to connect them to the beam. Also I've seen many use the Simpson galvanized steel T straps. I'm sure there are a few more people that can give good insight.

A hinged piece of PT plywood along one of the short walls should give you access to the crawl space.

The reason I pointed them out was my inspector warned me of both before I started and told me he would fail me if I didn't do it.

He told me he wasn't a fan of pier foundations, but he allowed them as long as everything else conformed to building code and they were skirted like a mobile home foundation.  I have seen people skirt them in all sorts of materials that almost all rotted.  I personally would skirt anything within 12" of the ground with anything that wasn't pressure treated.

Look on the bright side, in today's world you can ask questions and get feedback before you get to far.  Imagine failing an inspection after the cabin is built.

Do you mind if I ask what state this is in?  It may help people give more detailed and location specific answers.