Glazing of Heritage Sealed Units manufactured by Trinity Glazing Ltd should always be carried out in accordance with the principles and recommendations as follows. When glazing it is important to prevent the ingress of water into any rebate to retain the integrity of the seal. Do NOT use linseed oil putties or butyl glazing compounds that comes into contact with the units' edge seal when installing Heritage Sealed Units®.
All surfaces must be clean, dry and free from frost, grease and loose materials. Apply primer if required. In situations where an especially neat finish is required, use masking tape to cover the face edges of the joint and remove immediately once tooling has been completed.
*Note: Hodgson Heritage Putty working time 10 mins / skinning time 20 mins
Units should be measured to allow approximately 1mm to 1.5mm clearance all round where the rebate depth is 7mm. Allowance should be made where the opening is not perfectly rectangular. Where the rebate depth is in excess of 7mm, additional clearance can be allowed, but always ensuring that the sight line of the perimeter seal is below the sight line of the back rebate.
top-windowsAll rebates should be clean and clear of minor obstructions and brushed cleaned and primed. The rebate should be bedded with a non hardening compound (butyl) to provide a bed between the back rebate and glass of approximately 1mm to 1.5mm. The unit should be placed into bedded opening and pressed equally around the perimeter until the 1mm to 1.5mm back bed is obtained.
However whilst the back bedding should be a non hardening compound such as butyl commonly used, silicon is sometimes used but mainly on metal windows.
The unit should be held in position by sprigs, which are thin metal shaped diamonds which are fixed into the rebate with a sprigging gun.
The use of a sprigging gun ensures that the diamond sprig is less than 1mm from glass, and prevents any scratches to glass surface. The sprig should be set at 150mm centres or as necessary for small panes.
The fore putty should be carried out with Linseed Oil Putty or Steel Sash Putty for metal windows, as BS6262 to the rebate depth sight line or just below to allow for paint finish line over putty. Putty should not be painted for at least seven days. The minimum fore putty on rebate width should not be less than approximately 6mm. The function of fore putty is to protect the frame by shedding the water from the frame, and protect the double glazed unit from ingress of water which will cause unit breakdown.
It is important that the fore putty should be brushed with a fine duster brush to ensure that there is a good seal on the putty against the glass, and painting should overlap the foreputty by approximately 2mm to provide an important final seal.
All rebates should be clean and clear of obstructions, brushed clean and primed. The rebate should be bedded with non hardening compound (Butyl) to provide a bed of approximately 2mm between the glass and back rebate. The unit should be placed against the bedded back rebate and pressed equally around the perimeter until the 2mm back bed is obtained and only trimmed flush when glazing has been completed.
The rebate width should then be bedded with non hardening compound to obtain a very thin bedding not exceeding 2mm or gun grade which has a much thinner consistency. The timber bead which should be angled to provide a water shed and should be bedded against the glass by applying the compound to the front edge of the bead in sufficient quantity to prevent voids when fitted against the glass and excess trimmed, matching the water shed angle of the bead.
The finished height of the bead should be 2mm below the back rebate height to allow the painter to paint over the trimmed water shed angle of the compound to match the angled bead. The paint finish is important to provide protection against the rain and sun and the compound should be allowed to cure for at least 7 days before painting, and within 28 days.
Where timber beads are to be pinned into the rebate width is particularly narrow the beads should be pre-drilled with a very fine drill.
Heritage Self Cleaning Double Glazed Units are supplied with taped perimeter edges for protection and safe handling and glazing. Heritage is unaffected by Linseed Oil Putty. Linseed Oil putty has proved to be satisfactory over a long number of years and provided it is applied correctly as mentioned above should last a lifetime. It is necessary to paint over the putty at least every 5 years inland and 3 years in coastal areas. When putty cracks it is because of lack of paint protection.