When installing PVC trim outdoors, using the right screws is crucial to get a secure, long-lasting installation. The main considerations when choosing screws for PVC trim are preventing the plastic from cracking, choosing a material that won’t corrode or stain, and using the proper size and type of screw head.
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Preventing Cracks
PVC trim is plastic and can crack if too much pressure is put on it by screws. To prevent cracks:
- Use screws specifically designed for PVC. These have blunt tips to prevent cracking.
- Predrill holes slightly larger than the screw diameter. This prevents pressure from building up.
- Drive screws in straight and do not overtighten. Uneven pressure can cause stress cracks.
- Allow 1/32″ gap between trim pieces when installing. This gives room for expansion and contraction.
Choosing a Screw Material
For outdoor use, look for stainless steel or other corrosion-resistant screws. Avoid plain steel screws that can rust and potentially stain the trim. Good options include:
- Stainless steel – Most popular option, resists corrosion and stains.
- Ceramic coated – Steel screws with a ceramic coating to prevent rust.
- Aluminum – Lightweight, corrosion resistant, may have reduced strength.
- Composite – Plastic/wood screws that can match PVC trim colors.
Screw Head Types
Using the right screw head is also important for a secure install. Good options for PVC include:
- Bugle head – Extra holding power, trim sits flush against wall.
- Trim head – Countersunk head, drills own pilot hole.
- Pan head – Low rounded head, minimal visibility.
Avoid flat head screws – they can damage trim when overtightened. Also avoid phillips heads that can strip out plastic.
Choosing the Right Size
Use fine thread screws that are long enough to penetrate the wall structure by at least 1″. Recommended sizes include:
- 1″ screws for installing trim to framing or sheathing
- 1-1/4″ or longer for going through foam insulation
- At least 2-1/2″ for fastening trim over brick or stucco
For thickness under 1″, use screws that are the same width as the trim piece. For thicker trim, choose a screw length 2/3 the width. This provides enough holding power without risking poking through.
Recommended Screws for PVC Trim
Here are some top-rated screw options specifically for PVC:
| Screw | Features |
|---|---|
| Grip-Rite Plasti-Grip PVC Screws | – Blunt tip prevents cracks – Fine thread |
| Prime-Line Plastic Sheet Metal Screws | – Stainless steel – Trim head |
| DECK-DRIVE Composite Screws | – Ceramic coated – Star drive resists stripping |
| Spax Power Lag PVC Screws | – Tough stainless steel – Weather resistant |
Installing PVC Trim
Follow these best practices when installing PVC trim with screws:
- Drill properly sized pilot holes in trim to prevent cracking.
- Use impact driver or drill on slow setting to avoid damage.
- Drive screws perpendicular to trim and do not overtighten.
- Leave 1/8″ gap between trim and screw head.
- Use trim removal tool or putty knives to remove trim if needed.
- Caulk gaps after installing for waterproof finish.
Tips for Choosing PVC Trim Screws
- Pick screws designed specifically for PVC/vinyl.
- Stainless steel resists corrosion and blends in.
- Bugle or trim head provides secure hold.
- Fine threads and blunt tip prevent cracking.
- 1″ size works for most applications.
- Always predrill holes slightly bigger than screw.
Conclusion
Choosing the right screws is key to properly installing PVC trim. Specialized PVC screws with blunt tips and stainless steel construction prevent cracks and keep trim securely attached. Predrill slightly oversized holes and avoid overtightening. Allow small gaps between trim pieces and screw heads. Take care when installing and PVC trim can last for many years outside with minimal maintenance.