Buying foam, you must first start from what you need. If you are going to use it to insulate the walls, placing it under the lining, plasterboard, siding or MDF-plates, and inside the walls of refrigerating chambers, choose a foam density of 15 kg/m3. For insulation of walls from the outside is applied, the foam density 25 kg/m3 (it is marked by the letter "H"). And for the roof and flooring (under the plate) to warm the room and rid it of unnecessary noise, use material with a density from 35 kg/m3.
It is important to place the sale and, accordingly, the storage location of the foam. Keep in mind that if the heater is stored under the open sky, its thermal insulation properties are violated.
Do not hesitate to ask the seller the documents for the material you want to buy. If the manufacturer is reliable, it definitely supplies its products with all necessary certificates and conclusions.
Carefully inspect the package. It should be of high quality. And even if the material is sold unpackaged, on a separate sheet you should see the markings or stickers. If insignia is not, you risk your money.
Quality foam should only be white. If it is a little yellowed, so either made of poor raw materials, or stored in the sun, which degrades its properties. In addition, the material should have no smell. Its presence indicates the violation of the production technology.
Styrofoam pellets must be uniform in diameter and distributed evenly over the volume of the sheet. Any voids and holes with a diameter of more granules in the material should not be. During transport, the stove needs to keep his form. If you saw that from the leaves vyslushivaesh granules, keep from buying. This low-quality material.
It is advisable to consider a sheet of foam on the rift: to split up should granules, at least 50 percent.
Ask the seller to weigh a pack of foam, and then recalculate the result based on the cubic meter. A cubic meter of high-quality foam should weigh at least 16 kg.
Then take some sheets of Styrofoam and place them on the floor next. You will see (or not see) the difference in their sizes, thickness and bending or torsion, if any. The difference in size is not so terrible as the difference in thickness on all sides of leaves and deformation.
To the touch high-quality foam should be soft and elastic. Hard and crunchy it is, if the violation of the technology of its production. This material will not retain heat and is stronger to absorb moisture