Saturday, 28 September 2013

Insulating the floor

First as promised, my sketchy rain shelter.  It won't stand up to snow but the roof should be on before then.  The center beam is made up of two 2x4x14s butted up end to end and a 2x4x8 spanning the joint.  Hopefully there is no wind.

It was pretty hairy putting this up and it included almost having the main beam dropping onto the solar panels.  It will be a lot easier taking it down.

I spent Friday and today putting the insulation in for the floor.  My first choice was wool from Oregon Shepard but they didn't reply to my inquiries.  I ended up going with rock wool and here are my reasons:
  • loose fill has a lower R-value per inch
  • loose fill has to fluffed up
  • fiberglass is itchy and has a slightly lower R-value
  • rock wool is pretty dense and will probably resist settling and shifting
  • rock wool is fairly water resistant
  • rock wool was $220 vs fiberglass $130

My little spreadsheet to help my choice

Floor insulation

Cubic ft needed 92

ruxul loose ruxal batt FG loose FG batt Cellulose
Coverage/pkg in cubic feet 22.49 18.24 56.63 35.89 18.12
Cost/pkg 34.47 36.38 36.20 43.66 14.22
Weight/pkg 33.00 42.10 30.00 29.90 25.35

R/inch 2.82 4.00 2.70 3.64 3.33

Weight/cu ft (lbs) 1.47 2.31 0.53 0.83 1.40
Cost/cu ft 1.53 1.99 0.64 1.22 0.78
Cost/R 0.045 0.042 0.020 0.028 0.020

Weight total (lbs) 134.51 211.56 48.57 76.37 128.24
Bags needed 5.00 6.00 2.00 3.00 6.00
Cost 172.35 218.28 72.40 130.98 85.32

Now the fun part, installing it.  I wore long sleeves, leather gloves and a mask.  Rock wool is nowhere near as itchy as fiberglass and it washes off much easier.  I found it would give slivers without the gloves. I've finished installing 3 1/2 bags out of five.

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