In construction and in materials science, for breathability means the ability of a material to be traversed by steam (moist air) or gas.
The characteristic of breathability is therefore closely related to the porosity of the material, from its thickness, materials placed in it or applied to its external or internal surfaces.
And anyway, generally, It can be said that a building is more porous and more it is breathable, but also, more material will often be, treated with paints or shielded with other materials and more will oppose to this phenomenon.
The combination of all these factors, typical of any masonry or wall structure, you get a stocking SD (What is the coefficient of permeability of the material μ multiplied by the thickness) the WORLD DIABETES DAY (that expresses the amount of steam in grams that is disposed of through a square metre of wall structure in 24 hours).
Well, now, without much further, We are going to analyze and focus the inaccuracies that are said and written in the brochure, on the web, by informants, by the technicians and producers of materials for construction ’.
I would immediately force a too-obvious generalization and granted (I don't want those interested) but as always everybody pushes the water mill with the ’ intent to be convincing and selling your own product.
We find then that the productive chain of the Home energy saving (starting from the materials until the fixtures) does it prove that the wall is a simple membrane separating the inner and ’ external ’ which has purely supportive.
All because we want to appioppare a House totally sealed and weatherproof, with 40 cm thermal insulation, fixtures in class A (excellent for submarines) and air exchange systems with heat recovery (VMC) microprocessor controlled in ’ utopia of a saving of almost absolute heat.
If we are going to analyze producers of organic ecological materials We find that the wall and the ’ whole House becomes a living organism almost needs to breathe.
These aim to appiopparci the construction materials and highly secure mortars that do not emit noxious gases that do not affect too much on energy balance of the planet, they are recyclable 100%, which are absolutely non-toxic and manufactured without the use of soil and a Km 0 in ’ utopia of urbanized areas that do not provide all problems ’ environment and our health.
The truth, According to us, is in the middle and particularly in speaking out. We cannot accept then extremes that, Besides being very expensive for the portfolios of those who must build (or restructure), do not bring substantial benefits, Besides the fact that they are less durable and very complicated in maintenance.
We would then say that masonry has its own fundamental features that cannot be forgotten or erased from 3000 and more years of building history.
The walls and stone materials create, as a matter of fact, a basic interface for building and thermo-hygro for its users. Their thermal and breathable properties are unique and not reproducible in any other way or with any other materials of different genre or synthetic.
Today, Although many writers and researchers, blinded some’ the modernisation, continue to ignore these great features, I would like us to put much more attention especially on some points.
In modern studies is usually considered that the amount of steam dissipated by a wall is usually negligible compared to large quantities disposed from the Windows, and almost never the wall is inserted in the calculations, but in reality it is not so. The wall is indeed able to dispose of and Exchange an enormous amount of steam and gases with the outside ’, only that this exchange takes place very slowly.
But we have two accounts to prove what entity is: We take a room with a living room of dimensions 7 x 5 m (then a useful surface 35 m2) able to accommodate 4 people. On this surface will insist a perimeter of about masonry 107 m2 including even the intermediate floor (21+21+15+15+35).
We know that an average family 4 people issues, with the breath, about 10 litres of water in steam d ’ 24 hours and on average more 30 litres for their domestic activities (shower, kitchen, drying laundry, etc.).
Now consider that the average a masonry breathable both of ’ order 700 grams of water per square metre in 24 hours (in fact can be much higher than if the wall is dry new).
Is a simple multiplication, all masonry, considered in our sample room, will be able to dispose of ben 70 l d ’ water vapor per day, that level of gas and steam will be exchanged following the natural way from wetter to drier ones, by ’ inside air to the outside with ’ healthier air.
An Exchange so much more sophisticated than a VMC system that requires no energy and that is controlled by the same wall and external conditions existing at the time.
Apart from what has already been said, It should be added that a healthy dry masonry will also be able to regulate the external temperature limiting excursions to almost ideal levels.
I do not understand why it persists, today, to limit perspiration walls with paintings, plaster and plastic or synthetic coats with l ’ illusion of being able to save a few euros per month for heating pipe.
All it takes for a livable House provides an always healthy and dry wall, it will slightly improve the thermal insulation value provided you use only insulators fiber provided that natural breathable and non-occlusive.
When we meet with a damp wall, heat-insulating capabilities are severely compromised and the House will be more moist and cold, Steam Exchange with the external ’ will be very limited and welfare housing will be reduced considerably. In these cases only serves to purify the wall with IgroDry to bring it back to the State of traspirazone and thermal insulation, you don't need other.
IgroDry Research Centre