Replies

1. 
   FatRoman | Apr 16, 2009 05:05pm | #1

   #2 -- Cutting the XPS boards... I tried a number of ways. The best method I found was to score the cut with a utility knife with an up and down plunge-sawing motion, and then finish the cut with a Japanese pull saw.

   The putty knife method, I found, just crushed the foam. Same thing with trying to drag the utility knife down the cutline.

   The pull saw was nice and neat, and the wide blade helped keep it from wandering.

   'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb

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2. 
   Ted W. | Apr 16, 2009 05:47pm | #2

   1. What is the cleanest and fastest way to cut fiberglass insulation blankets?

   I lay a scrap strip of plywood unde the cut and use a sharp kitchen knife. The longer blade gets down into the insulation without haveing to burry your hand in the stuff. Just DONT use a serated knife, as it will pull the fibers. Also, keep a sharpening stone or something on hand, to resharpen every 8 or 10 cuts.

   ~ Ted W ~

   Cheap Tools! - MyToolbox.net
   Meet me at House & Builder!

3. 
   PedroTheMule | Apr 16, 2009 08:16pm | #3

   Hi Chief,

   1. What is the cleanest and fastest way to cut fiberglass insulation blankets?

   I use a 4' section of wood 2x4 that I gorilla glued a strip of 16g metal to with a 1/4" reveal. The metal side goes down with a knee and hand on top to compress the fiberglass......the free hand uses a utility knife to easily slice right through....I also wear deer skin gloves regardless of temp.

   2. cleanest way to cut 2” thick polystyrene insulation foam boards?

   I sharpen the edge of a long putty knife to a razor sharp edge for cutting to length. To cut width's, I use a 10" diablo blade mounted backwards in my portable table saw....even though it cuts without smoke, melting and dust.....I still recommend using outside with a respirator because the material you're cutting can be carcinogenic. Be sure to foam seal and/or tape the edges.....just because it fits with a squeak, doesn't mean it's airtight.

   I also like the idea of a Japanese pull saw as recommended by someone else but haven't tried that yet.....next time.

   3. What tape best sticks to 6-mil polyethylene?

   I've had good success with tyvek house wrap tape.....dependable and easy to get...be sure to overlap your plastic at least a full stud bay on framing.

   4. What is the standard R-value for insulating under a floor in a crawl space?(Location: Northern VA)
   5. What is the standard R-value for insulating in an attic for ceiling? (Location: Northern VA)

   Here's a reference:   http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table 

    do the job cheaper and quicker

   This sounds as if you're getting into a new area of work. If so, I realize it's common to underprice yourself to cut the competition.....and if you do so be happy with your choice but don't cut your quality. View your price of the job as such....."the job"......not how much you'll make per hour.....spend all the time necessary to perfect the job and you'll reap referals based on the customer getting what they wanted...lower utility bills....as a matter of fact that would be a good way to follow up in the future...see how much they're saving and ask if they have friends that would like the same quality of service.....in time you get paid for your level of performance which is always higher that the job/hour could ever produce......then you'll be the competition to beat!

   Pedro the Mule - takes more than furr to make good R-Value

1. 
   Chief | Apr 16, 2009 09:45pm | #4

   Thank you for your very thorough response. those are some great and helpful tips. However, I'm trying to visualize the fiberglass cutting jig you described. Is the 2x4 on the top of the insulation or bottom? and is that metal a guide for the knife? Would you mind clarifying?Chief of all sinners.

1. 
   PedroTheMule | Apr 16, 2009 10:35pm | #5

   Hi Chief,

   visualize the fiberglass cutting jig you described. Is the 2x4 on the top of the insulation or bottom? and is that metal a guide for the knife?

   I'm getting lazy these days so I generally set up a couple of short sawbucks and lay 2x4's and a sheet of plywood across them to make a 2' high table.

   Lay a piece of fiberglass on top of the table.

   Use your 2x4 jig with the metal dull blade facing down.

   I'm generally right handed so I use my right knee on the close side of the 2x4 and left hand on the far end and use my weight to press down. The metal edge compresses the fiberglass and I run my utility knife down the side of the metal edge where it meets the crease it forms in the fiberglass.

   Fiberglass batts cut so much easier when compressed and the metal edge focuses the pressure.

   Something I've never tried.....I wonder if I could find one of those old drafting swing arm style paper cutters.....that would be interesting to see if that would work.

   Pedro the Mule - Fiberglass, oh the hoof itch

1. 
   Chief | Apr 16, 2009 11:04pm | #6

   Thanks for the clarification... I too thought of a paper cutter with the arm that swings down, but the thought of something hitting that arm when fingers are near by gives me the eebe-gebees. Probably not a safe tool to have on site. And there's too many tools in the trailer as is.
   Chief of all sinners.

4. 
   Norman | Apr 16, 2009 11:11pm | #7

   2. cleanest way to cut 2” thick polystyrene insulation foam boards?

   I often use a long coarse blade in a cheepo skil jig saw. Easy and quick.

    

5. 
   fm | Apr 17, 2009 06:04am | #8

   A few years ago I needed to cut a bunch of R-38 fiberglass batts lengthwise.  DW came up with the best solution I've used so far.  Use that electric carving knife that is sitting unused in your kitchen.  Works slick.  Oh, use a good respirator.  You knew that.

   Frank

6. 
   mike_maines | Apr 17, 2009 06:09am | #9

   I find a tablesaw is the best way to cut sheets of foam.  A little dangerous, but very clean cuts.  Crosscut with a Skilsaw.

7. 
   Dinosaur | Apr 17, 2009 08:03am | #10

   1. Snap-off-type razor knife at full extension; compress the 'glas with a gyprock T-square or a piece of 2x or 1x used as a straightedge.

   2. Same type of razor knife, also at full extension. Set the blade at a very shallow angle to the face of the foam board, and slide it down--do not saw. Also, do not try to cut through the entire 2" of thickness in one pass. Use a T-square to start the cut, then for subsequent passes with the knife, open the kerf by bending the panel over a piece of 2x.

   3. Red (Glasclad) (Tuck) tape. The stuff sticks to anything and the acrylic adhesive just gets stronger with time.

   (4 & 5: I'm not familiar with the insulation needs in your region.)

   Dinosaur

   How now, Mighty Sauron, that thou art not brought
   low by this? For thine evil pales before that which
   foolish men call Justice....
   

   

8. 
   DonK | Apr 17, 2009 02:25pm | #11

   Just had a Code review class this week. We're in southern VA, but it's the same thru the state.

   (By Code, not necessarily practice...) Attic is R 38. Floors are R 19, but they say crawl spaces are 10/13. I would use the 19 if you can get it in there. 

   Don K.

   EJG Homes   Renovations - New Construction - Rentals

    

9. 
   DonNH | Apr 17, 2009 07:51pm | #12

   1)  I picked up an Insul-Knife from Amazon a few months ago.  Looks like a hand saw without teeth and some curvature on the blade.  Keep it sharp and it cuts well.  Around $30 if I remember correctly.

   2) snap-blade knife at full extension works pretty well up to 2" thick, doesn't leave dust.  Doesn't always cut perfectly square - depends a lot on tecnique.  Table saw cuts nice & square, but makes a lot of dust & it's easy to bind a little & have the saw try to grab the part from you.  Skilsaw w/ rip guide works ok also.

   Don