Whilst it is Everest’s policy to purchase only the best materials, natural materials such as timber and even manufactured products are not always blemish free. To be certain that Everest products are the best you can buy, a Visual Standard is applied to all products.
Assessment of glass
The clear glass used by Everest is manufactured by the industry standard float glass process which is of the highest quality available. Everest’s suppliers deliver selected quality glass in order to minimise the inclusion of faults, but it is not without imperfection, and the British and International standards which govern the quality of this glass allow for a minimal number of minor visual imperfections.
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 Everest 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
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. Everest’s factories use a specially designed lightbox to simulate this condition.
In all cases viewing will take place from distances as specified within the G.G.F. standards.
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/rejection of glass sealed units
These are as detailed within the G.G.F. Quality of Vision standard reproduced on the rear of this information sheet.
Assessment of frame materials
Imperfections fall into two categories:
- Imperfections in raw materials
- Mechanical damage
Imperfections in raw materials
A degree of imperfection in raw material is unavoidable and therefore acceptable if:
- A degree of imperfection in raw material is unavoidable and therefore acceptable if:
- The small imperfections in extruded components such as aluminium or PVC are not visible when viewed from one metre. If the imperfections are clearly visible from one meter the component will be either corrected or replaced in line with the Everest Policy stated below
NOTE: A fairly common imperfection in polyester paint finish products is minute paint inclusions under the surface.
They will be deemed acceptable, provided that they:
- Are fully covered by specification paint
- Do not occur at a frequency greater than one per metre
- Are not sharp to the touch, i.e. they will not snag a duster
Damage incurred during handling, fabrication, transit or installation.
Mechanical damage is not acceptable if such damage is:
- Clearly visible from one metre, or
- In the case of anodised, lacquered or painted components the damage penetrates through the finish to the base material
We will either correct or replace the defective components in line with the Everest Policy stated below.
Timber is a natural material and as such colour and surface texture will vary from component to component. A colour harmonisation stain is applied to reduce major colour variation but a perfect colour match is not achievable.
Surface texture and grain will vary and minor imperfections may need to be corrected on site by the application of colour harmonised fillers.
Everest’s 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 Everest 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 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
Stand in the room no less than 2 metres away from the sealed unit and look directly through it.
- For toughened, laminated or coated glasses, stand no less than 3 metres away
- Where it is not possible to stand at the right distance then stand as far away as you can from the sealed unit
- Do so in natural daylight, but not directly towards the sun and with no visible moisture on the surface of the glass
- Exclude 50mm wide band around edge of the glass from the check
- Glass must be viewed at an angle of 90º
What to expect when carrying out an inspection
Flat transparent glass, including laminated, toughened or coated glass is acceptable if the following are neither obtrusive nor bunched:
- Bubbles or blisters
- Fine scratches not more than 25mm long
- Minute particles
The obtrusiveness of blemishes is judged by looking through the glass, not at it, under natural light. It must be understood that the glass used in sealed units is a processed glass, and as a consequence, blemishes are to be expected.
Sealed units with optical defects such as smears, finger prints or other dirt on the cavity faces of the glass, or extraneous material in the cavity are unacceptable, if they are visually disturbing.
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.
This occurs in certain light conditions and is caused by multiple surface reflections within sealed units which may vary from pane to pane.
This document does not apply to patterned glass as its manufacturing process is different.