Integrated roller shutter boxes, which have a surface made from wood-wool building slabs on the inside, can be rendered directly. Non-absorbent backgrounds, e.g. a plastic covering are to be pre-treated using MultiGips Betonkontakt. With the use of thin-layer plasters the plaster end rail may have a lateral length of only 3 mm or 5 mm. With the absence of a rail one for a plaster thickness of 3 mm or 5 mm should be applied, 10 mm rails already assembled at the factory are to be exchanged. Roller shutter boxes due to the anticipated movements of the component are to be plastered using a whole surface reinforcing.
Heating and sanitary pipelines are to be laid
preferably in ducting or behind facings. Open slits for pipes and cabling
should be closed, e.g. using gypsum filler, before plastering. Alternatively
larger slits can be covered using a plaster carrier. The direct plastering of
pipeline/cabling installations in open wall slots is possible if sufficient
bonding surface is available and (with heating pipes) a sufficient thermal
insulation is ensured. Installations made from oxidised metals, which are to be
plastered, require corrosion protection.
Joints and expanding joints of structures must be
carried out at the same place and in the same width in plaster using suitable
plaster profiles. If the joint or respectively profile to be filled with
permanently elastic mastic it is to be examined whether the joint shape meets
the specifications of the mastic manufacturer.
Expansion joints in the plaster are produced using suitable joint profiles. They avoid cracks as a result of change sin volume of the gypsum plaster with larger spans. Expansion joints are to be placed from upwards of a continuous length of plastered surface of more than 10 m. Constructional joints in walls and ceilings (building separation joints), in accordance with VOB (German construction contract procedures), must be covered over at the same place and with the same possibilities for movement and in sufficient width. It is recommended that suitable joint profiles are specified in the performance description. Structural joints and expansion joints my not be rendered or filled.
At intersections between one material and another
in the rendering base there should always be reinforcing fabric embedded with ca.
two thirds of a plaster layer, so that possible stresses from the different
expansion of the building materials can be taken up.
Where plaster connects on to other materials, for example doors or windows, cracks can result through mechanical loading (e.g. slamming of doors) or the different behaviours of the materials with variations in temperature and humidity. Such positions of variation can be closed securely using water bars. Production of a clean transition is, in addition, simplified.
The frame width of the doors must be matched to the thickness of the wall including the wall plaster. Closed frames with variable opening, as a rule, can be adjusted without problem. Steel frames with fixed width have to be ordered in the appropriate size.
Before rendering the separation between window frame and intrados is to be checked. Under no circumstances may it be greater than the plaster thickness in the window intrados which, with thin-layer plaster is not always the case. Too large separations are to be pointed out to the site management. The intrados plaster can then, after its decision, be implemented appropriately thicker, or a covering profile is set over the gap.As a rule, in solid building, continuously applied interior plaster fulfils the function of the airtight layer. The planning section must give information on how the sealing of the connection at doors and windows against air and driving rain is to be carried out. Frequently a connection is planned using window connection foils. These foils are to be selected according to the building-physical loading and are to be installed according to the manufacturer’s data. The manufacturer must have released the foils specifically for over plastering. EPDM and polyisobutylene foils as well as non-fleece-lined foils cannot be plastered over directly!
Building units which are not connected to each other positively may not be bonded in the same plaster layer. Otherwise structural movements and settling can lead to cracks in the plaster. Special plaster surfaces on concrete ceiling slabs are to be notched at the edges as soon as the plaster bonds. With large ceiling areas, profiles or rigid foam strips are recommended for the edges. Cutting using a pointing trowel is to be carried out
- between ceiling and wall
- between bearing and non-bearing building units
- in the connecting are to building units made from wood, gypsum blocks and gypsum fibreboards
- always when relative movement of flanking buildings
has to be reckoned with.