(wood) construction advice

[Vinnie]

Hi folks,

In my garage I'm building a wooden floor which sits on top of 4 metal poles on each side (8 total). The metal poles have flat pieces of metal (8mm thick) welded on the end measuring 8x20cm. Initially I was planning of using one length of 720cm long wooden beam to cover the whole length but it's hard and expensive to come by such a piece so I'm now thinking of using 2 beams to go along each side.

Should I use 2x360 cm and have the split in between 2 poles (leaving 2 ends unsupported) or should I use sizes that make the split sit on top of a pole thus having the ends of all beams supported. The latter solution lets the beam end sit on 10cm of the flat metal plate.

What would you do?

Thanks,

Vincent.

 

[Fabrice]

you mean this?

where most front is your alternative vs what you wanted on the back?

 

[Vinnie]

That is exactly what I mean!

 

[OMS]

The joint for the board [ connections ] should be centered over the post

You would use 3 sections of wood for each side

 

[Fabrice]

yeah 3 sections connected with light plate 1/2 on support, vs a bigger connection in the middle would also be not only cheaper but stronger.

keep in mind, you're gonna have transversal beams every 30 cms, and prolly a car weight (even plastic corvettes are heavy )

which brings me to next question: you mentioned have a car there, how do you plan to lift it to this first floor?

 

[nailpounder]

you may want to use connecting plates @ the breaks you never want to make a break without support

 

[73pony]

You would need to do either one piece or piece them together so the joint is centered on the platform. Also the use of connecting plates as mentioned above would be my recommendation as well. Couple questions you need to answer so accurate information can be given.

What size beams are you using?

What material is the beam? IE Laminated beam, dimensional lumber (would also need to know wood species)

How much weight are you planning on storing up there?

Are there any local building codes in effect in the area as far as storage lofts go? If so what are the load carrying and max deflection requirements?

Once the beams are in place how are you planning on attaching the joists to the beams? Joist hangers?

What is the clear span between the two beams?

Let me know and I can calculate out what size lumber, species, and joist spacing you would need. Local codes here for storage lofts are pretty strict. For the one in my shop which the joists will only span 10' I had to run 2x12 Douglas Fir (Northern #1) 12" on center to meet code. Got real expensive real quick.

 

[Vicus]

Vinnie

Maybe a picture tells more than words. Imagine the lower beam as ome of your posts.



Cheers Frank

 

[73pony]

Vinnie

Maybe a picture tells more than words. Imagine the lower beam as ome of your posts.



Cheers Frank

In your photo you show using a square beam assuming either 4x4 or 6x6 post type material. This would not be sufficient as the shear strength of a 4x4 or 6x6 is far lass than that of say a 2x8, 2x10 etc. Additionally removing 1/2 of the material of the post is a no no as the greatly reduces the strength at the load points.

 

[Don C]

I agree with Jason, I was just getting ready to respond when I saw his post. The top girders would be seriously weakened at the point of maximum shear. The girder/joist on the right will likely split along the length of it along the wood grain.

The preferred splice/connector is metal. I'll see if I can find a picture and post it.

EDIT: I believe this type of connector/splice will suit your need much better:

https://www.strongtie.com/boltedcolumncaps_columncaps/cc-ecc-eccu_productgroup_wcc/p/cc.ecc.eccu

 

[73pony]

Technically the plates would not be the best option. The beams should bypass one another with an approx 8" or greater overhang on the other side of the plate and be connected with offsetting ledger locks to tie them together. See pic below. The blue outline on the bottom represents your plate. The green and yellow represent your 2x?? beams the grey spikes represent the ledger locks. You will also need to fasten this to the plates as well. I would suggest making the plates into a "U" shape to house the beams and eliminate any side to side deflection then run bolts through to keep it all in place. At that point yourbest bet would be to then set your joists on top of the new beams and tie in with your ledger board as opposed to using joist hangers.

 

[Vinnie]

Thanks for all the replies, I have to re-read them to get a better understanding I think.

This is what the top of the poles look like:

8x20cm flat, 8mm thick. I’m leaning towards letting the beams rest on it with the ends so the split is on top of the pole.

I had an engineer do the maths already but he “engineered” the split in between 2 poles, I’m just wondering if it ain’t better to have the split on top of a pole.

The beams I’m using are 7x20cm btw.

 

[Vinnie]

Btw: the floor is used for storage, not to put another car on

 

[73pony]

Thanks for all the replies, I have to re-read them to get a better understanding I think.

This is what the top of the poles look like:

8x20cm flat, 8mm thick. I’m leaning towards letting the beams rest on it with the ends so the split is on top of the pole.

I had an engineer do the maths already but he “engineered” the split in between 2 poles, I’m just wondering if it ain’t better to have the split on top of a pole.

The beams I’m using are 7x20cm btw.

Put the split on top of the plates do not let them hang freely between the poles. 7x20 cm or basically a 3x8 in beam is pretty stout. Butt the two beams at the center of the post and I would weld a plate with some holes in it on the outside the entire length of the plate they are resting on to make an L shape since the other side is against the wall and positioned to sandwich the beams between the wall and the new plate then run some lag screws through the holes in the new plate to keep everything in place.

 

[libram]

just a word of caution from someone who actually works in construction, or at least beside it and is somewhat familiar with how this all goes. Before anything else you need to establish and set your load goals, how much weight you expect the level to hold and then increase it for safety. After that you need a qualified (insured licensed and bonded) engineer to review the size and strength of your poles and platforms and determine the correct materials and configurations of the supports for the floor itself that distribute the weight of the floor and its contents to the load bearing poles. Not to disparage any advice given here on the forums but unless someone states they are an engineer its all just what we think not what it should be. The last thing that you want is to fall 10+ feet crashing to a concrete floor amid lumber and I assume large heavy metal parts all coming down with you and on top of you. There is a reason people have professions and spend the time to study things like this, its not because it costs you more money, its so people don't die in a collapse covered in engine heads when the floor gives way.

As an example, my grandfather decided to build a new garage to house this mustang, after receiving multiple quotes from reputable contractors he decided he didn't like the numbers and his neighbor down the street said he could build it for 1/3 of the cost. He put up foundations made of retaining walls and didn't get a permit from the local govt for inspection. I told him it would collapse and he was making a terrible mistake. He went on anyway, now a year later the garage still stands but its back 1/4 has shifted out almost an inch, it WILL collapse and when it does nothing in it will be covered by insurance.

No the mustang isn't in there and if I can help it never will be.

 

[Vinnie]

Cheers, I'll make the split on top of the poles then. The wood is also C24 quality which is strong construction wood. The same size wood is coming in between every 40cm, hence the wood that lies on top of the poles can not slide off sideways which makes those side plates unneccesary I think?

I'll post my progress up in my garage thread when I get cracking on the wood (Currently doing some electrics)

Thanks!

 

[rcadd1ct]

Make sure your posts will not twist or move.  You need some sort of triangulation or support as the posts only work if they transmit the load straight down to the foundation.

 

[Vinnie]

Make sure your posts will not twist or move.  You need some sort of triangulation or support as the posts only work if they transmit the load straight down to the foundation.

My wooden beams that go along the side (= the ones lying on top of the poles) grip around a really big metal H beam from the main construction so they can't move back and forth. Because the wooden beams in between the side beams push them against the wall of the main construction the whole thing also cannot move side ways.

All this was discussed with a certified engineer who calculated the metal and wood I need. The only thing he did was leave the split in between two poles and I think it's stronger to have it on top of a pole, which is what I'm gonna do now

 

[libram]

Make sure your posts will not twist or move.  You need some sort of triangulation or support as the posts only work if they transmit the load straight down to the foundation.

My wooden beams that go along the side (= the ones lying on top of the poles) grip around a really big metal H beam from the main construction so they can't move back and forth. Because the wooden beams in between the side beams push them against the wall of the main construction the whole thing also cannot move side ways.

All this was discussed with a certified engineer who calculated the metal and wood I need. The only thing he did was leave the split in between two poles and I think it's stronger to have it on top of a pole, which is what I'm gonna do now

the very fact that he approved and designed an open unsupported gap between supports is what would bring up questions of if he was truly qualified if it were me. If that is ok to him what else is? Sometimes a second opinion can make a big difference on what you believe.