Ventilation subfloor

In order to understand the chloride deposition rates in a confined spaces, such as ventilated subfloors in a sea coastal area, a special collecting box shown in Fig. 9.25 was used in which the airborne chlorides were collected on horizontal and vertical filter papers positioned at different locations from the box openings (Fig. 9.26). 

The Indiana State Board of Health measured formaldehyde in four specific office and commercial establishments that had poor ventilation. The concentrations ranged from 0.01 to 1.01 ppm. In one case, the source of formaldehyde w as urea-fonnaldehyde foam. In the others, it was particle board, plywood subflooring, and furniture (Konopinski 1983). 

Figure 2.3.10 shows that the vapor density has linear correlation with molecular mass and that for both alcohols and ketones (as well as the other solvents) the relationship is similar. The data also show that solvent vapor densities are higher than air density. This makes ventilation a key factor in the removal of these vapors in the case of spill or emissions from equipment. Otherwise, the heavier than air vapors will flow along floors and depressions filling pits and subfloor rooms and leading to toxic exposure and/or risk of ignition and subsequent explosions. 

Calculation of gas entry rates into buildings is an area where there is the greatest degree of xmcertainty when undertaking risk calculations. When gas protection is provided the gas entry is closely linked with the performance of both the subfloor ventilation measures and the gas resistant membrane. 

Passive subfloor ventilation (venting layer can be a dear void or formed using gravel, geocomposites, polystyrene void formers, etc.T Very good performance 2.5 Ventilation performance in accordance with Annex A of the British Standard. If passive ventilation is poor this is generally unacceptable and some form of active system will be required... 

Subfloor ventilation with active abstraction/ pressurisation (venting layer can be a clear void or formed using gravel, geocomposites, polystyrene void formers etc.) 2.5 There have to be robust management systems in place to ensure the continued maintenance of any ventilation system Active ventilation can always be designed to meet good performance Mechanically assisted systems come in two main forms extraction and positive pressurisation... 

Krylov, V. V. and C. C. Ferguson. 1998. Contamination of indoor air by toxic soil vapours The effects of subfloor ventilation and other protective measures. Building and Environment 33 331-347. 

Even if there is no warning sign for the presence of radon, there are several ways to detect radon using detectors available at hardware stores. Reduction of radon exposure starts with sealing cracks and openings in basement floors and increasing subfloor ventilation as well as ventilation within the home. 

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