Hi all

Just wondering whether anyone with expertise can comment on this: During a site visit to our new build we noticed surface rust on the lintels (external and internal). Our site supervisor said that it would be painted over. Would this just result in the rust bleeding through the paint later down the track and would the lintels continue to rust? Is it acceptable to insist that the builders put a rust treatment on the lintels or is there some other course of action we should insist on?

Regards

Definatley insist that they treat the rust. A lintel sits in the cavity as you probably know. This is where alot of moisture will be. If the rust is not treated there is a very good chance it will keep degrading. You probably wont notice much onj the outside unless the rust residue seeps through the paint. All they need to do is rub it back and cold gal it.

They really shouldnt install rusting lintels. Big no no!

TheEstimator

Thanks TheEstimator. I was quite surprised to see that they had installed a rusty lintel and wondered if this is normal and if I was being unrealistic expecting that my lintels were rust-free. What does "cold gal" mean/involve?

Completely unacceptable. In my opinion, given that this is a new build, the lintels should be removed and replaced. The absolute MINIMUM allowable corrosion protection for built-in structural steel members per BCA2011 Table 3.3.3.2 is an organic zinc silicate coating of 75um thickness. The notes for that table state that "the chosen coatings for built-in steel items must have sufficient impact resistance to ensure that they remain intact during transportation and handling on site".

The fact that you're experiencing rust already means that this has not been complied with - the corrosion protection coating is either damaged, substandard or missing altogether. The effectiveness of in-situ applied coatings is generally lower than a workshop-applied coating (due to access limitations and limitations in surface preparation that can be undertaken) so any site applied repairs are likely to be of a lower standard than you have paid for and the BCA requires.

In all likelihood the rub back and cold galv method would be fine, but if it were my new build I'd be insisting on the product I paid for and the peace of mind that comes with it.

Thank you for your comments, Integrity. Now to have that discussion with the builder.... What is "cold galv" - is this the same as applying a "rust treatment", which is what the builder has said they would do?

"Cold galv" is a contraction for "cold galvanizing", which is a term used to describe the application of zinc rich paint.

Interestingly the term "cold galvanizing" is actually incorrect, though it is a term which sees common use. "Galvanization" describes the application of a zinc coating to steel using a galvanic cell (also known as electroplating). This term is commonly stretched though to include hot dip galvanizing (where the steel is submerged in a bath of molten zinc) and cold galvanizing (where zinc rich paint is applied by brush, roller or spray).

The reason that zinc is used for this process is that it is acts firstly as a physical barrier between the steel and the atmosphere, and then as a sacrificial anode if the coating is damaged. The zinc will corrode in preference to the steel substrate, and the by-products formed by the corrosion of zinc are inert and assist in preventing further corrosion.

As I said - in all likelihood wire brushing of the lintels and application of a cold galv coating would be fine. But is "in all likelihood" what you paid for? Will the builder offer an extended lifetime warranty on corrosion of the lintels? They're neither cheap nor non-disruptive to replace once the house is occupied...

Thanks for that, Integrity. I'm much better informed to have that discussion with the builder now...

They should of been GAL, id get them coated asap.