Reinforced concrete – located on this bottom of the area "concrete walls" answers questions related to the drilling of this hard and perhaps even "dissuasive" substrate. You can avoid drilling into reinforcement metal in concrete, and what to do if you are hitting metal. Which drills are suitable? You will find our advice here. Please also note the general instructions for drilling work for the mounting of the climbing aids.
Concrete is a mixture of pebbles or other stones precisely defined of different sizes (so-called "sieve lines"), so that after casting and solidification in a basic framework of larger stones, all spaces between are evenly mixed with medium-sized and smaller stones. Once completed, they are embedded in grey or sometimes even a colored cement compound. Concrete walls can be done in formwork-rough and untreated, but also colorful, pebbled, or with tiles. Almost always it concerns "Ferro-concrete", that is the wire-like metal rods and grid-shaped iron which lends stability when poured in as an armoring. This rebar, in turn, is often divided into stronger rods of actual reinforcement with thin wires which attach to the rods during concrete casting for a desired positioning. The prescribed 'concrete covering' of the iron in reinforced concrete , used in outdoor areas (i.e. not indoors) is 3.5-4 cm, so holes are usually unproblematic up to approx. 3.5 cm.
Determine the wall thickness, if necessary, through a test hole. First, ensure that it is not a 'thin concrete wall'. Sometimes it is also important to keep the drilling depth lower than the wall thickness to prevent spalling - (splintering or chipping) on an inner wall - 1-2 cm. Works best with a hammer drill.
Due to the hardness of steel reinforced concrete, usually a hammer drill is needed. For that we provide high quality hammer drill bits. A hammer drill reaches a maximum for small holes, here is that special bit with good concrete cutting geometry which is suitable such as SB 77777 and as universal masonry drills such as SB 44444. Drill each pre-defined point of growth aid initially without percussion to prevent spalling in the surface layer, especially by concrete in open view. Please use the general remarks about drilling if required.
If during concrete drilling you are hitting metal, you may have encountered the reinforced steel within. Clean the drill hole and with a point light source, shine light into it. If you see a "thin" iron piece up to approx. 5 mm in thickness, it can be drilled with our hammer drill bits and must be cut by simple continued drilling. Cutting the thinner auxiliary wires in the concrete (see above) is often unnoticed. In the case of commercial industrial greening, any severance of inner reinforcement should be clarified with site management. Strong iron bars should not be cut, especially if multiple perforations of the reinforcing steel effect the stability of the structure and cause static problems. For the special case of "pre-stressed concrete", see below. Which alternatives, nevertheless, are there to fasten a wire rope holder after hitting reinforcement?
First, explore with illumination whether it is a vertical or horizontal iron. Then the hole is properly sealed with a white filling and filler for outdoor use, to prevent ingress of water and rusting of the inner reinforcement. Subsequently, the single hole and mostly all holes in this axis will be newly drilled and the holder(s) fastened as planned.
Sometimes with drilling the shaft is a little bit crooked along the iron. Then drill bits of Easy, Light and Heavy kits are snapped or bent before assembly by impact, and then cemented with composite mortar, so that the error is concealed. Alternatively, with 'Eco' - and 'Classic' -kits after screwing the crooked shaft of a standard cross-holder in, can the bit be set and corrected by a blow or strike (interleaved hardwood or aluminum block).
This variation is suited for all holders with metrical thread, with wooden thread, see below. Just use the area lying before the rebar area for the connection. However, it is important that the bore is still tight and correct and not larger and worn already by drilling attempts. If necessary, and more accurately drilled. Afterwards, the threaded shaft is inserted to the holder with a suitable brass anchor and is shortened with iron saw or dividing grinder accordingly , and thread-smoothly beveled. With medium kits the holder WM 10081 with brass anchor is alternatively useable. With plastered ferro-concrete again brass anchors are not suitable, because the plaster layer cannot take up the expansion of the anchor. Again, the threaded shaft is shortened to fit, but then bonded with composite mortar. The same procedure is also in wood threads.
Normally in this web section describing concrete walls, would the reinforced iron or steel mats in walls and concrete facades be built slack (without treatment) into the concrete. For a higher stability in ceilings of buildings and bridges, etc., there is also pre-stressed re-inforced concrete. Pre- stretched metal reinforcement made to alleviate future natural adjusting or movement of the components concerned. Hence the name "pre-stressed ". These components require special care with the mounting of growth aids, because here cutting the reinforcement can be disastrous!