painting galvanized metal? not car related

[bmwjohn]

Hi:
BITOG seems to have someone sharp on almost any topic, so.....I have a small 20 year old 2nd story balcony/deck with serious structural problems.Tearing into it reveals a mix of treated and untreated wood and galvanized construction u-brackets that seem to be quite rusty. They were underside the deck, so partially exposed to weather. Planning on replacing with new, and using 2x6 instead of 2x4. However, could I rustoleum metal brackets w/zinc rich galvanizing compound and have it hold up better? size is 6x10? bolted to side of house, 10' above ground, 2 4x4 treated support posts, plan to upgrade w/more support posts, 2x6 treated, perhaps stainless screws instead of regular rusty nails, possible add o/side stairs to ground. galvanized and wood both going defective a real concern - don't want to repeat problem in 10 years. It still seems safe enough to walk on but am looking to future. comments? Thanks.

 

[wrcsixeight]

Galvanized joist hangers are not all made to the same spec. I have tore into an old structure and found some hangers in near perfect condition, then ones right next to it, obviously a different make, have severe corrosion issues on some hangers while the same type right next to it showed little. The structure was obviously built at the same time, just whoever built it used 2 different brands of joist hangers, and one brand was not up to par.

Treated wood and deck screws are the way to go for the structure. The decking too if drainage is poor.

 

[JHZR2]

not sure if screws of any sort are the right fastener to the house.

Lag bolts or something, perhaps.

I think nails have better shear strength. Id use stainless screws to hold the decking down.

 

[bepperb]

I think it's common for deck builders and other pseudo-contractors to use brackets and nails with a galvanized coating that would react with the pressure treated lumber and corrode very quickly. No, don't try to re-invent the wheel, buy the correct brackets in the first place.

"Due to the high risk of galvanic reaction between the copper-impregnated wood and any dissimilar metals, fasteners and flashings should be stainless steel and copper whenever possible. At the very least, you need to use better grades of galvanized fasteners. Unfortunately, the fastener grades aren't always marked on the boxes of nails and screws.

Electrogalvanized stock is rated with a class scale that ranges from 5 to 110. Hot-dipped galvanization ratings are based on the actual weight of the coating. For example, a G-60 rating means that there's 0.60 oz. of zinc per sq. ft. of metal.

The G-60 and G-90 hot-dipped coatings are what we've been using until now. But engineers suggest stepping up to the heavier G-185 coatings for hot-dipped galvanized products, and they recommend class ratings of 40 or above when using electrogalvanized fasteners, such as expansion bolts."

EDIT: also, be careful where you use screws. To attach the decking is OK but generally it's an uphill battle to convince a building inspector to pass something done with screws where nails are the code standard. You may have to provide documentation that the screws you used have the same sheer strength which will be hard to get and probably not true anyway.

 

[andyd]

Good stuff, Bepperb. When we built my addition in '85, we lagged the porches, using 1x4 PT slats to stand the deck off the rim joist it was lagged to. Posts are 4x6s on concrete piles. I wanted 2 stairways from the 2nd floor for safety. But I didn't want to sacrifice interior room, so it connects the 2 decks. PT southern yellow pine. I extended the roof to cover the top deck. The whole job was hand nailed with hammers. I nailed off the decks with hot dipped US made 8d finish nails. It is weathered,but sound. Can you even get those today? Everything is electro zinc.

 

[Shannow]

Yeah, I was going to say, power station structural stuff, we specify hot dipped...electroplated never gets a start.

 

[doitmyself]

I think that painting galvanized metal would not be very effective.

Since the switch from CCA treated lumber to ACQ treated lumber (about 8 +/- years ago), there has been upgraded specifications for correct fasteners since the ACQ is even MORE corrosive.

Google treated wood fasteners and all your questions will be answered. The treated wood industry still only recommends hot dip galvanized or stainless fasteners.

Simpson Strong Tie "seems" to be on top of this problem and if you study their site, I "think" one could trust their products.

Here's their FAQ link: http://www.strongtie.com/productuse/PTWoodFAQs.html

Their "Deck" page: http://www.strongtie.com/deckcenter/index.html?source=topnav

And here's an example of their hangers: http://www.strongtie.com/products/connectors/LUS-HUS.asp

Nails or bolts for structural/load bearing components. Screws or nails for non structural. (Simpson Strong Tie has screws appropriate for some circumstances).

 

[bmwjohn]

Hey thanks for the quick response and LOADS of data. The above parts are NOT, I suppose, from Menards or Lowes. Amazon, e-Bay, McMaster-Carr, or where? BTW my sister built the deck, her first. Now in her 70's she won't do the next one, but it was excellent considering her techie but non construction background. Stuff came from Furrows, as I recall. She liked the no labor cost combined with low material cost, I always figure if the labor cost is low you can go conservative on getting better materials. I'll start looking. Thanks and more input is always welcome.Again, this is a first class site and shows what the internet can and should be.I talk to non i-net users at work and they keep repeating how bad it is and I explain they are just looking the wrong place.

 

[morris]

i only know two things about galvanized. dont weld it, and wash it with veneger before painting.