Sill joint

[pike]

Hey all,

Can anyone tell me if in the sill joint below, are the mortise for the sill tenon and the mortise for the post stub tenon connected. In other words, can you see the sill tenon through the posts stub mortise? I've looked in lots of books but nowhere seems to have the answer.

I'd have thought you just make sure the sill tenon is lower down so there is plenty of wood between the two mortises, but diagrams and photos suggest otherwise.

Cheers!
Carl

 

[bosshogg]

Normally the sill is the bottom rail of a window, or in some cases a door frame which has vertical mortices to both sides housing the uprights or side stiles. There would be not generally be any horizontal mortices as depicted in your post, then again I may be both reading your post and viewing it wrong...bosshogg

 

[pike]

Sorry I could have been more specific. This is the bottom sill of a timber frame building.

 

[Richard T]

I've just looked through "Discovering Timber - Famed Buildings" by Richard Harries and it's not clear either.
The two tenons can't occupy the same space, so I guess it's down to the proportion of the sill beam as to which passes which. In your drawing it looks like the post tenon would be better passing the end of the sill tenon. ? :| ?

Though I've built two timber frames, neither of them have sills - just free standing posts on brick pillar footings. So the problem has no arisen for me there.

 

[bosshogg]

OK...timber frame houses, today, are normally not mortice & tenoned, the bottom runners of the timber frames sit on a wall plate, whereupon the overlying but joints are staggered.
Looking at the pic you have posted, shows two dowels and recipient holes in the tenon of the horizontal bottom rails. whether draw or not, these would help against spread or opening of the joints due in part by age and part by contraction. The vertical - studs - would resist any similar movement through gravity and weight alone, but locating tenons would resist any side or lateral movement. Both tenons being of a different nature would not structurally benefit from being joined, the amalgamation of the mortices being neat rather than practical...bosshogg

You can't help a man who doesn't tell you what he wants (homer)

 

[pike]

Thanks for helping Richard. I realise they can't both be in the same space but in most books and photos I've seen it sort of looks like the post stub tenon would be sitting directly on the surface of the sill tenon (or have very little wood between them).

bosshog: I know when the joint should or shouldnt be used, I'm just asking a very specific question as to the location of the mortises.

Carl.

 

[rannndy]

in this situation the tenons are mitred
john

 

[Richard T]

You could be really snazzy and butt - mitre both of 'em but no one would ever know

Having said that, my most impressive dovetails are completely hidden at the ends of the tie beams.

Dratt ... beaten to it again ...

 

[RogerS]

Use a couple of Domino's? :wink:

 

[pike]

Use a couple of Domino's? :wink:

If I could I would I do have one. *Probably* not quite up to the job though.

 

[houtslager]

iirc the stub tenon "locks" the sill tenon into the mortice.

hth

K

 

[milkman]

The sill tenon can be a bit lower than center and the post tenon short enough not to clash with it.
The post relies more on the shoulders in this instance than the tenon.

 

[pike]

Thanks. I think what confused me was most drawings made it look like they would conflict. As you say milkman, you can just lower the sill tenon to make sure they don't. Also the post is a stub tenon so not very long at all.