splicing poles for pole barn

[mark123]

I had a 30 x 85 tarp building and I built it on a 5' high knee wall. The wall is built from 6x6's on 5' centers buried 4' in the ground with a double 2x8 as a top plate. My tarp building collapsed from a heavy snow load but the knee wall is still fine. I would like to possibly build a pole barn to replace it. Could I splice 6x6's onto my existing 6x6's to make them taller, I was thinking using a 2-3' half lap joint bolted together. Is this a crazy thought? What about building a 8' tall 2x6 wall on top of my existing knee wall, is that an even crazier idea or should I just pull all my existing poles out (38 of them) and start from scratch.

 

[TractorJeff]

There was a thread a couple of weeks ago where they bury PT wood and were splicing non-PT on top.

 

[csp]

I haven't seen that thread, but I'll bet bottom dollar that those spliced posts were laminated posts (three layers of 2x6 for example), not 6x6s like the OP is wanting to do.

 

[Deej-79]

I'd talk to an engineer but building on the knee wall isnt a crazy idea imo

 

[Rookie2]

That's how Morton Buildings are built. except the use 3 PT 2x6 in the groung cut at different lengths.

I believe they have a video showing how they build the walls on the ground and they hinge as they raise them in place.

 

[jkwilson]

If you do that, you'll be doing standard stick built construction. Pole construction relies on the lateral bracing of the posts in the ground to reduce the need for diagonal bracing or sheathing. A spliced joint on a pole 6ft out of the ground is either going to be so massive it would be cheaper to pull it out and start over or so weak it can't do the lateral bracing.

That doesn't mean you couldn't somehow reuse the knee wall, but you probably want to talk to an engineer.

 

[tomroblee]

I'm certainly not an engineer and have no experience with this sort of thing. That being said, I have seen a lot of buildings that are built on concrete stem walls. I've seen them built with wide spaced square posts attached to normal sill plates or attached directly to the concrete with steel brackets such as:

https://permacolumn.com/drill-set-models

I've also seen a lot of buildings built on what were described as "wood piers" (rather than pole barn knee walls). It seems like the same principal (but different?)

Before I tried this, I would want to consult an engineer. Replacing the posts might be cheaper than hiring an engineer and/or purchasing a lot of special brackets.

 

[matt_i]

The question for me would be: what was the treatment of the 6xs that were put in the ground? Do they sit on a concrete "foot"? Do they have concrete poured around them? Or were they just stuck in and backfilled.

A pole building relies on the pole being able to individually support a "moment" or "tip over" more than a stick built building. The stick building gets its racking or tip-over resistance from all the plywood or OSB siding judiciously nailed to it.

After that the question would be coming up with an accurate way of machining the existing timbers so you can splice into them. I envision a long square-bottomed "Y" that you would machine into it to thru-bolt a 2x6 in 2 spots about 6" apart. That would take some doing to be accurate and well made. Could it be done, yes, but a lot of pre work with chisels and hand planes and a couple dozen sawzall blades....

 

[mark123]

They are rough sawn true 6" eastern hemlock treated specially treated for in ground use (not common lumber yard material), no concrete footing and back filled with sandstone/baseball size and smaller. They are locked in there very well.

After thinking this through a bit more it probably doesnt make any sense to splice them. They are on 5 foot centers so splicing them all would mean I would have to buy 38 more timbers whereas if i started from scratch I would only need 26 on 8' centers and avoid the machining/ bolting etc...

As for building a 2x6 wall on top I can't envision what would stop it from tipping over sideways, the only thing holding the walls plumb would be the front and back walls and at 85 feet apart is that too much too ask? I might be better off just replacing the tarp structure with another one designed for heavier snow load. The one that collapsed was an extremely cheap chinese import i bought at an auction, new for $2700.00 (if it sounds too good to be true, it is) A quality tarp building of equal size will cost me approx $15000-$20000. The cost for trusses, steel roofing, siding and lumber will be in the $15000 range.

 

[flat tire]

years ago logs were spliced together with just wooden dowels
I have 8x8 pine timbers in the ceiling of my house and 2 of them are spliced.
I made a 4' lap, counter sunk the holes, used 3, 1/2" bolts and glue to put them together. saved the shavings/dust from the holes I drilled, mixed with a little glue, filled the holes, sanded, tiny bit of wood putty and stained
unless I was to point it out you would never see it

 

[Kevin54]

If you go with a half lap joint, I would also go with a 2x6 on each side to stabilize things. Basically you would have a laminated beam only with a 6x6 in the middles instead of a 2x6. Then bolt the complete setup together.

 

[gungatim]

never heard of those, exactly what is a tarp building? any pics? put a location in your profile, is this something in the US?

 

[finn]

I'd stick build on top of the knee wall using 2"x6" studs. No different than building on a concrete block stem wall.

Use temporary props staked to the ground to support the wall during construction. The roof Trusses ultimately tie the structure together.

 

[lakeroadster]

Mark123, sure you can splice them, if you splice them correctly.

The design type discussed in the other thread is referred to as "Built Up Lumber Columns"..

Even though your building has 6 x 6 columns the following links should help in designing the splices.

http://www.stepbystep.com/Nailing-Together-a-Built-Up-Lumber-Column-122827/

http://www.strongtie.com/ftp/letters/generic/L-F-SDWBLTUP15.pdf

The other thread:
http://www.garagejournal.com/forum/showthread.php?t=319469&highlight=column

 

[crackerjack222]

Cheap as I am, I would try to use what you have. Why not splice every other post? I would not hesitate to use a half-lap splice with thru bolts and large washers.

 

[MagKarl]

There is a hybrid construction method that starts just like you have with poles and then stick frame on top. What you have would be similar to building on top of a stem wall.

Would this be an open or closed wall building? If closed, could work for you.

 

[ryan77]

splice every other one(10ft centers) and use good x bracing in between and build that pole barn.

 

[mark123]

never heard of those, exactly what is a tarp building? any pics? put a location in your profile, is this something in the US?

Here is one of the larger manufacturers in Canada. http://www.norsemanstructures.com/
They are very popular as they allow light through, easy to build. The one I bought used single pipe structure and being a cheap chinese import I just discovered thinner wall tubing than the norm. Mine measures 0.060" wall 2.25" the norm is 2.375" 13 gauge tubing. I have another one that is a domestically built one and it is 10 years old and several times has had 3' of snow on it with no problems.

 

[mark123]

splice every other one(10ft centers) and use good x bracing in between and build that pole barn.

I assumed 10' spacing would be too much, what should i use for the top plate as there would be 4 trusses on it unsupported by posts, 2x6's inside and out on edge then capped with a 2x10 perhaps?

 

[mark123]

Cheap as I am, I would try to use what you have. Why not splice every other post? I would not hesitate to use a half-lap splice with thru bolts and large washers.

which way would be best to orient the half lap? Or maybe alternate every other one 90 degrees?

 

[lakeroadster]

Mark123, where are you located? The size of the upper column to column headers will need to be based on snow loads / winds loads in your geographic location.

 

[mark123]

I'd stick build on top of the knee wall using 2"x6" studs. No different than building on a concrete block stem wall.

Use temporary props staked to the ground to support the wall during construction. The roof Trusses ultimately tie the structure together.

Is the framing/sheathing the end walls the main thing preventing the whole structures from collapsing left or right when looking at it from the front. In other words what is stopping the left and right walls from both leaning one way or the other, I mean could you build this without end walls or are they the main reason it works? I would have a 12 X 12 garage door at either ends, would this weaken the end walls substantially?

 

[mark123]

Mark123, where are you located? The size of the upper column to column headers will need to be based on snow loads / winds loads in your geographic location.

Prince Edward Island, eastern canada.

 

[lakeroadster]

Mark you really owe it to yourself to at least buy a set of engineered plans that are applicable to your location.

It will detail construction methods and sizes of lumber that will answer the bulk of your questions.

You've already experienced the pain of a building design that isn't engineered for it's specific location.

The Garage Journal is a great place, but you never know if the guy answering your question is knowledgeable in the topic at hand, or is that neighbor guys kid that lives in the basement, that doesn't have the ability or desire to even change the flat tire on his Honda Civic.

Or in other words be mindful that "free advice is worth the price you pay".