We compare insulation for the house — polyurethane foam or expanded polystyrene

Ther­mal insu­la­tion mate­ri­als are indis­pens­able for high-qual­i­ty insu­la­tion of any build­ings and premis­es. The mar­ket is replete with many prod­ucts designed specif­i­cal­ly for this pur­pose. But, nev­er­the­less, the most pop­u­lar for a long time are poly­styrene foam and polyurethane foam. What are their fea­tures and what are the dif­fer­ences between them? Our experts will advise.

Structural features and material advantages

In order to have a more detailed idea of ​​​​both heaters and form the cor­rect con­clu­sions when com­par­ing them with each oth­er, it is worth famil­iar­iz­ing your­self with the prop­er­ties of each in more detail.

Styrofoam

Both heaters have a sim­i­lar “nature” (they are made from the same feed­stock), but at the same time their pro­duc­tion tech­nol­o­gy is dif­fer­ent and this deter­mines every­thing. Sty­ro­foam is known among ordi­nary con­sumers as Sty­ro­foam. It belongs to the group of poly­mers and is obtained by foam­ing poly­styrene.

Insu­la­tion is rep­re­sent­ed by 2 vari­eties: foamed and extrud­ed. The lat­ter is char­ac­ter­ized by a high­er den­si­ty, which sig­nif­i­cant­ly improves the ther­mal insu­la­tion prop­er­ties of the mate­r­i­al, and also pro­longs its “life”.

ON A NOTE. Vari­eties of expand­ed poly­styrene are dif­fi­cult to dis­tin­guish from each oth­er, but this can be done in a prac­ti­cal way. It is enough to break off a small piece from the foam plate. Foamed at the frac­ture site, small balls will be vis­i­ble, while extrud­ed, reg­u­lar poly­he­dra will be vis­i­ble.

Extrud­ed poly­styrene foam has a num­ber of oth­er, high­er qual­i­ty advan­tages:

1. Low lev­el of water absorp­tion;

2. High strength;

3. Dura­bil­i­ty

ON A NOTE. In no case should poly­styrene-based mate­ri­als be used for inter­nal insu­la­tion, since con­den­sa­tion forms between the insu­la­tion and the wall in a short peri­od of time, which can lead to accel­er­at­ed destruc­tion of the struc­ture.

polyurethane foam

In every­day life it is bet­ter known as “foam rub­ber”, only in every­day con­di­tions its soft vari­ety is found, and in con­struc­tion it is hard. The mate­r­i­al is char­ac­ter­ized by a closed cell struc­ture and the pres­ence of an edge, which great­ly sim­pli­fies the instal­la­tion process. And thanks to spe­cial com­po­nents, the insu­la­tion is fire­proof.

Polyurethane foam is pro­duced by man­u­fac­tur­ers in the form of plates or foam applied with spe­cial equip­ment. The sec­ond option is actu­al­ly devoid of typ­i­cal instal­la­tion flaws (in par­tic­u­lar, “ther­mal bridges”): the coat­ing will be con­tin­u­ous.

ON A NOTE. Unlike expand­ed poly­styrene, polyurethane foam can be used with­out a vapor bar­ri­er lay­er, since its water absorp­tion lev­el is very low (15 times low­er than that of poly­styrene).

Comparative characteristics

Thermal conductivity

One of the key fac­tors influ­enc­ing the final choice of a par­tic­u­lar insu­la­tion for the house. The best options have low ther­mal con­duc­tiv­i­ty, while it is allowed to reduce the thick­ness of the mate­r­i­al dur­ing instal­la­tion.

Com­par­ing poly­styrene foam and polyurethane foam, there is a clear lead­er­ship of the first: 0.04–0.06 W / m * K ver­sus 0.019–0.028 W / m * K. Due to its denser struc­ture, expand­ed poly­styrene retains heat bet­ter, but at the same time weighs more (although this cri­te­ri­on is not con­sid­ered impor­tant when choos­ing a suit­able insu­la­tion).

Strength

Expand­ed poly­styrene is con­sid­ered a fair­ly durable mate­r­i­al, which was incor­po­rat­ed into it at the pro­duc­tion stage (its struc­ture is very homo­ge­neous). But polyurethane foam is a set of mol­e­cules inter­con­nect­ed through expo­sure to high tem­per­a­tures.

If we com­pare in terms that the resis­tance of expand­ed poly­styrene to bend­ing is 0.4–1 MPa, and polyurethane foam — 0.07–0.2 MPa. It is the mechan­i­cal impact that is often the cause of the destruc­tion of the lat­ter — it sim­ply crum­bles. Any bend, impact dur­ing instal­la­tion is enough to dam­age the insu­la­tion.

Expand­ed poly­styrene, on the oth­er hand, is dis­tin­guished by sig­nif­i­cant strength, which makes it a suit­able option for mount­ing on load-bear­ing walls: it is not afraid of tem­per­a­ture surges, defor­ma­tion, shrink­age, etc.

combustibility

Fire resis­tance or com­bustibil­i­ty is an impor­tant indi­ca­tor, espe­cial­ly when it comes to warm­ing the roof or rooms, hous­es made of wood. Both con­sid­ered mate­ri­als have sim­i­lar flam­ma­bil­i­ty class­es: G2 (polyurethane foam) and G3 (poly­styrene foam). G2 implies that the mate­r­i­al has an aver­age flam­ma­bil­i­ty index, G3 — that the mate­r­i­al is flam­ma­ble.

In fact, a high com­bustibil­i­ty is a key dis­ad­van­tage of both heaters. It is for this rea­son that man­u­fac­tur­ers began to mas­sive­ly add flame retar­dants to the prod­uct being cre­at­ed — spe­cial com­po­nents that pre­vent the igni­tion of the insu­la­tion. If it is cre­at­ed accord­ing to tech­nol­o­gy, in the event of a fire, its atten­u­a­tion will be almost instan­ta­neous.

Environmental friendliness

Unfor­tu­nate­ly, both expand­ed poly­styrene and polyurethane foam are tox­ic mate­ri­als. But only when they are exposed to high tem­per­a­tures: they emit poi­so­nous gas. It is for this rea­son that both heaters are rec­om­mend­ed exclu­sive­ly for out­door repair and con­struc­tion work.

By the way, sub­ject to the instal­la­tion and oper­a­tion tech­nol­o­gy under nor­mal con­di­tions, none of the con­sid­ered mate­ri­als pos­es any dan­ger to human health and the envi­ron­ment.

moisture resistance

Hydropho­bic­i­ty is one of the key cri­te­ria for choos­ing a heater and should nev­er be ignored. The resis­tance of a mate­r­i­al to mois­ture indi­cates how it will be able to with­stand mois­ture dur­ing oper­a­tion. The water absorp­tion index should be min­i­mal, oth­er­wise it threat­ens to destroy the insu­la­tion, increase its weight (this will increase the load on the struc­ture), and lose the main prop­er­ty — ther­mal insu­la­tion.

Our experts con­duct­ed a sim­ple but reveal­ing exper­i­ment: they immersed sheets of expand­ed poly­styrene and polyurethane foam in water for a day. The first absorbed only 0.2% of the vol­ume of water (a very small indi­ca­tor), the sec­ond — about 2%. Such a sig­nif­i­cant dif­fer­ence is due to the struc­ture of expand­ed poly­styrene: its closed cells prac­ti­cal­ly do not let water through.

Vapor permeability

The lev­el of vapor per­me­abil­i­ty also can­not be missed, because it depends on whether addi­tion­al use of a vapor bar­ri­er lay­er is required. If we talk about polyurethane foam, then its vapor per­me­abil­i­ty index is approx­i­mate­ly 0.05 units, but for poly­styrene foam it is actu­al­ly zero. This sug­gests that the lat­ter option does not allow steam to pass through, so you don’t have to wor­ry about addi­tion­al pro­tec­tion (but only if we are talk­ing about “breath­ing” sur­faces).

Soundproofing level

None of the options con­sid­ered can be called suit­able for use as sound insu­la­tion. Since the den­si­ty indi­ca­tors of both mate­ri­als are close, they will not have any spe­cial dif­fer­ences in the lev­el of sound absorp­tion. If you need to pro­vide a room or house with high-qual­i­ty sound insu­la­tion, we rec­om­mend that you addi­tion­al­ly use build­ing mate­r­i­al spe­cial­ly designed for this pur­pose.

Shrinkage degree

The ten­den­cy to change the orig­i­nal shape is the “Achilles heel” of many heat-insu­lat­ing mate­ri­als, and one of these is polyurethane foam. This neg­a­tive prop­er­ty is espe­cial­ly evi­dent when the insu­la­tion is heat­ed: with pro­longed expo­sure to warm air, the plate will begin to deform. You should not use polyurethane foam for the “warm floor” sys­tem, and when insu­lat­ing the facade, you should wor­ry about using plas­ter with an ultra­vi­o­let pro­tec­tion func­tion for wall dec­o­ra­tion.

Expand­ed poly­styrene is dis­tin­guished by excel­lent “resis­tance” to shrink­age: dur­ing oper­a­tion, the mate­r­i­al does not change its orig­i­nal shape, regard­less of the con­di­tions and instal­la­tion site.

Mounting Features

And speak­ing of instal­la­tion. Both con­sid­ered heaters can be installed with­out pro­fes­sion­al help: the mate­ri­als are very easy to use and do not require spe­cial skills. For the con­ve­nience of work­ing with expand­ed poly­styrene, its sides were equipped with side pro­tru­sions, which form an inte­gral lay­er dur­ing instal­la­tion. In addi­tion, they increase the strength of the mate­r­i­al and speed up the work process.

Polyurethane foam is mount­ed using a sim­i­lar tech­nol­o­gy, but the process is com­pli­cat­ed by the absence of the “sides” described above: when work­ing with it, you will have to process the joints with adhe­sive or foam.