PU foam: seal, assemble and fill with polyurethane foam

PU foam, construction foam and mounting foam

PU foam: seal, assemble and fill with polyurethane foam: seal

The common building blocks are based for the most part on polyurethane. Therefore, the term polyurethane foam or short PU foam is commonly used for construction foam. This foam is a very versatile building material. You can do it for Mount, fill and isolate use as well as for Gluing, fixing and modeling.

This versatility owes the foam on the one hand its good adhesive properties and its insulating power, on the other hand, the high stability after curing. It causes hardened PU foam grind, saw and cut leaves. In addition, it can be plastered over, glued, painted and painted with common wall paints.

Just as diverse as the possible applications are the names in the trade. Whether mounting foam, gun foam, construction foam, insulating foam, fountain foam or Zargenschaum - usually is always a PU foam meant, which differs not too much from the others.

1K and 2K foam

PU foam: seal, assemble and fill with polyurethane foam: fill

For home improvement, the use of a one-component foam is usually the most sensible solution. It is easy to apply and can be processed directly from the can.

Nevertheless, there is two big product groups, which must be clearly separated: PU foam is available as one-component 1K foam or as 2-component foam as 2K foam. Two-pack foam only solidifies when adding a special hardener, which is supplied separately. One-component foam hardens on the other hand by the ambient humidity and therefore does not have to be mixed first with a hardener.

No wonder then that 1K PU foam the largest share 2K foam is more prevalent in the sold building spaces - only where hardening needs to be precisely defined, fast and in dry environments, 2K foam is more widespread, and these applications are mostly in the professional field.

Do-it-yourselfers usually deal with 1K foam. He will shaken thoroughly with the can, until the ingredients have mingled, and then injected by a pressure on the can valve on the spot - a simple thing. After insertion, the foam reacts with the humidity and hardens from outside to inside. This can be accelerated and supported with suitable objects by first spraying the adhesive surfaces with water.

To the extent that the foam cures, it is also steadily stronger: After a quarter of an hour, the surface is hardened so far that the foam no longer sticks when touching. After about one hour, the hardening inside is usually so advanced that the PU foam can be cut. After several hours, finally, construction and assembly foam is fully loadable.

Although this time usually applies, you should always follow the instructions of the respective manufacturer and follow any instructions that may differ.

PU foam in use

The Possibilities for shell construction and interior work are extremely numerous. Windows and doors, for example, are inserted and fixed with PU mounting foam. Incidentally, it is worthwhile to look for an expansion-free assembly foam, because the expanding after injection foam develops enormous forces, if it can not easily escape through a large opening. Expansion pressure-free foams then help to defuse dangers for less stable subsequent constructions.

Even openings such as wall and ceiling ducts for pipes and pipes can be With PU foam, precisely and tightly fill. Cavities can be insulated with the foam, gaps in Dämmkonstruktionen can be filled. In addition, mounting foams are used to glue components and fix.

PU foam: seal, assemble and fill with polyurethane foam: foam

Window frames are usually fixed with wall anchors. Here, PU foam serves to seal the space between the frame and the masonry.

PU foam: seal, assemble and fill with polyurethane foam: fill

Door frames are also fixed with mounting foam on the adjacent wall reveals.

PU foam: seal, assemble and fill with polyurethane foam: polyurethane

Cavities as here for installation purposes can be filled with PU foam. At the same time, the foam keeps the empty pipes in place.

If something goes wrong during processing, fresh PU foam can be removed with acetone. However, you should hurry, because once hardened construction foam can be eliminated only mechanically, so for example by scraping with a spatula.

Properties that you should know

PU foam: seal, assemble and fill with polyurethane foam: foam

Bauschaum adheres very well to most common construction substrates. Adhesion and curing can be supported by previously sprayed the adhesive surfaces with water.

After curing, PU foam is insensitive to water, he also takes up little water. Its water vapor diffusion resistance is approximately in the same range as expanded polystyrene or concrete and therefore fits well into building structures.

The good adhesion on numerous substrates and the compatibility with almost all materials used in construction - which includes stone, concrete and wood as well as metals and painted surfaces - also help. Porous, absorbent substrates are best treated with a suitable primer. Like almost all coatings or adhesives, PU foam only has Adhesion problems with polyethylene (PE), polypropylene (PP), silicone and oil films. In individual cases, however, an adhesion-promoting primer can help here.

Extreme temperatures also tolerate building foam well. His Resistance to cold and heat ranges from -40 to + 90° C, even dimensional changes due to temperature fluctuations or the shrinkage and swelling of wood he picks up easily. The foam is also resistant to pressure and abrasion, it does not rot or rot. A weak point is only the sensitivity to UV light:

Ingredients and ingredients of construction foam

Mounting foam yellows very clearly after a relatively short time, when exposed to light. That's why he should always be covered.

There is no finished polyurethane in the construction cans, but the two basic substances polyol and polyisocyanate. Added to this is a propellant that pushes the mixture out of the can. Stabilizers, accelerators and flame retardants serve the durability, the hardening process and the later foam properties.

The components mixed by shaking prior to spraying react with 1K foams with the ambient moisture as described above, with 2K foams with the separately added hardener. This produces gaseous CO2, which forms the foam structure in the form of many small bubbles.

Danger: MDI in PU foam

One of the mentioned polyisocyanates is methylene diphenyl diisocyanate (MDI). It stands suspected of being carcinogenic. Therefore, since December 2010 PU foams with more than one percent MDI are subject to sales restrictions. They may not be offered for self-service, and the sale must be accompanied by a trained and properly trained personnel with training certificate (popularly known as "gift certificate").

Conversely, this means that the over-the-counter foams have a lower content of MDI - sometimes less than 0.1% - and pose no serious health threat. Incidentally, MDI is found only in the liquid product, after curing, there is no danger.

Building foam and building material class

Most PU foams count to Building material class B2. This means that they are normally flammable, comparable to construction wood, which also belongs to class B2.

For special applications There are also flame retardant PU foams. They then count to building material class B1. The classification in a certain building material class must be proven by a test certificate.

Recycle and store PU foam cans

PU foam: seal, assemble and fill with polyurethane foam: assemble

Consumers can easily return PU foam cans by dropping them into storage bins in building materials stores or hardware stores.

Technically conditioned remains in a PU foam can always a small rest of the content back. Therefore, they may be placed in the trash can still in the "yellow sack" or the rubble container.

However, in order not to let the consumer sit on the problem, leading European manufacturers have set up a joint venture for PU can recycling - the P.D.R. Empty PU cans can be given as an end user in hardware stores and building material stores, where they are from the P.D.R. picked up.

When storing construction foam before use, you should look always adhere to the specifications of the manufacturer. PU foam cans are under pressure and therefore subject to external hazards such as high heat or external pressure depending on the circumstances in individual cases explosive. Manufacturers can reduce this risk in part by selecting the propellant gas mixture. If one adheres strictly to the printed safety instructions, the risk is reduced again very clearly.

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