Aluminum trim wrap corrosion

[clkimmel]

My garage was built last summer and the other day I noticed that the aluminum wrap aound the big door is starting to bubble up from underneath IIRC, they used some PT to frame the opening and then it was wrapped. I suspect that the bubbling I am seeing is caused by the aluminum being in direct contact with the PT. Is there a standard way the trim installers deal with this? The builder is comming out this week to look at it, and he says he'll take care of it, but I have seen this before and I wonder what the correct fix is.

Thanks
Casey

 

[cowboy73]

A good coat of primer and a quality paint over the pressure treated should prevent the chemicals in the PT lumber from attacking the aluminum. The newer ACQ pressure treated lumber is very corrosive to metal. I would have them paint the lumber before reinstalling any aluminum trim.

 

[CrewCabGuy]

I covered my posts with heavy plastic first. seems to be holding up after 3 years.

 

[clkimmel]

Thanks, I'll talk to the builder before he fixes it to make sure the pressure treated wood is covered with something before the trim goes on.

 

[rlitman]

New ACQ pressure treated is especially harsh on aluminum. You cannot use aluminum flashing with it. Just hot dipped galvanized or copper.

Paint or plastic underneath -may- be sufficient for protecting aluminum trim. I'm just not 100% on that one, but it will certainly help.

Is the trim coil the builder used bare aluminum on the back side? That could be part of the problem. Painted coil is done on both sides. PVC coated is not, and is known to have issues with ACQ contact.