Installing screws into a quartz countertop requires some special considerations to avoid damaging the material. Quartz is an engineered stone made from quartz crystals held together with resin, making it very hard and durable. However, it is still possible to crack or chip quartz if you use the wrong techniques or tools. Follow this guide to learn the best practices for pre-drilling and screwing into quartz safely and effectively.
Selecting the Right Screws
The type of screw you use is important for getting a good hold in quartz without causing cracks. Here are some screw characteristics to look for:
- Machine Screws – Machine screws with a flat bottom and sharp threads are ideal for quartz. The flat bottom prevents the screw from piercing through the quartz.
- Stainless Steel – Stainless steel or other metal screws are preferable over wood screws. The harder material is less likely to crack quartz.
- Fine Threads – Screws with finer threads grasp the quartz better than coarse threads and reduce the chance of cracking.
- #8 or #10 Size – Choose a screw diameter between #8 and #10 size. Larger screws increase the risk of damaging the quartz.
Pre-Drilling Holes
Always pre-drill holes for screws in quartz prior to screwing them in. This prevents the screw from forcing its way into the quartz and cracking it.
Follow these pre-drilling tips:
- Use a carbide drill bit suited for drilling into stone. Carbide provides hardness to cut through quartz without abrading.
- Drill the pilot hole 2/3 the diameter of the screw. For example, for a #8 screw, drill a 5mm hole.
- Drill the hole 1/4″ deeper than the screw length to allow room for fragments.
- Drill straight down with light pressure to avoid cracking at the quartz surface.
- Lubricate the drill bit with cutting oil to reduce friction and heat.
Driving in Screws
When ready to insert the screw, follow these guidelines:
- Place a neoprene washer under the screw head to prevent cracking. The washer evenly distributes pressure.
- Use a low speed setting on your drill to drive in the screw gradually without generating excess heat.
- Apply hand pressure on the drill to “feel” when to ease up to avoid stripping or cracking the quartz.
- Avoid over-tightening the screw. Tighten just until the head is flush with the quartz.
Filling Holes
For a smooth finish, fill any gaps around the screws with the following materials:
- Clear silicone caulk designed for stone. Match the caulk color to your quartz.
- Two-part epoxy resin formulated for stone repair. Mix and apply per the product directions.
- Quartz filler available through quartz fabricators. It will match the color and texture.
Apply the filler into the gap and allow time to cure completely. Then sand flush for a seamless appearance.
Tips to Avoid Cracks
Here are some extra precautions to take whenever screwing into quartz:
- Only drill and screw into solid quartz, not near seams or weak points.
- Clamp the quartz securely to a sturdy surface when drilling holes.
- Clean drill bits often to reduce heat buildup.
- Use a drill with a clutch or torque setting to prevent over-tightening screws.
- Hand tighten screws for better control and feel to stop when snug.
- Limit the number of screws drilled into a single quartz piece to lower the chance of cracks developing.
FAQs About Installing Screws in Quartz
Here are answers to some frequently asked questions about screwing into a quartz countertop:
Should I use a center punch before drilling quartz?
No, avoid using a center punch. It can crack or chip the quartz surface. Start drilling directly into the quartz.
What size drill bit should I use for a #8 screw?
For a #8 sized screw, make the pilot hole around 5mm in diameter – about 2/3 the width of the screw.
Can I use a hammer drill on quartz?
Do not use a hammer drill as it can fracture quartz. Use a regular drill on slow speed with light pressure.
Is silicone or epoxy better for filling quartz holes?
Silicone works well for small gaps around screws. For larger holes, a quartz-specific epoxy filler will match the color and texture better.
How soon can I screw into newly installed quartz?
It’s best to wait 24-48 hours for new quartz to fully cure before drilling into it. Rushing the process risks cracking the quartz.
Should I pre-drill holes for quartz bracket installation?
Yes, always pre-drill holes for brackets or supports that attach under quartz. Follow the same drill size guidelines based on screw diameter.
Conclusion
Installing screws into a quartz countertop takes careful preparation and technique. With the proper drill bits, screw selection, pre-drilled holes, and filler, you can screw securely into quartz without causing damage. Always drill slowly into the stone with light pressure. If cracks do appear, consult a professional fabricator immediately to prevent further propagation. With some caution and patience, you can screw into quartz countertops successfully.