The elements are a closed system, where the elevated amounts of moisture can only result from improper handling of the items. The most common cause of moisture damage is roof soaking during the construction phase.
Every action has responsibility for own work, thus also to avoid moisture in construction. For guidance the text of Chapter 4.1, subsection. 5, in Building 2010 appears explicitly:
- Planning and design phase with a focus on avoiding materials and building solutions that are unnecessary moisture sensitive.
- The client demand and explicitly schedule to allow the necessary time for drying of building materials and constructions.
- At the client, if possible before the supply, making a cost-benefit analysis of total coverage of the building during construction and prescribes total flashing where it is economically advantageous, or where in the specifications prescribed particularly moisture sensitive materials or building solutions.
- The developer shall provide separate contracts that joint facilities for the storage of moisture sensitive materials.
The diagram below shows a method for the evaluation of materials (Guidance on the management of moisture in construction Institute, December 2009).
Preventions and moisture damage repairing.
Moisture damage can avoid if you follow the legal requirements, good building practice, planning of works and contracts, quality control.
Preventions and repairing moisture damage.
• Building Regulations 2010.
Supplier’s quality control:
• Dispatch Control.
- Measurements / logging.
- Acceptance criteria.
Measurement of moisture in building materials with hand-held measuring instruments associated with great uncertainty. A proper assessment of the results requires knowledge of the possible sources of error and measuring equipment limitations – read more on page 218 in the SBI guidance note 224 (1st ed. 2009) and the Institute’s guidance for developers (sept. 2011).
Troxler method: Troxler measurements are suitable for moisture measurements on steel roofs, as capacity meters and electrical resistance gauges are disturbed by conductive materials.
Troxler method is an isotope gauge based on a radioactive neutron source, which emits neutrons. The hydrogen in water slows down the neutrons, and the slow neutrons are detected. Troxler method is a quantitative measure; the moisture content may not read directly as water content, but as relative terms about the individually measured areas. Samples try of mineral wood will used to calibrate the water content. The operator demands a special certificate.
Measuring the relative humidity: It may have to make a hole in the roof membrane and the roof element from the outside. Visual evaluation of the moisture content of the elements and the relative humidity of the elements makes by inserting an attached sensor into the material. The instrument measures the relative humidity, the temperature of the material and the dew point. Thus, give it a good indication of whether the material is wet.
If the relative humidity is above 95% in the material, there may be too much moisture in it. Different places should measure because only the moisture in the nearby insulation can affect the gauges.
A water content of up to 250 g / m2 in the roof element will indicate as acceptable.
The water content determined by taking a sample, drying, and weighing the sample. As mineral wool may contain only a very limited amount of moisture, it would be acceptable with a measurement result up to 100% RH, which would correspond to a maximum water 5gr / m2 roof element.
Link til Byg-Erfa’s hjemmeside
SBi’s Vejledning om håndtering af fugt i byggeriet.
SBi’s vejledning til bygherrer om krav til fugtteknisk dokumentation samt fugtsag-kyndiges kompetencer og virke
SBi anvisning 224 – Fugt i bygninger.
SBi anvisning 170 – Målemetoder til bygningsundersøgelser.