Eliminating drafts in PVC windows

Eliminating drafts in PVC windows

Brief overview

Drafts from PVC windows reduce comfort and increase heating bills. Causes range from worn seals and misaligned sashes to poor installation or failing insulated glass units. This guide explains how to diagnose drafts, perform DIY fixes, when to call a professional, and how to prevent recurrence.

Summary

• Quick home checks to find drafts
• Typical causes of leaking air
• Recommended materials and tools for sealing
• Step-by-step DIY repair and adjustment
• When to replace a glass unit or call a technician
• Maintenance tips to avoid future drafts

1. How to find the source of a draft

• Paper or candle test: move a thin sheet of paper or a candle along the sash perimeter; movement indicates airflow.
• Visual inspection: look for damaged seals, gaps in the frame, or uneven sash contact.
• Check drainage holes and weep channels: blockages can affect sash seating and drainage.

2. Common causes

• Worn or deformed rubber seals
• Incorrect hardware adjustment and weak sash pressure
• Faulty installation joints between window and wall
• Faulty or aged insulated glass units with broken seals

3. Materials and tools you will need

• Self-adhesive EPDM sealing tape or silicone cord
• Neutral cure silicone sealant suitable for windows
• Screwdrivers, hex keys for hardware adjustment
• Utility knife, cleaning cloth, solvent for degreasing
• Caulking gun, expanding foam for larger external gaps if required

4. Step-by-step DIY repair

1. Preparation. Clean the frame and reseat areas, remove old sealant and debris, degrease.
2. Replace the seal. If the seal is cracked or flattened, replace it with new EPDM. Remove the old gasket and fit the new one into the groove.
3. Adjust hardware. Close the sash and turn the adjustment screws on hinges and keepers to increase sash pressure and alignment.
4. Seal the installation gap. For gaps between frame and wall, use expanding foam for large voids, then finish with silicone or exterior-grade sealant.
5. Verify. Repeat the paper or candle test and fine-tune adjustments as needed.

5. When to replace the insulated glass unit or call a pro

• Replace the IGU if you see condensation inside the panes, or if the spacer is damaged and the unit has lost seal integrity.
• Call a technician when sash alignment or frame deformation cannot be corrected by simple adjustments, or if major installation work is needed.

6. Cost and time estimates

• Replacing a seal DIY: 1–2 hours, low material cost.
• Hardware adjustment: 30–60 minutes; often covered under warranty if the window is new.
• IGU replacement or major installation repair: several hours to a day, cost varies with glass type and labor.

FAQ

Q: Can I permanently seal a gap with silicone?

A: Silicone can be an effective temporary fix, but replacing seals and proper hardware adjustment provide a more durable solution. Silicone does not restore mechanical fit and may crack over time.

Q: Which gasket type is best?

A: EPDM rubber gaskets are preferred for longevity and elasticity. Foam tapes are useful for interim fixes but wear out faster.

Q: My window drafts at the bottom. What should I check?

A: Inspect drainage and weep holes, and check that the sash engages fully with the frame. Often clearing drains and adjusting keeps fixes the issue.

Q: Will insulating the window reveal reduce drafts?

A: Insulating sills and reveals reduces heat loss but does not replace the need to fix sash seals and proper sealing.

Q: How long does a new seal last?

A: With regular care, EPDM seals last 7–15 years depending on exposure and usage.

If you prefer, we can send a printable checklist for self-inspection or schedule a technician visit to assess and repair drafts professionally.