joist to rafter connection

[RickH]

I have been putting in a cut roof ..... where the joist crosses the rafter I have arranged that these meet side by side rather than meeting under each other (as in a truss)
What is considered best way of joining these together ...
they are 100 x 50 treated C24 timber.

i.e. as per this sketch ...
http://tinyurl.com/m3l86gk

I could simply screw together with 2 coach screws per joint, using http://tinyurl.com/mnr8ll6

This would seem strong enough to me, these are the fixing that are used to join joists together to make double joists .. have a load left over from a truss roof job.

I could even put a timber connectors between them as well
http://tinyurl.com/ke3fkrt

Or to use those would I need to put a thru bolt
http://tinyurl.com/ktnuc3b

and have this pass thru the timber connector ...... just the thru bolts will not look nice as open rafters on show.

 

[catlad]

Over construction if you have these to spare than use them by all means.

 

[^woody^]

4" nails will do fine

 

[RickH]

nails?
only nails in this job will be on the roofing battens.
Everything is screwed with SPAX wirox screws.

 

[noseall]

Try and pry apart a connection with a pair of 4" nails in it particularly if the nails have been opposed skewed.

 

[RickH]

also seen many joists split by skew nailing.
The other big issue on a roof structure that has no side walls, is that after you bash in nails on one raster, when you then go to next one the bashing in . loosens the previous, and so on.
Weakens the structure.

I decided to move to 21st century and use wirox washer-head screws, specifically designed for 1st fix.

 

[catlad]

If you want to move into the 21st century then buy yourself a 1st fix nail gun with ring shank nails.

 

[RickH]

I have had a 1st fix & finish nail gun since last C.
Good for framing, fencing but I don't like them for joists, as not a fan of skew nailing

 

[noseall]

also seen many joists split by skew nailing.

Seen many joists split with skewed screw heads, ho hum.

Weakens the structure.

Total roast and blarney.

I decided to move to 21st century and use wirox washer-head screws, specifically designed for 1st fix.

Good for you. I exclusively screw too but that's because i don't have a nailer.

 

[RickH]

>Total roast and blarney.

I don't agree with that .... if you have for example 30 rafter to put up on a roof supported by 4 corner posts only .... i.e. no walls.

To nail rafters to joists is a large amount of hammering and sideways bashing of structure. (unless you use nail gun)

If using 2 x 4" nails (as mentioned above) ... the continued movement will weaken joints already nailed as you make each successive one.
Maybe joist to beam is not so much of issuer, but rafter to joist joint is the concern.

Putting screws in avoids the flexing of the roof. ... and in 6this case the ring beam around the 4 posts.

I recently put up a fully trussed roof .. and the structural guarantee was specifically stated as void if fitting was via skew nailing rather than using supplied joist & rafter clips ...

 

[noseall]

You obviously don't know how to use a hammer and a nail then.

 

[^woody^]

nails?
only nails in this job will be on the roofing battens.
Everything is screwed with SPAX wirox screws.

WOW. Nails are not good enough, and nor are any old screws either, so it has to be some impressive sounding screws. That reads like some sort of conceited statement, which we are supposed to marvel at.

How did we all manage to build roofs for the last 5000 years without good old Spax wirox screws?

Screws shear, whereas nails flex, and that is why they are the fixing of choice for cut rafter roofs, unless a certain connection requires a rigid fixing normally a structural member.

Your reference to some or other warranty requiring screws for a trussed roof, does not apply to other timber frame construction, as the two types act completely differently

 

[noseall]

I recently put up a fully trussed roof .. and the structural guarantee was specifically stated as void if fitting was via skew nailing rather than using supplied joist & rafter clips ...

Are you aware that truss companies supply sheradised twisted NAILS and not screws to secure their truss clips?

 

[RickH]

yep ... and used those for the wall plate connections on that job ...

Putting in square twist 35mm nails into a wall plate on to of a solid wall was no problem.

This job nailing joists to side of rafters would cause too much side ways vibration on a 4 post only supported roof, so used screws.

i.e.: as it is so far:
http://tinyurl.com/nog6yo2

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