Adding pillar support for RSJ

[tony1851]

The beam I've been told to use is a 203 203 UC 46, based on the 5.8m span. That's quite heavy no? Surely the single skin wall could just collapse with the weight of that plus roof
End of beam would be covered with fascia yes.

Far too big for a roof of that span - that's not engineering, just guesswork.
IMO and with a back-of-fag-packet calc, a 203 x 133 x 25 would be the optimum in bending and deflection.
And you don't need a pier - waste of time and money.

 

[Ab12]

Far too big for a roof of that span - that's not engineering, just guesswork.
IMO and with a back-of-fag-packet calc, a 203 x 133 x 25 would be the optimum in bending and deflection.
And you don't need a pier - waste of time and money.

Thanks

So you'd sit the steel straight onto e.g. 300 x 100 x 100 padstone on the single skin wall? Is that even enough beam sitting on the wall (100mm?)

Or would you go for UC pillars/posts?

 

[tony1851]

UC posts! OMG NOOOOOO!!

OK, lets get to basics.

Your beam will be carrying approx 16 m2 of flat roof over a span of 5.7m, right?
Live load will be 0.75 kN/m2, so tot 16 x 0,75 = 12kN - x 1.6 for the partial s/factor = 19.2kN
dead load (assuming joists + chip deck + finish) will be approx 0.5kN/m2. so tot. 16 x 0.5 = 8kn x 1.4 = 11.2 kN
so total design load supported = 30.4 kN. Lets add 2.0kN for the design load of the beam itself, so grand total =
32.4kN.
One-hafl of this will be the load on your 1/2 brick wall, = 16.2kN, which is peanuts.
A suitable stock padstone would be 215 long x 100 wide x 140 high. The stress under this on the brickwork would be
16.2 x 1000 /215 x 100 = 0.75N/mm2. Most brickwork will take 2N/mm2 plus so you are well under.
If you don't want a padstone showing below the fascia board, you could use a steel bearing plate 215 x 100 x 12-15mm thick.

 

[Ab12]

UC posts! OMG NO!

OK, lets get to basics.

Your beam will be carrying approx 16 m2 of flat roof over a span of 5.7m, right?
Live load will be 0.75 kN/m2, so tot 16 x 0,75 = 12kN - x 1.6 for the partial s/factor = 19.2kN
dead load (assuming joists + chip deck + finish) will be approx 0.5kN/m2. so tot. 16 x 0.5 = 8kn x 1.4 = 11.2 kN
so total design load supported = 30.4 kN. Lets add 2.0kN for the design load of the beam itself, so grand total =
32.4kN.
One-hafl of this will be the load on your 1/2 brick wall, = 16.2kN, which is peanuts.
A suitable stock padstone would be 215 long x 100 wide x 140 high. The stress under this on the brickwork would be
16.2 x 1000 /215 x 100 = 0.75N/mm2. Most brickwork will take 2N/mm2 plus so you are well under.
If you don't want a padstone showing below the fascia board, you could use a steel bearing plate 215 x 100 x 12-15mm thick.

Building is 5.7 x 5.7.

Beam will carry "both sides" of the flat roof /split in half ...

I assume this doubles the 32.4kn though and changes calcs?

if not, do I need to worry at all about lateral stability?

 

[Ab12]

UC posts! OMG NOOOOOO!!

OK, lets get to basics.

Your beam will be carrying approx 16 m2 of flat roof over a span of 5.7m, right?
Live load will be 0.75 kN/m2, so tot 16 x 0,75 = 12kN - x 1.6 for the partial s/factor = 19.2kN
dead load (assuming joists + chip deck + finish) will be approx 0.5kN/m2. so tot. 16 x 0.5 = 8kn x 1.4 = 11.2 kN
so total design load supported = 30.4 kN. Lets add 2.0kN for the design load of the beam itself, so grand total =
32.4kN.
One-hafl of this will be the load on your 1/2 brick wall, = 16.2kN, which is peanuts.
A suitable stock padstone would be 215 long x 100 wide x 140 high. The stress under this on the brickwork would be
16.2 x 1000 /215 x 100 = 0.75N/mm2. Most brickwork will take 2N/mm2 plus so you are well under.
If you don't want a padstone showing below the fascia board, you could use a steel bearing plate 215 x 100 x 12-15mm thick.

To give current standing.

Front is open for double garage door - this will I assume be the same steel as for the centre of the building carrying roof/splitting roof in half

The span from side to side is 5.7m
The span from front to back is 5.7m

 

[tony1851]

Is this the arrangement?

 

[Ab12]

Is this the arrangement?

Yes pretty much, opening is much bigger and I expect will need a steel above it. Joists will run from back wall to beam above garage door opening, because right side is wall facing garden

 

[Dereekoo]

,

 

[robinbanks]

Surely the single skin wall could just collapse with the weight of that plus roof

Not surely, no. The beam only weighs ~150kg, and quarter of the roof maybe another 450kg

Are you saying if you and five mates climbed up there to start fitting a roof, but sat next to each other for a coffee, then the wall would just plain collapse under your combined weights?

If it would, it needs rebuilding cos it ain’t fit for purpose.

 

[Ab12]

,

Should I worry about the single skin wall collapsing outward or inward rather than being crushed?

If the steel is sat on top of it on either the plate or padstone, does it need to be bolted down? Or does the entire roof just need to be strapped down as normal?

,

 

[robinbanks]

Should I worry about the single skin wall collapsing outward or inward rather than being crushed?

Is it bowed?

 

[Ab12]

Is it bowed?

Not at all

 

[Ab12]

Also to add, the wall as you can see in the photos in the first post, does have stiffener single pillars. So I'm guessing that helps stop the inward outward collapsing I'm thinking about

 

[tony1851]

Bolting-down in that situation would serve no useful purpose.
As long as the garage wall is not too high, and there are reasonable lengths of brickwork returns each end, lateral stability under wind load wouldn't be an issue.
If the roof joists are running parallel to the wall in question, they should be well-tied to the brickwork with the usual 30 x 5/6 mm steel straps engaging at least three joists, on each side of the garage.

 

[Ab12]

Bolting-down in that situation would serve no useful purpose.
As long as the garage wall is not too high, and there are reasonable lengths of brickwork returns each end, lateral stability under wind load wouldn't be an issue.
If the roof joists are running parallel to the wall in question, they should be well-tied to the brickwork with the usual 30 x 5/6 mm steel straps engaging at least three joists, on each side of the garage.

Thanks Tony,

This is what I'm working with here:

And some bits below just to clarify so I understand fully. And answer your last comments.

Brick wall is 2.3m tall, the other block wall is 3.3m tall (it's built up from lower garden ground) but still at the same top level all the way round. The back block wall has a return where it is attached to the brick wall return with starter kit. The front (garage door opening) has a small return of 2 bricks thick on the brick side.

1. To confirm I can use 203*133 ub25 for the centre of the roof to split the roof in half and carry one end of the roof joists?

2. I can also the same size steel 203*133 ub25 across the double garage opening to carry the span of the roof there, and potentially a lightweight roller shutter?

3. So that I don't see a padstone, but see brick instead, I can use a steel plate under each bearing of the steel onto the brick wall of 215 x 100 x 12-15mm thick instead of the padstone recommended

4. The steel can sit on the single brick, does not need piers where the steel will rest, but as long as I have my single brick wall with supporting piers along then it's okay?

5. Question: if it's sat on the single brick, am I simply bricking it in from the sides to stop it moving sideways? BUT what stops it from potentially sliding off the 100mm it's sat on, as you said it needs not be bolted down

Thanks ever so much