Can anyone recomend

[RRG]

a website that will help me understand how to calculate live/dead loads so that I can figure sizes for my beams,posts,and joists?
I've googled and searched this forum and am still at a loss.

[bkrahmer]

Are you talking about actually trying to understand how to figure out what loads to use, or how to calculate sizes of whatever based on given loads?

I believe most people typically use 40/10 for most rooms, 30/10 for sleeping rooms, and 20/10 for attics. I just used 40/10 for both of my floors, and I won't have an attic.

Do you have a specfic reason for thinking that your loads won't be 'typical'?

[RRG]

I am trying to calculate the sizes I need for my basement beam, posts, and first and second floor joists. Of course the ridge beam and rafters too.

If your suggestion of 40/10 is on the money, then that gives me a place to start figuring!

I have no reason to think my loads will not be typical.

We are building a cabin, 32' long by 26' deep. 8' basement, "D" log first floor, "L" shaped loft over bedroom-bath-kitchen, open to dining and living room, with an 18' shed dormer up for bedroom, 1/2 bath, and loft.

Front joist to be 14' and rear joists 12' ers.

I have been thinkiing of using 2x10 , but will run the 40/10 load thru a load calculator to see what is recommended.

Thanks

[bkrahmer]

Yeah, it sounds like 2x10's would work just fine. For the 14', you could use 16" oc, 12', 24" oc. Personally, I recommend using i-joists for your floor joists and rafters. They are lighter, stronger, and more importantly, straight!

Let us know if you need any help spec'ing the beams and posts.

Good luck.

[RRG]

I'll take all the help I can get :lol: .
I am thinking a built up beam made of 2x10 (3 or 4 of them) spaced approx 10 foot apart in the basement with joists breaking in the middle and riding on top of the beam.
6x6 press. treated posts...

Thanks for the previous post too. I didn't know I could go 24" OC on the 12 footers. I will probably stick to 16" though. I will definatly check out I-joists if they are cost effective.

[bkrahmer]

For your basement beam(s): I'm not sure what you mean by by "spaced 10' apart". I was assuming that if you are going to use a 14' and a 12' joist, that you would have one single beam where those meet.

I wouldn't be comfortable actually spec'ing a built-up beam. Again, I would recommend engineered lumber. However, for a house of your dimensions, a basement beam which carries only a single floor, with a single column at 16', TrusJoist specs their Parallam at 5.5x14". That would be about 4 2x12's. With two columns, you might be able to work with 3 2x12's for the beam. Again, that would be if your columns that bear the second floor fall directly over the columns that bear the first floor.

If you use a built up beam, don't forget to stagger the lumber, and don't put any of those stagger joints within 12" of a column.

If you go with dim. lumber, consider hanging your joists off of the beam w/ hangers instead of riding on top. If they ride on top, you'll then have to splice the floor joists. That's another reason to use I-joists. 26' is no problem, you'll save a day or two on installation.

Also consider this: pressure-treated wood is not graded. I would not recommend it for major structural elements.

Again, for your columns, I would suggest using engineered lumber. A #2 6x6 is rated at about 13,000 lbs. Compare that to a 5.25x5.25 Parallam at 27,000 lbs. A single column in your basement, if my calcs are right, would be carrying 28k. Two would be carrying 14k each. Two glulams or Parallams would probably work great.

[RRG]

Thanks bkrahmer,

I appreciate all the advice and will be checking into what you've mentioned.
Makes sense!

I imagine it is fairly straight forward to frame in stair openings and box for bathroom plumbing with i-joists?

[mjpliv]

Here is the specs for your original beam idea. It works out to a 4 ply 2x10 beam. I used my load preferences of 40LL/15DL which is only slightly higher than yours. The centers for your columns would be 10'-8" measured from outside of foundation.

Note that the reactions t the bearing points for the beam are show in KIP values (1000's of pounds). Therefore your loads at the columns will require footings to support factored loads of 11,500 pounds. The factoring values used are 1.5 for live loads and 1.25 for dead load (standard limit state design)

[mjpliv]

I went back and double checked my input (a good habit to get into) and found an error on my input for the live loads (I used 12 foot instead of 13 foot tributary length)

Here is the revised spec sheet. Same centers factored reactions at the column are now 12,200 pounds.

[mjpliv]

For those interested, here is a graphic of the forces working on a typical multi-span beam using multiple load case scenarios.

[RRG]

Wow, thanks for all your work on this!

I have been reading up on i-joists for the past two hours ( I'm starting to go cross-eyed).
They seem to be an excellent product, and depending on prices, I am still un-decided on which to use.
I framed for 6 years, but it has been a while back, and I am used to regular 2x lumber.

In the plans I have drawn up, I have 3 posts in the basement.
The post furthest right is spaced 10' from the right basement wall. This will carry (part of) the first floor beam and have a post above it which carries the corner of the 2nd. floor loft. I have specified a footer under this and the other two posts which are spaced approx. 8' apart.

[mjpliv]

Before deciding to use a pre-manufactured or engineered floor system (such as I-joists) be sure you understand the constraints as well as the advantages of using them. Get complete installation instructions for the product you are considering and make sure the finished product is worth the extra expense and effort.

[mjpliv]

Here are the spec sheet and graphic for your revised post layout (spans are guesses). Note that the reactions at all bearings include first floor loads only - nothing has been added for the second storey.

[bkrahmer]

Note #4 at the bottom of that sheet that mjpliv generated... That design assumes that each of the plys is continuous. Therefore, if you are scabbing together shorter pieces of 2x10, I'm not sure they'll be the same strength.

make sure the finished product is worth the extra expense and effort.

Extra effort? Huh? Like much lighter weights to deal with? Like ability to span the entire house with one piece?

As for the stair question, they aren't too much different. You may have to use a couple extra hangers, that's about it. I have previously posted pics of my framed stair openings with the i-joists.[/b]

[mjpliv]

You can add joints to the beams as long as you use the accepted rules. The joints should be staggered on either side of a column location (not end bearings) within and not exceeding 25% of the open span. Avoid adding joints at the column location as this is the ocation of the highest bending loads. Properly nailed, all plys and segments of plys will act as one unit.

[mjpliv]

Extra effort?

I am refering to dealing with special rims, squash blocks, web stiffeners, web backers, blocking details, detailed nailing patterns, etc. I am, in fact, a fan of engineered floor systems. I just don't want anyone to proceed with a purchase on the assumption that I-joists are a direct replacement for dimensional lumber framing.