Fixing Proseam Sheets
When fixing Proseam standing seam sheets, it is essential that a fixed end is identified, and the roof verge is perpendicular to the eaves line. Any out of square at this stage, will result in an uneven eaves line, or ‘sawtoothing’. Once the first sheet has been positioned, and secured to the verge halter by a verge clip (please refer to Cladwell’s fixing instructions for details), the next sheet can then be fixed, by overlapping it onto the first sheet, and onto the next row of halters at the leading edge. Once the sheet has
been checked for square and the overlap is fully engaged, the seam can be closed, securing it to the halters. The seam is secured by firstly clamping the eaves end using the hand crimper. The motorised seaming tool is then used to fully seal the seam along the remaining sheet length.
The roof can then proceed in a similar manner. Cladwell would advise that the roof length is checked and the Proseam standing seam sheets are positioned such that the dimension from the verge cleader rail to the first line of halters, is approximately the same at both ends. This will give a more pleasing appearance overall. Care must be taken to ensure that the correct halter spacing is used in the calculation, especially for curved roofs.
Mis-alignment of halters can cause visible sheet deflection or distortion. It may also cause the Proseam seam to not fully engage, leading to detachment under wind loading.
Proseam sheet seam allow for thermal expansion, as there is no positive fixing of the sheet to the halter. However, it is necessary to create a fixed point, by inserting an aluminium blind rivet through the underlapping seam into the head of the halter, at the upper end of the sheet (under the apex flashing).
For sheets in excess of 12m long, fixed points should be created by inserting 2 No fixings through the Proseam upstaged, into the halter. Care must be taken to ensure that these fixings are positioned such that they do not affect the operation of the zipping tool.
All screws to be bi-metallic stainless fixings. The liner panel is to be Cladwell 32/1000 x 0.7mm thick, which will then act as a working platform (Detail 1). If the liner is to be considered as a Vapour Control Layer (low humidity situations), side laps are to be sealed using 50 x 1 polyband tape, and end laps sealed with 2 rows of 6 x 5 sealant, positioned either side of the of the fixing. It is important to ensure that the perimeter details create an airtight junction. When a separate VCL is specified, laps and perimeters are to be sealed, to ensure its full effectiveness.
The liner panel is to be fixed in every trough at sheet ends and at sheet laps, and in alternate
It is important to calculate the set out of the halters, prior to fixing the first line. Ideally, the distance from the verge to the first line of halters should be the same at both ends of the building. Halters are spaced at 400mm, where the Proseam sheet is not curved, so a simple calculation can be carried out, taking the length of the building and then calculating how many spaces of 400mm fit into it. The remaining dimension is then to be divided by 2, and this will then be the dimension from the verge to the first line of halters.
When fixing the first line of halters, ensure that they are in line using a string line, or other straight edge, as if they vary too much, the Proseam sheet will not properly engage onto the head of the halter ((Detail 2). Secondly, ensure that the halters are square to the purlins. Failure to do this will cause the the sheet ends to be stepped (saw-tooth).
When fixing the halters, it is essential that they are correctly orientated – the groove in the head of the halter should be facing the direction of lay (ie facing away from the starting end of the building).
It is not recommended to fix halters to the entire roof prior to fixing any sheets. Set out a maximum of 6 lines of halters, so that any mis-alignment can be corrected as work proceeds.
Once the first line of halters has been fixed, mark the top flange of the spacer bar 400mm away from the centre of the first halter. Using a string line, or similar, fix the second line of
halters. The first Proseam sheet can now be laid, rotating it onto the first line of halters, and bringing it down onto the second line (Detail 3).
Once the first sheet has been fixed, the verge is to be secured – see detail 5 or 6.
Proceed along the roof by laying a line of halters and then fixing a Proseam sheet. Once the second sheet has been laid, the first seam can be secured, by clamping the ends of the sheets onto the halters, using the hand crimping tool.
When the sheet ends have been secured, the Zipping Machine can be positioned on the seam, and the seam clamped to the entire length of the sheet. Zipping of the sheet seams can be carried out from either end of the sheets.