Building Horizontal Beam?

PaoloM

I'm building a one floor, open concept (one room) 16x32 Hunt Cabin (Basically a Rough Cottage with no Electrical/Plumbing) in the bush on my farm. I'm going to be using 2 concrete blocks on top of 2 Concrete Pads (8' apart - 15 Total) on the ground as my footings which will give me about 22" from the ground and then build 3 beams out of 2x8x16's Pressure Treated at 32' lengths spread 8' apart sitting on the concrete blocks. What is the best way to connect the 3 individual 2x8's together (nails, bolts, Carriage)? Do I NEED to use any glue in between the beams? I know I'll be staggering the 16 footers to make the 32' beam. Wherever there is a joint in the beam a concrete block will be under for support as shown below.

Then I'm going to build the floor joists on top of the beams using 2x6's. Do I need to anchor the Floor Joist to the Beams or do I leave it "free floating"? What would I use to anchor it down to the beams? Do I need to put anything in between the joists and the pressure treated beams (plastic, Alum, etc)?

Do I need to build up my conrete blocks by using 2 for each layer (4 block total for 2 layer) or can I just put one on top of another? Is there a specific concrete block I should use?

I did a quick plan to give you an idea of what I'm doing. The photo below does not show the Joist.
Thanks!

Attached Images

  

Wildie

Leveling the pads will be tricky! This why wooden posts are a favorite way of building decks.
Once they are in place the tops can be easily cut off to form a level surface.
If I were doing this, I would drill post holes and install SONO tubes in the same manner as building a deck.
Using steel mounting plates, I would attach pressure treated posts to the concrete. The beams would them be mounted on the posts.

Termite

Your idea of building a structure of this size on pads at grade is not good, unless you're in an area that never gets below freezing. Frost footings are a must if you want to be able to open and close the doors and windows a year after building the shack. When it freezes and the soil heaves, it will easily lift the building up and will drop it back down when it thaws. Over time this will really do harm to the building.

You need to pier the building or dig a trench footing to the required depth in your region.

Termite

How far is this 3-2x8 beam spanning? That isn't much of a beam when carrying 16' of tributary floor joist load.

Nails will adequately connect the laminations of your wood beams. I'd suggest three rows of 16D nails staggered at about 12" centers. A little subfloor adhesive never hurts, but is not necessary, and certainly won't reduce the need for nails.

Be sure that anywhere your beam has a splice in it that there is support underneath. You should buy the same lengths of lumber as your footings will be spaced...Basically, don't stagger the joints in the span.

PaoloM

I can't Auger into the ground (Canadian Shield)...solid stone so that is why we are using pads and blocks. We leveled the area with crushed stone last year and the ground has become rock solid over the winter. There won't be any shifting problems here...that I can guarantee.

The 3 beams will be 32' in length and just so we are clean EACH beam will consist of 3 rows of lumber nailed together.

So I don't have to worry about bolting the 2x8's together when I make the beam, nails are enough? The Floor Joists will be going in the opposite direction using 2'x6'x16' lumber.

There will always be a footing under each joint...it works out perfect since I'm putting footings every 8' so when I combine the 2 16' pieces together there will be a footing under the joint plus a footing in the middle of the 16 footer and of course at both ends.

When making the 32' support beam should I just use 6 - 16' pieces (making 3 rows of 32' for each beam) with the joint in the same for all 3? OR should I do as I show above .... staggering the middle row with 2 8's and 1 16'?

Thanks

Termite

Using longer pieces of lumber in your beam will make it a stiffer beam overall. I'd use a 16' piece in there like you suggested. Bolts could be used, but are not absolutely necessary.

PaoloM

Is it ok to have all 3 pieces to have the exact same joint? I would have thought staggering the joints would make it stronger?

What would be best to use under the beams where they sit on the concrete...piece of plastic?

Thanks

Termite

I would mount a metal Simpson or USP post base, which will elevate the beam an inch or so off the concrete. You can anchor the post base to the pier before setting the beam in place. Take a look at the ABU66, or similar. There are some nice ones that you pour in place as well.

www.strongtie.com

Staggering the joints of the beam WILL make it slightly stronger. Use 8' pieces and a 16' piece in the middle. The other option is to use all 8' pieces. Just be sure that no breaks occur between the bearing points.

PaoloM

"Staggering the joints of the beam WILL make it slightly stronger. Use 8' pieces and a 16' piece in the middle."


Thats exactly what I'm going to do...just as I showed in the diagram above.


Since there will be no interior walls or posts, all the load will be held on the exterior walls. I just have to figure out what kind of prefab rafters I'm getting for this design. I Need something that doesnt need any posts/beams or interior walls. That will be a entirely different thread

As much as I would like to be able to pour concrete, I can't ... I'm in the middle of nowhere and just bringing the material to the location is going to be a days worth of work if not 2 days! So I think I'll just put a Sil Plate in between the beam and concrete block to prevent any damage.

As for concrete blocks ... would a cinder block be ok? Or do I need a solid concrete block without any holes in it?

Thanks for all the feedback!

Termite

Slug the concrete block full of concrete when you place it. That way there are no voids and the unit's compressive strength will be greatly increased.

PaoloM

I was thinking of that but my problem is how the heck am I going to mix concrete when I don't have any water there. Even if I had water, mixing it and then bringing it to the site, is out of the question (too far)....filling the blocks ahead of time (if I could, would add way too much weight and we can only get in by ATV. I'll have to come up with something! If I can find Solid Blocks already it will save time but weight is still a factor....I have some planning ahead of me still

Maintenance 6

For the amount of load they'll be carrying, filling the block really wouldn't be necessary. I am curious though, if you can get concrete pads in place, why couldn't you fill the block?

PaoloM

I know what you are saying but 30 Concrete Pads is bad enough ... if I had to fill 60 or 120 Concrete Blocks, depending if I go single stack or double stack, that would take forever to fill and transport to where we have to go it's bad enough we have to bring that many blocks and pads !!! Besides I don't have any access to water to mix the concrete anyway. If I did, I would have formed my own concrete footings which would have been much easier!

I don't think I have to go so crazy with the footing design as there won't be that much of a load especially with all the footings that I will have supporting the cabin (15).

I just realized if I did anchor the beams to the blocks what good would that do if the blocks are not anchored together? Anyway...thanks for all the info everyone...this forum is great . Now...on to my next question (roofing for this cabin - new thread)

Wildie

I like kctermites suggestion!
"I would mount a metal Simpson or USP post base, which will elevate the beam an inch or so off the concrete. You can anchor the post base to the pier before setting the beam in place. Take a look at the ABU66, or similar. There are some nice ones that you pour in place as well."

www.strongtie.com

Big Bob

Build a rain catch out of tarps... Let mother nature bring the water you need to you.