Working with elements: mounting
Set the profiles
Set the required profiles. Profiles are placed in the same way as they are placed when erecting brick walls; place the stands so that they do not interfere with the panel mounting machine.
Make the first layer construction
- Make Silka first layer mortar. This mortar is tailored to the material properties of Silka calcium silicate, hardens quickly, has a high pressure strength and is suitable for load-bearing and non-load-bearing constructions.
- For this first layer, special Silka blocks are supplied (or Silka Thermokim blocks, which prevent thermal bridges in walls made, via the floor, come into contact with uninsulated spaces)
- Place the first layer blocks, making sure they are completely flat, and aligned at the height of the thread in the mortar.
- Thickness of joint: 10-30 millimetres.
- Add adhesive mortar to the butt joints or fill them with mortar.
- Allow the first layer to harden sufficiently before mounting.
- Make sure that the cove joint is fully supported by the floor, in other words, don’t ‘overlay’.
- A well-made first layer guarantees a perfectly flat surface, that is level both longitudinally and transversely.
- Select the correct first layer height to avoid having to adjust the top layer of the wall being created. This saves work.
Make Silkafix adhesive mortar
- Use only the adhesive mortar supplied by the factory.
- Delivery in bags of 25 kilograms.
- Follow the instructions on the packaging during processing.
- Mix the adhesive mortar for about 4 minutes, so that the water in the mortar can adhere well to the cement particles and a workable, smooth mass is created in which no more dry matter is present.
- Process summer mortar within 4 hours and winter mortar within 2 hours. Special winter adhesive mortar can be processed at temperatures down to approximately minus 3°C and is available from November 1st to April 1st. See also Working in summer and winter.
Process the wall elements
- Process Silka calcium silicate wall elements mechanically with a two-man team. One person operates the element mounting machine, picks up the elements, and transports them to the construction wall. The second applies the adhesive mortar to the bed and butt joints and carefully puts the elements in place.
- Apply bed joints using the adhesive mortar tub.
- Adjust the slide of the box so that a joint thickness of 2 millimetres remains. Using the adhesive mortar scoop, apply the adhesive mortar to the joints on the already set element from the bottom upwards.
- Advice: with elements 300 millimetres thick, leave applying the adhesive glue to the butt joints to the team member operating the element mounting machine before he transports the element to the wall.
- Advice: use the glue scoop to apply adhesive mortar to the butt joint.
- After fitting, drive the element with a heavy-duty rubber hammer to close the butt joint properly.
- Remove excessive mortar, after it has hardened slightly, with a putty knife.
Shave off the walls
It has been proven from calculations that walls with a height of 2.70 metres and a thickness of up to 214 millimetres must be properly braced every 5.0 metres until the floor (or the roof construction) being placed on the walls has been fully installed.
Point of attention: expansion joints
As calcium silicate walls are subject to some change in shape (shrinking) when moisture escapes, you may have to include expansion joints in walls. Because the wall length between these dilatations is limited, they are mere tenths of millimetres in size. Deflecting surfaces can also affect the movement in the expansion joints. The criteria for including expansion joints depend, among other things, on:
- Wall height
- Wall thickness
- Weakening as a result of openings
- Obstacles due to connecting walls
- Whether or not the wall in question is well-founded
Ask the constructor to indicate expansion joints that are structurally required.
Included in BIM building model
Xella will include the expansion joints in the building model.
The taller and thicker a wall is, the more tensile stress it can absorb. Obstruction of wall deformation can lead to cracking. There are horizontal and vertical obstacles.
- A horizontal obstacle means that the wall is held rigidly in place at the top and/or base. If the wall is on a floor and another floor is resting on it, the wall is obstructed horizontally at both ends:
- Obstructed on one side: all non-load-bearing walls
- Obstructed on both sides: all load-bearing walls
- A vertical obstacle concerns the connection at the side end of a wall, for example, piers in façades that connect to a residential partition wall. Possibilities:
- Flexural weakness: the wall is connected at the ends with a transverse wall (retracted or lead joint) smaller than or equal to the thickness of the wall in question
- Flexural stiffness: the wall is connected at the ends with a transverse wall (retracted or lead joint) greater than or equal to the thickness of the wall in question
- Unobstructed: the wall has a free end
Expansion joint varieties
There are two versions of expansion joints:
- Cold expansion joint, joint thickness about 1 millimetre, without filling. For shrinkage seams in walls on non-bending sub-surfaces for which no additional adjustment space is needed (for example residential partition walls).
- Filled expansion joint, joint thickness approx. 10 millimetres, with elastic and air-tight joint filling. For walls requiring a real constructive expansion and walls requiring mounting space (for example non-load-bearing partitions and inner cavity sheets).
Fire-resistant expansion joints
Silka wall elements are not primarily intended for creating fair-faced brickwork. Nevertheless, fire-separating walls are often made of Silka wall elements without being provided with the usual thin plasterwork. Keep in mind that the fire resistance requirements apply to the entire wall, including all joints. This means that the expansion joints must also be fire-resistant.
Finishing expansion joints
Cold expansion joints can be finished in two ways:
- By applying a load-distributing mesh with a width of 150 millimetres.
- By having the plasterer cut the skimming at the expansion joint.
- If the wall sections alternate with each other on both sides of the expansion joint, even out the joint first by means of skimming and let it harden before applying the load-distributing webbing.
- Filled expansion joints can be made to remain clearly in view in the wall finish by topping the plaster layer on both sides with a so-called plaster stop profile. Keep the plaster profiles at least 3 millimetres away from each other and fill the opening with a permanently elastic, paintable sealant, making it airtight.
- Create cold expansion joints in a plastered wall with a non-elastic coating covered with a plaster stop profile with 1 to 2 millimetres in between each, and an elastic sealant kit.
Point for attention: anchoring
Due to the thin bed joints (± 2 millimetres), a complete anchoring program is available for walls made of Silka wall elements.
Adhesive coupling strips
Perforated flat strip anchors for coupling lead joint attachments on walls that join onto each other.
- 1 strip anchor per coat, in other words 1 anchor per 600 to 645 millimetres.
- Apply two anchors to thick walls, in consultation with the constructor.
Cavity wall ties
Anchors with a flat strip on one side.
- Anchor in adhesive joints up to the stop unit with the closed side up
- Number per square metre to be determined by the constructor and depending on the façade layout.
Adhesive frame anchors
For frames placed before adhesion.
- Available in left and right variations.
- Fasten the anchors to the frame with grip anchor nails.
- For adjustable frames, apply corner anchors so that the frames can be fitted in length and breadth afterwards.
- Number of anchors dependent on the size of the frame.
Wall anchors are for rigid and expansion joints on partition walls glued to load-bearing walls. Dilating wall anchors can also be applied to uncoupled ceiling connections.
Anchors for safety
Available in trade as a building aid and to promote workers’ safety. Handrail anchors, to be processed in the bed joints of the inner cavity sheets for ensuring safety on the edge of scaffolding. The following, among others, pertain to edge safety:
- Edge safety braces, the number of which is assigned by the contractor;
- Edge safety adhesive plates for fastening edge safety braces. Fasten 1 adhesive plate per brace in the adhesive seam between the upper two layer elements.
Point for attention: working in summer and winter
Working in the summer
- In dry periods, dampen the adhesive surfaces of the wall elements before processing. While applying the adhesive, apply the adhesive joints no more than 2 metres in advance to prevent ‘burning’ the mortar.
- Do not place the tub with prepared adhesive mortar in full sunlight, unless the mortar is properly covered.
Working in the winter
Gluing is less frost-sensitive work, though it is not necessary to immediately stop when frost is expected. Thanks to the rapid strength development of adhesive mortars, fresh adhesive is less sensitive to the consequences of incidental frost than adhesive for brick mortars. Nevertheless, take precautionary measures, also to prevent downtime:
- Protect material and tools by covering them, for example with a Silka foil or by having pallets with fitting pieces and cove joiny blocks fitted with a protective foil at the factory. Heating and storage in frost-free sheds is also an option.
- Provide shelter at the construction site. Keep fresh adhesive and cove joint constructions free of frost by covering or heating them. Do not apply frozen or frosted elements.
- Keep lewis holes clean.
- Prevent puddles on floors as a result of precipitation, to avoid slipperiness and the build-up of water in the first layer.
- Do not use salt or agents that reduce the freezing temperature to prevent slipperiness, but rather apply coarse (breaker) sand.
- Unloading: unload the elements onto a flat surface on scaffolding parts or floor joists and cover them with tarpaulin. If necessary, weigh the cover down with stones or secure it with slats at the end of the elements.
- Transferring: cover the elements that have been delivered to the workplace. To prevent the build-up of moisture and pollution, store the elements off the ground on at least two floor joists or wooden slats.
Working through the winter: Silka Winter Work
Silka Winter Work means that Xella – for a small additional charge that greatly outweighs the costs of downtime and delays – will deliver the calcium silicate wall elements dry and among others with a foil providing optimal protection from winter weather conditions.
- The average humidity of calcium silicate elements is, at most, 10%
- The pallets with fitting pieces are packaged in foil
- Cove joint blocks are placed on pallets and packaged in foil
Want to know more?
Do you have questions about the possibilities or the processing of Silka elements? We are happy to tell you more about this and other building solutions from Xella.