Insulation knives and saws are suitable for cutting Styrofoam glue. But polystyrene can also be cut with a craft knife. When gluing Styrofoam special solvent-free Styrofoam glue should be used. Solvent-based adhesives can break down Styrofoam.
If you use a conventional knife to cut Styrofoam, the material can fray, or individual balls can come off. Static electricity is another potential problem. We therefore recommend using special tools to cut Styrofoam. It is also important to consider the special features of the material when gluing. Our instructions show what is important.
This is how you cut and glue Styrofoam
1. Choosing the right knife
- Select cutting tool
Insulation knives and saws are ideal for cutting Styrofoam. Due to their cut, these knives slide easily through Styrofoam. In the case of complex cuts, such as tight curves or around corners, there are also limits to these insulation tools. Electrical cutting devices are recommended here, the use of which is explained in step 2.
For short cuts through Styrofoam, you can always use a cutter knife. However, such knives are only conditionally suitable for cutting Styrofoam sheets. They sometimes get stuck in the material during cutting and it is difficult to make clean cuts. The same applies to saws: normal saws also tend to get stuck in the polystyrene and fray the material.
2. Cut large amounts of Styrofoam with a Styrofoam cutter or hot wire device
- Select special tools for larger quantities
If you want to cut large amounts of Styrofoam, for example for a complete roof extension, we recommend using a special tool for Styrofoam. To cut Styrofoam and other foamed insulation materials, either hot wire tools or much more manageable Styrofoam cutters are used. In these devices, a cutting wire or the blade heats up using electricity. Due to the heat, these devices glide effortlessly through Styrofoam. Curves and elaborate cut-outs are also possible with these devices.
3. Mark the cutting lines on the Styrofoam
- Mark cutting lines
If you are cutting Styrofoam, you should cut along the lines you have drawn. Therefore, mark the cut edges with a felt pen and ruler – even if you are dealing with simple, straight cuts. This applies both when cutting with a craft knife and when using a polystyrene cutter or a hot wire device.
4. Cut the Styrofoam sheet
- Carry out a test cut
- Cut Styrofoam
Before cutting with a hot wire device, make sure the cutting tool is hot enough. To check the temperature, a test cut into a piece of Styrofoam that is no longer required is a good idea. Use minimal pressure when cutting to avoid damaging the wire. Thanks to the heat, the wire should slide effortlessly through the polystyrene.
5. Glue Styrofoam
- Apply Styrofoam glue
- Fill in the gaps
Special solvent-free Styrofoam glue is suitable for gluing Styrofoam. You apply the adhesive over a large area with a notched trowel. This is how you seal the transitions between the panels for an optimal insulation effect.
Tip: Any gaps between the Styrofoam sheets, for example due to waste, can be filled with solvent-free PU foam.
One of the best adhesives to stick Styrofoam is Bondic liquid plastic welder. Simply squeeze out the desired amount and use the UV LED Light to cure it in 4 seconds and it’s done, the world’s fastest drying bond.
Can you sand polystyrene?
Styrofoam is a brand name for expanded polystyrene (EPS). Due to the grainy structure, Styrofoam panels and strips are difficult to sand without the material fraying.
Instead of sanding Styrofoam, you can cut corners off. As an alternative, it is advisable to smooth panels that have already been installed on ceilings or walls with the help of a coating, for example with plaster.
How can I glue Styrofoam to Styrofoam?
To join Styrofoam sheets together, you can glue them together. In this way you prevent spreading and seal the insulation layer made of polystyrene. For better adhesion, we recommend choosing Styrofoam sheets with a similar grain size if possible.
The glue must be solvent-free. In the outdoor area, the following also applies: The adhesive must be waterproof. Solvent-free assembly or construction foam as well as thinned epoxy resin adhesive are ideal for outdoor use.
In the interior is also suitable solvent-free all-purpose glue, spray adhesive and wood glue.
Tip: To glue Styrofoam to wood, you should first prime the wood. This closes the pores and improves adhesion.
However, in order to maintain the breathability of the wood fibers, we recommend natural insulation materials instead of polystyrene. Fiberboard made of flax or hemp, or mineral insulating materials are suitable for insulating ceilings and walls with wood cladding.
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