pricing birdcage and fascade retension help (1 Viewer)

luis211

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Can some one help me out with some formulas for estimating an internal birdcage to support a gable end 12m long,(gable) 18m wide(internal) 11m high???
fascade retention!!
 
Formula's are only half the story luis or so they tell me.:cool:

What's the problem, is it just for pricing or what you need to hold it up?
 
Is it a Raking shore that you need as a birdcage is normally internal ?
If its being used to support then you will definitely need a design to calculate what weight is coming onto the scaffold
 
a raking shore would of been ideal however the pavement to external of the gable is only 2.0m wide so have to tie back through all the windows this is why i was building an internal birdcage??
 
Luis,

I think you will definitely need a design for a scaffold of this type (but then I would say that lol).

Seriously tho, raking shores, or shores of any kind are complicated and often made more so by the magnitude of the loads the scaffold needs to carry. In this case you are supporting the horizontal loads induced on/by the facade (wind + 5-10% of self weight).

Therefore the bracing in the scaffold is key, the main load will be induced from the outside, in (wind + s.wt) so the bracing will need to be of sufficient capacity to support this load and transfer it to a point of restraint. Unless the building is open then the only load acting outwards will be s.wt, so the overturning generating an uplift on the scaffold will be much less and you will probably be fine in this case.

Pricing this kind of job is tricky, you will either not put enough in and then lose your leg when you see the design or put too much in and then price yourself out. Jakdan is right, I would strongly suggest you persuade your client to get a design done first and price that.

B
 
a raking shore would of been ideal however the pavement to external of the gable is only 2.0m wide so have to tie back through all the windows this is why i was building an internal birdcage??

Its a design job whichever way you look at it, phone Phil Barber Desing on 0113-397-0411 for assistance
 
Luis,

I think you will definitely need a design for a scaffold of this type (but then I would say that lol).

Seriously tho, raking shores, or shores of any kind are complicated and often made more so by the magnitude of the loads the scaffold needs to carry. In this case you are supporting the horizontal loads induced on/by the facade (wind + 5-10% of self weight).

Therefore the bracing in the scaffold is key, the main load will be induced from the outside, in (wind + s.wt) so the bracing will need to be of sufficient capacity to support this load and transfer it to a point of restraint. Unless the building is open then the only load acting outwards will be s.wt, so the overturning generating an uplift on the scaffold will be much less and you will probably be fine in this case.

Pricing this kind of job is tricky, you will either not put enough in and then lose your leg when you see the design or put too much in and then price yourself out. Jakdan is right, I would strongly suggest you persuade your client to get a design done first and price that.

B

An interesting point BMB, do you get many non scaffold clients coming to you for design? I only ask as we lost a job recently because they demanded I got the drawing which aroused my suspicions about all sorts, payment responsibility and the like. I usually find we have to speak to a designer first for a chat and rough price guide which is pretty good but would prefer just to price the clients drawing.
 
AOM,

The majority of our works comes from scaffolding contractors however we do quite a few designs direct for main contractors. It depends who it is really and the type of job. We have a few ongoing at the moment for main contractors, one who will tender the drawings, the other already has a scaffolder on board but get the drawings done themselves anyway.

Rail jobs are most common to go down this route mainly due to the paperwork involved. We produce all the designs, calcs, RA, Form C and check so that it can be submitted to NR for approval well in advance. More often than not, by the time the scaffolder is involved its all 'go go go' so waiting for design approval at this stage is costly.

B
 
Thanks BMB, might work on the bigger projects but you could probably count on your one hand the amount of times I have been handed a drawing to price. I can never really work that one out, if you were going to build a house you get a drawing and hawk it round all the builders to see who is best, why not scaffold. I think it's the whole slopey shoulder scenario should there be an issue, it's your design you deal with it. We had one in particular who moaned and moaned all day long about 2 months into a job about the sheer amount of bracing in it and it was slowing his men down, there were 2 lifts of beams to support a hanging elevation over a lower roof and he moaned about that as it reduced the work face area then finally after telling him any alteration would need to be designed and charged he tried to claim thousands of us as inside the lower roof the ceiling was cracking and it must be our scaffold sinking. Eventually I agreed to pay for an engineer but wanted refunded should we be cleared which he duly did, turned out the cracking was just natural shrinkage from the new plasterboard ceiling. I'm still waiting for my refund though.

Sorry for that but I feel better already.:)
 
Luis,

I think you will definitely need a design for a scaffold of this type (but then I would say that lol).

Seriously tho, raking shores, or shores of any kind are complicated and often made more so by the magnitude of the loads the scaffold needs to carry. In this case you are supporting the horizontal loads induced on/by the facade (wind + 5-10% of self weight).

Therefore the bracing in the scaffold is key, the main load will be induced from the outside, in (wind + s.wt) so the bracing will need to be of sufficient capacity to support this load and transfer it to a point of restraint. Unless the building is open then the only load acting outwards will be s.wt, so the overturning generating an uplift on the scaffold will be much less and you will probably be fine in this case.
Pricing this kind of job is tricky, you will either not put enough in and then lose your leg when you see the design or put too much in and then price yourself out. Jakdan is right, I would strongly suggest you persuade your client to get a design done first and price that.

B

An interesting point BMB, do you get many non scaffold clients coming to you for design? I only ask as we lost a job recently because they demanded I got the drawing which aroused my suspicions about all sorts, payment responsibility and the like. I usually find we have to speak to a designer first for a chat and rough price guide which is pretty good but would prefer just to price the clients drawing.

Hi BMB

Can you expand please, where has the wind gone if the building is open?
 
Scarf,

Wind will always act on the outer face of the wall you are restraining. Wind will only act on the inner face of the wall if the building is open and wind can physically blow through the building. If the building is enclosed, wind will hit the other outer walls and not the inner face of the wall you are restraining.

A portion of self weight will always have to be taken as acting horizontally when considering the loads on the inner and outer face / in each horizontal direction.

The above assumes you are restraining one wall of a rectangular building.

B.
 
BMB,

I misread your previous post.

However, would we not need to take into account suction on the wall ?
 
Scarf,

Depending on the size and shape of it, yes you will.

B
 
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