Hi

I have just had the steel dropped off for some supporting parts of my house.  There is 10 steel posts going in and will be attached to the foundation and also some beams between them.  The person doing the steel has not painted it and there is some surface rust on it.  Does this matter as most of it will be internal.

 

thanks

2 hours ago, GrantMcscott said:

Hi

I have just had the steel dropped off for some supporting parts of my house.  There is 10 steel posts going in and will be attached to the foundation and also some beams between them.  The person doing the steel has not painted it and there is some surface rust on it.  Does this matter as most of it will be internal.

 

thanks

If any part of the steel is exposed to the outside The whole steel should be dipped galvanised 

A bit of rust on the internal steel won’t matter  

13 hours ago, nod said:

If any part of the steel is exposed to the outside The whole steel should be dipped galvanised 

A bit of rust on the internal steel won’t matter  

So if some of the steel is a 1 metre below ground and encased in concrete this should be ok as it will be protected from the ground?

2 minutes ago, GrantMcscott said:

So if some of the steel is a 1 metre below ground and encased in concrete this should be ok as it will be protected from the ground?

It’s normally if the steel is exposed to the elements 

I had all ours hot dipped as 7 of the 11 where required 

Not that expensive and will never corrode

It should say on Your engineers drawing  

Red oxide paint isn’t expensive and it would only take you a couple of hours to paint the lot. 5 litres will cover 12-14sqm by brush so you would probably only need one tin and it should be £20 at most. Buy a pack of gloves and some disposable brushes too. 

4 hours ago, PeterW said:

Red oxide paint isn’t expensive and it would only take you a couple of hours to paint the lot. 5 litres will cover 12-14sqm by brush so you would probably only need one tin and it should be £20 at most. Buy a pack of gloves and some disposable brushes too. 

Problem I have is a timing issue ground worker that is doing concrete needs to get it done ASAP as going to another job. for 8 weeks

 

so what I take from this is that if they are encased in concrete from foundation to FFL then I should be OK as they will not be exposed to the earth.

 

is that correct?  

We get our galvanized steel picked up and back in 2 days  ( wedge group) others are available  ? , if you go down this route your steel can be a little rusty but no paint on it .Painted or very rusty steel will need shot blasting  which will be additional  cost.

4 hours ago, GrantMcscott said:

Problem I have is a timing issue ground worker that is doing concrete needs to get it done ASAP as going to another job. for 8 weeks

 

so what I take from this is that if they are encased in concrete from foundation to FFL then I should be OK as they will not be exposed to the earth.

 

is that correct?  

 

Paint the ends that are going in the ground then paint the rest when it’s up. 

22 hours ago, nod said:

If any part of the steel is exposed to the outside The whole steel should be dipped galvanised 

A bit of rust on the internal steel won’t matter  

 

Be real careful with sealed, box section fabrications if having them galvanised. You need gas escape holes in them. 

 

If you don't put them in the galvanisers will. They don't really care where they drill. 

 

You can end up with holes, open to the elements in the top side of your fabrication which then fills up with water!

Been using this at work for years:

 

https://www.firwood.co.uk/blog/product-news-and-information/about-bitumen-paint

Have put some zinc phosphate primer on it

Hi, I have just found out that the steel work that was fixed to the foundation was also not painted so it was raw steel and then encased in concrete.  Should I be concerned or is this OK as it is the main support for the house?

It will be fine assuming it is being kept dry and inside the fabric of the building. If it was exposed to the outside / rain etc then coating the visible surfaces with red oxide would be preferable

I think I may need to paint some galvanised steel, does anyone know if you can get a reasonable finish? 

47 minutes ago, GrantMcscott said:

Hi, I have just found out that the steel work that was fixed to the foundation was also not painted so it was raw steel and then encased in concrete.  Should I be concerned or is this OK as it is the main support for the house?

 

I'm not sure about the coating pre-encasement, but we have a similar situation that steel columns will be fixed to concrete pads about 1m below ground then encased in concrete.

 

I was concerned about potential groundwater so asked for the whole encasement to be then coated in liquid DPM. The SE, architect and groundworkers all seemed fine with this, and no-one said out loud they felt this was over-kill. I felt that it costs little, might add protection, and you really don't want below-ground corrosion of the steel to foundation junction as you will never be able to monitor it. This has not been built yet so don't have any practical feedback.

Edited June 24, 20206 yr by kxi

18 minutes ago, kxi said:

 

I'm not sure about the coating pre-encasement, but we have a similar situation that steel columns will be fixed to concrete pads about 1m below ground then encased in concrete.

 

I was concerned about potential groundwater so asked for the whole encasement to be then coated in liquid DPM. The SE, architect and groundworkers all seemed fine with this, and no-one said out loud they felt this was over-kill. I felt that it costs little, might add protection, and you really don't want below-ground corrosion of the steel to foundation junction as you will never be able to monitor it. This has not been built yet so don't have any practical feedback.

Yes my engineering spec said that it had to be painted with bitumen but they did not bother and encased raw steel in concrete. 

9 minutes ago, GrantMcscott said:

Yes my engineering spec said that it had to be painted with bitumen but they did not bother and encased raw steel in concrete. 

 

Ok, you'll have to speak to your SE about this before going further. I suspect 99.99% of reinforced concrete is concrete over raw steel so it's not a totally crazy thing to do, but I believe the depth of concrete cover is important. If you have a groundworking team that is not following engineering specifications then this is presumably an issue in itself to be addressed.

 

In my proposal the WHOLE encasement i.e. the concrete around the steel, is coated in something (bitumen, liquid DPM, etc), which is my belt and braces solution in the event any of the concrete cover cracks after 80 years in the ground. This is also a potential fix for your situation in the event your SE thinks additional protection is needed.

 

 

Traditionally, concrete around steel provides an alkaline, protective environment. Over the years CO2 and moisture seep seep in and turn it acidic. There's some weird reactions set up, with silica in the various aggregates used, that accelerate the rusting of the steel, which expands and can crack the concrete.

 

There's various coating that can be applied from Thompsons Water Seal to Sika FerroGard. The later is used extensively to protect historic concrete structures. Similar has been used to save some of the 1930s art deco buildings. 

 

 

1 hour ago, PeterW said:

It will be fine assuming it is being kept dry and inside the fabric of the building. If it was exposed to the outside / rain etc then coating the visible surfaces with red oxide would be preferable

It is inside the fabric was just worried about water from the ground seeping through the concrete .  It is encased in at least 200 mm of concrete all round most probably more

If it is above ground, a coat of primer and of bitumen paint will protect it.

16 minutes ago, Mr Punter said:

If it is above ground, a coat of primer and of bitumen paint will protect it.

It is below ground in concrete with nothing on it 

I have had specs where the base of columns is wrapped in fabric mesh and encased in concrete to prevent corrosion.  Unless there are very adverse ground conditions I cannot see the issue.

20 minutes ago, Mr Punter said:

I have had specs where the base of columns is wrapped in fabric mesh and encased in concrete to prevent corrosion.  Unless there are very adverse ground conditions I cannot see the issue.

There is a lot if water in the ground but we are draining it