Installation
Electronic17.9Copy The sub-frame is cleaned to ensure that it is free from mortar. The brickwork must be allowed to set before attempting to fit the window.
16 General
Window preparation and fitting 17.10 The fitting of windows to the sub-frame must be carried out in accordance with the Duraframe Fabrication Guide.
16.1 Installation of the system must be carried out in accordance with the Duraframe Fabrication Guide.
17.11 The correct window is selected to suit the sub-frame. All protective wrapping is removed.
16.2 Reference should be made to the typical installation details shown in Figures 3 and 4 when reading the installation details given in section 17. The windows in these figures are shown for information only and do not form part of this assessment.
17.12 Snappers are screw fixed to the outer frame jambs and sill (see Figures 3 and 4) 100 mm from each corner, behind each mullion/transom and at centres not exceeding 600 mm. A minimum of two clips per member is required.
16.3 At the build-in stage it must be ensured that the sub-frame remains plumb, level, square, and with parallel sides.
17.13 A bead of silicone sealant is applied to the upstand, where available, of the sub-frame.
17 Procedure
17.14 The window is offered up to the sub-frame, positioning it squarely in the aperture and clipped into place by applying even pressure to position the window back against the sub-frame flange (where available). The head member of the window is secured using lugs or screw fixings positioned not less than 150 mm from the corners and at centres not exceeding 600 mm.
17.1 The sub-frame is supplied to site as a complete frame with the joints between the jambs and sill sections welded together or mechanically jointed using the corner brackets and cross brace fixed in place at the head. The sub-frame is ready for building into the construction of cavity walls using traditional building methods.
17.15 Alternatively, window frames used with the system may be conventionally fixed by lug or through fixing into the masonry.
17.2 The cavity wall is built to the sill level, ensuring that the coursework is level, flat, and that all excess mortar is removed.
Finishing 17.16 A bead of silicone sealant is applied around the perimeter of the window internally prior to plastering.
17.3 The cavity closer/sub-frame is positioned in the cavity with the plaster stop, if available, in the correct position relative to the cavity, so that the inner surface of the window frame is set in at least 30 mm from the inner surface of the outer leaf. The closer frame is aligned with a spirit level. The course work is built up by one course and butted to one side of the sub-frame.
17.17 Dry lining or lightweight plaster (see section 10.1) is used for internal plastering around window reveals. 17.18 Finishing trims are fitted after completion of the window installation, where required.
17.4 The position of the sub-frame is checked and the coursework on the opposite side of the subframe is built up by one level.
17.19 The window is weather-proofed externally, using a suitable low modulus silicone sealant.
17.5 Brick ties are inserted into the channel of the sub-frame jambs, rotated through 90º and built into the mortar bed joints. These ties should be fitted after the first brick and then at 300 mm centres. The ties should be inserted alternately, tying the sub-frame into both inner and outer courses. A minimum of three ties per vertical member is required.
Technical Investigations The following is a summary of the technical investigations carried out on the Duraframe Cavity Closer System.
18 Tests 18.1 Confirmatory tests were carried out in accordance with MOAT No 8 : 1973 and MOAT No 17 : 1990 on PVC-U extrusions made from reground material, to determine: • Vicat softening temperature
17.6 The lintel is set and bedded in position. 17.7 The cross brace and cross brace brackets are removed before the windows are installed. 17.8 In all installations the top brick course should be arranged to ensure that, when bedded in, the lintel does not exert a load on the window frame/sub-frame.
• shrinkage on heating • verification of gelation by heating • ash content 10