Roof joist installation

[Gauss]

Hi - My builder is in the process of finishing off my 8m by 9m outbuilding and he’s installed the roof joists as attached.

Does this look right? Any advise or thoughts are appreciated.

TIA.

 

[Bonni]

Where's the wallplate on the steel? Where's the structural engineer's plans? You would normally fix a timber wallplate to the steel and then fix the top of the timbers to the wallplate.

Are there any horizontal timbers on the structural plans just below the steel? If so, the timbers sit side by side at the top so horizontal timbers will now not fit unless you pack out by the thickness of the timbers. I normally bolt mine together with dog washers in between (teethed washers).

 

[catlad]

It may be my eyes but that beam looks slim for 8mts
as per Bonni the beam has been drilled for timber to be bolted to it? He might line the rafters up before he continues.

 

[Gauss]

Rafters are interlaced and are screwed together? They then placed wood between them and screwed along too.

Beam is 150 x 150

 

[^woody^]

It could be nit-picked, but it looks like a nice job.

 

[paulrockliffe]

If it's an outbuilding then that method may be preferable as it'll let you get a block and tackle running along the bottom flange of the beam.

 

[bobasd]

just saying, not criticising - its not a sloppy job so things may have been done for a purpose?

looks like the angle of the roof comes out at 15 degrees - kind of low.
as mentioned above, collar ties would help - so would Simpson angle brackets tieing the rafters at the wall plates - cant tell if the rafters are birds mouthed?
and allowing the rafters to run past the RSJ before snipping off the corners (to be in plane) would have allowed more rafter meat to screw to.

 

[noseall]

looks like the angle of the roof comes out at 15 degrees - kind of low.

I think you need to swot up on your trig mate. 18 degrees at least.

 

[bobasd]

Thanks, your right, its 18.43 degrees.

 

[catlad]

I've just noticed how little those rafters overlap at the ridge
That's a poor detail.

 

[Leofric]

Some photos were posted on here recently showing some neat examples of dual pitched roofs with one example using a steel ridge beam and another using a timber ridge beam. These had the basics of good construction with the rafters in line and birdsmouthed over a timber plate on the top of the steel beam and collar ties as others have mentioned under the ridge beam. The rafters at the apex also need tying together.

 

[noseall]

Some photos were posted on here recently showing some neat examples of dual pitched roofs with one example using a steel ridge beam and another using a timber ridge beam. These had the basics of good construction with the rafters in line and birdsmouthed over a timber plate on the top of the steel beam and collar ties as others have mentioned under the ridge beam. The rafters at the apex also need tying together.

Thanks for the compliment....

Congon23

• noseall
• 19 Jul 2018

Congon3

• noseall
• 19 Jul 2018

20170322_085233

• noseall
• 30 Mar 2017

20170322_085235

• noseall
• 30 Mar 2017

 

[catlad]

I take it the apprentice cut the collar ties in the first picture
being that short!

 

[noseall]

I take it the apprentice cut the collar ties in the first picture
being that short!

Lol.

They aren't collars in the true sense although they will act as such and add stiffening. The roof was designed without collars. They are more cosmetic i.e. there to cradle the plasterboard hence the spindly 3" x 2". You are right though that 'my right arm' did a lot of the work on that job. It was his 'test', being as it's my connie that was being bashed about. The snots he left on the back of the blockwork, almost spanned the entire cavity.

 

[Leofric]

Whatever you want to call them the horizontal timbers under the ridge beam basically fasten the rafters together and are best taken across the full width of the rafters (with splay cut ends of course )