Raindrop drainage mat and metal siding advice

[Bill Houghton]

Can I get some advice?  I want to use pole building metal for the siding on our build (we have it on the roof). There has been house wrap on since January 2010, when we shelled in the structure.    I am thinking it would be a good idea to use a drainage mat under the metal siding - I can special order Raindrop from Menards:  http://greenguard.pactiv.com/residential.aspx?building-wrap.raindrop  Does this make sense?  I have 1/2" OSB sheeting on 2x4 framing with spray foam insulation.  I used a vapor barrier on the inside and have 3/4" tongue and groove pine paneling.

Bill

[Alan Gage]

Depending on the profile of the steel it seems like it might make a pretty good drainage plane by itself.

I don't have any experience with Raindrop or any other drainage type of housewrap. The guy at my local building center recommended it to me when I told him I was thinking about doing a rainscreen but in the end decided to do an actual rainscreen (cedar bevel siding) instead.

How much experience do you have with steel siding? I thought about doing that on my house but was worried about the flashing around the windows and doors being a pain in the butt.

Alan

[Bill Houghton]

Hi Alan, no experience with metal siding but I had a guy flash all of the openings for me so that is already done.  The metal is approx 3 ft. wide with ridges about 8" apart.  In between the ridges the metal is more or less flat and in contact with the house wrap.  I am concerned with the metal sweating or if some water does get behind the metal.

[Ernest T. Bass]

Cutting the pieces to fit perfectly is tedious and unforgiving.. Make sure you buy/rent/borrow an electric shears for cutting the stuff. We got one that fits on a cordless drill and makes things a lot easier. I'm sure you'll get condensation behind the metal from time to time, but then again all siding leaks. As long as the wrap is in good shape and the windows are good and water tight I doubt it'll be a problem. Using a "rat guard" flashing (looks like a ledge) at the bottom instead of enclosure strips will allow water that does get behind the panels to drain out.

[PA-Builder]

I used 30# felt behind my corrugated steel siding (over 1/2" square edge Advantech) in 2004 and have had absolutely no problems.