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Concrete screw stair bolt W-BS/A4 with connecting thread
Highest loads and efficient installation. Ideal for mounting attachments outdoors in concrete that need to be removable, A4 stainless steel
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![](https://media.wuerth.com/source/eshop/stmedia/wuerth/images/std.lang.all/resolutions/category/78px/819973.jpg)
![](https://media.wuerth.com/source/eshop/stmedia/wuerth/images/std.lang.all/resolutions/category/78px/4718153.jpg)
![](https://media.wuerth.com/source/eshop/stmedia/wuerth/images/std.lang.all/resolutions/category/78px/37850891.jpg)
![](https://media.wuerth.com/source/eshop/stmedia/wuerth/images/std.lang.all/resolutions/category/78px/574255612.jpg)
Variants
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- Extremely flexible to use due to three anchoring depths
- Very high loads
- Smallest axial and edge clearance due to very low expansion effect
- Very fast and simple assembly, immediately load-bearing and easy to dismantle
- Pre-positioned, push-through or stand-off installation possible
- Attachment can be adjusted up to two times after assembly
European Technical Assessment ETA-16/0043 for fixing point, option 1, cracked and non-cracked concrete:
- Static and quasi-static effects (∅8 - ∅10)
- Seismic effect, performance category C1 (∅8 - ∅10)
- Fire resistance R30, R60, R90, R120
DIBt National technical approval/general type approval Z-21.1-2075 as bonded screw anchor for anchoring in concrete (∅10, type ST stair bolt)
- Use in combination with injectable mortar WIT-BS as bonded screw anchor WIT-BS
- In reinforced and non-reinforced and cracked and non-cracked concrete C20/25 to C50/60
Tensile capacity in concrete hollow body ceilings, (∅8 - ∅10) - expert report no. 21641 - 2016
From size 8, we recommend the use of a suitable tangential impact screwdriver for installation. The recommended nominal torque must be observed. When used outdoors, the drill hole can be sealed with WIT-BS injectable mortar.
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/normal/348px/4332957.jpg)
Adjustment - subsequent aligning possible
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/37435254.jpg)
Create the drill hole
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162590.jpg)
Clean the drill hole
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162589.jpg)
Place screw
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162588.jpg)
Screw in the screw
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162587.jpg)
Considered installed when the head is close fitting
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162586.jpg)
Screw out the screw max. 2x each by max. 10 mm. Underlay. Screw in
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/12162592.jpg)
Considered installed when the head is close fitting. Lining max. 10 mm. The required embedment depth must be maintained as a minimum
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662258.jpg)
Locate the tensioning strand
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662259.jpg)
Mark the tensioning strand and locate the next one
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662260.jpg)
Mark the tensioning strands. Specify the drilling range
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662261.jpg)
Create the drill hole. Observe spacing
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662262.jpg)
Clean the drill hole
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662263.jpg)
Screw in the screw
![](https://media.wuerth.com/stmedia/wuerth/images/std.lang.all/resolutions/category/348px/3662264.jpg)
Considered installed when the head is close fitting. Observe the embedment depth/mirror thickness
European Technical Assessment ETA-16/0043 for fixing point, option 1, cracked and non-cracked concrete:
- Static and quasi-static effects (∅8 - ∅10)
- Seismic effect, performance category C1 (∅8 - ∅10)
- Fire resistance R30, R60, R90, R120
DIBt National technical approval/general type approval Z-21.1-2075 as bonded screw anchor for anchoring in concrete (∅10, type ST stair bolt)
- Use in combination with injectable mortar WIT-BS as bonded screw anchor WIT-BS
- In reinforced and non-reinforced and cracked and non-cracked concrete C20/25 to C50/60
Tensile capacity in concrete hollow body ceilings, (∅8 - ∅10) - expert report no. 21641 - 2016
Fixing point:
Normal weight concrete C20/25 to C50/60 (cracked and non-cracked concrete)
Ideal for securing medium to heavy loads in concrete where disassembly of the attachment part is required:
- Securing e.g. stadium seats, barriers, railings, steel structures, supports and carriers, fence systems etc. in pre-positioned and push-through installation
- Fastenings under seismic conditions in earthquake areas
- Fastenings under exposure to fire
W-BS/A4 (A4 stainless steel) can be used in dry indoor conditions, outdoors (including in industrial atmospheres and coastal areas) or in wet rooms, provided that no particularly aggressive conditions are present.
For use in concrete < C20/25 and pressure-resistant natural stone (without approval)
Select RAL-colour code
!! NOTE: On-screen visualisation of the colour differs from real colour shade!!