I have a 20'x40' shed that I want to use as a shop. I plan to pour a concrete floor and build walls to create a closed space. The problem is that since it has a metal roof it "rains" inside from condensation when the conditions are right.

I've seen advertisements for a foil faced foam. One brand is Ag Therm. Is there a special insulation procedure for the stuff to prevent condensation from forming and dripping through the joints?

I'd like to end up with a dry space I can use without having tools and equipment rust.

-- Darren (df1@infi.net), January 03, 2002

Answers

The foil should go down before the metal.Remove metal ,Lay down foil,Put metal back on!

-- David R In TN. (srimmer@earthlink.net), January 04, 2002.

I appreciate the response Dave, but removing the roof when everything is accessible from the underside seems a bit extreme. The insulation is rigid styrofoam.

-- Darren (df1@infi.net), January 04, 2002.

I think the first thing you need to do is ventilate the bldg. I suggest a ridge vent, full length. That will dramatically reduce the rain.

-- john (natlivent@pcpros.net), January 04, 2002.

I built a new 24X40 steel pole building 10 years ago and had the same problem. I put gable end vents in and then put 1/2" foil faced, 4X8 sheets of insulation board up, I attached them to 1X3 firing strips, (with 1-1/4" deck screws & fender washers) I had naild across the trusses on 24" centers.

-- hendo (redgate@echoweb.net), January 04, 2002.

The building is a shed which is open on the East side. There is no peak or gables to install vents.

-- Darren (df1@infi.net), January 05, 2002.

Ok, with an open side, you are looking at building a whole wall here anyhow. For the roof, the metal is going to be a problem. It should have been insulated first as someone suggested. You need to allow the _cold_ air to get to both sides of it, so you need a false ceiling to allow that air gap. Then insulate your false ceiling, put a vapor barrier on the inside (warm side) of it. And be sure there is room for the air to curculate next to the metal roof.

Another option it have foam sprayed on it, that takes care of the vapor barrier & all in one shot.

Any other type of batt insilation stuffed up tight will just cause problems with moisture coming off that metal roof & soaking it up.

Hard for us to see exactly what you want to get done here, so maybe talk it over with some loacal experts?

--->Paul

-- paul (ramblerplm@hotmail.com), January 06, 2002.

I have used polyurethane spray foam insulation in two buildings and it works great. The cost is a little high but once you do it you are done. It is like being inside a styrofoam cooler. My buildings never get below 35 degrees and that is with no heat. The going cost is around $1.00 per square foot and most sprayers will go down in their price during the summer which is the slow season. The actual cost for the chemical is .33 per sq ft. if that helps any. One inch on the walls is enough or 11/2 is plenty for ceiling and walls. good luck

-- jim phillips (jhphillips@ccrtc.com), January 06, 2002.