Building 30 foot beam question

[mcw]

Hey, I purchased the plans for the 20X30 1 1/2 story cabin. I'm currently in the process of pouring the piers for the beams. My question is about building the 30' beams. Looking at the material list it shows 12 2x12x16' boards. I was wondering the best way to stagger the boards and keep the 4' distance between joints and also what part of the material list is for the 1/2" plywood that goes between the boards? Is it the 11 7/8" x 12' OSB Rim Board? If so it only calls for 60 LF or 5 boards. Wouldn't I need twice that? Thanks for any help. I'm justing getting started so I know there will be many more questions to follow. This site is full of good inforation. Thanks.

[MountainDon]

The best builtup beams will have the breaks or splices between 2x's positioned over the bearing piers/posts. These should be staggered from layer to layer so they all do not all occur over the same pier in all three layers. Construct them in place on the piers where they will be used; much easier than trying to build them in one place and then move them to the piers.


I believe that the 11 7/8" x 12' OSB Rim Board you mention are meant to be used IF you are building with engineered wood floor joists in stead of 2x12 lumber , but I am not certain on that. I don't have the materials list.

[Don_P]

I'll go a little bit stronger than Mt Don here, the building code states that all girder splices are to occur over a support. This applies to the 2x material only, the plywood is not considered structural so its' splices can occur anywhere.

[new land owner]

We made the beam in place splicing it over the suport posts.  We put up the first one and then attached one floor joist to stablize it.  It was not bad at all.

[MountainDon]

It helps to have some good bar clamps. Once you have them you find all sorts of uses for them. They are also handy for twisting joists when they don't want to do what you want them do as you are nailing them into place.


http://woodworker.com/bessey-2x4-tradesmen-bar-clamp-mssu-134-405.asp?search=bessey%20bar%20clamps&searchmode=2

[mcw]

Thanks for all the information. I'm thinking about making splices on the outside boards over the center pier and having two splices on the inside board over the other two inside piers. This would minimize my splices and the middle boards would overlap at least 4" so I could have the bolts go through both of the pieces. I was wondering if I need to just buy plain plywood and cut into 12" X 8' pieces to go between the 2 X 12's. I appreciate all of the comments. As soon as I figure out how to post a pic, I will post a copy of the piers with brackets in place.

[MountainDon]

Bolts? To fasten the layers together? Multiple nails, spaced several inches apart, are actually better than using bolts. Bolts can create concentrated load points, nails spread that out.

Plywood: Yes just cut it up whatever sizes you can best handle, 4 foot even. It is simply spacer material that is used to make the beams fit the standard metal brackets.

[Squirl]

I was just reading up on my nailing today.  Since Girders and Headers are used interchangeably in the code, I assume they have the same nailing requirements.

Built-up header, two pieces with 1/2" spacer 16d (3 1/2" × 0.135") 16" o.c. along each edge

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_6_sec002_par005.htm

More nails are better as long as you aren't splitting any wood.

[mcw]

I am planning on glueing and nailing the boards together. The bolts are for connecting the beams to the brackets on the piers. Since both of the outside boards will splice over the center pier, I figured I could overlap them about six inches so that the bolts would not go through the splice.

Another question I have is whether I can use the 2X12X20' structural grade for the floor joist? Will I need to space them 12" o/c to keep the floor from having much bounce? I am getting ready to price my material and trying to figure out how many joist to price. Thanks for all of the comments.