Heavy clay roof. Need some advice on the calculator

[Don P]

@Jim_Rogers 

[Jim_Rogers]

Thanks Don. @Jim, might you be able to post the picture? Thanks

 
To be accurate, you need to calculate the shrinkage of the ridge beam from left to right as well as up and down. And make sure your gap is bigger than that amount. If the ridge beam shrinks to the point where the rafters lift off the ridge then the thrust could be increased.
Jim Rogers

[DBoyle]

Thanks Jim. The picture is very helpful and the clarification to account for both horizontal and vertical shrinkage. I must admit, I hadn't immediately thought of the vertical component.

[DBoyle]

This is more of a venting exercise as I think I might need a day or 2 off from framing work. Moved 3 x 20 footer English oak 6 x 9" beams into my garage to work on as the rain just wouldn't stop. Using snap line square rule and thought I'd get 2 of these marked up in preparation for the wall plate joinery... Was completely busted after moving these and then a bit disappointed when there was more bow in the wall plate pieces than I had thought . About 1/4 over 20' (maybe that's not much or maybe it is?): if I were to do the joinery and set the plate on the 3 jowled posts either the 2 post end tenons would fit and the middle not, or vice versa.  

Should have enough margin in the stock to account for bow. I had thought about using the persuader and leaving this in and letting the frame suck it up but I have concerns that additional outward pressure on the plate tenon could help split the jowled post between post tenon and teazle tenon.

Anyway, broke my chalk line >:(and thought I'd try using a laser line I already had. A lot slower as you have to draw in the line but worked quite nicely as a backup and much nicer than the photo shows. Unless you had a really expensive model, it wouldn't be much use in strong daylight though (green lasers apparently work better in strong light).



 


The previous day's work was test fitting sill members. You can see my beam transportation apparatus at the right   



 


 

I made a slight modification of my boring machine to help get more consistent depths. I had been counting revolutions which was fairly accurate but found my mind wandering back to the roof details which continue to keep me awake and so kept loosing count. So instead I made some markings on the upright with zero corresponding to the top of the sliding guide and when the snail is fully engaged and the cutters just touch the surface. Originally just light penciled in but couldn't properly see so now lightly scored. Anyway, I feel a bit better having got that all out. Apologies for the ramble.


 

 
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[DBoyle]

I'm about to drill holes in teazle tenons in jowled posts. These will be offset down towards their shoulders but I read in a TFEC publication on drawboring that these should also be offset horizontally to anticipate post shrinkage and mitigate as much as possible post splitting. I assume that the horizontal offset is towards the plate side (towards center of post). Can someone confirm this is correct as per my crude diagram?

 

[Jim_Rogers]

The way to remember which way to offset a peg hole is put out your two hands. The drawing you showed the post is your right hand. The plate would be your left hand. To offset the peg hole, you want to move your left hand to the right because that is the way you want your timber to move, then that is the way to offset the peg hole. Offset the peg hole in two directions does take some thought. And if you do it wrong, you'll push the joint apart. Once you've pushed a joint apart, you'll learn how to offset the peg holes correctly. I would rotate the left arrow to the right.
Good luck with your project.

Jim Rogers

[Don P]

The horizontal offset is not a drawbore, simply a note to move the peg left as you indicate in the drawing so that when the post shrinks it is less apt to create tension perp to grain between the locked plate and tie in the post.

It's in a way the same admonition not to bolt a 2x12 deck rim to post wider than 5" apart on the bolts or it'll probably split as it dries.

[DBoyle]

Is there any merit in not pinning the teazle at all given the weight of the roof and siding should hold things snug 

or

pinning in a few years and not offsetting in any direction as it wouldn't be possible then anyway.