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An analysis of moisture accumulation in the roof cavities of manufactured housing

Burch, D.
1995
Airflow Performance of Building Envelopes, Components, and Systems, ASTM STP 1255, Mark P. Modera and Andrew K. Persily, Eds., American Society for Testing and Materials, Philadelphia, pp. 156-177
attic ventilation, HUD Manufactured Home Constniction and Safety Standards, manufactured housing, mobile homes, moisture control guidelines, moisture in attics


Burch, D., (1995), "An analysis of moisture accumulation in the roof cavities of manufactured housing", Airflow Performance of Building Envelopes, Components, and Systems, ASTM STP 1255, Mark P. Modera and Andrew K. Persily, Eds., American Society for Testing and Materials, Philadelphia, pp. 156-177.
Abstract:
A detailed computer analysis is conducted to investigate whether moisture prob-lems occur in the roof cavity of manufactured homes constructed in compliance with the current Department of Housing and Urban Development (HUD) Standards for manufactured housing. Ile current HUD Standards require a ceiling vapor retarder, but do not require outdoor ven-tilation of the roof cavity. In cold climates, the analysis revealed that moisture accumulates at lower roof surface and poses a risk of material degradation.

The analysis found the following combination of passive measures to be effective in pre-venting detrimental winter moisture accumulation at lower surface of the roof: 1) providing a ceiling vapor retarder, 2) sealing penetrations and openings in the ceiling construction, and 3) providing natural ventilation openings in the roof cavity.

In addition, the performance of a roof cavity exposed to a hot and humid climate is inves-tigated. The analysis revealed that outdoor ventilation of the roof cavity causes the monthly mean relative humidity at the upper surface of the vapor retarder to exceed 80%.- This condition is conducive to mold and mildew growth.


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Author Information and Other Publications Notes
Burch, D.
  1. A computer analysis of the moisture performance of roof constructins in the U.S. DOE Moisture Control Handbook
  2. A mathematical analysis of moisture and heat transfer in the roof cavities of manufactured housing
  3. A prarmeteric study of wall moisture contents using a revised variable indoor relative humidity version of the "MOIST" transient heat and moisture transfer model
  4. Computer analysis of wall constructions in the moisture control handbook
  5. Empirical validation of a transient computer model for combined heat and moisture transfer
  6. Experimental verification of a moisture and heat transfer model in the hygroscopic regime
  7. Heat and moisture transfer in wood-based wall construction: measured versus predicted
  8. Indoor ventilation requirements for manufactured housing
  9. Manufactured housing walls that provide satisfactory moisture performance in all climates
  10. MOIST: A PC program for predicting heat and moisture transfer in building envelopes, Release 3.0
  11. Water vapor permeability measurements of common building materials
  12. Water vapor sorption measurements of common building materials
  13. Water-vapor measurements of low-slope roofing materials  



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