Steel Beams - Galvanised or Red Oxide

[NewToAllOfThis]

We are having piling with Steel ring beam that will be around 500mm above soil level. Block and Beam on the steels and then a timber frame.

 

I have had two quotes for the Steel Beam, one has said it has to be Galvanised and the other said it can be either Galvanised or Red Oxide.

 

Reading through Google, there seems to be a variety of views, not sure if they are all based on UK so building regs may depict what has to be used.

 

Galvanised adds another £2200 on to the price, Red Oxide £4500, Galvanised £6700

 

None of the steels with be visible when the property is completed so doesn't matter about the looks.

 

Has anyone any experience of this.

 

[PeterW]

Red oxide - no need for galvanizing as they aren’t exposed to the weather. 
 

Out of interest is that a supply and fit price for the steels and how many ..?? Seems a bit pricey that’s all !!

[Mr Punter]

I would want a foundation ring beam galvanised.

[PeterW]

35 minutes ago, Mr Punter said:

I would want a foundation ring beam galvanised.

Even 500mm off the ground ..?? I’d agree if it was 100mm but this seems to be a lot of air under the floor and very little chance for corrosion. 

[NewToAllOfThis]

2 hours ago, PeterW said:

Red oxide - no need for galvanizing as they aren’t exposed to the weather. 
 

Out of interest is that a supply and fit price for the steels and how many ..?? Seems a bit pricey that’s all !!

Hi,

It is for supply only, the steels are 203 x 203 x 46.  Approximately 70 metres of steel, also a number of connecting bits, not sure of total as some beams seem to be split into 2 or more sections< i guess to keep steel to suitable lengths. quick count looks like 20-25 joints

 

 

[PeterW]

Ouch !! So 203x203x46 shot blasted and painted is ~£35/m ex VAT. It comes in lengths up to 12m, so even using 8m lengths you’ve got a cost of around £2450 so you’ve another £2000 for connection plates ..??

 

I would shop around - £3k would be my target. 

[Gus Potter]

Hope this helps.

 

For NewToAllOfThis.

 

Lots of fabricators initial estimated prices are based on a price per tonne. If you are buying say 70 tonnes the price tends to be less. If you want a small amount for a one off job the price per tonne goes up. This is partly to do with the sequencing, taking off the quantities from standard drawings, programming, the cutting and drilling line and so on.

 

The 203 x 203 x 46 are what we call a universal column section, UC's, you also often see mention of UB's these are more of an I shape where as UC's are more squat.

 

For NewTo.. You have 70m of UC's @ 46kg weight per metre = 70 x 46 / 1000 = ~ 3.2 tonnes. Take roughly a mid range domestic one off figure of £2200 per tonne. If you get it for less then you can spend the saving on something else!

 

For a smallish domestic job budget on .. 3.2 tonnes x £ 2200 per tonne = £ 7040. For this you get the steelwork with the connections, painting and so on comes next. Often some connections will be a bit more complicated and need heavier, different types of welds and so on, the fabricators know this when they are estimating. Some connections will be very simple, some not, but on balance it often all evens out for standard stuff.

 

Next you need to prepare the surface of the steel. This needs to be done whether you are galvanising or painting it..neither will adhere properly if this is not done. Preparation of the surface is also controlled, often you see a term, shot blast to grade SA2.5.. this is to do with the amount of cleaning, preparation. The steel can lie about in a yard for a while and get a bit of surface rust, it also has what is called "mill scale" which roughly is loose material on the surface due to the rolling process. The shot blasting cleans this off.

 

Here things start to diverge a bit. Some fabricators use the surface area of the section to work out how much paint they need. A 203 x 203 x 46 UC has a surface area of 1.19 m sq /per metre length. So 70m is 70m x1.19 ~ 84m sq. The paint varies a lot in price and the thickness is also important. But take the shot blasting and paint cost as say £ 10 / sq m thus you add £ 840.00 to the 7040 = 7880.00.  Work that back now to a painted price per tonne.. 7880 / 3.2 = £ 2462.00 per tonne. All the figures I give are ex vat.

 

The galvanizing is worked out in a slightly different way. Here the galvanizers often work on just a price per tonne but again it's partly due to the section shape / area. The cost of the zinc moves about a fair bit. Take a figure of £ 330.00 per tonne for galvanising. 330 x 3.2 = £1056 + 7040 = £ 8096 / 3.2 = £2530.00 per tonne

 

Not much difference.. but much depends on the length of the section. One of the keys here is that if you have a long section then it needs a long galvanizing bath and there are fewer galvanizers with "long baths" so the price varies accordingly especially if it is a smallish order. If your section is too long then the galvanizer needs to double dip the section, this takes time and uses more zinc. However, there is often an extra transportation cost as the fabricator needs to fabricate the sections send them for galvanising and return back to their yard. So this needs to be added to the price too and these handling etc features can add quite a bit to the cost.

 

What you can do is to introduce splices into the sections and thus make them shorter, yes there is an extra connection cost but this is offset by the range of galvanizers you can approach so more competition on price. Another benefit for the self / extension builder is that often you can collect the steel on say a trailer from the works , thus saving on the costs of a large wagon.

 

Generally galvanising is more expensive than standard red oxide type painting but it tends to last longer. However if the steel is not exposed to the weather then painting is often sufficient. Lastly you may find that your Enginner has specified a grade of steel that is suitable for external use. The steel specification can vary when the steel is external and exposed to lower temperature (steel becomes more brittle in lower temperatures) than internal steel. This again can impact on the cost of the steel.

 

 

 

 

[Mr Punter]

14 hours ago, PeterW said:

Even 500mm off the ground ..?? I’d agree if it was 100mm but this seems to be a lot of air under the floor and very little chance for corrosion. 

 

I have seen the underside of static caravans vans 25 years old that were elevated and the rust is significant to the point of structural failure.  After they were moved you could see the outline of the chassis on the ground in rust.

[Onoff]

Based on that size UC, my fabricator said:

 

"£1500 per tonne plus £700 per ton for galv but depends on the drilling and amount of holes"

[Nickfromwales]

On 06/08/2020 at 21:11, PeterW said:

Even 500mm off the ground ..?? I’d agree if it was 100mm but this seems to be a lot of air under the floor and very little chance for corrosion. 

Galv buys you a few extra nights sleep no? 

 

11 hours ago, Mr Punter said:

 

I have seen the underside of static caravans vans 25 years old that were elevated and the rust is significant to the point of structural failure.  After they were moved you could see the outline of the chassis on the ground in rust.

Serious food for thought there.

 

On 06/08/2020 at 19:14, NewToAllOfThis said:

I have had two quotes for the Steel Beam, one has said it has to be Galvanised and the other said it can be either Galvanised or Red Oxide.

And which one of these are willing to put their balls on the line and offer warranties reflecting what they say? And how long for? 

This is a significant decision, and one not to be taken without the backing of the company supplying as 'fit for purpose'.

[dpmiller]

static vans are often by the sea tho, so salty air. Is the OP on the coast or inland?

[Russell griffiths]

I would get the price of the steel and fabrication down, and then use the saving on galvanising. 

[Onoff]

@NewToAllOfThis, whereabouts in the UK are you? 

[Onoff]

On 07/08/2020 at 01:19, Gus Potter said:

Next you need to prepare the surface of the steel. This needs to be done whether you are galvanising or painting it..neither will adhere properly if this is not done. Preparation of the surface is also controlled, often you see a term, shot blast to grade SA2.5.. this is to do with the amount of cleaning, preparation. The steel can lie about in a yard for a while and get a bit of surface rust, it also has what is called "mill scale" which roughly is loose material on the surface due to the rolling process. The shot blasting cleans this off.

 

I've been having stuff galvanised for over 30 years now and to my knowledge they acid dip to remove mill scale before galvanising.

 

The only time I've had stuff shot blasted is prior the zinc flame spraying or painting. ALL steel I have put on site is either galvanised (the majority) or zinc flame sprayed. Never, ever, not in a million year just painted.

 

Even if I'm powder coating then it'll be zinc flame sprayed or galvanised underneath. Imho I think it is total b@llocks that powder coating over blasted steel is good long term if there is any chance of the coating being damaged. (As moisture then gets in). 

[scottishjohn]

when I built my workshop -30.5 x24m 

the fabricator wanted to just red oxide  and we could paint it --that ,ll be right!!! --spend another 2k in getting it painted  -better to coat it before erection

we went for hot dip Galv -38 years later the frame still looks like new + didn,t have to spend more money painting it and it match,s in with the galv electrical conduits and the galv air lines

I have seen painted red oxide beams in buildings  and over time the top coat peels bringing red oxide with it--cos no one will spend the days of prep required etc -- plus red oxide is a porous coat anyway  + its probably not REAL red oxide anymore-can,t use red lead now 

the galv company will dip it in hot acid cleaning tank ,then into the hot dip tank 

 going back in time the steel work cost 30K in 1982 +£1500 for transport there and back and hot dip 

just no decision to make - obvious 

 as for red oxide that will be done by the boy and just lashed on ,as they expect you to then top coat it ,as its only a transport coat 

-fine if its support beams for inside  the house where its dry 

For me -there is no argument -if buried .got to be galv

 finally h why is it buried anyway -surely it will be bolted to poured concrete boxs   and be above ground? 

Edited August 8, 2020 by scottishjohn

[Danny68]

This is a fair price in my opinion , please  bare in mind these are 46kg per meter which means fork truck handling or overhead crane at the workshop and it might be 70 metres on site but could easily be 85 metres ordered from the stockholder and seeing that its 46kg  per metre you would be absolutely barmey getting it galvanised unless you intend to leave it to your great great great grandchildren , a coat of red oxide sloshed on by the lacky will see the beams through to well into the next century. 

[Onoff]

Bunch of wusses! We manhandled and fixed over 1/2km of 46kgm I beam (in 3m lengths).

 

My chiropractor made the most money out of that job...

 

?

 

 

 

 

Edited August 8, 2020 by Onoff

[Gus Potter]

Hello all. CE Marking and Structural steel holding your house up! But first.

 

Great points all, much appreciated (onoff - both posts were spot on)

 

As an aside, be encouraged. The prices I used were based on Glasgow area, rather than say Linconshire. If you live next to Scunthorpe then you may well get a better price. Also, if you have connections to the trade this helps too. We have some pretty big fabricators up in Scotland so if you are near one of them, again more promising price wise.

 

Currently (don't know how leaving the EU will impact) it is a legal requirement that all structural steel must be CE marked and thus in compliance with the BS EN 1090 series of codes. These codes are partly to do with welding quality, painting etc. It has a lot of benefits, but also some negatives! One of the things that attracts me to this is that you have more control (well you hope so) over the provenance of supply.. seen some bad Chinese steel and forged mill certificates now and again.

 

When you specify structural steel you want to include a reference to these codes and CE marking. If you are designing to the Eurocodes / British Standards for example then you need to be sure that the strength / properties of the steel and welding etc match your design assumptions.

 

All a bit dry,  but if you are say getting the house signed off by a warranty provider then they too will want to know that the steelwork that is actually supplied to the site matches the design that they are covering. If it turns out later that it does not then what happens?

 

 

 

 

 

 

 

 

[NewToAllOfThis]

Thank you for all the replies, mixed view of comments regarding if Red Oxide or Galvanised and also price. I have asked for another quote to see what they come up with so it will give me a choice of three.

 

I was told that I will need to check with the building inspector as he is likely to have a view as to if they have to be galvanised. At what point can I get a building inspector to provide advise as to if he will allow Red Oxide or require galvanised steel.

 

As mentioned, the beams will sit on steel piles, these will not be protected at all. It is estimated that they will be 14-16 metres deep into the ground and then 500 mm above ground. The ground is constantly wet from around 500mm below the ground. Will these not rust faster than the beams if the beams are covered in Red Oxide.

 

Also should the 500mm of the piles above ground have any treatment.

[PeterW]

Steel piles or end driven concrete piles..? What is the spec of what has been agreed ..?

 

And what is the ground you’re on - have you considered an insulated raft..?