Normal consumption is three horizontal facade screws and one or two angled facade screws per floor and vertical nail batten c/c 600 mm. However, this depends on the design wind load and the weight of the intended facade cladding.
The angled facade screws must always be placed together with a horizontal facade screw, 100 mm above the horizontal one. There is no limit in height as an increased number of angled facade screws increases the load-bearing capacity.
Here, the permissible relative deflection of the batten with regard to wind load against the façade is stated. L1 is the distance between the attachment points (the horizontal facade screws) which can be varied from 600 to 1200 mm. Permitted relative deflection depends on the type of facade cladding. A wood panel cladding can withstand a greater relative deflection than a facade cladding consisting of ceramic panels or facade panels that will have a plaster layer.
• L1 / 100 (where L1 from 600 to 1200 mm gives a relative deflection from 6 to 12 mm)
• L1 / 200 (where L1 from 600 to 1200 mm gives a relative deflection from 3 to 6 mm)
• L1 / 300 (where L1 from 600 to 1200 mm gives a relative deflection from 2 to 4 mm)
• L1 / 400 (where L1 from 600 to 1200 mm gives a relative deflection from 1.5 to 3 mm)
• L1 / 500 (where L1 from 600 to 1200 mm gives a relative deflection from 1.2 to 2.4 mm)
Contact the supplier of the current facade cladding for information and requirements for maximum relative deflection.
The calculation for capacity load with regard to wind load against the facade is made as below. The program selects and reports the lowest value as load capacity and specifies limiting capacity taking into account selected and entered parameters.
- Load capacity limited by tensile strength in facade screw, in back wall or batten.
- Load capacity limited by torque failure in the batten.
- Load capacity limited by shear failure in battens.
- Load capacity limited by the maximum permitted deflection of the batten.
Contact the supplier of the current facade cladding for information and requirements for maximum relative deflection. A wood panel cladding can withstand a greater absolute deflection than a facade cladding consisting of ceramic panels or facade panels that will have plaster layer.
The calculation for dimensioning vertical load capacity with regard to the self-load takes into account the pull-out force from the batten and rear wall as well as the compressive force of the horizontal facade screws. The program selects and reports the lowest value as dimensioning vertical load capacity and specifies limiting capacity taking into account selected and entered parameters.
Existing wooden frame structures such as unfolding walls may in some cases need a full-covering layer of a building board like plywood or OSB with a thickness of at least 15 mm to provide a stable base for fastening the facade cladding.
Tick the box and enter the thickness in the box that opens on the right. Increasing the thickness improves wind load capacity and vertical load capacity.
The program adjusts the length of the facade screws with regard to insulation thickness, thickness of nail batten and setting depth. For lightweight concrete, bricks/masonry site pull-out tests are required. Site pull-out tests should also be performed for concrete with unknown quality. The results from the site pull-out tests are entered into the form. The program will then take this information into account.
Calculations of dimensioning capacities are based on ETA-12/0038, ETA 11/0284 and ETA 15/0784 issued for the facade screws and Eurocodes 3 and 5. The results of pull-out test in lightweight concrete, brick and unknown concrete are calculated statistically according to Eurocode 6 alternatively ETAG 029-B. The partial coefficient for safety class 2 and coefficient 1.99 (kn) are used.
To ensure the quality of the substrate, site pull-out tests must be carried out with at least 15 samples evenly distributed over each individual facade surface. For lightweight concrete, bricks/masonry site pull-out tests are required. Site pull-out tests should also be performed for concrete with unknown quality.
The results from the pull out test are entered into the form and the program takes this information into account in the calculation of dimensioning wind load capacity and vertical load capacity.
Here are three choices. Solid wood, (also called CLT), Concrete (uncracked) and Lightweight concrete / Brick / Unknown concrete. The substrate can also consist of a timber frame and in that case the choice CLT is selected and the box next to "Frame with building board" is ticked and the thickness is stated. The thickness must be at least 15 mm to provide a stable base for attaching the facade cladding.
In the alternative Lightweight concrete / Brick / Unknown concrete, the performance of the substrate can vary partly due to quality and partly due to age and therefore the substrate must always be tested by pull-out testing. For the dimensioning to be reliable and statistically significant, 15 pcs pull-out samples per façade area are required.
The input data below gives an estimate of the material consumption. The program does not take into account doors and windows as the number and size of these affect the material consumption, often more facade screws are needed than the program calculates. The principle is that each nail batten must be able to absorbed both wind load and vertical load regardless of length.
Vertical nail battens in connection with windows and doors, fitted with horizontal facade screws with the same distance as stated above (L1). In addition, an angled facade screw is mounted in the upper edge 100 mm above the upper horizontal facade screw according to the figure. Depending on the size of the window or door, and thus the length of the nail batten, more angled facade screws may be required, use the same distance as stated above (L2).