UPVC windows are renowned for their durability and low maintenance, but even the best windows require periodic resealing to maintain their performance. Proper sealing prevents drafts, water ingress, and energy loss while extending the life of your windows. This comprehensive guide covers everything you need to know about UPVC window resealing.
Table of Contents
Why UPVC Windows Need Resealing
UPVC windows rely on sealant to create weathertight barriers between the frame and the wall, as well as around the glass units. Over time, several factors cause sealant to deteriorate:
UV Exposure
Sunlight breaks down sealant compounds, causing cracking, shrinkage, and loss of adhesion over time.
Temperature Fluctuations
Expansion and contraction from temperature changes stress the sealant, leading to gaps and cracks.
Moisture Exposure
Constant exposure to rain and humidity degrades sealant, particularly lower-quality products.
Natural Aging
Even quality sealant has a finite lifespan, typically 10-20 years depending on conditions and product quality.
Consequences of Failed Sealant
- Water ingress: Leads to damp, mould, and structural damage
- Drafts: Increases heating costs and reduces comfort
- Condensation: Moisture buildup between panes or on frames
- Energy loss: Reduced thermal efficiency increases bills
- Frame damage: Water penetration can damage UPVC and surrounding walls
Key Takeaway
UPVC window sealant deteriorates naturally over 10-20 years due to UV exposure, temperature changes, and moisture. Failed sealant causes water damage, drafts, and increased energy costs, making regular inspection and timely resealing essential.
Signs Your Windows Need Resealing
Regular inspection helps catch problems early. Look for these warning signs:
Visual Signs
- Cracks or gaps in the sealant
- Sealant pulling away from frame or wall
- Discoloration or yellowing
- Visible mould or mildew growth
- Crumbling or flaking sealant
- Hardened, inflexible sealant
Performance Issues
- Drafts around window frames
- Water leaks during rain
- Condensation between glass panes
- Increased outside noise
- Higher heating bills
- Cold spots near windows
Touch Test
- Sealant feels hard and brittle (should be slightly flexible)
- Sealant feels sticky or tacky (sign of breakdown)
- Pieces come away when touched
- Surface feels rough or degraded
When to Act
Immediate action required if you notice:
- Active water leaks
- Large gaps or missing sections of sealant
- Visible mould growth
- Significant drafts
Plan resealing within 3-6 months if you see:
- Minor cracks or shrinkage
- Discoloration
- Slight pulling away from surfaces
- Hardening of sealant
Key Takeaway
Inspect your UPVC window sealant annually for cracks, gaps, discoloration, and performance issues like drafts or leaks. Address active problems immediately and don't hesitate to call professionals for complex jobs or when DIY results are unsatisfactory.
Enjoying this article?
Get more expert sealant tips delivered to your inbox monthly.
Choosing the Right Sealant for UPVC Windows
Not all sealants are suitable for UPVC windows. The right choice ensures longevity and performance:
Recommended Sealant Types
Neutral Cure Silicone (Best Choice)
The professional standard for UPVC windows, offering optimal performance:
- Excellent adhesion to UPVC, glass, and masonry
- Won't corrode or damage UPVC frames
- Highly flexible to accommodate movement
- UV and weather resistant
- Long lifespan (15-20 years)
- No corrosive byproducts during curing
Recommended brands: Dow Corning 791, Soudal Silirub 2, Everbuild 825
Hybrid Polymer Sealants (Alternative)
Modern alternative with some advantages:
- Paintable surface (if needed)
- No shrinkage
- Good adhesion and flexibility
- UV resistant
- Can be more expensive
Recommended brands: Soudal Fix All, CT1, Everbuild Stixall
Avoid These for UPVC Windows
- Acetoxy cure silicone: Can damage UPVC and produce corrosive acetic acid
- Acrylic sealant: Not flexible enough, poor weather resistance
- Cheap "general purpose" sealants: Short lifespan and poor performance
Colour Selection
- White: Standard for white UPVC frames, most common choice
- Clear: For glass-to-frame seals, less visible
- Brown: For brown or woodgrain UPVC frames
- Grey: For grey UPVC or modern aesthetics
Key Takeaway
Always use neutral cure silicone or hybrid polymer sealants for UPVC windows. Never use acetoxy cure silicone or acrylic sealants, as they can damage frames or fail prematurely. Match the colour to your frame for best appearance.
Enjoying this article?
Get more expert sealant tips delivered to your inbox monthly.
Preparation and Tools Required
Proper preparation is crucial for successful resealing. Here's what you'll need:
Essential Tools
Removal Tools
- Sealant remover tool or utility knife
- Scraper or putty knife
- Wire brush (for stubborn residue)
Application Tools
- Sealant gun (skeleton or cartridge type)
- Sealant smoothing tool or profiler
- Masking tape (low-tack)
Cleaning Supplies
- Methylated spirits or isopropyl alcohol
- Lint-free cloths
- UPVC cleaner (optional)
Safety Equipment
- Protective gloves
- Safety glasses
- Dust mask (for removal work)
Materials Needed
- Neutral cure silicone sealant2-4 cartridges (per window)
- Sealant remover (optional)1 bottle
- Methylated spirits500ml
- Masking tape1-2 rolls
Estimated total cost: £40-70 for materials and tools
Weather Considerations
Ideal conditions for resealing:
- Dry weather (no rain forecast for 24 hours)
- Temperature between 5°C and 25°C
- Low humidity (below 80%)
- Calm conditions (minimal wind)
- Surfaces completely dry
Avoid resealing in freezing conditions, direct hot sunlight, or when rain is expected.
Key Takeaway
Successful resealing requires proper tools (removal tools, sealant gun, cleaning supplies), quality materials (neutral cure silicone), and ideal weather conditions (dry, 5-25°C, low humidity). Budget £40-70 for a DIY job.
Step-by-Step Resealing Process
Follow this professional process for best results:
Remove Old Sealant
- • Use a sealant remover tool or sharp utility knife to cut along both edges of the old sealant
- • Carefully peel away the old sealant in strips
- • Use a scraper to remove stubborn residue
- • Apply sealant remover chemical if needed (follow product instructions)
- • Ensure all old sealant is completely removed
Tip: Take your time with removal – it's the most important step. Any remaining old sealant will prevent proper adhesion.
Clean Surfaces Thoroughly
- • Wipe surfaces with methylated spirits on a lint-free cloth
- • Remove all dust, dirt, grease, and residue
- • Clean both the UPVC frame and the wall/glass surfaces
- • Allow surfaces to dry completely (at least 30 minutes)
- • Check for any remaining contamination
Tip: Clean surfaces are essential for good adhesion. Don't skip this step or rush it.
Apply Masking Tape
- • Apply low-tack masking tape along both sides of the joint
- • Leave a gap of 3-5mm for the sealant bead
- • Ensure tape is straight and pressed down firmly
- • Tape helps create clean, professional lines
Tip: This step is optional but highly recommended for neat results, especially for beginners.
Apply New Sealant
- • Cut the sealant nozzle at a 45-degree angle (5-6mm opening)
- • Load cartridge into sealant gun
- • Hold gun at 45-degree angle to the joint
- • Apply steady, continuous bead of sealant
- • Move at consistent speed to maintain even bead
- • Slightly overfill the joint
Tip: Practice on cardboard first if you're new to using a sealant gun. Maintain steady pressure and speed.
Tool and Smooth
- • Immediately tool the sealant with a smoothing tool or wet finger
- • Draw tool along joint in one smooth motion
- • Apply light, even pressure
- • Wipe excess sealant from tool regularly
- • Create a neat, concave profile
Tip: Work quickly – silicone starts to skin over within minutes. Keep a bowl of soapy water nearby for wetting your finger or tool.
Remove Masking Tape
- • Remove masking tape immediately after tooling
- • Pull tape away at 45-degree angle
- • Remove before sealant skins over (within 5-10 minutes)
- • Don't touch the sealant bead
Tip: If you wait too long, the tape will pull the sealant away with it.
Allow to Cure
- • Leave sealant undisturbed for 24 hours minimum
- • Avoid touching or testing the sealant
- • Keep windows closed during initial cure
- • Protect from rain if exterior work
- • Full cure takes 7 days for most silicones
Tip: Patience is key. Disturbing the sealant during curing can compromise the seal.
Common Mistakes to Avoid
Not removing all old sealant
Insufficient surface cleaning
Applying to wet surfaces
Using wrong type of sealant
Inconsistent bead application
Not tooling immediately
Removing tape too late
Disturbing during cure time
Key Takeaway
Success depends on thorough old sealant removal, meticulous surface cleaning, steady application technique, immediate tooling, and proper cure time. Take your time with each step – rushing leads to poor results and premature failure.
Maintenance and Prevention
Proper maintenance extends the life of your window sealant and prevents problems:
Regular Maintenance Schedule
- Visual inspection for obvious damage
- Wipe down sealant with damp cloth
- Check for water stains or leaks
- Detailed inspection of all sealant
- Clean with UPVC cleaner
- Check for early signs of deterioration
- Comprehensive inspection of all windows
- Test for drafts and water tightness
- Plan any necessary resealing work
Cleaning Best Practices
Do:
- Use mild soap and water for regular cleaning
- Wipe gently with soft cloth
- Dry thoroughly after cleaning
- Use UPVC-specific cleaners when needed
Don't:
- Use abrasive cleaners or scouring pads
- Apply solvent-based cleaners
- Use high-pressure washers directly on sealant
- Scrub aggressively
Preventive Measures
- Ensure good ventilation: Reduces condensation and moisture exposure
- Address leaks promptly: Don't let small problems become big ones
- Maintain drainage: Keep weep holes clear to prevent water buildup
- Trim vegetation: Keep plants away from windows to reduce moisture
- Use quality products: Invest in professional-grade sealants
When to Call a Professional
Consider professional help if:
- You have multiple windows requiring resealing
- Windows are difficult to access (upper floors, awkward positions)
- You lack confidence in DIY skills
- Previous DIY attempts have failed
- You discover structural issues during inspection
- Time constraints make DIY impractical
- You want guaranteed, long-lasting results
Key Takeaway
Regular inspection (monthly visual checks, quarterly detailed inspections, annual comprehensive reviews) and gentle cleaning extend sealant life. Address problems early and don't hesitate to call professionals for complex jobs or when DIY results are unsatisfactory.
Professional UPVC Window Resealing
While DIY resealing is possible, professional service ensures perfect results with guaranteed workmanship. Our experienced team uses premium materials and proven techniques to deliver long-lasting window seals across Greater Manchester. Save time, avoid hassle, and get it right first time.
Professional Window Resealing Services
Stop draughts and water ingress with expert uPVC window resealing. Our team delivers weatherproof results with long-lasting guarantees.
Window & Door Sealant Manchester
Expert uPVC window and door resealing service
Mastic Sealant Manchester
Professional mastic application for window frames
Mastic Sealant Greater Manchester
Window resealing across all Greater Manchester areas
Commercial Sealant Manchester
Large-scale window resealing for commercial properties
You Might Also Enjoy
How to Remove Black Mould from Bathroom Sealant
Learn effective methods to remove black mould from bathroom sealant, prevent its return, and know when professional help is needed.
8 Clear Signs Your Bathroom Needs Resealing
Learn to identify the warning signs that indicate your bathroom sealant needs replacing, from mould growth to water leakage.
Silicone vs Acrylic Sealant: Which Should You Use?
Understand the differences between silicone and acrylic sealants, their best applications, and how to choose the right one.