The effects of moisture and the potential for no structural damage

  • Mois­ture can pen­et­rate con­struc­tion­al ele­ments in a vari­ety of ways and can nev­er be com­pletely elim­in­ated
  • However, ex­cess­ive mois­ture causes struc­tur­al dam­age
  • It is not the tight­ness or dens­ity of a va­pour re­tarder that de­term­ines wheth­er dam­age to con­struc­tion­al com­pon­ents is avoided or not but the dry­ing re­serves the com­pon­ent has
  • Va­pour re­tarders with high dif­fu­sion res­ist­ances do not al­low suf­fi­cient sub­sequent evap­or­a­tion of the struc­tur­al com­pon­ent to the in­side

In­tel­li­gent air seal­ing mem­branes provide a high level of pro­tec­tion for com­pon­ents

section summer winter

The best approach: Intelligent membranes

Vapour retarder membranes with a humidity-variable diffusion resistance provide the best protection against condensation water damage to building structures. They become more impermeable to diffusion in winter and protect the insulation against moisture penetration in an ideal manner.
In summer, they can reduce their diffusion resistance very significantly and thus ensure the best possible drying-out conditions.

Operating principle of moisture-variable airtightness membranes

Operating principle of moisture-variable airtightness membranes

Mois­ture-vari­able lay­ers op­er­ate on the prin­ciple of cli­mate-driv­en mem­branes. They re­spond to the hu­mid­ity in their en­vir­on­ment and ad­just their dif­fu­sion res­ist­ance in­tel­li­gently to the cur­rent re­quire­ments.

In winter, the mean am­bi­ent hu­mid­ity of the va­pour re­tarder is ap­prox. 40 %. The dif­fu­sion dir­ec­tion is from the heated in­teri­or to the ex­ter­i­or. The va­pour re­tarder now must have a high res­ist­ance to dif­fu­sion in or­der to pro­tect the struc­ture against con­dens­a­tion.

In the sum­mer, the mean am­bi­ent hu­mid­ity of the va­pour re­tarder is more than 80 % and the dif­fu­sion dir­ec­tion is re­versed. Now the va­pour re­tarder must be per­meable in or­der to al­low the hu­mid­ity to evap­or­ate.

sd-(g-mean-)value with different moistures influences

Diffusion resistance depending on ambient humidity

The vapour retarder and air sealing membrane pro clima INTELLO meet the requirements listed above.

The values of INTELLO

  • most EU: sd-value
    less than 0.25 m up to >25 m (in summer <0.25 m)
  • GB & IE: g-value
    less than 1.25 MNs/g up to >125 MNs/g (in summer <1.25 MNs/g)

INTELLO & INTESANA: Diffusion [US perms]

for the US

The vapour retarder and air sealing membrane pro clima INTELLO meet the requirements listed above.

The values of INTELLO

  • US: water vapor permeance
    more than 13.12 US perms down to <0.13 US perms
    (in summer >13.12 US perms)

For all regions
The greater the spread of the diffusion resistance/permeability from summer to winter, the more protection is provided for constructional elements - even in case of unforeseen moisture penetration.

For the best possible protection from structural damage, the drying reserve must be higher than the maximum theoretically possible moisture level.

Diffusion rules

Construction phase: Hydrosafe value (70/1.5 rule)

... using the sd-value, respectively '70/7.5 rule' using g-value

A vapour retarder should have a hydrosafe sd-value of 1.5 m (g-value 7.5 m; 2.2 US perms) in order to protect structures against dampness even in the case of the increased relative humidity that can be present during construction work.
The hydrosafe value specifies how well sealed a humidity-variable vapour retarder still is at an average humidity of 70%. Average humidity of 70% will be present if there is 90% indoor air humidity and 50% humidity in the space between the rafters, for example; this level of indoor air humidity can occur when installing screed or plastering walls.
The requirement that sd should be > 1.5 m and < 2.5 m comes from DIN 68800-2 and is described in further detail by the 70/1.5 rule.

Means for g-value:
The requirement that g should be > 7.5 m and < 12.5 m comes from DIN 68800-2 and is described in further detail by the 70/7.5 rule.

INTELLO fulfils these requirements reliably.

Increased moisture should always be allowed to escape from the building as rapidly as possible by opening windows for ventilation. Dryers can accelerate the drying process in the winter. Permanently high relative humidity should be avoided.

INTELLO & INTESANA: Diffusion rules [US perms]

for the US

... respectively '70/2.2 rule' using wa­ter va­por per­meance:
The requirement that the values should be > 2.2 and < 1.3 US perms comes from DIN 68800-2 and is described in further detail by the 70/2.2 rule.

INTELLO fulfils these requirements reliably.

Increased moisture should always be allowed to escape from the building as rapidly as possible by opening windows for ventilation. Dryers can accelerate the drying process in the winter. Permanently high relative humidity should be avoided.