Overview of the best insulation for ventilation pipes


Ther­mal insu­la­tion (insu­la­tor, heat insu­la­tor) is a struc­tur­al ele­ment or mate­r­i­al that pro­vides resis­tance to heat trans­fer or its reduc­tion. Its use is the main way to pre­vent con­den­sa­tion in ven­ti­la­tion sys­tems. Insu­la­tion for the prop­er oper­a­tion of ven­ti­la­tion pipes (vent pipes, vent pipes) is a must. In addi­tion to pro­tect­ing against mois­ture, insu­la­tion per­forms an addi­tion­al func­tion — it drowns out wind noise.

Fig.1 Insu­la­tion of the ven­ti­la­tion sys­tem

What is dangerous condensate

The appear­ance of water droplets inside the ven­ti­la­tion pipes is an inevitable process in the col­li­sion of warm and cold air flows, high humid­i­ty, vio­la­tions in the oper­a­tion of the sys­tem and the rules for oper­at­ing the premis­es. Con­den­sa­tion not only grad­u­al­ly destroys the mate­r­i­al, but cre­ates favor­able con­di­tions for the devel­op­ment of mold and fun­gi. This increas­es the risk of spread­ing aller­gic and res­pi­ra­to­ry dis­eases. It is espe­cial­ly nec­es­sary to insu­late ven­ti­la­tion pipes in an unheat­ed attic. In win­ter, the tem­per­a­ture dif­fer­ence between the air in the ven­ti­la­tion sys­tem and the pipe walls increas­es. More mois­ture is formed, it can accu­mu­late not only on the inner sur­face of the duct, but also out­side. Only rel­a­tive­ly new tex­tile (fab­ric) pipes do not need ther­mal insu­la­tion; due to the char­ac­ter­is­tics of the mate­r­i­al, mois­ture does not accu­mu­late in them.

Fig.2 Con­den­sate on the pipe

Types of ventilation systems

Ven­ti­la­tion sys­tems are divid­ed accord­ing to the prin­ci­ple of oper­a­tion into exhaust, sup­ply, sup­ply and exhaust. There are no dif­fer­ences in the instal­la­tion of ther­mal insu­la­tion for them. At the instal­la­tion site, ven­ti­la­tion sys­tems are domes­tic and indus­tri­al. The area, air exchange of pipelines, the vol­ume of harm­ful fumes in pro­duc­tion are many times high­er than in a res­i­den­tial, office or retail space — more pow­er­ful equip­ment is required. Anoth­er dif­fer­ence is that plas­tic pipes are more often used in domes­tic ven­ti­la­tion sys­tems, while gal­va­nized met­al pipes are used in indus­tri­al ones.

Met­al ven­ti­la­tion pipes are espe­cial­ly in need of pro­tec­tion against con­den­sate. In the process of cut­ting into pieces of the desired length, the gal­va­nized lay­er is bro­ken. From con­tact with mois­ture, the met­al quick­ly rusts, the pipe becomes unus­able with­in 2 — 3 years.

Fig.3 Indus­tri­al ven­ti­la­tion sys­tem

Heaters for domestic premises


You can insu­late a ven­ti­la­tion pipe in a res­i­den­tial build­ing or a pri­vate house with the fol­low­ing mate­ri­als:

  1. Min­er­al wool (min­er­al wool).
  2. Basalt (stone) wool.
  3. Foamed poly­eth­yl­ene.
  4. Foamed rub­ber.
  5. Sty­ro­foam.
  6. Sty­ro­foam.
  7. Asbestos boards.
  8. PIR plates.

Organ­ic heat insu­la­tors, such as cel­lu­lose ecowool, are not suit­able for insu­lat­ing ven­ti­la­tion in a room or in an attic, as they cake for 2 to 3 years and lose their prop­er­ties. Wrap­ping pipes with cloth, felt is point­less. Such pro­tec­tion is quick­ly sat­u­rat­ed with mois­ture and will give the oppo­site effect to the desired one.

Rice. 4 Insu­la­tion of the ven­ti­la­tion pipes of the house­hold sys­tem

Relat­ed arti­cles — how to cut min­er­al wool cor­rect­ly.

Mineral wool

Under the name “min­er­al wool” sell­ers and man­u­fac­tur­ers under­stand insu­lat­ing mate­ri­als made of glass, slag or basalt fibers, in the form of plates or flex­i­ble mats. Basalt wool dif­fers sig­nif­i­cant­ly in price and char­ac­ter­is­tics, slag wool is rare on sale (due to harm­ful­ness), there­fore glass wool is usu­al­ly called min­er­al wool. Oth­er names are min­er­al wool, glass wool, glass wool.


  • good insu­lat­ing and noise-absorb­ing prop­er­ties — ther­mal insu­la­tion coef­fi­cient 0.030–0.052 W / m ° C;
  • elas­tic­i­ty, easy to mount over round pipes;
  • strength;
  • fire safe­ty, with­stands tem­per­a­tures up to 450 ° C;
  • low price.


  1. Glass wool fibers are brit­tle, in the process of cut­ting and instal­la­tion, a lot of very small and sharp frag­ments are formed. They eas­i­ly pen­e­trate under clothes, into the skin, lungs, eyes, you need to work in a res­pi­ra­tor, gog­gles and over­alls.
  2. The com­po­si­tion of cheap min­er­al wool may include phe­nol-formalde­hyde resins. They cause poi­son­ing and can­cer. When buy­ing a heater, ask the sell­er for an expert opin­ion on the com­pli­ance of the prod­uct with san­i­tary, epi­demi­o­log­i­cal and hygien­ic require­ments.
  3. Glass wool strong­ly absorbs water from the air, mois­ture lingers inside and is dif­fi­cult to remove. The solu­tion to this prob­lem is min­er­al wool with a foil coat­ing that acts as a vapor bar­ri­er.
  4. With con­stant con­tact with mois­ture for 3 years, glass wool los­es up to 50% of its heat-insu­lat­ing prop­er­ties. This does not apply to foil min­er­al wool.
  5. Even in dry rooms, glass wool grad­u­al­ly cak­ing.
Rice. 5 Min­va­ta


To insu­late round ven­ti­la­tion pipes, min­er­al wool in mats (rolled) is used. She, like a blan­ket, is wrapped around the pipe and fixed with annealed wire (for knit­ting rein­force­ment), met­al or syn­thet­ic pack­ing tape. Square vents can be pro­tect­ed with glass wool plates. They are glued with spe­cial glue.

Basalt wool

Basalt (stone) wool con­sists of fibers of molten rocks (basalt). This is a more mod­ern, improved min­er­al insu­la­tion. Stone wool, like glass wool, is sold in slabs and mats. Their instal­la­tion is car­ried out in the same way as with min­er­al wool insu­la­tion.

For quick and con­ve­nient ther­mal insu­la­tion of chim­ney pipes or cir­cu­lar ven­ti­la­tion, some man­u­fac­tur­ers pro­duce fin­ished cylin­ders made of basalt fiber, with or with­out foil coat­ing. Cylin­ders are eas­i­ly cut into pieces of the desired length. They are put on a pipe, like a cov­er or a shell. Groove locks on the cylin­ders ensure tight fas­ten­ing with­out gaps.

Rice. 6 Basalt wool cylin­ders

Advan­tages of basalt wool:

  • fire safe­ty — the mate­r­i­al is non-com­bustible, with­stands tem­per­a­tures up to 1000 ° C;
  • dura­bil­i­ty — unlike min­er­al wool, basalt mats do not deform over time, do not set­tle (the thick­ness of the insu­la­tion lay­er does not change);
  • ther­mal insu­la­tion coef­fi­cient from 0.034 to 0.038 W/m°C.


  • dan­ger to human health — applies only to cheap brands, expen­sive ones use a biopoly­mer binder instead of phe­nol-formalde­hyde resins;
  • high­er price com­pared to min­er­al wool.

To pro­tect against mois­ture absorp­tion, high-qual­i­ty basalt wool is impreg­nat­ed with a water-repel­lent com­po­si­tion (water repel­lent) and cov­ered on one side with alu­minum foil.

Rice. 7

Foamed polyethylene


An inex­pen­sive and easy way to insu­late round ducts or ven­ti­la­tion ducts is to cov­er them with poly­eth­yl­ene foam. This is a mate­r­i­al that looks like foam rub­ber, but with larg­er cells. Its vari­eties:

  1. Ordi­nary. Trade names — isolon, penolone, tepo­fol, etc. The mate­r­i­al is cut into pieces, wrapped around the pipe and glued with tape.
  2. Foil. On one side it is cov­ered with alu­minum foil. It repels mois­ture and reflects heat. Trade names — peno­fol, ultra­flex, far­alon, mos­fol, tepo­fol. For glu­ing insu­la­tion seams with a reflec­tive lay­er, alu­minum tape or spe­cial glue (for exam­ple, Iso­com) is suit­able.
  3. Self-adhe­sive. A lay­er of adhe­sive has already been applied to one of the sides of this mate­r­i­al. This makes the job eas­i­er.
  4. Pipe ther­mal insu­la­tion. From foamed poly­eth­yl­ene, as well as from basalt fiber, ready-made shell cylin­ders for round pipes are made. Trade names — ener­gyflex, ter­maflex, etc.
Rice. 8 Poly­eth­yl­ene foam


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — depend­ing on the brand from 0.031 to 0.051 W / m ° C;
  • mois­ture resis­tance — water absorp­tion from 0.2 to 1%;
  • oper­at­ing tem­per­a­ture range — from ‑60°С to +100°С;
  • ser­vice life — up to 10 years.


  • elas­tic­i­ty;
  • strength;
  • resis­tance to acids, alka­lis, oth­er aggres­sive sub­stances;
  • sim­ple instal­la­tion with­out waste, cut with an ordi­nary knife, weighs lit­tle;
  • pos­si­bil­i­ty of dis­man­tling and reuse.


  • melts at tem­per­a­tures above +100 °C;
  • flam­ma­bil­i­ty class G2 (mod­er­ate­ly flam­ma­ble) — now brands with the addi­tion of flame retar­dants that belong to class G1 (low flam­ma­ble) have appeared on sale;
  • high smoke-gen­er­at­ing abil­i­ty — class D3;
  • harm­ful to the envi­ron­ment — the peri­od of decom­po­si­tion is 200 years.

When buy­ing foamed poly­eth­yl­ene, pay atten­tion to the label­ing. Accord­ing to the method of pro­duc­tion, two types of it are dis­tin­guished:

  • cross-linked — PPE;
  • uncrosslinked (gas-foamed) — NPE.

PPE costs a lit­tle more, but is supe­ri­or to NPE in all respects. It is pos­si­ble to dis­tin­guish NPE from PPE by the smell of gas (butane, fre­on are used in its pro­duc­tion). In Europe, non-crosslinked poly­eth­yl­ene foam is gen­er­al­ly pro­hib­it­ed for con­struc­tion.

Fig. 9 Cross-linked and non-cross-linked poly­eth­yl­ene foam

Foamed synthetic rubber


This mate­r­i­al is designed specif­i­cal­ly for pipe insu­la­tion, 90% con­sists of closed cells. Exter­nal­ly, foamed rub­ber is sim­i­lar to PPE, but has increased flex­i­bil­i­ty. It is pro­duced in the form of sheets, mats, rolls and tubes (cylin­ders), includ­ing those with a lay­er of foil. Instal­la­tion is car­ried out in the same way as when using foamed poly­eth­yl­ene, there are grades with an adhe­sive lay­er on one side.


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — from 0.024 to 0.038 W/m°C
  • oper­at­ing tem­per­a­ture range — from ‑200°С to +175°С;
  • ser­vice life — up to 30 years.

Advan­tages of foamed rub­ber:

  • mois­ture resis­tance;
  • mold resis­tance;
  • flam­ma­bil­i­ty class G1, self-extin­guish­ing;
  • does not emit dust, fibers, harm­ful sub­stances and unpleas­ant odors — suit­able for use at facil­i­ties with increased san­i­tary and hygien­ic require­ments;
  • low price.
Rice. 10 Foam rub­ber


Sty­ro­foam is a foamed mass of poly­mers (plas­tic), the main vol­ume of which is occu­pied by gas. One of the sides can be cov­ered with foil. The mate­r­i­al is hard, it is pro­duced in the form of slabs or pipe insu­la­tion (shells of two to three sec­tions con­nect­ed by a thorn-groove lock). Sty­ro­foam in plates is suit­able for insu­lat­ing pipes only with a square sec­tion.


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — from 0.032 to 0.050 W/m°C;
  • water absorp­tion — 4% for 30 days;
  • ulti­mate strength in sta­t­ic bend­ing — from 0.07 to 0.20 kgf/m2;
  • oper­at­ing tem­per­a­ture range — from ‑50°С to +75°С;
  • ser­vice life — up to 25 years.



  • high­ly flam­ma­ble — flam­ma­bil­i­ty group G3 or G4;
  • when burn­ing, it emits harm­ful sub­stances — you can buy poly­styrene only of well-known brands, of high qual­i­ty;
  • attrac­tive to rodents.

The instal­la­tion of plates or cylin­ders from this insu­la­tion is car­ried out accord­ing to the prin­ci­ple of brick­work (with the ele­ments shift­ed rel­a­tive to each oth­er). The pieces are fas­tened with spe­cial glue for foam plas­tic — any one is not suit­able, since this mate­r­i­al melts upon con­tact with many sub­stances.

Rice. 11 Sty­ro­foam cylin­ders


Expand­ed poly­styrene (Peno­plex, Techno­plex, EPPS) is an improved, more durable, mois­ture-resis­tant and expen­sive type of foam. This insu­la­tion is pro­duced in the form of plates or tubes (shells) with thorn-groove locks.


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — from 0.028 to 0.034 W/m°C;
  • water absorp­tion — 0.4% for 30 days;
  • ulti­mate strength in sta­t­ic bend­ing — from 0.4 to 1 kgf/m2;
  • oper­at­ing tem­per­a­ture range — from ‑50°С to +75°С;
  • ser­vice life — up to 50 years.

Advan­tages and dis­ad­van­tages of EPPS, instal­la­tion rules are the same as for poly­styrene.

Rice. 12 Sty­ro­foam


asbestos slabs

Asbestos (asbestos-cement) slabs were pre­vi­ous­ly used to insu­late ven­ti­la­tion pipes and insu­lat­ing ther­mal insu­la­tion of the roof. Now in many coun­tries it is for­bid­den to use mate­ri­als made on the basis of asbestos. This is due to the risk of devel­op­ing can­cer with reg­u­lar inhala­tion of asbestos dust, which inevitably appears dur­ing man­u­fac­tur­ing, cut­ting, and instal­la­tion.

PIR plates

A new gen­er­a­tion of insu­la­tion with a rigid cel­lu­lar struc­ture, PIR, is made from poly­iso­cya­nu­rate foam. On both sides of the plate of this mate­r­i­al are cov­ered with foil.


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — 0.021 W / m ° C;
  • water absorp­tion — no more than 1%;
  • com­pres­sive strength — 120 kPa;
  • ser­vice life — up to 50 years.


  • com­bustibil­i­ty group G1 — G2 (low or mod­er­ate­ly com­bustible);
  • there is no risk of dam­age to the fas­ten­ers dur­ing instal­la­tion;
  • decay resis­tance.

Flaw — Releas­es tox­ic fumes when burned.

Rice. 13 PIR plates

Heaters for industrial systems

For ther­mal insu­la­tion of pipes of indus­tri­al ven­ti­la­tion sys­tems, in addi­tion to the list­ed heaters, more expen­sive meth­ods are suit­able:

  1. Fill­ing with sprayed polyurethane foam.
  2. Instal­la­tion of fin­ished air ducts with ther­mal insu­la­tion.

polyurethane foam

One of the best ways to pro­tect the ven­ti­la­tion pipes of indus­tri­al sys­tems is with sprayed polyurethane foam insu­la­tion. With the help of spe­cial equip­ment, the sur­faces of the air ducts are filled with a lay­er of foam.

Types of polyurethane foam:

  1. Closed-cell (hard) — in addi­tion to excel­lent heat-insu­lat­ing prop­er­ties, it pro­vides water­proof­ing (absorbs no more than 4% mois­ture).
  2. Open-cell (elas­tic, light­weight) — weighs sev­er­al times less, absorbs sound bet­ter, costs less, but requires addi­tion­al water­proof­ing (absorbs up to 15% mois­ture), unsuit­able for out­door use.


  • ther­mal con­duc­tiv­i­ty coef­fi­cient — from 0.019 to 0.04 W/m°C;
  • oper­at­ing tem­per­a­ture range — from ‑160°С to +150°С;
  • com­bustibil­i­ty group — G1;
  • com­pres­sive strength — from 150 kPa;
  • ser­vice life — from 20 years.


  • tight fit of the insu­la­tion lay­er to the pipes;
  • com­plete absence of seams;
  • the pos­si­bil­i­ty of apply­ing to pipes of any com­plex shapes;
  • quick instal­la­tion.


  • high price;
  • com­plex instal­la­tion — expe­ri­ence with this mate­r­i­al is required;
  • the com­po­si­tion includes tox­ic sub­stances — it is nec­es­sary to use over­alls, a res­pi­ra­tor, glass­es (after the foam has hard­ened, there is no dan­ger of poi­son­ing).
Rice. 14 Insu­la­tion of pipes with polyurethane foam

Thermally insulated air ducts

Anoth­er option for solv­ing the prob­lem of con­den­sa­tion in the ven­ti­la­tion sys­tem is to use already insu­lat­ed air ducts dur­ing instal­la­tion.

Their types:

  1. Flex­i­ble — con­sist of a wire spi­ral frame, a met­al­lized film, a lay­er of insu­la­tion and a cov­er from the same film.
Rice. 15. Flex­i­ble heat-insu­lat­ed air duct
  1. Rigid — from PIR boards (Pir­roVen­tiDuct), from fiber­glass boards Cli­maver etc. . In terms of strength, pipes made of this mate­r­i­al are com­pa­ra­ble to con­ven­tion­al steel pipes. Air ducts from insu­la­tion boards can be con­nect­ed to stan­dard steel ven­ti­la­tion pipes using flanges.
Rice. 16 Pir-plate ducts

Advan­tages heat-insu­lat­ed air ducts:

  • reduc­ing the cost of mate­ri­als;
  • reduc­ing the weight of the entire sys­tem;
  • quick instal­la­tion.

There were no sig­nif­i­cant short­com­ings in the heat-insu­lat­ed air ducts.

Expert advice

When choos­ing a suit­able mate­r­i­al for the ther­mal insu­la­tion of the ven­ti­la­tion sys­tem, con­sid­er:

  1. The ther­mal con­duc­tiv­i­ty coef­fi­cient should be as low as pos­si­ble.
  2. Mois­ture resis­tance. The loss of insu­lat­ing prop­er­ties due to mois­ture absorp­tion can nul­li­fy all the advan­tages of the mate­r­i­al, includ­ing the low price.
  3. Dif­fi­cul­ty of instal­la­tion. The cost of the ser­vices of spe­cial­ists depends on the dan­ger of the mate­r­i­al and the fea­tures of its fas­ten­ing. Insu­la­tion with cheap insu­la­tion can end up cost­ing more than the high­est qual­i­ty. If the work is sup­posed to be done inde­pen­dent­ly, then the costs of time and effort are impor­tant.
  4. Fire safe­ty class. This indi­ca­tor can be deci­sive when choos­ing between two heaters with sim­i­lar char­ac­ter­is­tics, if we are talk­ing about a room with a high risk of fire.

Accord­ing to experts, the best option for warm­ing the vent pipe is poly­eth­yl­ene foam. Foamed rub­ber sur­pass­es it in all char­ac­ter­is­tics and has no draw­backs.


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