How to Avoid Slab Moisture Ingress

Slab moisture ingress can cause indoor mould growth because it not only adds moisture and humidity to the indoor air environment but it can also cause the house to act as a petri dish where mould will grow, spreading spores around the house. This can happen if it hasn’t cured properly, of if there are gardens with soil covering the weep holes—small rectangular spaces left between the bricks at the bottom of the outside wall—where moisture from inside the building envelope can’t escape. Another reason is the slope of the property, rainfall needs to drain away: Don’t expect that ridiculously heavy rainfall will soak into the ground, it needs to run away from the property of into drainage channels.

I found out the consequences of slab moisture ingress at my last residence, before this rental property, when I lived in The House of Mouldy Horrors. (I do have a post in my drafts folder titled, The House of Mouldy Horrors, which is why I have been referencing it in my posts for like, the last two years or is it three now?), on how we (My Daughter and I) managed to remediate this situation including most of our possession kept in the house, including medical assistive devices such as InovaAir Purifiers but due to the stress or ustress (stress you use to create action), that I’m under, I’d rather not think about that right now. I have a mould-free house to build; or rather, lay in bed an write about it. I’ve not been there since I became chronically ill from a bunch of things at the house.)

(Just a note to new readers: my health went from good to bad in The House of Mouldy Horrors, and I suffered painful symptoms that were the beginning of chronic illness on top of chronic illness, I now react to outdoor moulds as well. I’m trying to get on top of this; and I’m trying to build a safer, mould-free home, where I WILL recover. Right now though, I can smell damp soil all the time because I live in a draughty beach-house. One doctor, recently diagnosed me with “what appears to be CIRS (Chronic Inflammatory Response Syndrome) caused by mould” illness. Another doctor, my main Allergist, says I do indeed get sick from mould but he also says, “It’s not your only problem.”, meaning inhalant allergies to other chemicals other than mould.)

Damp patch of concrete causing humidity and mould in the house efflorescence (a build up of a white coloured powdery substance)

The inside part of the house’s slab edge during wet winter months

Damp patch after drying out (before vacuum) with salt powder efflorescence (a build up of a white coloured powdery substance)

The inside part of the house’s slab edge during dry summer months

The white patches are efflorescence (a build up of a (harmless) white coloured powdery substance). The three rooms, all bedrooms, that had these wet patches in the concrete, coming from the slab edges that ran parallel with the outdoor gardens originally had carpet in them. When I moved into this house, the owner removed the carpets due to my allergies; ergo, if we hadn’t of done this it may have taken longer for the concrete leak to become apparent. I imagine the carpet would have taken on a mildewy odour–but not before the mycotoxins (the chemical in mould) outgassed into the air making me ill. Instead, each time it rained heavily, the house took on the odour of damp soil. And then I got sicker. It was inconvenient to pack up and move but necessary.

Those photos were taken in the main bedroom where I slept for the first year in that house; it had a garden bed and a tap on the outside of the house, running parallel to my to the room.

As a precaution, for the Build an Eco-Friendly, Allergy-Free House project, we’ve particularly asked our plumber, Kale from KLM Plumbing not to install any taps near the edge of the house anywhere near the slab edges.

We’re also not putting any garden beds or grassy areas around the house. In fact, we’re using more high-energy-embodied concrete to put a pathway around the whole house. (And, so that we can conserve energy within the building via our slab [thermal], we’ll add insulation between the house slab and the concrete path. But more on this later.)

The majority of houses incorporating wellconstructed and well-detailed concrete slabs and footings experience no problems with slab edge dampness. Where problems do occur, there may be one or more of several causes. A thorough investigation is required to determine the most appropriate course of action to rectify the problem. Most slab edges are occasionally damp due to rain, garden watering or by contact with the ground. In some cases this dampness is able to permeate from the outside to the inside and affect the internal walls and/or finishes such as the floor coverings. Preventative measures are far more effective than facing the often difficult and costly repairs required to remedy problems caused by slab edge dampness and moisture ingress.

Not to mention the cost of a water damaged building (WDB) to human health!

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Indoor mould caused by dampness and high humidity can impact on medical conditions such as Asthma, Inhalant Allergies, chemical sensitivities, respiratory inflammation, Toxic Encephalopathy, Occupational Asthma, Irritant-associated Vocal Cord Dysfunction, Reactive Airways Dysfunction Syndrome (RADS), Irritant-induced Asthma, Small Airways Disease or Multiple Chemical Sensitivity (MCS).

The initial indication of a problem is usually persistent dampness of the exposed face of the concrete slab/footing, often resulting in associated efflorescence (a build up of a white coloured powdery substance) below the damp-proof course (DPC). There’s your red herring, right there: The DPC may have had lost it’s integrity or may never have been laid properly in the first place.

To fix the above problem, we needed to employ someone to dig out the gardens and pour tar against the slab edges, therefore, sealing them from slab moisture ingress. Due to my sensitivities to petrochemicals, this wasn’t an option. However, had I known before I moved in, it might have been. It was 2010 and my health had recovered from the mysterious chemical sensitivities; but by 2012, my health and level of tolerance for fragrance, petrochemicals and solvents was at ground zero.

To avoid slab moisture ingress:

  • Slope the surrounding soil around your building by 50mm before attempting to lay any paths or garden beds
  • If you suffer symptoms from mould exposure, keep garden beds away from the side of the house
  • When laying concrete around your house, make sure to insulate or better still, water proof the edge of the slab
  • Get professional Arborist before planting large trees to avoid tree roots blocking outlets to storm water drains
  • Avoid over watering adjacent to slab footings and edges
  • Have your plumber install unground pipes that drain water away from your home, which is what KLM Plumbing are doing for us


Toxipedia: Dangers in our Home, Mould and More

Build an Eco-Friendly, Allergy-Free House: D&C Fear Concreting

Build an Eco-Friendly, Allergy-Free House: KLM Plumbing

Build an Eco-Friendly, Allergy-Free House: Come Shopping with Us at Reece Plumbing

Build an Eco-Friendly, Allergy-Free House: We Wrapped Our House in Plastic

The Labyrinth: DuPont’s Worse Nightmare

Coming up

uPVC windows: Are They the Right Choice For You?

A Hardwood House Frame!

Kingspan Insulation: How we Wrapped our House



Michellina Van Loder is a Professional Writer, Journalist and Blogger. This is where she shares her tales about trail blazing her way out of the Labyrinth of Chemical Sensitivities and Mould. This is also where you will find the latest Research on related topics.

KLM Plumbing

Meet Kale, our plumber for the project Build an Eco-Friendly, Allergy-free House. Kale has his own business, KLM Plumbing, based in the Bellarine/Surf Coast region of Victoria, Australia. (Sorry, my global friends, I don’t think he can make it out your way across all those oceans to install your plumbing. But I do have some tips on how to find a plumber or tradesperson who is this accomodating.) However, if you live on The Bellarine, in Victoria, Australia, and need some plumbing work done, then we cannot recommend him highly enough.


Contact Details:

Mobile: 0433 811 481

Email: kalemccainplumbing [at] outlook [dot] com


So how did I go about finding the right plumber? A plumber who is willing to get their head around all my special needs? It took some time, and besides, there was also the big issue of finding and testing materials, glues and other substances that are going to be okay for my particular chemical sensitivities.

I phoned seven plumber dudes in total. I have three that are suitable to come into my house, and that are willing to be fragrance free; and I’ll post their details down below. Just mention Michellina and Dan, the couple building an Eco-Friendly, Allergy-free House, and say that you have the same or similar condition as me. (In the late Kathryn Treat’s words, though: “It’s not a cookie cutter illness; we are all different in what we can and can’t use.” Ergo, what works for me might be the perfect starting place for you to find your plumbing/building/renovating solution! Or it may not. Do your own research but feel free to use mine as your launchpad.)

(There’s two posts coming up: ‘How to Find the Right Tradesperson’ and ‘How to Ask for Stuff (samples)’, so brush up on your interview skills and stay posted for that one. As with most of the minutiae of life, I’ve been scribbling copious notes about nothing and everything, and I’m excited to share all the details with you in the hope that by paying it forward it’s going to improve the lives of disabled and abled people within our global community.)

But for now, I’ll share with you how I found Kale and crowned him the right person for the job:

First, at my boyfriend’s recommendation, I made a list of plumbers from a local trade website. Then I rang around and, always starting with: “Hi, I have a medical condition where my health is impacted on by various chemicals such as solvents, petrochemicals, moulds and fragrances, and I need to find a plumber who is willing to accomodate my needs.” (Sometimes, I drop in the disability label if I feel that I’m not being understood.) I then go from there. I always, always, make sure I say: “Would you be willing to make sure you are not wearing any fragrance, spray deodorants or hairspray on the days that you are going to come into our house?” It’s the number one starting point; and their answer is indicative of whether they will help you—or not.

All was cool. Kale was understanding from the start. We then emailed our house plans and other particulars, got a quote and set up a date and time to meet up at our house—out on the front patio. Here’s a review for a plumber you won’t find online: He arrived without any noxious chemicals emanating from his person! :)

But seriously, he did arrive without any solvents or fragrance from sprays!

The quote was within range, too. We then grabbed some samples from him just as far as the Cross-linked polyethylene (PEX) tubing went.


A piece of PEX piping

I would have to say that even if you know that your health isn’t physically impacted on by polyethylene, you should still grab a sample. One plumber whom we ‘interviewed’ gave us some from a massive roll on his truck, but it reeked of engine oil. So that’s why we asked Kale for some more…

The glue, which is incredibly toxic and will stick your hands together if you play with it, had already been supplied by another cool plumber dude who also passed our interview (details at the end of this post and on the tradespeople page (coming up!)).


I didn’t test the glue until it had dried for over two weeks as 1), it’s the only choice because it’s an industry standard, so it’s not like I have a choice of glues; and 2), if a tradie [Aussie for tradesperson] tells you it’s bloody toxic by their recommendations, then you’re going to want to hold off on breathing that stuff in! Kale uses the pink one as it’s easier to see when it’s time to clean up and when painting it on black surfaces.

KLM Plumbing have already installed our water connection and underground piping. We have gone with the Cross-linked polyethylene (PEX) piping system for all incoming water, outgoing sewage travels through PVC. The PEX system uses less glues because it screws together, and has some fundamentally important benefits over copper piping.

If you are chemically sensitive, suffer from respiratory conditions such as Asthma, Inhalant Allergies, chemical sensitivities, respiratory inflammation, Toxic Encephalopathy, Occupational Asthma, Irritant-associated Vocal Cord Dysfunction, Reactive Airways Dysfunction Syndrome (RADS), Irritant-induced Asthma, Small Airways Disease or Multiple Chemical Sensitivity (MCS), you may find the following information useful:

More from My Chemical Free House:

Here is the breakdown:
Copper = Alzheimers & EMFs
PVC = highly toxic
PEX = Low VOC/the best we have right now.

Polyethylene (PE or PEX), The Real Deal

So if you want running water, Polyethylene is the least harmful option. It will leach small amounts of VOCs for some years. You can avoid drinking warm water from the tap and other than that, wait it out. After a few years, the VOCs will be practically nil.

However, from an ecological and environmental perspective, the copper is recyclable and the PEX isn’t:

“Copper is a naturally-occurring mineral with associated mining impacts, but it’s easily recyclable (and often contains a high recycled content), while cross-linked polyethylene is not.”

As sustainable as copper may be, it has been found to be a threat to human and environmental health. Copper needs to be soldered with lead free solder, and since 1988, that’s standard procedure. But, copper smelting and production creates environmental emissions which are bad for humans and our planet! (Just pick your poison already, yeah?)

However, there’s also the issue of copper dissolution:

“This occurs in new piping, and in piping carrying acidic water, soft water (low dissolved solids), or water with high dissolved oxygen. It is recommended that water sitting in copper supply pipes for more than 6 hours be flushed for 30 to 60 seconds before using for drinking or cooking, that hot water (more dissolved metal) never be used for drinking, cooking or (especially) baby formula.”

So for now, and as far as my research and conversations with other MCS-ers shows, PEX is our best option. It’s even been approved, after an extensive Environmental Impact Study, by the state of California for all water supply systems, observing that it would be “an environmentally superior action with respect to public health and hazards, water quality and air quality.”:

“Cross-linked polyethylene (PEX) piping, on the other hand, is flexible, smoother, does not scale or corrode, is resistant to acids, and is relatively resistant to frost-breakage. Because it comes in long spools, it has far fewer fittings (usually just one at each end) to leak or cause turbulence, and requires no solder or torch fuels. Because it is far simpler to install, it can typically be done less expensively, even with the now-common “home run” system in which each hot and cold fixture gets supplied by a separate pipe, allowing the use of smaller-diameter tubing, eliminating the pressure-drop common in most homes and allowing a centrally-located “switch panel” to isolate each fixture.

PEX has been used in Europe since the 60’s and in the US since the 80’s. It’s made from a petrochemical plastic and, while it has 46% more embodied energy per pound than copper, because it is so much less dense (lighter) it has 85% less embodied energy per unit volume.”


The fact that it’s less likely to leak is what sealed the deal for me. A mould free house is a safe house! We also had to arrange for termite control, which happens in two stages, and the first stage has to coincide with the plumbing installation and laying of the concrete slab, which I’ll blog about next… If you need to know, like right now, about termite control for those who can’t or don’t want to use pesticides, then the product we’ve used is called Termimesh.


Our House Block with Plumbing!

Above: the final result of stage 1 of the plumbing installation by KLM plumbing. Some of the PVC pipes have the PEX piping inside them to protect them from the sun until the indoor plumbing is installed. PEX breaks down in sunlight, whereas PVC doesn’t.

Suggested Plumbers for the Chemically Sensitive in Victoria, Australia

(Note: if you are, or know of a plumber willing to help people who are sensitive to chemicals, then please drop the details in the comments below.)

Bellarine/Surf Coast: KLM Plumbing0433 811 481

Malvern East: Leo Breen: P: 0418 312 824

Drysdale: Craig Trewan’s Plumbing P: 03 5253 2744


Environmental Building News: Piping in Perspective: Selecting Pipe for Plumbing in Buildings

Green Building Adviser: How Safe is PEX Tubing

Green Building Adviser: PEX vs Copper

My Chemical Free House: Best Options for Pipes

The Steps to Building an Eco-Friendly, Allergy-Free house

The Steps to Building an Eco-Friendly, Allergy-Free house and the tradespeople and companies we used (So far we have been really lucky with the team of people who we’ve found to help us build a low-toxic house.):

Design your house. We used Quin Wyatt, eco-Designer, and new beforehand, via testing with a doctor, what to avoid using before hand, plus, and apart from the actual style and design (the look), we knew exactly what we wanted: allergy-wise

Find your workers (yes I have a post: How to Find or Organise Fragrance Free Workers [post coming up]

How to Test Building Products and Products for you own or someone else’s Suitability [post coming up]

How to Apply to Council so that it passes through quickly [post coming up]

A fully, well-cured Concrete Slab, solid as a Rock from D&C Fear Concreting

Low-toxic Pluming installed by a fragrance-free plumbing team: KLM Plumbing

Choosing Fittings for the bathroom, kitchen and laundry: @Reece Plumbing

Choose your internal Building structure: We went with Hardwood from Calco [Post coming up]

Build a frame: we went with Damien and his team from Pristine Carpentry [Post coming up]

Choose a roof style, find a roofer [post coming up] , which are often, but not always a plumbing and roofing job (because plumbers and roofers often do both); We have the maddest Japanese style roof, which we are over the moon about, installed by Yeo Roofing and designed by Quin Wyatt, eco-draftsperson.

Virtual House Tour: using Sun Study Designs made by Quin our eco-draftsperson [up-and-coming post]


Michellina Van Loder is a Professional Writer, Journalist and Blogger. This is where she shares her tales about trail blazing her way out of the Labyrinth of Chemical Sensitivities and Mould. This is also where you will find the latest Research on related topics.

Information, products and views presented by guest bloggers @The Labyrinth are not necessarily the same as those held by this blog's author, Michellina van Loder. Reviews are my own personal opinions (unless stated otherwise); and satire is used throughout personal posts. Any health topics discussed are not to be taken as medical advice. Seek out medical attention if needed and do your own research; however, you're welcome to use mine as a start.
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