PROCESS FOR THE CONSTRUCTION OF A DORMER WINDOW, AND A BUILDING KIT INTENDED FOR CARRYING OUT SAID PROCESS

Abstract: In a proces for the construction of a dormer window, a rectangular piece is sawn out of the roof boarding while sawing through the purlins (2) present there and a cheek (3) is fixed along the two slanting boundaries of the hole formed in such a way that two congruent triangles project from the roof face, a window frame (5) is fixed between or against the cheeks (3) and a roof section is placed on the cheeks. Finally the joint round the opening in the roof boarding is sealed. To simplify the fitting of the dormer window the bottom edge of the cheeks is provided with a trimming joist which is fixed against the sawn faces of the purlins (2) which have been sawn through. Preferably a groove is provided in the top edge of the trimming joist and in the bottom edge of the cheeks (3), and wedge pieces are slid into opposite grooves of trimming joists and cheeks. The trimming joists are made flush with the bottom face of the roof boarding and are fixed in this position. The wedge pieces are fixed in a position in which the bottom edge thereof projects slightly beyond the tile laths and the bottom edge of the cheeks is flush with the top edge of the tile laths.

Description: The invention relates in the first instance to a process for the construction of a dormer window, in which a rectangular piece is sawn out of the roof boarding while sawing through the purlins present there, a cheek is fixed along the two slanting boundaries of the hole formed in such a way that two essentially congruent triangles project from the roof face, between or against the cheeks a window frame is fixed, a roof section is placed on the cheeks, and the joint round the opening in the roof boarding is sealed. Such a process is known from US patent specification 2,724,152. With such a process, starting from a number of parts, a dormer window can be made in a sloping roof with widely differing roof pitches. The known method is, however, relatively time-consuming: both outer and inner cheeks have to be fitted; filler strips are necessary to bridge a gap between the rebates in the side uprights of the frame and the trimming joints, and the outer cheeks must also be sawn to match the inner cheeks. An even more important disadvantage is that if a kit of parts of a dormer window is used for roofs having various thicknesses of roof boarding, some parts must be adapted by sawing. The object of the invention is to avoid the above mentioned disadvantages and to simplify the fitting of a dormer window so that starting from a standard kit of parts, these parts can be used for various thicknesses of roof boarding without adapting them by sawing. For this purpose the process referred to in the preamble is characterized in that trimming joists are fixed against the sawn faces of the purlins such that the top face of the trimming joists is flush with the bottom face of the roof boarding, wedge pieces are slid into a preformed groove in the top face of the trimming joists, which wedge pieces are fixed so that the upper edge thereof projects slightly beyond the tile laths, and a performed groove in the lower edge of the cheeks is slid over said projecting edge of the wedge pieces. The ends of the trimming joists will rest with their top faces against the existing roof boarding. Tiles are placed on the fitted roof section, preferably the tiles which lay originally on the sawn-out piece when the roof was still whole. In principle, two cheeks, a window frame and, if necessary, sealing strips can be supplied in one construction kit. The cheeks are, for example, triangles with angles of 110, 50 and 20 degrees. There is no need for the front-facing outside edges of the cheeks to stand vertically in the finished dormer window; consequently, the construction kit with standard parts is suitable for very differing roof pitches, for example between 30 and 50 degrees relative to the horizontal. An easy, firm fixing of the trimming joists on the sawn-through purlins can be achieved if use is made of a purlin shoe. The front edge of the cheeks will stand more or less at an angle depending on the pitch of the roof. In order to conceal this slanting position, a covering piece is fixed in front of the front edge of the two cheeks. The seal preferably consists of an elastic, deformable plastic strip folded over the roof tiles and a strip fixed on parts of the dormer window. A suitable sealing system is described in Dutch patent application 161,836. This is the so-called concealed gutter system, which is universal for all types of imbricated roof covering. The cheeks are preferably made of waterproof and weatherproof sheet material and provided with a finishing layer on the inside. The invention also relates to a construction kit designed for the above mentioned process. Apart from at least two cheeks and a window frame the kit comprises trimming joists, a groove being provided in the upper face of the trimming joists as well as in the lower face of the cheeks. Further the kit contains wedge pieces which can be slid into opposite grooves of the trimming joists and the cheeks. The invention will now be explained in greater detail with reference to the figures. Figure 1 shows a perspective view from the inside, partially in cross section, of a dormer window made in accordance with the invention. Figure 2 shows a perspective view of the complete dormer window according to figure 1, in which a part is imagined cut away. The first phase of the construction of a dormer window in an existing sloping roof is to saw out of the roof boarding a rectangular piece which will serve as the roof of the dormer window. This piece is indicated by 1 in the figures. The purlins of the roof boarding are indicated by 2. A cheek 2 is disposed along the two sloping boundaries of the hole formed. These cheeks are in the form of a triangle and are made of waterproof and weatherproof sheet material, with which the inside-facing face is also finished when the construction is complete. A trimming joist 4 is secured to the bottom edge of the triangles in a way to be elucidated. The trimming joists 4 are fixed against the sawn faces of the sawn-through purlins 2 and at their ends are preferably fixed against the first purlins not damaged. The top edge of the trimming joists is flush with the bottom face of the roof boarding. A prefabricated window frame 5 is then placed between or against the cheeks 3 on the existing roof boarding and fixed in a vertical position. The front-facing faces of the cheeks need not be vertical, which means that the cheeks are suitable for a wide range of roof pitches (for example within 30 and 50 degrees). The sawn-out roof boarding piece 1 is placed and fixed on the cheeks 3 and the cross girder of the frame 5. For the fastening, use can be made of hinges with which the top edge of the piece 1 is connected to the roof boarding. It is not out the question to use another roof section instead of the sawn-out roof boarding piece. After laying of the roof tiles on the roof and the roof boarding piece 1, the seam round the cutout made in the roof boarding is covered with a so-called concealed gutter construction, comprising an elastic, deformable plastic strip 7 and a covering fillet 8. Use is preferably made of the system described in Dutch patent specification 161,836. Drifting snow sealing elements can be added to this concealed gutter system. The strips 7 are folded over the roof tiles 9. The original roof tiles 9 can be placed on the roof boarding 1, so that no additional expense need be incurred for roof covering (zinc, mastic) of the roof of the dormer window. This tile covering is also virtually maintenance-free. A neat finish is achieved by fixing the trimming joists 4 against the sawn faces fo the purlins 2. The connection between the trimming joists 4 and the cheeks 3 is designed in such a way that a possibility of adjustment is given. A groove is provided both in the top edge of the trimming joists 4 and in the bottom edge of the cheeks 3, and a wedge piece 11 is slid into each pair of opposite grooves. The sequence of operations for producing the correct position of the various parts is as follows: First, the trimming joists 4 are fixed against the sawn faces of the purlins 2 in such a way that the top edge of the trimming joists 4 is flush with the bottom face of the roof boarding. This flush position is achieved by itself by making the ends of the trimming joists grip the roof boarding. The fixing against the sawn faces can take place by interconnecting purlin shoes 14. A wedge piece 11 is inserted into the groove of each trimming joist to such a position that the top edge of the wedge pieces projects about two centimeters beyond the top edge of the tile lath 15. In this position the wedge pieces 11 are fixed by means of screws relative to the trimming joists 4; a cheek 3 is then placed on each of the wedge pieces, one wedge piece also projecting into a groove in the bottom face of a cheek. This bottom edge runs essentially parallel to the fixed top edge of the relevant wedge piece and is flush with the top edge of the tile laths. This position is also fixed with screws. The side walls can be finished by planks 12, it being possible to dispose a piece of foam 13 between each plank 12 and the wedge piece 11. The shoes 14 consist of an L-shaped strip with two slanting struts. In general the front edge of the cheeks will be slanting, which is ugly next to the vertical frame uprights. Therefore, as shown in figure 2, the side uprights of the frame are provided with an external rebate in which an edge of an L-shaped covering piece 16 engages, concealing the front edge of the side wall 3 concerned. The advantage of the structure described is that the construction kit with two cheeks and a window frame is suitable for roof boarding elements with thickness differences up to about 10 cm and for roofs with very differing roof pitches. The triangular cheeks with angles of for example, 110, 50, 20 degrees can of course assume a position in which the outward facing edges 3a of the cheeks are vertical in the case of only one roof pitch. In the above mentioned example this roof pitch is 40 degrees. In the case of other roof pitches these front edges 3a stand at an angle. The object of the covering pieces 16 is to accomodate differences in the slope of the front edge of the cheeks which are due to differences in the pitch of the roof. Various modifications of the construction shown are possible within the scope of the invention according to the appendent claims.

Claims: 1. Process for the construction of a dormer window, in which a rectangular piece (1) is sawn out of the roof boarding while sawing through the purlins present there, a cheek (3) is fixed along the two slanting boundaries of the hole formed in such a way that two essentially congruent triangles project from the roof face, between or against the cheeks a window frame (5) is fixed, a roof section (1) is placed on the cheeks, and the joint round the opening in the roof boarding is sealed, characterized in, that trimming joists (4) are fixed against the sawn faces of the purlins (2) such that the top face of the trimming joists is flush with the bottom face of the roof boarding, that wedge pieces (11) are slid into a preformed groove in the top face of the trimming joists (4), which wedge pieces are fixed so that the upper edge thereof projects slightly beyond the tile laths (15), and that a preformed groove in the lower edge of the cheeks is slid over said projecting edge of the wedge pieces (11). 2. Process according to claim 2, characterized in, that the sawn-through purlins (2) are fixed to the trimming joists (4) by means of a purlin shoe (14). 3. Process according to claim 1 or 2, characterized in, that a covering piece (16) is fixed in front of the cheeks (3). 4. Construction kit designed for the process according to one of the preceding claims, comprising at least two cheeks (3) and a window frame (5), characterized in that the kit further comprises trimming joists (4), and a groove is provided in the upper face of the trimming joists (4) as well as in the lower face of the cheeks (3), and the kit contains wedge pieces (11) which can be slid into opposite grooves of the trimming joists and the cheeks. 5. Construction kit according to claim 4, characterized in that the kit has purlin shoes (14) for fixing the sawn-through purlins to the trimming joists (4). 6. Construction kit according to claim 4 or 5, characterized in that the kit has two covering pieces (16) for covering the front edge of the cheeks (3).

Inventors: BRUEREN, HERMAN WILLEM FRANCISCUS PETRUS, ISEGER, LEENDERT ADRIAAN
Applicants: RBB DAKPANNEN B.V.
Application year: 1988
Main classification: E04B7
IPC codes: E04B7