On Sat, 08 Mar 2014 08:41:09 +0000, harryagain wrote:

Yes it will corrode in the absence of air but it's not a problem in your
case is it?

The plates will be against the timber, thus an absence of air.
I wouldn't be concerned about it except that an engineer that I trust has
said there may be a problem. However I'm not having brass brackets!