Porous Heritage Basement

The shocking damage at Wamberal Beach in NSW caused by a severe coastline storm  in July exposed more than just the fragility of cement footings due a dramatic erosion of sand.

The images also exposed some of our basic assumptions about the buildings in which we live and inhabit. The frailty of a buildings structural integrity when subject to excessive water penetration and erosion over time. The images demonstrate the underlying life-and-death responsibility architects and builders take on, when designing for structural integrity and water and erosion management.

 

Porous Paving to offset Damp

Salt damp is one of the more familiar and insidious incarnations of water damage that requires erosion control. This is particularly complicated for federation age properties, which are often constructed of natural materials and rudimentary methods typical of ‘old buildings’, (defined by heritage house as constructed before 1920)

This is where porous paving became pivotal to the remedial works in the lower level basement of this beautiful old heritage building. The basement level belies a retail store in the CBD on Adelaide’s iconic North Terrace.

South Australian builders Total Commercial Maintenance were contracted to solve a number of perplexing  challenges to alleviate the chronic problems of timber rot and salt damp.

Notably, the low temperatures overnight in the cold basement were causing the day time moisture (humidity) to settle as water in the brickwork. This is most prominent in the lower sections of the wall which were beginning to crack and spall –  The effect was particularly bad around the sections of the wall that were constructed with the older style natural lime based mortar and contained the more porous stone.

Not only were the federation age natural stone walls highly conducive to wicking up water from the damp floor, but the load on the basement walls meant a significant structural if risk trying to engineering or retrofit damp course membranes. Further, a lack of modern, adequate subsurface drainage had led to the floorboards trapping the water underneath, forcing more moisture wicking up the walls together with terrible wood rot and a permanent musty smell.

The builders were brilliant in recognising their limitations in trying to use a modern building material to ‘control’ moisture via the typical impervious membranes, silicones and gypsum injections. Instead, the solution was intuitive – if a structure suffers from too much moisture, it needs to be able to breathe. What has since evolved in building technology that allows the floor surface to breathe?

Porous Paving a breathable surface

That’s exactly how novel this application of StoneSets Porous Paving was as another erosion solution. Instead of wanting water to soak down into the soil, porous paving was used to allowed moisture to rise up out of the soil.

Now, instead of trapping that damp and rot under the floorboards, a combination of regular positive pressure ventilation and a breathable hard surface paving like StoneSet has completely transformed this area. By replacing timber rot with an equally functional and natural hard surface, the basement is less musty, far safer and more stable when using lifting trolleys and heavy weights and the integrity of the walls is being protected by allowing the floor moisture to be released into the air, not the walls.

StoneSet porous paving enables freshwater to evaporate up through the pavement. This means the water can freely undergo the necessary transpiration from the soil below the paving, spreading all of that water out into the soil of the park. Forget the expense and risk of experimenting with a retro fit of complex engineered drainage facilities for the water; the permeable paving prevents the concentration of water by allowing free migration, whether it sits during colder high humidity or evaporates during day time with lower humidity .

FORM AND FUNCTION

Not only that but the Resin bound natural ‘Cudgee beach‘ stone really did well to retain the rich heritage aesthetics and original character of the basement- complimenting the stack stone walls, offsetting the hardwood beams overhead and even framing this original cast iron fireplace

It’s a perfect example of architectural form and function, where a new technology like a polyurethane stone binder simultaneously improves usability and aesthetics. And at a significantly lower cost and risk of damage too – retrofitting drainage and other damp course prevention methods to 100-year old natural stone basement level walls.