Maximum tenon width

[Anonymous]

I'm in the middle of making a replacement for my garage personal door - frame, ledge and braced with t&g on the outside. I was going to make a straight copy because the proportions look good.

But I'm worried about the width of the rails - about 18cms. If I have 18cm tenons at each end, that are going to be glued into mortices in the stiles, am I going to have problems with the rail splitting if it shrinks in the future.

Any ideas welcome.

Thanks in advance.

Steve

 

[johnelliott]

So, 49 views and no answers so far, there must be a problem with the question. I think you need to provide more info. For instance-
What material are you using? (hardwood, softwood?)
How deep are the styles?
Is the garage heated, dry?
Will the tenons be wedged (this is quite common on large doors)
What glue will you use?

All the above info will be of interest, and may affect the answers, but I really can't see that there's going to be a problem, ie the joints coming apart, especially if you wedge or peg them
John

 

[Dewy]

Wedged tenons go right through the styles so the tenon length depends on the timber width of the styles.
This is the standard type of tenon used on doors often with a haunch to improve stability.

 

[Steve James]

Hi SJB

As you are copying the original doors, does this not give you some indication of the size of tenon?
A 180mm (middle and bottom ?) rail, does not sound big, in fact it is a common size.
I think if you have a closer look at the original door, you should find that the tenon is a "twin tenon" as the theory say`s that the tenon should not be more than 4 times deeper than it is wide (I think it`s a factor of 4, but may be 5).
I think you will have to have bare faced tenons on a framed, ledged, braced and battened door.

This is all from memory of college over 20 years ago!
but I think it`s somewhere near.

Steve

 

[Dewy]

A haunched tenon is the strongest joint used for rails on a door with the haunch approx 1/3 of the tenon.
This resists twisting but does not overweaken the style.

A twin mortice and tenon (with centre haunch) is normally used for the centre rail of doors.

Sorry for poor attempt at using MSPaint. :wink:

 

[Anonymous]

Thanks for the replies chaps.

John, the material will be iroko (I have some I picked up second hand) - unusual I know, but it should last! I want to use through tenons and wedges, and because it's iroko, I'll be using Extraphen as the glue. Stiles are about 10 cms wide.

Lock and bottom rail will be bare faced to allow for the width of the t&g boards on the outside. The garage does get damp over winter so there will be a fair amount of movement in the wood I should think.

Dewy/Steve Thanks for the tips. I can follow the reasoning behind the tenon size and shape, and the need for the haunch to stop twisting.

It's just the width of the tenon that worried me. If you glue up a panel in a frame you risk splitting, so you leave it unglued so it can "float". I was just worried that glueing an 18cms tenon might also lead to splitting. As you say I can just copy the original, which seems to work, and it is a standard size.

I guess I was just looking for confirmation that it would be ok. ( It even occurred to me that the tenon might only be glued on one half to allow the other end to move, but I've never seen this mentioned anywhere).


Thanks for the help

Steve

 

[johnelliott]

Steve, with the doors being subjected to some damp, may I recommend polyurethane glue? I use the Titebond poly from Axminster, g'teed to be totally waterproof
John

 

[Anonymous]

John,

I did think about polyurethane, but I'm sure I read somewhere that extraphen is equally waterproof and copes well with oily woods like iroko.

I've never glued iroko before, and especially for this application, I want something that's going to be ultra strong and resist the damp.

Steve

 

[andrewm]

An interesting discussion. My garage doors are getting to the end of their life and my local builders merchant offers hardwood up and over doors or softwood standard doors. I was enquiring about standard (side opening) hardwood doors and was told that they didn't do them because of the risk of them warping. Is this likely to be a problem? If not (and they were wrong) then I might revisit my ideas of hardwood doors since I would also like a matching front door.

Andrew