Sheets should always be laid with the side lap corresponding to the prevailing wind direction to prevent any uplift. When fitting fibre cement roof sheets, some corners of roof sheets must be mitred.
Mitring roofing sheets involves the cutting of opposite corners of roof sheets to prevent four overlaps of roof sheet from occurring. To do this, use a hand or power saw to cut a clean and straight line.
Each sheet should have two mitres, apart from roof sheets on the perimeter of the roof. The only other exceptions are the first and last sheets — these will remain unmitred. Before fixing the fibre cement sheets to the building, it is important to pre-drill the fixing holes in the purlins horizontal bars on the roof which attach the fibre cement sheets to.
Alternatively, use self-drilling or self-tapping top fix fixings. Each fibre cement sheet should be fixed twice at each purlin. To do so, drill a hole 2mm larger than the fixings at the apex of the profile, never in the valley. Additionally, always use a drill, never hammer through the fibre cement sheet — this could invalidate the manufacturers guarantee, as fibre cement sheets may shatter under the impact. Once the hole has been pre-drilled, insert the fixing, including the sealing washer.
When this has been done, ensure the sealing washer has been tightened correctly to prevent the ingress of water. It is important to ensure that fixings are never put through two layers of roofing sheet, as this will prevent the possibility of thermal movement, which can result in cracking or splitting of roof sheets.
On low pitched roofs, it is important to seal the overlaps with butyl strips. These will prevent the ingress of wind-driven precipitation, as well as preventing wind uplift. Additionally, on roofs with pitches of 5 degrees, double lap sealing can be necessary. In this case, the second butyl strip should be around mm below the fixing. This is only for some specific products, such as the Cembrit B5 or Eternit Profile 6. Other profiles are for degree pitch, but make sure to check with the manufacturer.
Fibre cement roof sheets are generally quite fragile. For this reason, it is important to always use crawling boards or walkways and roof ladders.
Additionally, it is crucial to always use safety netting and drop harnesses, and ensure that no one is working below the roof whilst fitting the fibre cement sheets to the roof. If working in wet or windy weather, or after poor weather, roofing sheets can be slippery, making handling difficult.
Take extra care in these weather conditions, or if working with painted sheets. When fitting fibre cement roof sheets, never wear loose clothing or wellington boots, in case they catch on the sheets. If you want to know more about fibre cement roofing sheets or the installation process, feel free to call our team on or use the live chat and they will be more than happy to help offer guidance and advice.
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Roof Vents All Roof Vents. Pitched Roofing All Pitched Roofing. Flat Roofing All Flat Roofing. Attach a house wrap material over the exterior sheathing. Follow the cutting, hanging, attachment, and sealing instructions for your chosen house wrap material. House wrap can be used over other wall materials, like concrete blocks, but the hanging procedures will be somewhat different.
Follow the product instructions. Always hang a house wrap material beneath fiber cement siding used in exterior applications. Mark all stud locations on the house wrap with chalk lines. For instance, if the framing studs beneath the house wrap and sheathing are spaced at 16 in 41 cm , unroll and snap vertical chalk lines at this spacing. Use a stud finder if needed to confirm the stud locations. Install flashing at the top of any windows or doors.
Use a metal flashing material that is the proper size and shape to direct water over the front edge of the top of your window and door trim.
Nail strips of wood lath where the lowest siding course will hang. Measure up 0. Nail the lath into the marked framing studs using galvanized or stainless steel nails. All subsequent courses of siding will share this outward angle because they will overlap the top of the course below them. Your lowest course of fiber cement siding should always be at least 6 in 15 cm above ground level to prevent moisture wicking.
Part 2. Subtract 0. Measure the siding so it ends on a stud if it is too short to span the wall. In this case, measure the pieces of siding so that they meet in the middle of one of the framing studs that are marked on the house wrap. Instead of butting together a full 12 ft 3. Wear eye and breathing protection whenever you cut fiber cement.
Fiber cement is a durable product that is easy to work with, but it creates a great deal of dust when you cut it. Even worse, the dust contains particles that can cause lasting lung problems. Before cutting any fiber cement, put on a breathing mask or respirator that is in the U. Cut fiber cement outdoors if possible, and always in a well-ventilated area.
Use a saw, scoring knife, or shears to cut fiber cement. Other than the dust problem, fiber cement cuts easily in a variety of ways. Consider the pros and cons of the following options: [8] X Research source Circular saw.
This is the most common option, especially for straight cuts, but it also creates the most dust. Use a blade designed for cutting fiber cement and attach a dust collecting vacuum to your saw, if possible.
This shares the pros and cons of a circular saw, but is easier to use if you need to make any curved cuts. Fiber cement shears. These are essentially powered scissors that attach onto the end of a power drill. They create less dust than saws, and are good for straight and gently-curved cuts.
Scoring knife. You can cut fiber cement in a process similar to that used for drywall—score the cut line with several passes of a scoring knife, then snap the board at the edge of a work table. Use a carbide-tipped scoring knife for better results. Part 3. Hang the vertical trim pieces with galvanized or stainless nails. Likewise, you can use either galvanized or stainless steel nails. Fibre cement sheets come in all shapes and sizes and are rather simple to cut and install.
Unlike other types of roofing sheet, they come in generously large sizes, making them ideal for use on large buildings. You should first ensure that you have everything you need, from the fibre cement sheets themselves to fixings, tools, and any other equipment.
Ensure all of your equipment is functional and stable, and that your tools all operate properly. Check the sheets for any damage, cracks, or sharp edges. When fitting fibre cement roof sheets, the best way to lay them in order to avoid any damage to the sheets themselves or to your roof, is to lay them in columns from the eaves of your roof to the ridge. Always remember to lay fibre cement sheets according to the wind direction, as trying to place them with the side lap against the wind could cause uplift and potentially serious damage.
Simply clear away your sheets in the meantime, as leaving unsecured sheets on your roof could be dangerous. Unlike most other sheet roofing, when fitting fibre cement roof sheets some corners will need to be mitred.
This process involves cutting opposite corners of some fibre cement sheets to prevent unnecessary overlapping. Each sheet you use should have two mitres, except for those on the edges of your roof. The first and last sheets you fit should be left untouched. Always perform this process on the ground, never at height. Using the fixings themselves will cause damage and potentially severely decrease their performance and lifespan.
The holes should be drilled into the purlins, with each sheet fixed twice on each purlin. A hole around 2mm larger than the fixings should be drilled at the peak of each profile never between the corrugations.
This is particularly important when fitting fibre cement sheets, as they may shatter under impact. Do always remember to use sealing washers along with the fixings, and never drill fixings through two sheets.
This is both to weatherproof and allow thermal movement, as if the sheets cannot do so, they may become damaged. Insert the fixings once these holes have been pre-drilled, ensuring that they are properly tightened, and any accessories such as washers and caps are present. The final step in fitting fibre cement sheets to your roof is sealing any overlaps.
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