For most roofing crews, the best cap stapler for roofing underlayment in 2026 is the Stinger CH38-2 Cap Hammer 2.0, a 2.6 pound airless hammer tacker that drives a 3/8 inch staple and a 1 inch plastic cap in one swing for about $55 to $60. It needs no compressor or hose, which is why many crews reach for it first on synthetic underlayment and felt. If your production volume is high or your decks are large, a pneumatic model like the Stinger CS150B earns its higher price. Below we rank five tools by the job they fit best, then explain when a cap stapler is the wrong choice and a cap nailer is required.
This roundup is based on published manufacturer specifications, retailer pricing, aggregated contractor sentiment from trade forums, and building code language. It is not a hands-on lab test. Prices are typical mid-2026 figures and vary by retailer.
Best cap staplers for roofing underlayment at a glance
The table compares the five tools on drive type, weight, fastener, magazine capacity, typical price, and the job each one fits. A manual hammer tacker wins on cost and mobility. A pneumatic stapler wins on speed across large decks. A cap nailer wins when the underlayment stays exposed or the wind zone demands nails.
| Tool | Type | Weight | Fastener | Capacity | Typical price | Best for |
|---|---|---|---|---|---|---|
| Stinger CH38-2 Cap Hammer 2.0 | Manual hammer tacker (airless) | 2.6 lb | 3/8 in staple + 1 in cap | 168 staples and caps | $55 to $60 | Top pick: most crews, mobility, value |
| Stinger CS150B | Pneumatic stapler | 4.2 lb | 18 ga 7/16 in crown, 5/8 to 1-1/2 in legs + 1 in cap | 200 staples and caps | $255 to $270 | High-volume crews, large decks, variable leg length |
| Bostitch SL1838BC | Pneumatic stapler | 3.9 lb | 18 ga 5/16 in crown, up to 1-1/2 in + 1 in cap | 160 magazine | $260 to $280 | Crews standardized on Bostitch and Stanley air tools |
| Stinger CH38A | Auto-feed manual hammer tacker | Approx 2.6 lb | 3/8 in staple + 1 in cap | 168 staples and caps | $80 to $85 | Airless crews who want fewer reloads |
| Stinger CN100B | Pneumatic cap nailer | Approx 5 lb | 1 in nail + 1 in cap | 200 nails and caps | $290 to $330 | Exposed underlayment and high-wind zones that require nails |
How we picked
We ranked tools on five factors that decide a cap fastener on a real roof: whether the 1 inch cap meets code and warranty terms, drive type and the compressor it does or does not need, weight and reload frequency across a full day, staple or nail length range, and price against the volume of work it will see. Sources were manufacturer spec sheets, listings at Home Depot, Walmart, Lowes, Acme Tools, and Nail Gun Depot, and contractor threads on Contractor Talk and JLC. We did not disassemble or bench-test any tool.
Top pick: Stinger CH38-2 Cap Hammer 2.0
The Stinger CH38-2 Cap Hammer 2.0 is the best cap stapler for most roofing crews because it delivers a code-sized 1 inch cap with zero setup cost. At 2.6 pounds it holds 168 staples and caps, drives a 3/8 inch staple, and needs no compressor or hose, so one worker can move across a deck fast. It won a 2017 Pro Tool Innovation Award and typically sells for $55 to $60. The trade-off is a swing tool: it can fatigue the arm on very large decks, and the staple length is fixed at 3/8 inch.
- Pros: Lowest cost of entry, no air setup, light, fast slap-style driving, code-sized 1 inch cap.
- Cons: Manual swinging tires the arm on big roofs, single staple length, slower than pneumatic on high-volume days.
- Best for: Repair crews, small to mid-size decks, and any contractor who wants one affordable airless tool.
Best pneumatic for high-volume crews: Stinger CS150B
The Stinger CS150B is the pick when a crew covers large decks all day and wants to vary staple length. It weighs 4.2 pounds, holds 200 collated 1 inch caps and 200 18 gauge 7/16 inch crown staples in 5/8, 7/8, 1-1/4, and 1-1/2 inch legs, and offers bump-fire or sequential firing. It typically runs $255 to $270. The cost is the air setup: you need a compressor and hose, which cuts the mobility a manual tacker gives you.
- Pros: Fast across big decks, variable leg length from 5/8 to 1-1/2 inch, large magazine, two firing modes.
- Cons: Requires a compressor and hose, heavier, four to five times the price of the manual pick.
- Best for: Production crews on large residential or light commercial decks.
Best for Bostitch and Stanley crews: Bostitch SL1838BC
The Bostitch SL1838BC suits crews already running Bostitch and Stanley pneumatics who want shared fittings, parts, and dealer support. It weighs 3.9 pounds, holds a 160-staple magazine, drives 18 gauge 5/16 inch crown staples up to 1-1/2 inch with a 1 inch cap, and offers tool-free adjustable depth of drive plus sequential or contact firing. It ships as a kit with a case, air fitting, and fastener samples, and typically costs $260 to $280.
- Pros: Adjustable depth of drive, kit packaging, wide dealer and parts network, dual trigger modes.
- Cons: Higher price, needs air, narrower 5/16 inch crown than the CS150B.
- Best for: Shops standardized on the Bostitch and Stanley air platform.
Best auto-feed manual: Stinger CH38A
The Stinger CH38A is the airless pick for crews who like the hammer tacker format but want fewer stops to reload. It auto-feeds both the staple and the 1 inch cap in tandem, drives a 3/8 inch fastener, and keeps the compressor-free mobility of the CH38-2 while adding a smoother feed. Expect to pay $80 to $85, roughly $25 more than the standard CH38-2, which buys the auto-feed mechanism.
- Pros: Airless, auto-feeds staple and cap together, keeps full mobility.
- Cons: Still a swing tool, costs more than the CH38-2, fixed staple length.
- Best for: Airless crews who reload often and want to lose fewer minutes to it.
Best when underlayment stays exposed: Stinger CN100B cap nailer
When underlayment will sit exposed for weeks or the wind zone demands nails, a cap stapler is the wrong tool and a cap nailer like the Stinger CN100B is the right one. It fires a 1 inch nail with a 1 inch plastic cap at up to five per second, holds 200 nails and caps, and the maker states its NailPac is tested for winds up to 180 mph and passes 2012 ICC building codes. It typically costs $290 to $330. A nail resists pull-through far better than a staple leg when the membrane flaps in wind before shingles go on.
- Pros: Nails hold better under uplift, high-speed firing, wind-rated fastener, code-focused design.
- Cons: Highest price here, needs a compressor, heavier than the staplers.
- Best for: Underlayment left exposed past a manufacturer window, and high-wind regions.
Cap stapler vs cap nailer: which does your job need?
Choose a cap stapler when shingles go down the same day and the wind zone is standard, and choose a cap nailer when the underlayment stays exposed or codes and warranties call for nails. Many underlayment makers allow staples if the roof cover is installed promptly, which describes most jobs, so a stapler is often enough. Nails become the safer choice as exposure time and wind speed climb.
- Same-day shingles, standard wind: A cap stapler with a 1 inch cap usually satisfies the spec and moves fastest.
- Underlayment exposed for weeks: Move to cap nails, which resist pull-through when the membrane flaps before cover goes on.
- High-wind zone at or above 120 mph basic wind speed: Follow the product data sheet and code grid pattern, which commonly points to cap nails.
- Warranty-sensitive system: Read the manufacturer instructions first, because using the wrong fastener can void coverage.
What building code and warranties require for cap fasteners
Building code sets a minimum cap size that most competitor buying guides skip, and it decides whether your fastener passes inspection. Under the International Residential Code, underlayment cap nails must have a cap diameter of not less than 1 inch, and metal caps must be at least 32 gauge sheet metal. This is why every tool above drives a 1 inch cap: a bare staple or nail without the cap does not meet the load-spreading requirement.
High-wind attachment tightens the pattern. Where the basic wind speed is at or above 120 mph, code commonly calls for underlayment fastened in a grid pattern with roughly 12 inch spacing in the field and 6 inch spacing at the side laps, using 1 inch cap fasteners, and it points underlayment to ASTM D226 Type II, ASTM D4869 Type IV, or ASTM D6757. Confirm the exact figures against your local code and the underlayment data sheet, since jurisdictions and products vary.
Warranty terms can be stricter than code. Most roofing systems require an approved underlayment and the specified fastener to keep coverage valid, and synthetic underlayment warranties often run 20 years or longer. If the manufacturer instructions name cap nails for exposed installs, a cap stapler on that job may cost you the warranty, so read the printed instructions before you pick the tool. For the layer beneath these fasteners in leak-prone areas, see our guide to the best ice and water shield.
Cap fasteners sit inside a wider tool kit. For the shingle nailing that follows underlayment, compare options in our guide to choosing a coil roofing nailer, and for the blade work around valleys and laps see the best roofing knife. Because underlayment work puts crews on bare, slick decks, our DIY roofing injury report shows why fall protection belongs on the same purchase order as any fastening tool.
Frequently asked questions
Can you staple synthetic underlayment? In many cases yes, if the manufacturer allows staples and the shingle cover goes on the same day, which describes most jobs. The fastener must carry a 1 inch plastic cap to meet code and spread the load. When the underlayment will stay exposed for weeks or the wind zone is severe, most makers require cap nails instead, so read the product instructions first.
What size cap staple do I need for roofing underlayment? The plastic cap must be at least 1 inch in diameter to meet the International Residential Code. Staple leg length depends on the deck: a 3/8 inch leg suits a hammer tacker like the Stinger CH38-2, while pneumatic tools such as the CS150B drive legs from 5/8 to 1-1/2 inch. Match the leg to your sheathing thickness and the underlayment data sheet.
Is a cap stapler or cap nailer better for underlayment? A cap stapler is faster and lighter and works well when shingles follow the same day in standard wind. A cap nailer holds better against uplift and is the safer pick when underlayment stays exposed or the wind speed is at or above 120 mph. The right answer depends on exposure time, wind zone, and what the manufacturer instructions require.
Do you need a compressor for a cap stapler? Not always. Manual hammer tacker models like the Stinger CH38-2 and the auto-feed CH38A are airless and need no compressor or hose, which keeps a single worker mobile. Pneumatic staplers such as the Stinger CS150B and Bostitch SL1838BC do require a compressor and air hose, which trades mobility for speed on large decks.
Why does underlayment need a plastic cap and not just a staple? The 1 inch cap spreads the fastener load across enough surface to resist tearing and pull-through, and code requires that minimum cap diameter. A bare staple or nail can slice through the membrane when it flaps in wind or when it carries the weight of a walking crew, so the cap is what keeps the underlayment attached and the installation code-compliant.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.