4 heat treatment lines with precise control for consistent case depth.
Cinder Block Screws
Webbed Grip, No Loosening
Hollow & Grouted Ready
Bulk Tested, On-Time
Sinsun Cinder Block Screws: Engineered for Hollow Masonry Anchoring
Sinsun cinder block screws with deep threads and knurled shank design for secure grip in hollow CMU. 1/4" and 3/8" diameters, 2-1/4" to 6" lengths. 450+ lbs pull-out in lightweight block. Factory direct pricing. Request samples.
Get a Quick QouteSinsun Cinder Block Screws: The Solution for
Hollow Masonry
Hollow Masonry
Cinder block has some unique problems, like thin walls, hollow cores, and different densities. A screw made from solid concrete might not work right. It might go through the wall without cutting threads, or the threads might not have enough material to hold on to.
Sinsun cinder block screws are made just for hollow masonry. The deep, sharp thread pattern is meant to cut into the thin walls of concrete blocks without breaking them. The knurled shank keeps the screw from spinning in holes that are too big or not round. And the case-hardened steel gives the strength needed to keep lightweight block materials from pulling out.
Since 2010, we've been making these, and they are now the first choice for contractors who need to put up electrical boxes, shelves, railing brackets, and more in CMU construction.
-
01
Extra-deep threads: The thread depth is increased to get the most contact with the thin shell material. More contact with the thread means more holding power in a small amount of material.READ MORE -
02
Knurled shank: A knurled section just above the threads holds the block material in place so the screw doesn't spin if the hole is too big. This happens a lot in blocks where drilling can cause breakouts.READ MORE
-
03
Sharp, aggressive point: The tip starts cutting right away, which lowers the risk of cracking the block face.READ MORE
-
05
Partial thread design means that only the part that connects to the block has threads. The smooth upper shank passes through fixtures without sticking.READ MORE
-
05
Case-hardened steel is sturdy enough to cut through blocks and ductile enough to handle torque without breaking.READ MORE
-
06
The result is a screw that stays in place in a block. It can hold up to 450 pounds for a 1/4" diameter screw, as tested in a standard 8" CMU.READ MORE
| Parameter | Value |
| Materials | 10B21 carbon steel (8.8-grade); 316 stainless steel (A4, 10.9-grade) |
| Hardness | HRC 45–50 (carbon steel); HRC 48–52 (stainless steel) |
| Thread Type | Web-Lock Hi-Lo (hollow); Full Aggressive (grouted) |
| Drive Types | Torx T30/T40, Hex Washer, Phillips |
| Length Range | 2-3/4” – 6-1/4” (matched to 4”–10” CMU thicknesses) |
| Diameter Range | 3/16”, 1/4”, 5/16” |
| Embedment Depth | Min. 1-1/2” (hollow CMU, into web); Min. 2” (grouted CMU) |
| Working Temp | -40°C to +80°C |
| Substrate Compatibility | Hollow CMU (webs ≥ 1” thick); Grouted CMU; Solid Brick |
| Corrosion Resistance | Blue Ruspert (720h); Hot-Dip Zinc (480h); A4 Stainless (unlimited) |
Applications: Where Cinder Block Screws Excel
Sinsun cinder block screws solve real-world anchoring challenges in industrial and commercial B2B projects:
Attaching conduit straps, junction boxes, and wire management to walls made of 6" to 8" hollow blocks.
- Web-Lock Thread: Holds on to webs 1" or more wide.
- Efficiency: Cuts installation time by 25% compared to expansion anchors.
Securing HVAC units, compressors, and conveyor bases to grouted block floors 8 to 10 inches thick.
- Heavy Load: 5/16" Hot-Dip Zinc screws can pull up to 900 pounds.
- Compliance: Meets OSHA recommended safety standards.
Fastening handrails, canopy supports, and solar panel mounts to coastal grouted CMU structures.
- Material: A4 stainless steel screws for maximum durability.
- Durability: Resists saltwater corrosion for more than 10 years.
CMU made ahead of time: Temporarily attach formwork and trim to precast block panels.
- Flush Finish: Countersunk flat head screws won't hurt surfaces.
- Precision: Cuts down on production mistakes by 12%.
| Feature | Sinsun Cinder Block Screws | Standard Concrete Screws |
| Thread depth | Extra deep | Standard |
| Shank design | Knurled anti-spin | Smooth |
| Point | Aggressive for block | Standard |
| Thread length | Optimized for shell thickness (1"-1.5") | Often longer |
| Typical pull-out in CMU | 450-1,200 lbs | 250-600 lbs (if they hold) |
| Spinning in oversize holes | Knurling prevents | Common problem |
| Best for | Hollow block, CMU | Solid concrete |
The bottom line:If you're fastening to cinder block, use a screw designed for cinder block. Standard concrete screws may work in some block, but Sinsun cinder block screws are engineered to work reliably in all CMU.
Learn More
| Diameter | Length | Thread Length | Head Style | Drive | Drill Bit Size | Min. Embedment | Pull-Out (8" CMU) |
| 1/4" | 2-1/4" | 1" | Hex / Flat | T-30 / #3 / 5/16" hex | 3/16" | 1" | 450 lbs |
| 1/4" | 2-3/4" | 1" | Hex / Flat | T-30 / #3 / 5/16" hex | 3/16" | 1" | 450 lbs |
| 1/4" | 3" | 1" | Hex / Flat | T-30 / #3 / 5/16" hex | 3/16" | 1" | 450 lbs |
| 1/4" | 4" | 1" | Hex / Flat | T-30 / #3 / 5/16" hex | 3/16" | 1" | 450 lbs |
| 5/16" | 3" | 1-1/4" | Hex | T-30 / 5/16" hex | 1/4" | 1-1/4" | 600 lbs |
| 5/16" | 4" | 1-1/4" | Hex | T-30 / 5/16" hex | 1/4" | 1-1/4" | 600 lbs |
| 3/8" | 3" | 1-1/2" | Hex | T-40 / 5/16" hex | 5/16" | 1-1/2" | 800 lbs |
| 3/8" | 4" | 1-1/2" | Hex | T-40 / 5/16" hex | 5/16" | 1-1/2" | 800 lbs |
| 3/8" | 5" | 1-1/2" | Hex | T-40 / 5/16" hex | 5/16" | 1-1/2" | 800 lbs |
| Screw Diameter | Drill Bit Size | Drill Bit for Block | Hole Depth |
| 1/4" | 3/16" (4.8mm) | Carbide-tipped masonry bit | Through block face + 1/4" |
| 5/16" | 1/4" (6.4mm) | Carbide-tipped masonry bit | Through block face + 1/4" |
| 3/8" | 5/16" (7.9mm) | Carbide-tipped masonry bit | Through block face + 1/4" |
| 1/2" | 7/16" (11.1mm) | Carbide-tipped masonry bit | Through block face + 1/2" |
Note: Drill completely through the face shell of the block. The screw should not penetrate the far side of hollow block unless engaging the back wall or a solid web.
Embedment Guidelines
For cinder block, the screw must engage the front face shell fully. Typical face shell thickness is 3/4" to 1". The threads should be fully embedded within that shell; the tip may extend into the hollow core, which is fine.
Minimum embedment in shell: 3/4"
Optimal: 1" to 1-1/4"
Do not over-drive – stop when head seats; over-tightening can strip the threads in the relatively soft block material.
Real Customer Feedback
"We used Sinsun 1/4" cinder block screws to secure thousands of electrical boxes in a new 40-story residential tower in Dubai Marina. The block here is lightweight and often brittle—other screws we tested would spin or crack the block face. Sinsun screws drove clean every time, and the knurled shank prevented any spinning. Zero failures across 15,000 installations."
"In Germany, we build with high-density concrete block, and precision matters. I needed a screw that would hold firmly in the thin face shell without over-torquing. Sinsun 5/16" cinder block screws worked perfectly on a school renovation project—deep threads bit hard, and the Torx drive gave me full control. These are now my go-to for any block anchoring."
"We do high-rise residential electrical installations, and cinder block is everywhere. I was tired of screws stripping or pulling out. A supplier recommended Sinsun, and I tested a box of 1/4" screws on a 20-floor job. They drove smoothly, held tight, and we had zero callbacks. Now I specify Sinsun on all my projects."
"Our data center uses concrete block partitions, and we needed to mount heavy cable trays. I was skeptical about using screws instead of through-bolts, but Sinsun 3/8" heavy-duty cinder block screws held over 800 lbs in pull-out tests. Two years later, every tray is still rock-solid, even in Singapore's humidity."
FAQ: Cinder Block Screws
Q
What's the difference between cinder block screws and concrete screws?
Cinder block screws have deeper threads, a knurled shank to prevent spinning, and thread length optimized for the thin face shell of hollow block. Standard concrete screws are designed for solid concrete.
Q
Can I use cinder block screws in solid concrete?
Yes, they will work in solid concrete, but standard concrete screws may be more economical for that application.
Q
What size drill bit do I need for 1/4" cinder block screws?
Use a 3/16" carbide-tipped masonry bit.
Q
How deep should I drill?
Drill through the face shell of the block (typically 3/4" to 1" thick) plus an extra 1/4" for dust. Do not drill deep into the hollow core unless necessary.
Q
Do I need to use a hammer drill?
Yes, a hammer drill with a carbide bit is required to penetrate the block effectively.
Q
Can I install these screws into mortar joints?
It's better to avoid mortar joints if possible—mortar is weaker than block. If you must, use a slightly larger screw or test holding capacity.
Q
Are cinder block screws removable?
Yes, they can be unscrewed and reused. The threads remain intact unless damaged.
Q
What's the pull-out strength in block?
For 1/4" screws, typically 450+ lbs in standard 8" CMU. For 3/8" heavy-duty, up to 950+ lbs. Always apply safety factors.
Q
Do you offer stainless steel cinder block screws?
Yes, 304 and 316 stainless available by special order. Lead times apply.
Q
Can I get samples?
Yes. Contact our sales team for sample requests. We'll send up to 5 sizes for testing.
Q
What's the minimum order quantity?
Stock sizes: 100 pieces. Custom production: 5,000 pieces.
Sinsun Factory: Quality Control
Japanese thread rollers holding 0.02mm tolerances.
Knurling machines for anti-spin shank texture.
In-house pull-out testing in actual cinder block.
Salt spray testing per ASTM B117.
Every batch is tested for hardness, thread dimensions, and pull-out performance before release.
Keep In Touch
TO KNOW MORE ABOUT Sinsun, PLEASE CONTACT US！
We are committed to providing you with the best quality service and look forward to communicating with you to solve problems together and bring you a better experience.
our experts will solve them in no time.