The 9 Best Insulation Knives
Special Honors
Olfa If you aren't a skilled professional, but rather a homeowner looking to equip yourself for a one-off renovation project, then you might be able to get away with using a standard utility knife instead of a specialized tool. In this arena, Olfa has been a giant for decades, and offers a limited lifetime warranty on many of its affordable choices. On top of that, they make a great multipurpose asset to have around the house, so you're likely to find more uses for your purchase in the future. olfa.com
Insulation Tools When it comes to hand tools, this company's got the insulation-installation niche covered, offering a wide variety of gear that includes, but certainly isn't limited to, a nice selection of knives and shears. insulationtools.com
Editor's Notes
March 11, 2021:
We ended up retaining most of our previous picks for this list, but decided to do away with the Hultafors FGK, Vintool Insulation Knife and Everhard Long Cut, due to availability issues. We also added a couple new items to our list.
Our first fresh inclusion, the Stanley FMHT10327-1, sports a notably long 14-inch blade that, on this list, is only rivaled by the comparable length of the Morakniv Craftsmen. It’s a reasonably priced model from a trusted brand, but we can’t help but wondering if it’ll be a bit on the long side for some of our audience members — an opinion that will likely hinge on what type of material they’re cutting.
Our second new choice was the Milwaukee 48-22-1920, which, at 11 inches, is about half the length of our pick from Stanley (proportionally, its 5-1/2-inch blade is even shorter). This might make it less suitable for taking on thick materials, but it also makes it a little more practical to wear regularly. For the right person, this model might easily double as an everyday-carry utility knife, and many users report appreciating how well its plastic sheath holds it in place. Both of our new choices this time around are backed by limited lifetime warranties.
We put some serious thought into including some hot foam cutters on this list, as they would superficially appear to present a great solution for users who hate the massive mess generated when cutting foam insulation by knife, but it seemed questionable whether any of the models we researched were really built for regular use in construction. Some, for example, recommended a 15-second cool down period after every 15 seconds of use, which hardly presents a practical option for continuous operation. If, however, you think that it’s something you still might be interested in, then you might find something on our list of hot wire foam cutters.
April 16, 2019:
We included knives in a variety of sizes and styles to suit different tasks. Double-sided blades offer the versatility to work with multiple types of insulation. The Klenk Dual Duct, Malco Serrated, and Klein Tools Stainless Steel all have a serrated side and a smooth side, and the latter also has a metal cap on the end of its handle that can double as a hammer. If you need a longer blade, the 18-inch Hultafors FGK and 14-inch Morakniv Craftsmen are both good options, and the Fuller Tool Double Sided is 11 inches long with two different serrated edges. Designed for ISO board insulation, the Everhard Long Cut is sharpened on all sides, and the chisel tip is useful for opening plastic packaging, but it does not have a nonslip grip and can be rather dangerous when using a lot of pressure. The Slice Industrial has a replaceable ceramic blade that's great for foam, fiberglass batts, and other soft materials, but it is more brittle than metal and may break if dropped or used on tougher materials.