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Old building renovation  Building physics | Moisture protection | Construction | Ecologically building | Imprint

2.8. Substrate and environment-influxes on the growth from the dry rot

The role of the humidity and temperature covered on the growth-condition was explained in the above named sections. Work additionally in the practice of more influential factors.

Like already named the pH plays an important role at the enzyme-activity. Construction-materials, like bricks or sand are preferred by the fungi. They have a pH of 5-6. However, alkaline construction-materials like lime work, Limestone, cement, concrete and Excelsior-easily-construction-plates hinders sooner. (White-rock, at at least 3 cases of damage, this can be confirmed. In one about. Was 60-70 year old villa completely perfoliate the concrete-concave-board. The alkaline effect as growth-brake is strongly reduced here surely. In the normal condition of the concrete through about (OH) 2 - solution amounts the pH 12,6. With porous concrete, where is 2 about (OH) through C02 karbonatisiert, the pH is with 8-10. As well, the pH of concrete and cement-finery decreases, since these from-gases over longer time CO2, with lime-finery, the bandage-strength is also decreased. In the WTA-leaflet, it is referred that alkaline materials like above named are required by it dry rot in order to neutralize those of it produced oxalic acid. (WTA-leaflet S.4). This should be a product and inter-product respectively in the citrate-cycle of the fragmentation of the carbon-molecule-chains of the Oxalacetat. The white pore-sponge (Antrodia vaillantii) neutralizes chemically protected wood, for example, in the copper-links is available. Through the elevated production of Oxalic acid, copper-oxalate is created. This salt precipitates from. Other elements like chrome- and Arseniclinks lose its fixation and become water-soluble. [Wood-protection-convention 2000] Several older, relatively smaller active affection-flocks (circa 1 - 2 m 2) were plastered by a lessee with the even executed housing redevelopment with new lime-finery years ago. The growth-halt occurred. The mortar of the wall-joints didn't show anything mcelium and the finery. Analogously one can observe this if wall-stones were processed in the stonework out of different materials. Here, a very small border-area is available in the course to the other building material. In the practice, this can be a later masoned brick-wall. Lime-sandstones are coated by the mycelium as well, like bricks. However the brick is more porous and the mycelium grows into these joints. With easy affection of stonework out of clay-stone, the mycelium grows merely into the joint-mortar of clay. If a firm affection is available, so one finds the mycelium also in the clay-stone itself. With Stampflehmwände, above all the straw is reduced. So, the affection-area can also stretch until into completely dry wall-sections.

Mycelium from the dry rot in einer stamped clay-wallsMyzel from the dry rot in a stamped clay-walls


Slowly however, an inferior water damage going back by several years caused dry rot a damage by it continuously. The low fresh mycelium under the boards grew with a wood-humidity by under 12 per cent. The former moisture-source, a water pipe, had been loaned for many years. Analogue case in point is a stairway-podium where this grew quite powerful mycelium of the middle in direction of the outside-walls and AWCs. The cause obviously was the water of the periodic stairway-rectification, that was discontinued at least before a half one until one and a half years, however. This was determined with staircase-working with the spatula of the cover since the finery-bearer of straw held the finery no more. The wood-humidity of the Dielung was in the area by 12 per cent. Damage-areas more similarly older with the majority finished the growth from alone someday. The laboratory-examinations about degradation-services of different trunks were between 4 to 35 per cent of loss of dryness after 16 weeks of incubation period, with 20-21°C and 20-40 per cent of wood-dampness. The different woods show a very irregular degradation-sample [Abou Heilah 1977]. Through Walchli 1973, dry-wood-weight losses become 31,5 per cent with European larches and pinetree-alburn of 60 per cent and at pinetree-heartwood after 18 weeks and 21°C as well as boasted 1,8 per cent at oak-heartwood. The elevated own-resistance to pinetree-heartwood could be determined with a strongly damaged object. The alburn-share of this well 170 year old blanket-great commissures from pinetree was completely destroyed and the heartwood-share almost undamaged. With the section of the blanket-great commissures, the wood smelled right of resin. Not only in the laboratory but in the practical cases of damage, different trunks should cause the partially different damages with different growth-conditions. An exact source and statement of reasons, why 1,00 m the wood-great commissure over the visible damage-area to do and 1,50 m the finery, to take away as security-zone, is, cannot be given.

The Hauswamm attacks all carbon-sources, also briquettes, practically

Former examinations in boar-forest showed that a growth is possible over the visible area of a wood-beam until 40 cm. The low border of the exception can be regarded as a plausible size with it in the DIN 68800 and in the Beuth-Commentary to the DIN with 50 cm.

For the redevelopment of a case of damage, several partially quite different elements play a role with it.

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