Glass and Glazing Condition Surveys
At Colchester Windows, every glass unit undergoes a thorough assessment to ensure quality and clarity. Minor imperfections are evaluated under natural light to meet strict standards. Only sealed units that pass our inspection for performance and appearance are installed in your home.
Know Exactly What State Your Glazing Is In
Visual standards laid down by the Glass & Glazing Federation have been developed to set standards which both represent the best quality from current manufacturing technology and fairness to Customers, as such Colchester Windows & Doors Ltd fully support the G.G.F. Standard.
To legally comply with Building Regulations Document L (England & Wales) and Building Standard Regulation J (Scotland) your windows and doors will have been fitted with either hard coated ‘K’ glass or soft low ‘E’ glass.
In some rare instances of strong lighting, the coating may be seen as a transparent film. This is not a fault but simply a transient effect which can be considered evidence of the coating being present. There is also the possibility of a slight colour reflectively differences between units. This should not be noticeable on units within the same frame but could become apparent with adjacent frames or where a replacements is fitted. The probability of this is very low.
Condition of inspection
Viewing: When assessing the quality of sealed units on site the unit will be viewed looking through the glass from the room side in natural daylight and not in direct sunlight.
Viewing Distance: In all cases viewing will take place from distances as specified within the G.G.F. standards.
Viewing Areas: For assessment purposes, the glass or sealed unit is divided into two areas, namely an edge zone 50mm (2 inches) wide, not considered as part of the normal viewing area, and a centre zone.
Criteria for Acceptance or Rejection of Glass Sealed Units
Seeds and bubbles in glass sealed units are assessed according to the G.G.F. Quality of Vision standard, as detailed on the reverse of this information sheet. This ensures that only units meeting the recognised quality criteria are accepted for installation.
Assessment of Frame Materials
Imperfections in frame materials fall into two main categories: imperfections in raw materials and mechanical damage. A certain degree of imperfection in raw materials, such as aluminium or uPVC extrusions, is considered acceptable if it is not visible from a distance of one metre. If imperfections are clearly visible from this distance, the affected component will be corrected or replaced following Colchester Windows & Doors Ltd policy. It is also worth noting that small paint inclusions beneath the surface are a common occurrence in polyester-finished products and are generally considered acceptable.
Acceptable Imperfections
Imperfections in materials will be considered acceptable provided they meet certain criteria. They must be fully covered by the specified paint, occur no more than once per metre, and be smooth to the touch so they will not snag a duster or other cleaning tools.
Mechanical Damage
Mechanical damage can occur during handling, fabrication, transit, or installation. Such damage is deemed unacceptable if it is clearly visible from one metre or, in the case of anodised, lacquered, or painted components, if it penetrates through the finish to the base material. Any defective components will be either corrected or replaced in accordance with Colchester Windows & Doors Ltd policy.
Colchester Windows & Doors Ltd policy
Colchester Windows & Doors Ltd policy is to purchase only the best materials available and have rigorous control systems in place to maintain the quality of those materials during the manufacturing and installation process. Should part of your finished installation not meet with the standards contained herein, then Colchester Windows & Doors Ltd will undertake to initially correct any fault using factory standard equipment, if this is not technically possible we will replace the defective part of your installation under the terms of the guarantee.
Quality of vision
Sealed units
Sealed units provide a high standard of vision. The following is a guide to the quality that can be expected.
Glass used in the manufacture of sealed units is similar to that used traditionally for single glass and will, therefore, have similar level of visual quality.
Viewing sealed units for scratches on the outer faces of the panes must be carried out before any rendering, plastering or other works adjacent to the glazing takes place, and as early as reasonably practicable following installation.
How to do a professional inspection
Inspection Guidelines for Sealed Units
When inspecting a sealed unit, stand at least 2 metres away from the glass and look directly through it. For toughened, laminated, or coated glass, maintain a minimum distance of 3 metres. If standing at the recommended distance is not possible, stand as far back as you can. Perform the inspection in natural daylight, avoiding direct sunlight and ensuring the glass surface is free from visible moisture. A 50mm-wide band around the edge of the glass should be excluded from the check, and the glass must be viewed at a 90º angle.
What to Expect During Inspection
Following these guidelines ensures a proper and accurate assessment of the glass. Observing from the correct distance and angle, under suitable lighting conditions, allows you to identify any imperfections or defects while accounting for acceptable variances in the sealed unit.
Acceptable Imperfections in Flat Transparent Glass
Flat transparent glass, including laminated, toughened, or coated varieties, is considered acceptable if certain minor imperfections are neither obtrusive nor clustered. These include small bubbles or blisters, fine scratches no longer than 25mm, and minute particles. The visibility of these blemishes should be judged by looking through the glass, rather than at it, under natural daylight. It is important to recognise that sealed unit glass is processed, so minor blemishes are to be expected.
Unacceptable Defects in Sealed Units
Sealed units with optical defects that are visually disturbing are not acceptable. This includes smears, fingerprints, or other dirt on the cavity faces of the glass, as well as any extraneous material within the cavity. Any such imperfections that affect the clarity or appearance of the glass must be addressed.
Condensation
Whilst sealed units will generally reduce the incidence of condensation, it may still occur under certain conditions. See GGF Leaflet: Condensation Some Causes, Some Advice.
Brewster’s Fringes – the Rainbow Effect
Small transitory rainbow effects are sometimes produced by the glass refraction of light. Their appearance is due to high quality flat glass sheets being placed parallel to each other.
Multiple reflections
This occurs in certain light conditions and is caused by multiple surface reflections within sealed units which may vary from pane to pane.
Patterned glass
This document does not apply to patterned glass as its manufacturing process is different.