Insulating a 40x40x14 Metal Building

[dude47]

Hi Everyone, I have been reading through a lot of postings and might I say wow, some of you have got some amazing garages! I am going to be moving into a new house in a month that has a 40x40 metal red steel building on the property. They did not insulate it when they installed it. I know the proper way is to get vinyl faced fiberglass rolls and put it in under the sheeting. Well it is already built and I really don't feeling like removing all the sheeting and adding it in.

Spray foam? I would loved to do a few inches of closed cell spray foam but I haven't got 12k cash laying around.

So here is where I am at. I like the idea of finishing the building and either drywalling or using OSB to sheet the inside. I recently scored 3100 sqft of R30 kraft faced fiberglass insulation 2x4ft batts from Lowes on clearance for 16 cents a sqft. The price was too good to pass up. I couldn't say no. $505 for enough R30 to do the walls and the roof. Probably a little overkill but hey, the price was right!

Now here is my plan Stud out the front of the perlins an additional 2" on 2 ft centers to make room for the R30 and hang drywall or OSB. I was planning on putting plastic sheeting between the OSB and the insulation to form a vapor barrier. The red steel beam that runs through the center I was planning on wrapping with Foil backed duct insulation to keep it from being a thermal bridge.

Couple questions for anyone who can help.

Is the plastic sheeting for a vapor barrier between the interior sheeting and the insulation the right place for it?

Should I sell off the ridge vent?

With Shopping around on Craigslist for the rest of the materials I can make this happen for around $1800-$2000 total cost and have the entire show well insulated and finished inside.

Here is the building.

<a href="http://s1363.photobucket.com/user/dude471/media/Workshop%20outside_zpshntrzzoq.jpg.html" target="_blank"><img src="http://i1363.photobucket.com/albums/r717/dude471/Workshop%20outside_zpshntrzzoq.jpg" border="0" alt=" photo Workshop outside_zpshntrzzoq.jpg"/></a>
<a href="http://s1363.photobucket.com/user/dude471/media/Workshop2_zps8iqfbrxb.jpg.html" target="_blank"><img src="http://i1363.photobucket.com/albums/r717/dude471/Workshop2_zps8iqfbrxb.jpg" border="0" alt=" photo Workshop2_zps8iqfbrxb.jpg"/></a>
<a href="http://s1363.photobucket.com/user/dude471/media/Workshop_zpshmnd7xng.jpg.html" target="_blank"><img src="http://i1363.photobucket.com/albums/r717/dude471/Workshop_zpshmnd7xng.jpg" border="0" alt=" photo Workshop_zpshmnd7xng.jpg"/></a>

 

[bandaidmd]

When asking questions about insulation it's helps to have an idea of where your located.

Sent from my SM-N900V using Tapatalk

 

[matt_i]

My feeling about "thermal bridging" in terms of structural members, primarily wood and metal is that its about the last 5% of the battle after a large number of other things have been done. So, I would prioritize that lower on your list.

I would seal the ridge vent, as that will be like trying to trap heat in a chimney.

Something has to be done to the underside of the metal roof to keep it from sweating and raining if conditions are perfect. Spray foam is a popular option, might be the only option at this point after the panels are installed.

 

[dude47]

Sorry, I am located in the High Desert of California. So 110-120f during the day in the summer, during the winter it will get down int he 20s at night but not that often. Usually stays just above freezing. A Random Thunder Storm here and there during the spring but for the most part low humidity.

 

[bandaidmd]

i would at least use spray in the ceiling.

 

[dude47]

I love the idea of spray foam but if I am using R30 and a vapor barrier is it required? They usually use Fiberglass insulation directly on the metal surface with a vapor barrier when they assemble these buildings correct?

 

[readhead]

A couple of things need to be addressed here. The building was not sealed correctly when it was erected as indicated by the missing closers at the eave and ridge. Since that was left out I can only assume that there was no thermal break tape installed on the purlins and girts.

If a metal building is to be insulated after erection then the tape is a must. Normally the thermal break is made when the insulation is pinched between the sheeting and the structure. At this point you will need to insulate everything you see which isn't as bad as it sounds. Spray foam would be the obvious choice but that sounds like it is off the table. The walls are easy. The purlins can be insulated with ridged foam or the lid can be fired down to provide an insulation cavity and covered with what ever finish you choose.

 

[dude47]

Yea I was looking at the rubber strips for sealing the edges. Something like this. Seal
I was thinking about just loosening the panel screw and sliding them in and re tightening them.

Spray foam wont provide a thermal break between the purlins/beams and the sheet metal either though would it?


Another idea I had was get a few sheets of 1" poly iso and if the screws are long enough loosen all the screws on the panels and slide strips of ridged foam in between the sheet metal and re tighten the screws. Everything I have read says that when you screw the panels on the outside and compress fiberglass that the r value of the fiberglass drops to near nothing between the pulins and sheet metal.

 

[readhead]

The spray foam would cover everything. Yes, when the insulation is squeezed between the framing and the sheets it reduces the R value but provides a thermal break. 1" poly would be to thick. Thermal break tape is 3/8" and squeezes down to about 3/16". That is the wrong clouser. Talk to a metal supplier.