Faulty double glazing covers windows and doors whose sealed glass units or operating hardware no longer work as intended — most often because seals have failed, moisture has entered between panes, or hinges and locks have worn. This guide helps you spot blown or misted units, explains how mechanical faults affect comfort and security, and gives practical, Sussex-focused advice on repair, prevention and budgeting. You’ll find quick DIY checks, clear comparisons to help decide between repair and full replacement, and an outline of common services that restore insulation and operation. We also map typical price ranges, suggest maintenance routines to limit coastal corrosion, and answer the questions homeowners usually ask before calling a professional. Use the checklists, EAV-style tables and inspection tips below to diagnose most window problems in Sussex and make informed repair decisions.

Start by looking for visible symptoms and running a few simple tests to tell whether a fault is cosmetic, a failed sealed unit, or a mechanical problem. Frequent issues include misted or blown units from seal failure, cold spots and draughts caused by degraded weather seals, and sticking or misaligned sashes from hinge wear or corrosion. Catching faults early helps keep energy bills and security risks down, so do a quick visual and tactile check before booking a professional survey. The sections that follow list the main signs and include an EAV-style quick reference you can use to match symptoms with likely causes and urgency.

The most useful homeowner checks are: inspect for fogging and rust; touch the glass to locate cold spots; and operate each window and door to check smoothness and locking. These tests narrow down likely causes and help you prioritise repairs. Persistent fogging between panes or corroded spacer bars usually means a blown sealed unit and will need a specialist. If your checks point to a blown unit or serious hardware corrosion, contact a glazing specialist for measurements and a free survey.

Blown or misted units show as persistent clouding or condensation trapped between the panes — a diffuse fog, streaks or a film that won’t clear when you wipe the inner or outer glass. That trapped moisture means the IGU’s hermetic seal has failed (often due to degraded sealant or a corroded spacer bar), which reduces thermal performance and can look unsightly. You can tell surface condensation from a blown unit by wiping both sides of the glass — if the clouding stays, the seal has failed. If you spot fogging, photograph the pane and measure it where possible to speed up diagnosis when you speak with a pro.

Act sooner rather than later: a failed sealed unit lowers the window’s U-value over time and can encourage frame decay, especially in coastal locations. If you have fogging plus cold spots at the glass and rising heating bills, replacing the sealed unit is often the most effective fix. The next section explains how hardware faults differ and what operational tests to run.

Worn hinges, failing locks and damaged handles cause stiff operation, misalignment, draughts and reduced security — symptoms range from a sash that sticks to a door that won’t lock properly. These failures are usually down to wear on moving parts, corrosion (salt spray speeds this up in coastal Sussex), or lost adjustment in multi-point systems. Simple homeowner checks include opening and closing each window and door several times to feel for resistance, checking that locks engage smoothly, and looking for visible rust or bent keeps. Short-term fixes like lubrication or tightening screws can help, but persistent misalignment or broken parts needs a professional repair or replacement to restore security and weather-sealing.

When the frame is still sound and the fault is limited to the sealed unit or hardware, repair is usually the quicker, cheaper and greener option. Repair targets the failed component — replacing the IGU or renewing hinges/locks — so you keep the existing frames, avoid major disruption and restore thermal performance and security faster than with full frame replacement. Repairs produce less waste and embodied carbon, and many jobs can be completed in a single visit with minimal redecorating. From a performance point of view, fixing the problem element typically restores insulation almost immediately while conserving resources compared with full-frame replacements.

Repair isn’t always the right choice: extensive rot, severe warping or persistent thermal bridging may mean replacement is the sensible long-term solution. Choose repair when problems are isolated to glass or hardware; choose full replacement when the frame can no longer meet structural or efficiency goals. The next section explains a simple cost-comparison framework to quantify typical savings from repair versus replacement.

Hinge issues usually come from wear, lost lubrication or corrosion, with salt spray making metal parts fail faster in coastal locations. Repairs can include realigning sashes, replacing hinge pins or whole hinge units, re-tensioning friction stays, re-greasing moving parts and renewing adjacent weather seals. Where corrosion is present, installers often fit corrosion-resistant hardware or stainless/coated options and may recommend sacrificial coatings for extra protection.

A successful hinge service restores smooth movement, corrects sagging sashes and re-establishes even compression around seals — this reduces draughts and prevents extra wear on locks. Regular hinge checks and targeted replacements extend the life of the whole window assembly.

Prevention is about routine maintenance and protection tuned to Sussex’s coastal climate: keep seals healthy, hinges and locks moving freely, and corrosion at bay. A simple schedule works well — clean seals monthly, lubricate moving parts quarterly and clear drainage channels and weep holes at least once a year. Properties exposed to the sea will benefit from more frequent checks; sheltered homes can follow an annual service. Regular inspections catch early corrosion or seal wear so targeted repairs remain cost-effective.

These routines help preserve U-values and security while cutting the likelihood of emergency repairs or full replacements. The list below highlights practical maintenance tasks homeowners can do and what to record for any professional visit.

To limit corrosion and seal failure, rinse frames and hardware with fresh water after salty weather to remove salt deposits, apply a light corrosion-inhibiting lubricant to metal moving parts, and check spacer bars and edge seals for early signs of deterioration. Use non-abrasive cleaners so protective coatings aren’t removed, and make sure drainage paths remain clear so water cannot collect at the frame base. For exposed Sussex locations, consider switching to stainless or specially coated hardware recommended by professionals to resist salt spray and extend service life.

Regular checks catch small problems — loose screws, slight misalignment, worn weatherstrips — before they become sealed-unit failures or structural decay, protecting thermal performance and security. A simple inspection checklist should include testing operation, looking for gaps or draughts, examining seals and glazing beads, and listening for unusual noises when opening and closing. For most homes, an annual check is enough; for coastal or exposed properties, inspect more often. Keeping a log of findings and actions creates a maintenance record that helps with future repairs, warranty claims or insurance queries.

Frequent, straightforward inspections reduce emergency costs and let you plan and budget repairs rather than reacting under pressure. The next section outlines typical costs to help set realistic expectations.

Knowing these ranges helps homeowners judge whether to repair, upgrade the glass or consider full replacement. Sussex Glazing Solutions offers free quotes and phone estimates to give accurate local pricing once you have measurements and photos from your initial checks.

Getting multiple estimates and a free survey from a local specialist helps ensure competitive pricing and avoids surprises from access or bespoke fabrication needs. The following subsection shows the main factors that increase or reduce the final price.

Parts availability, frame material (uPVC, aluminium, timber), labour time and emergency or out-of-hours call-outs are the primary variables that affect mechanism repair costs. uPVC parts are usually easy to source and cost-effective, while specialised aluminium or heritage timber components can be pricier or take longer to obtain. Accessibility matters — upper-floor or awkwardly sited units increase labour and safety-equipment costs — and extra services like re-sealing, repainting or weatherstrip replacement add to the bill. Warranties or guarantees influence perceived value and sometimes price.

Simple, regular maintenance makes a big difference. Clean seals monthly, lubricate moving parts every few months and clear drainage channels annually to stop moisture building up. Check for early corrosion or seal wear and carry out extra checks for coastal properties. Keeping a maintenance log helps you track issues and schedule timely professional inspections.

First, identify the cause: look for seal failure or condensation between panes. Do a visual check for fogging or cold spots. If you find these signs, arrange a diagnostic survey with a glazing specialist. They’ll confirm whether a sealed-unit replacement or other repair is needed. Fixing insulation issues promptly saves energy and prevents further damage.