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Projecting Sign Load Calculations
What do most sign makers here do about calculating the loads on a projecting sign and how strong their anchor bolts have to be?
It obviously is related to size for wind loading and the weight of the sign, but other factors are important too such as how far apart the bolts are and the size of the wall plate which may act as a fulcrum when load is applied.
Do you do these sort of calculations yourself or do you employ a structural engineer.
Whenever i have asked the services of a structural engineer they always put me off by implying it is too small a job and there is no need.
So how do you decide if your sign is safe? -
20 Replies
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Stuart, there is a book available on Kindle called Engineering Sign Structures which although very technical answers all the question regards the calculations required , including pole supports, wind loading / surface area, worth a read, it also gives the formulas to allow you to calculate any questions you may have now or in the future, the reason why most engineers would avoid taking on your project is because it is a science which they would shy away from as it is a very specialized area of engineering.
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Thanks Graham.
however the link does not work for me.Also it seems quite a complicated calculation and if you say structural engineers shy away from it what do most sign makers do.
There must be loads of projecting signs put up every day, yet I have never yet heard how other sign makers on here approach this area of the job. -
I suspect many sign makers just wing it and hope for the best… which is fine until it goes wrong.
If it’s bespoke built, some manufacturers will do the calculations for you (or wing it for you), or tell you to get structural engineer to send over designs.
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Yes Dave I’m sure they do just wing it and I have only ever up to now replaced boards and swing panels on existing signs.
I have also installed the small Tradesignz Ject rigid panels which are quite small and light and been happy that my anker bolt fixings are well above what is required for them.
Now I have been asked to install a completely new Bracket and swing sign for a shop.
In theory this also needs planning permission and I presume I will have to show the safe construction and engineering details for the planning permission.
As I have said above this must be an area that every sign maker encounters on a regular basis yet it appears to be a dark art that no-one is able to help with.
I have asked the sign manufacturers and they just say it is up to you to arrange your own structural engineer.
I can understand that a large project can price for and hire an engineer but for a £200 shop projecting sign which can be bought off the shelf it seems overkill. However if that’s what others do and price for it then obviously I will go down that route but after calling at least 6 structural engineers none of them seemed to understand the request or want to help as they see their job as larger construction projects, and want to charge £300 just for a simple consultation.
I am hoping there would be some sort of template that we could use when planing this type of thing. -
quote Graham Shand:Stuart, there is a book available on Kindle called Engineering Sign Structures which although very technical answers all the question regards the calculations required , including pole supports, wind loading / surface area, worth a read, it also gives the formulas to allow you to calculate any questions you may have now or in the future, the reason why most engineers would avoid taking on your project is because it is a science which they would shy away from as it is a very specialized area of engineering.
thanks for trying to help graham bit this has led me into 2 hours of frustration with Kindle, amazon, downloading the app, trojan virus, app not loading properly. app not connecting tio amazon, app not being able to uninstall and amazon tech support.. phew
Still no better off with the original query ;( -
As a trade supplier whenever we design a projecting sign (or a monolith sign or anything else vulnerable to wind loading) we draw upon years of experience and generally (well) over engineer what we make. Too many instances of signs failing and hurting (or worse) and so would rather sleep at night knowing we have done all we can to supply a safe sign. Of course you can never count on extreme weather like last week. All I would suggest is draw on experience and do what you think is right and build/fit to last. If your customer says one of your competitors is much cheaper too then there may well be a reason for that!
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I think planning are more concerned with it not being a nuisance to neighbours etc if illuminated, and that it meets requirements if a conservation area etc. They’ll require scale drawing etc.
Same with submitting plans for an extension, planning approve it, but building control will inspect it and sign it off as done correctly.
I suspect the wind loading etc is more to cover your backside should it blow down, you can prove you did everything possible to prevent it.
As above, I suspect 90% of sign makers don’t bother working it out, and just do the best they can.
I suspect BSGA will disagree with this, and we should all cough up to be members of their club, if we want to know how it all works.
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Yep
I’m sure that is how it works>
However I am a member of the BSGA as I thought it may be worth joining to find out more. But despite me asking them they just cover them selves and say its up to you to make it safe. So joining didn’t help there !!
As I have an engineering background I am now on a mission to actually find out how to do it as I would like to know for my own knowledge.
Thanks for the replies but looking like i should just trust my judgement and use big anchor bolts, but somehow I feel like a cowboy which I don’t like. -
Stuart , if you have an engineering background, you will find out that the book I mentioned will be of value to you, because it details the calculations required to work out what you need for particular jobs, what I have noticed is that once all the elements are factored in the formulas can be calculated using a spread sheet. The other factors apart from wind loading etc, the type of structure the anchor bolts are being fixed to , timber, hollow, stone, cladding etc, the entire section on projecting signs takes all these elements and explains them in mind blowing detail, I have read this several times and find it useful as a reference manual, with good links to external info sources
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Yes Graham I have been trying to get hold of the book. It seems only available on Kindle and did you not see my post about how that led me into a whole horror show of trying to down load the kindle app.
I would love to get that book and look at the calculations, as I have info for wind loading and materials etc.
Is there another link as the one you gave for th spreadsheet download did not work?
thanks for trying to help -
google the last part of the link he posted 😉 😉
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https://www.amazon.co.uk/gp/product/B00 … UTF8&psc=1
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It’s not really that hard a series of calcs, the reason it "costs so much" to get a structural engineer (like me) to do it is because it takes a lot of time to do, it’s usually requires a series of sketches and there are a lot of things to check!
Also, if you are doing it yourself you should be aware of the implications/risk. There are different temporary and permanent works codes of practice. If you are doing a large free standing sign board for a building site that’s going to be there for a few months needs a different set of codes to one that will be there for 2 years.
Another issue, if you design it "correctly" to the codes, a lot of the time the chap making the thing will say "gawd this is over designed, I’ve been doing these for 20yrs and never had to do this before!"
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quote Chris Ranner:It’s not really that hard a series of calcs, the reason it “costs so much” to get a structural engineer (like me) to do it is because it takes a lot of time to do, it’s usually requires a series of sketches and there are a lot of things to check!
Also, if you are doing it yourself you should be aware of the implications/risk. There are different temporary and permanent works codes of practice. If you are doing a large free standing sign board for a building site that’s going to be there for a few months needs a different set of codes to one that will be there for 2 years.
Another issue, if you design it “correctly” to the codes, a lot of the time the chap making the thing will say “gawd this is over designed, I’ve been doing these for 20yrs and never had to do this before!”
Thanks for that perspective Chris and I totally agree with you. From an Engineers point of view it is time consuming and therefore costly. I understand that and also what you say that the sign manufacturer says it is over engineered etc. but that Still leaves us as the installer being the scapegoat and is everybody just burying their head in the sand and hoping nothing happens to the signs we fit.
I find it hard to believe that in this day and age that no specific training in this area is available, or am I missing it? -
The IStructE (Institute of Structural Engineers) have branches covering the entire country, almost on a monthly basis they have talks on various things from temporary works to the shard in Londinium. They are usually free to attend and open to anyone, my local branch talks have had demolition experts, sign makers, architects and even a few structural engineers attend 😉
If you look up IStructE, you can find a local branch on the website and there would be a list of the local talks etc.
There is something similar for ICE (Institute of Civil Engineers) and ABE (Association of Building Engineers)
As intimated earlier in the thread, the calcs are pretty similar if the signage frame is of similar shape so you can quite easily whip up a spreadsheet to do it. So, given this, you could approach an engineer and task them to create a template for xxx fee based on a discounted rate each time for future framing because most of the donkey work is done. That way you get their PI and experience on the design each time 😉
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I was fitting signs for Twenty years and on projecting signs used nothing but M10 Roll bolts.
But all the information on loading etc will be useless if the wall you’re fitting it to is week.
So the first thing is to establish that you have a good solid wall to fix it too.
Make sure you can do the Roll bolts up without the wall cracking and don’t fix near to a corner.
No engineer can give you any advise at all unless he knows what your fitting it to, and every site will be different.
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I dont understand this post, i get that your trying to find the sweet spot in which it will be perfectly safe and hoping there is someway to gauge this… but the same can be said for any sign, even a flat panel or tray sign.
I have fit pretty much every sign out there and still do, in the 20odd years the company’s been going we’ve only ever had a couple come down due to wind, ironic that they were also flat panels.
You have to have some confidence in your ability and also your method, if you dont.. you shouldnt be doing it.
If you at any point have doubts in your fixings, you havent chose the right ones or fitted correctly -
Chris, I think that the question was raised because more clients now require facts and figures for Risk assessments, method statements for detailed planning applications, to have self confidence in you abilities is all well and good but unfortunately does not cut it when hard facts are required for the paper work which is now required before the job is undertaken.
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quote Graham Shand:Chris, I think that the question was raised because more clients now require facts and figures for Risk assessments, method statements for detailed planning applications, to have self confidence in you abilities is all well and good but unfortunately does not cut it when hard facts are required for the paper work which is now required before the job is undertaken.
Thats fair enough i guess, Ive yet to be asked for these figures… hopefully doesn’t happen as seems a ball ache.
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