Weld up building beam coatings

[tx_mike]

We have finally gotten to a point where we can get our shop/RV storage built. The contractor we are thinking about builds full weld up buildings. One of my concerns is, he doesnt normally paint/prime the beams or the weld areas. He can do it, for a price. ($600-$800). The purlines/gurts are primed from the manufacturer.
Other than aesthetics is it really necessary? Is it common to see building put up with out coated beams. Anything outside I would think should be coated to protect from rain and eventual rusting. The picture is a building he recently completed I was able to look at last week.

 

[dcg9381]

Inside? I've had a building up for 3-4 years, we foam insulated without painting the welds.
I'd say outside it's more necessary here... If that price is painting all the beams, I might bite, if it's just painting the exposed welds (which is really what needs to be done) - no way.

 

[Walkers]

Buy a sprayer and paint it after the structure is up, but before the tin goes on.

 

[tx_mike]

I dont plan to spray foam so it would be exposed like the picture. This guys builds in College Station area. If I was in a coastal area it would be a no brainer..

I am guessing there is no delay between frame up and tin for me to paint. especially 16ft tall at the eave...

 

[readhead]

The primer is for protection during transportation and storage. The building will be fine without it. We install unprimed structural steel on commercial jobs quite often.

 

[Coasterbuilder]

From AISC 10.1- Painting Requirements

"As stated in the AISC Specification Section M3.1, "Shop paint is not required unless specified by the contract documents." Therefore, fabricated structural steel is left unpainted unless painting requirements are outlined in the contract documents.

In building structures, steel need not be primed or painted if it will be enclosed by building finish, coated with a contact-type fireproofing, or in contact with concrete. When enclosed, the steel is trapped in a controlled environment and the products required for corrosion are quickly exhausted. As indicated in the AISC Specification Commentary Section M3.1, "The surface condition of unpainted steel framing of long-standing buildings that have been demolished has been found to be unchanged from the time of its erection, except at isolated spots where leakage may have occurred. Even in the presence of leakage, the shop coat is of minor influence (Bigos et al., 1954)." A similar situation exists when steel is fireproofed or in contact with concrete; in fact, paint is best omitted when steel is to be fireproofed because primer decreases its adhesion.

In exterior exposed applications, steel must be protected from corrosion by painting or other means. Likewise, steel must be protected from corrosion in special applications such as the corrosive environment of a paper processing plant or a structure with oceanfront exposure."