What is a hook blade, and which utility knife blade cuts shingles, felt and membrane? Hook blades vs straight utility blades, roofing and carpet knives, linoleum knives, snap-off blades, blade steel, how to change a blade and when a blade is done
A hook blade is a utility knife blade with the cutting edge curved back into a hook at each end, so it slices downward through shingles, felt, synthetic underlayment, roofing membrane and carpet without the point digging into whatever is underneath. It fits any standard utility knife in place of the straight trapezoid blade. Roofers run hook blades for cutting shingles at rakes, valleys and ridges and straight blades for everything else; a dedicated roofer’s knife takes the heavier Talon and bow-tie blades for all-day shingle work. Blades are consumables: change one when it tears instead of slicing, which on asphalt shingles is a few bundles.
C&R 208-005 Hook Blades, 5 countThe product data lists the SupraHook as a heavy-duty hook blade in a 100 count pack and a 5 count tubeWhy the blade matters more than the knife. Every utility knife on a roof holds the same 2-7/16 by 3/4 inch blade; what changes the cut is the blade shape, the steel and how often it is swapped. A straight blade pushed through a shingle drags granules, dulls in a course and nicks the underlayment below; a hook blade pulls through from above and stops at the hook. The questions people ask — what a knife with a hooked blade is called, where to buy hook blades, what the standard blade is, how to snap or change one, whether a box cutter is a utility knife, what steel the blades are — are all answered below, followed by the knives built for roofing, carpet, linoleum and single-ply membrane.
Blades and knives, question by question
Dimensions and counts are from the blade packs and our product data; no claim here goes beyond what is printed on them.
Blades in plain words
- Hook blade: curved edge, point stays out of the deck; for shingles, felt, membrane, carpet. Fits any standard utility knife.
- Straight (trapezoid) blade: 2-7/16 x 3/4 x 0.025 in with two notches; the 207. Turn it end for end, then replace it.
- Roofer blades (Talon, bow tie) are thicker and go in a roofer’s knife, not a utility knife.
- 208 standard hook, 208H with hole, 210X extra deep, 208XL SupraHook heavy duty, 308 Talon combination.
- Change a blade when it tears instead of slices; on asphalt shingles that is a few bundles.
- Quick-change and twist-lock knives swap blades without a screwdriver; folding knives close in a pouch.
- Membrane slitter for TPO and PVC strips; carpet knife for carpet; curved linoleum knife for sheet goods.
- Cut shingles from the back at the rake so the granules do not dull the edge.
Questions people ask
What is a knife with a hooked blade called?
A hook blade knife, roofing knife or carpet knife; the blade itself is a hook blade or hooked utility blade and fits any standard utility knife.
What do you call a utility knife?
Utility knife, box cutter, razor knife, Stanley knife or carpet knife; the handle and the 2-7/16 inch blade slot are the same.
What is the standard utility knife blade?
A trapezoid 2-7/16 inches long, 3/4 inch tall and about 0.025 inch thick with two locating notches; our 207.
How to snap a utility knife blade?
Extend one scored segment past the handle, grip it with the handle cap or pliers and bend it down until it breaks at the score. Trapezoid blades are turned and replaced, not snapped.
What steel is used in utility knife blades?
High-carbon steel as standard, bi-metal (high-speed steel edge on a spring steel body) for longer life, and carbide-edged blades for the longest life.
Is a box cutter better than a knife?
They are the same tool; a box cutter is a utility knife used on cardboard. Against a fixed kitchen knife, the replaceable edge is the advantage on a jobsite.
Where can I buy a hook blade?
From roofing supply houses and hardware stores in cards of 5, and from us by the box, dispenser, 100 pack and case; the band on this page has the current prices.
How to change the blade in a carpet knife?
Open the body with its thumb screw or release, lift the blade off the pins, seat the new hook blade and close it.
What kind of blade does the safest utility knife have?
A hook blade or a rounded-tip safety blade in a self-retracting handle; the point cannot stab and the edge hides when the thumb lets go.
Is a utility knife the same as a prep knife?
No. A prep knife is a fixed, honed kitchen blade; a utility knife has a replaceable trapezoid or hook blade.
Is it illegal to carry a utility knife?
Knife laws are local. On a jobsite it is a tool, usually carried closed in a pouch; check the rules where you work.
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