6 metre Lintle / RSJ advice please?

[wavetrain]

So is that how the roof set up I have works... with very little load on the front & rear walls ?

Wrong!

Having thought further on this matter, the trussed purlins are trussed because there is not a central supporting wall for the purlins to be supported via struts. Therefore underneath that insulation there must be horizontal joists coupling the front and the back rafters together.

Without that coupling the whole roof would slide off and crash to the ground.

Therefore the weight of the roof is taken by the front and back walls. You will need a SE to confirm this for you of course.

 

[RonnyRaygun]

So is that how the roof set up I have works... with very little load on the front & rear walls ?

Wrong!

Having thought further on this matter, the trussed purlins are trussed because there is not a central supporting wall for the purlins to be supported via struts. Therefore underneath that insulation there must be horizontal joists coupling the front and the back rafters together.

Without that coupling the whole roof would slide off and crash to the ground.

Therefore the weight of the roof is taken by the front and back walls. You will need a SE to confirm this for you of course.

Not quite...the joists at loft level should take out the horizontal tensile forces to stop the roof spreading, but the trusses will still be transferring most of the axial roof load to the side walls. The only roof load that will get to the front and back walls is half of the total load between the trusses and the front / back walls.

 

[wavetrain]

I had assumed (because I could not see in the photo) that the rafters were resting on a corner of the purlin without a notch cut out of the rafter. If the rafter does have a notch like the one cut in the rafter over the wall plate, - and I sure it does, no one would design a roof with a rafter resting on the corner of a length of wood, would they?, then yes RR your are quite correct and I am wrong. At least I got a bit of it right, there is still some weight to support by that front wall.

 

[hammerswinger]

I had assumed (because I could not see in the photo) that the rafters were resting on a corner of the purlin without a notch cut out of the rafter. If the rafter does have a notch like the one cut in the rafter over the wall plate, - and I sure it does, no one would design a roof with a rafter resting on the corner of a length of wood, would they?, then yes RR your are quite correct and I am wrong. At least I got a bit of it right, there is still some weight to support by that front wall.

There's no cut out over the purlin, there are some big nails though

Maybe there should be a cut out, but I can only guess that they had hammers but no saw so they took the nail option....remember we're talking about houses that were thrown up here!


Thanks.

 

[geraint]

clue for gerraint

m=wl2/8 (for a udl) and don't forget the partial safety factors!

still waiting for the so called enlightened ones.....

where are you...

not reading...

 

[deanomy]

geraint = troll

203x100 uc = section does not exist!

gerraint you could mean a 203x102x23UB, not sure if that would be adequate if it had to support the load from a new extension, show us your workings?

Gerraint why don't you try & help people rather than trolling.

 

[wavetrain]

I agree, geraint = troll

he has won the 'most trolled thread award' for this season.

 

[geraint]

geraint = troll

203x100 uc = section does not exist!

gerraint you could mean a 203x102x23UB, not sure if that would be adequate if it had to support the load from a new extension, show us your workings?

Gerraint why don't you try & help people rather than trolling.

get your facts right please... a 203x100uc is rolled...

so please get your facts right before you accuse me of being a troll...

bloody jo boys that try and think..... dangerous...

please keep the insults up to prove yourself......

 

[geraint]

I agree, geraint = troll

he has won the 'most trolled thread award' for this season.

so when will you present me with my award....

what is it with people when they are proved wrong...

i guess the best form of defence is attack...

cowards in my book...

 

[Static]

get your facts right please... a 203x100uc is rolled...

Well i've never seen or heard of a 203x100UC so would be interested in a link to a steel manufacturer who rolls one..
Just i've read BS4-1 and its not listed.. is it a non UK size?
Or perhaps a cold rolled section.. or do you actually mean a structural tee?

 

[RonnyRaygun]

get your facts right please... a 203x100uc is rolled...

Well i've never seen or heard of a 203x100UC so would be interested in a link to a steel manufacturer who rolls one..
Just i've read BS4-1 and its not listed.. is it a non UK size?
Or perhaps a cold rolled section.. or do you actually mean a structural tee?

Definitely means a 203x102 section doesn't he.
Might be a UB, Joist, or Tee, is never going to be a UC...

 

[^woody^]

One of our local steel merchants stocks beams in some wacky [european ?] sizes which are close to BS4 but not quite the same, and you have to be very careful to check what beam he sends out.

He's cheap though

 

[geraint]

get your facts right please... a 203x100uc is rolled...

Well i've never seen or heard of a 203x100UC so would be interested in a link to a steel manufacturer who rolls one..
Just i've read BS4-1 and its not listed.. is it a non UK size?
Or perhaps a cold rolled section.. or do you actually mean a structural tee?

a structuall tee....

so please enlighten us all as to what
size section that tee would come from...

 

[geraint]

One of our local steel merchants stocks beams in some wacky [european ?] sizes which are close to BS4 but not quite the same, and you have to be very careful to check what beam he sends out.

He's cheap though

must be indian or chinese...

as our countries imports of steel beams are....

 

[RonnyRaygun]

a structuall tee....

so please enlighten us all as to what
size section that tee would come from...

OK, I'll enlighten you Grrraint...a 203x102 structural tee comes from any 203x203 UC section.
Basically a 203x203 section chopped straight down the middle of the web.

I don't think a 203x100 structural tee exists...in fact, looking through British, American, European, Indian, and Chinese section tables, I can't find a 203x100 section anywhere...