Joining different dimensioned posts

[Woodenskye (Bryan)]

Thread transferred from previous forum - Original Post by Puka

Original Post:

QUESTION

 

Whats a good simple method for joining a square 100mm post [upper] to a square 125mm square post [Lower].

 

At the Crib in Taranaki I have concreted in some short 125mm H5 Treated piles. These are a standard dimension for a wood pile. I now wish to extend the height of this pile by a few meFotres to brace the end of an extended roof.

 

I had a brief net search but the only thing I could find that sort of sounded right was using a lapped joint. I could cut a slot but it would need to be off to once side as there would only be 25mm [or for you guys an inch] of wood to play with. 

 

I'm thinking a lapped joint sounds pretty good as I could then run a couple of bolts through them both. Perhaps I could also add a metal plate on either side with 4 holes two above through the joint and two below the joint for added strength?

 

What do you guys recon. Its been doing my head in thinking about a fix for a couple of weeks now.

 

Follow Up Posts:

 

1)  11 VIEWS ZERO REPLIES

Which means jackity boo because I will be buying what I need in 14 hours and i won't be checking this forum again till Monday. So cheers .

I'll just go then with what I have figured out from some of the engineering sites I looked at.

TA

 

2)  Well, you're talking construction, not really what we do..  Most of us have done some construction work but, probably not a lot.

In the end, you're looking to extend poles.  Regardless of the joint, this will be the weak spot.  I'm guessing that the metal plates will be your best option.

 

3) ALL I'M SEEING HERE ARE EXCUSES...OLD BUDDY.

Since I posted the question I have since found 4 or 5 different fixes all using basic wood joining techniques that I reckon are all viable. A couple don't even use metal hardware.

Basic traditional wood frame joints.

I was after ideas.

So don't be shy put them out there.

 

4)   Buy a longer 125 mm post.

 

5)  You could do a mortise an tenon. How much lateral pressure would the post have on it? Or just downward force. That would be the most important question on the type of joint an fastener you could use.

 

6)  Absolutely correct which is why I couldn't come up with a quick answer.  Vertical forces wouldn't be an issue, it's how to stop lateral forces from things as simple as the building settling.  I suppose if you were to tie in lateral supports at the joint, that would be plenty strong.

 

7)  I would use a bridle joint and put the male on the lower post .

 

8  Have been busy so haven't really been doing much surfing on here. The posts main job will be to anchor the roof and stop the wind from blowing it up the valley.

So with this in mind there will be sweet little nothing of down ward force with mostly upwards when it blows. Since its at the bottom of the valley the wind tends to funnel threw and blow a bit of a gale.

I did some surfing here and there and looked at various building specifications and have come up with a new bracket setup. Will drop a pic or two in here when i have it bent to shape drilled and welded together.
 

Unfortunately after I bolted the bearers to the posts I discovered that the excess post length that I needed just wasn't there anymore so the chamfering I was going to do along with the bolted lap joint is now not an option. Instead of bolts I will be using coach screws. due to the lack of room.

 

This is what happens when u change the building design after you have concreted the 125 sq posts into the ground.

 

Yayeee for me...