PVCU Installation Guidelines
Each structural opening should be measured independently to ascertain the correct manufacturing size. Each opening should be measured to check for squareness. Check the width and height in various positions on the opening, the smallest width and height should be used. Where windows are fitted behind reveals adequate cover should be allowed to ensure that there is sufficient profile showing to apply sealant and that outward opening casements do not catch the fabric of the structure. The size ordered should be the overall opening dimension, therefore if packers are required these are deducted from these dimensions to give the window dimension. All frames should have a tolerance to allow for expansion. When installing PVCu to bay and dormer locations a complete inspection should be made to confirm that the window is to be non load-bearing.
Removal of the old frame
Check the internal and external structure for existing damage and report any such damage to the customer before commencing work. Check that the dimensions of the new windows are correct and will fit the aperture. Move any items of furniture, soft furnishings etc. away from the work area, place dust sheets over carpets and furniture to avoid damage and facilitate the cleaning up operation. Carefully remove the opening vents and dispose of them. Chisel out the beads and old putty around the glass, now saw through the cross pieces of window, remove these carefully with the glass. Remove any fixings, saw through the outer frame and lever away with a bolster chisel. Remove frame and clean off any old material and obstructions.
Installation of new frames
Windows and doors shall be installed plumb and square within the aperture, without twist, racking or distortion of any member, in accordance with recommended tolerances. When external cills are required, firstly apply silicone to the grooves on the bottom of the window returning up each end. Fix cill onto the base of the window by screwing through the cill into the window. Silicone should not be applied to the immediate front edge of the window where it butts against the cill as this would impede the drainage.
Frames should be fixed to the structure by one of the following methods
• Through-frame fixing.
• Brackets / lug fixing.
Foam fixing offers a useful supplementary method of fixing where through-frame or lug fixing proves impractical. Care should be used in the use of foam fixing to avoid distortion of the frame. Foam fixing should not be used as the sole method of fixing a frame into an aperture.
Note: There shall be a minimum distance of 25mm – 35mm from the front edge of the frame to the front face of the brickwork.
Particular care is required when the outer frame is located forward of the DPC to ensure that the DPC is not damaged. The installer must ensure that the DPC is continuous and intact. Any portions of the DPC damaged must be replaced.
If timber is used as the packing piece then this timber must be suitably treated.
Fixing distances – corner fixings should be a minimum of 150mm and a maximum of 250mm from the internal corner. Fixings for transoms and mullions should be a minimum of 150mm and a maximum of 250mm from their respective internal corners. Intermediate fixings should be at centres no greater than 600mm. There should be a minimum of two fixings on each jamb.
Due to the presence of precast or steel lintels, it may be impractical to achieve the required number of fixings. In these circumstances the installer should fix as described below and support the fixing with the application of fixing foam.
1. If the outer frame is narrower than 1350mm, then no frame fixings are required.
2. If the outer frame is between 1350 and 1800mm wide the one central fixing is essential.
3. If the outer frame is between 1800 and 3000mm wide, then two equally spaced fixings are essential.
Fixing to sub-sills should be in accordance with that of precast lintels as above. Providing an adequate bed of silicone or mortar is provided.
Temporary installation packers should be used adjacent to fixing positions to prevent frame distortion during installation. The packers should bridge the full width of the outer frame profile. The fixings should be tightened so that
the frame is held securely against the packers. Apply a small amount of silicone mastic to the shanks and heads of any screws or fixings that pass through to ensure that no water penetrates into the outer frame.
After installation, the packers should be left in position.
Bay window assemblies, ensure that no applied load are carried by the individual segments of the window. Bearing plates must always be used when loads are transferred from or to brickwork, stone or timber. Care must be taken to ensure that loads are transmitted correctly from and to the structure of the building and the bay pole assembly. This is achieved by having the bay pole pass through the cill. Particular attention shall be paid to the installation of the bay pole, as the integrity of the finished assembly and its ability to sustain the applied load depends upon the correct techniques being followed.
Every attempt should be made during installation to ensure that debris such as wet plaster does not foul drainage or impair the operation of hardware. Internal reveals should be made good, ready for the customer to redecorate. Neither cement or plaster should be used to fill the gap between the back of the frame and the structural opening. When sealing the window to the opening internally, the sealant used should be capable of accepting paint. Protective films applied to the framing should be removed as quickly as possible.
External perimeter sealing needs to be of the highest standard to ensure weather tightness of the window.
Gaps up to 6mm in width can be sealed solely with a ribbon of sealant. When sealing a gap between 6mm and 11mm the use of a backing strip is essential. Care must be taken when sealing the perimeter joint to ensure that no drainage channels, or pressure equalisation slots are blocked.
Glazing must comply with the requirements of BS6262 & double glazed units should be manufactured to BS5713 to conform to BS7412.
All windows and doors are supplied unglazed with gasket supplied loose for site glazing. Gaskets are simply fitted into the frame by inserting the back arrow section into the glazing groove. Gaskets should be cut in the corners. With the gaskets in place, silicone sealant should be injected at the corners to fully seal the gasket prior to the unit being fitted.
A combination of the size of the glass should be such that there is sufficient clearance between the edge of the glass and the glazing platform (minimum 5mm) Bridge packers should be used in the bottom glazing platform to allow for free drainage. When glazing on site, packing of the glass should be adjusted to ensure easy operation of the opening lights. In some situations different packer thicknesses should be fixed into position with silicone sealant. A general point to make is that all panes of glass should be packed behind any locking point and fixed lights on a tilt and turn window.
All beads are co-extruded and mitre cut, therefore once the unit is in place, fit the smallest beads first and then spring into place the longest beads. All beading will only require a slight tapping with a glazing mallet. Once all beads are in place, trim off any excess on the co-extruded gasket.
(Fire escape windows and doors)
The following are for floors that are no more than 4.5 metres above ground level. The window should have an unobstructed openable area that is at least .33mtr sq. and be at least 450mm high and 450 mm wide. The bottom of the opener must not be more than 1100mm above the floor.
All habitable rooms in the upper storeysof a house require escape windows
To achieve the above required opening there are the options of
1. Tilt turn windows.
2. Egress hinges to 600mm side opening casements.
3. Flying mullion windows.
Document L (Energy saving)
As from October 2010 the regulations have changed.
Windows have a minimum 2.0WM2/K
Windows have a minimum 2.2WM2/K.
Replacement Windows and Doors both Domestic and Non Domestic –
Windows must have a minimum window energy rating (WER’s) of C
A whole window value of 1.6WM2/K, (Doors which contain more than 50% glass. must have a minimum U value of 1.8WM2/K)
A centre pane value of 1.2W2/K or lower (only acceptable in certain circumstances) Exemptions for listed property
Domestic conservatories under 30mtr sq will not be introduced to into part L.
as long as thermally separated from the main part of the house, separate heating system from main property.
Document N (safety)
Any glass over 250mm width within a door or within 300mm of a door up to a height of 1500mm must be safety glass.
Any glass that is below 800mm of floor level either internal or external must be safety glass.
The threshold bar should be no higher than 15mm approached from both sides. The clear width of the opening should be no less than 775mm.
All habitable rooms should have a minimum of 5000mm sq equivalent area.
Non habitable rooms should have a minimum of 2500mm sq equivalent area. 1/20th of floor area as opening windows.
Replacement windows need only have equivalent ventilation to that on the original windows.