Sopping Wet Underfloor Crawl Space & Mould

Author: Rhys Brenton

This building was purchased without the knowledge of what a “sick building” could do to the new owner’s health.

After a few months of troubled breathing, tightness in the chest, not sleeping well and feeling constant fatigue, it became evident to the new owner that there may be an issue.

After consulting her doctor, it was suggested that mould may be a significant player in her conditions, since some of her symptoms would begin to clear after being away from the dwelling for a while.

On inspection, the building appeared of sound integrity. The building was situated on a flat block, cornering two quiet streets to the South and West sides.

Vegetation had been planted within about 1 – 2m off the South and East walls (not touching the building and not too densely planted), whilst some low lying garden was planted along the North wall of the building.

The roof and areas of possible external water ingress were all in good condition. However, drainage across the property was limited on such a flat block of land and no additional positive drainage away from the buildings footings was present around it’s periphery.

Prevailing winds entering the property were limited to the S through SW and W sides of the property due to proximity of adjacent buildings on the N and E sides. Air flow under the building was heavily restricted by the solid brick wall footing around the building periphery, which included minimal vent size and spacing.

Inside the musty odours were quite over powering, though no visible mould growth could be seen. The flooring was predominantly hardwood with no carpets or rugs, whilst the bathroom and kitchen were tiled.

The odour was found to be strongest in the kitchen and particularly from the kitchen cupboards, which were constructed of particle board. No leaks were noted in the plumbing, nor was there any evidence of previous water damage on the timbers and joinery.

The underfloor crawl space was approximately 1m high. Many frogs were present, along with enormous huntsman’s and lizards. A plumbing outlet from the bathroom floor overflow vented into the crawl space.

Wet Underfloor Crawl Space and MouldThe soil had a very high clay content and was found to be very wet. Mould was visible across some sections of the soil and on discarded building debris. Hardwood sections of the flooring were installed directly onto the joists with moisture readings of 13-16%. The kitchen subfloor was constructed of particle board, which contained moisture readings of up to 24% and visual mould growth was present across all of this material.

Given the nature of the evidence observed – poor landscape drainage and lack of subfloor ventilation was found to be the significant cause for musty mouldy odours inside the building.

The occupant systematically followed the recommendations given below with immediate positive results in her health.

 

Recommendations involved:

  • Immediate deployment of an air purifier if the occupant could not move to a healthier premises while positive steps were taken to remedy the areas of concern
  • Replacement of effected timber flooring and kitchen materials
  • Re-route the bathroom floor overflow plumbing to the appropriate drain
  • A microbial remediation process conducted in the crawl space and internally to ensure the removal of mould spores, plus an assisted drying process of the ground under the building
  • Increased ventilation of the crawl space – first by increasing the ability for natural ventilation – second, by the inclusion of mechanical ventilation (solar powered)
  • Significant increase in drainage by inclusion of paving or something that promoted run off of water with a positive aspect of drainage away from the building around its periphery
  • The inclusion of a drainage ditch around the periphery of the building to allow natural seepage of moisture from the ground into the drain and then plumbed away off of the property to assist its natural drainage
  • Removal of vegetation in close proximity to the building.

If you have any concerns, please contact a qualified Building Biologist – you can find one close to you here.

Always look for the ASBB logo – the ASBB checks the qualifications of all Building Biologist.

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