The project, Build an Eco-Friendly, Allergy-Free House, now has a concrete slab as the foundation for what’s to come. After living in The House of Mouldy Horrors back in 2012, when I got sick, where the slab edges in the three bedrooms, including the main, that ran parallel to the garden and concrete driveway outside was leaking water, drying out to effervescent white in summer to wet patch in winter (the solution was to tar it, which we couldn’t). At night time, the damp night air stunk of soil, and ruined my health, I’m sure; while back at the farm house my health was fine enough to go back to school until I lived in that house with a ‘faulty’ slab. However, this slab is different: its smooth, with neat square edges, perfect lines; it’s solid as a steel-grey rock with a texture smooth-as-a-polished-knife.
After the moisture ingress issue with the slab at my last residence, ‘The House of Mouldy Horrors’, back in 2012, the place where my health deteriorated after exposure to mould caused by the quagmire of soggy soil surrounding the slab edges, we knew we had to find a good concreter who could lay us a chemical-free-as-possible slab with no petrochemicals or solvents used on site or on it; one that would serve as a solid foundation for our blog project, Build an Eco-Friendly, Allergy-Free House; but most of all, one that wouldn’t expose me to unnecessary chemicals most especially mould!
After shopping around via phone interviews, and gathering four different and varied quotes, I found this great concreting business:
Daniel from D&C Fear Constructions Pty. Ltd.
Location: 58 Lake Avenue, Ocean Grove, on the Surf Coast of Victoria, Australia.
P: 04 0369 3794
Daniel Fear and his team where not only helpful, respectful and careful in helping me stay safe within the parameters of my medical condition but were active in doing so. You can tell when a tradesperson is going to be helpful straight off the bat: They convey an understanding immediately, often asking questions with the gist of, How Not to Make you Sick. In my mind it’s pretty simple: I tell the dude or dudette that I need to avoid any exposure to petrochemicals, solvents, cleaners and any chemical not tested by us. (I also email or hand over an Allergist’s letter to all people we consider hiring.) After a couple of chats on the phone, we met up at our block and, yes dear readers, he was free of after-shave, fragrance and sprays.
Some people just get ‘it’ when asked, thankfully.
Yes, I know. I base my tradespeople reviews on whether they are wearing chemicals (dispersed onto their person via sprays from deodorants and fragrance—like, for real—I can tell even if it was sprayed on yesterday because it’s not as volatile and, when I breathe it in, it doesn’t sting my eyes not even one quarter as much.). The mantra I always say to all people whom I’ve asked to go fragrance free:
It’s not the smell; it’s the chemicals.
For the slab this wasn’t so important, but when I visited after it was finished, the place didn’t reek of petrochemicals. I was happy.
Also, when I arrived at the Build an Eco-Friendly, Allergy-Free House project site on day 4, the last day of the concreting job, our load of hardwood (from Calco) for the house’s frame was just arriving on a big bloody truck, spewing out diesel fumes into the air.
Not one to trust my boyfriend to take a photo (one in portrait and one in landscape) with correct white balance, a steady hand and sharp focus and from the right bloody angle, I popped on my 3M mask, assessed the wind direction and jumped out of the car to get some shots. (The ones with all the concreting action.) I noticed two things straight up: The jerry-cans of petrol were kept off the property by the gate [tick]; and, as I went to walk near the entrance to the block, Daniel, picking up a petrol can, asked, “Do you want this moved?”, I said “no” cause I was leaving after getting my shots… (Like about 20 clicks of the camera and I was out of there.) But that’s my point: tradespeople taking our medical condition seriously. What can I say, make it happen.)
I cannot recommend D&C Fear Concreting highly enough for people who have allergies, chemical sensitivities or conditions relating to respiratory symptoms.
Dan and I came back later to check out our slab. Back when I imagined the concept of actually having a slab, I thought we would have a slab picnic but, due to some friends‘ advice, I was just playing it cautious by totally avoiding sitting on it for a few days until it was completely dry.
But here I am, contemplating the end result and feeling like I’m in a dream. Me? In my own house? It’s actually happening.
Click on of the images below for a slideshow of the action.
Our eco-designer specified for the slab to be 200 mm high. And most of the north-facing windows are large, coming all the way down to the floor so that it can absorb the sun’s heat in winter. Our eaves come out 600 mm so that the higher-in-the-sky summer sun is blocked by them, therefore, allowing the slab to stay cool because the sun is kept of the windows (I’ll blog more on this issue once I get time to post my research online.)
More on Thermal Mass
In rooms with good access to winter sun it is useful to connect the thermal mass to the earth. The most common example is slab-on-ground construction…
A slab-on-ground is preferable to a suspended slab in most climates because it has greater thermal mass due to direct contact with the ground. This is known as earth coupling. Deeper, more stable ground temperatures rise beneath the house because its insulating properties prevent heat loss. The slab assumes this higher temperature which can range from 16° to 19°C.
In summer, the earth has the capacity to ‘wick’ away substantial heat loads. It also provides a cool surface for occupants to radiate heat to (or conduct to, with bare feet). This increases both psychological and physiological comfort.
In winter, the slab maintains thermal comfort at a much higher temperature with no heat input. The addition of passive solar or mechanical heating is then more effective due to the lower temperature increase required to achieve comfortable temperatures.
Use surfaces such as quarry tiles or simply polish the concrete slab. Do not cover areas of the slab exposed to winter sun with carpet, cork, wood or other insulating materials: use rugs instead.
Chemical-based Curing Agents
Daniel also suggested not using a curing agent as they often contain petrochemicals because they’re oil based. I’ve even read about US companies pouring diesel over it to assist in curing correctly. However, even though chemical-based curing agents do guarantee the slab will cure perfectly, they may or may not be suitable for people sensitive to chemicals; it will depend on the individual and their sensitivities.
More from Holcim Australia:
Reasons for Curing:
To sum up the advantages of careful control of moisture and temperature in curing:
- The strength of concrete increases with age if curing conditions are favourable. Compressive strength of properly cured concrete is 80 to 100 per cent greater than the strength of concrete which has not been cured at all;
- Properly cured concrete surfaces wear well;
- Drying, shrinkage, cracking is reduced;
- Greater watertightness of constructions is assured;
Points to keep in mind when curing:
- Start curing operations as soon as possible after concrete has been placed;
- For proper curing concrete needs moisture;
- Continuity in curing is a must; alterations of wetting and drying promote the development of cracking;
- If during curing the concrete is allowed to dry out – as may happen in hot weather – the chemical stops right at the point where the concrete loses its moisture;
- The ideal curing temperature is 23°C;
- Cure concrete for at least 7 days;
From Ei Wellspring, Things to Watch Out For:
- Besides avoiding the concrete additives, there are various other pitfalls.
- As mentioned some contractors pour diesel fuel [or other chemicals,which may or may not be safe for you to use] over a finished concrete slab to create a nice finish. This happened for an MCS house. They were unable to correct the problem in any other way than cover the slab with a heavy membrane and then pour a new slab on top. This worked well, but cost a lot of money.
- a barrier will also block any radon gas that may come from the soil, especially in areas with bedrock. It is best to use multiple overlapping layers.
- Make sure the slab inside the house is not exposed to the outside, or there will be great heat loss. Such errors have been seen where the slab under the house extends out on a small patio or walkway. Such thermal bridging is especially important to avoid when the slab is heated with an in-floor heating system.
- Insulation used in the foundation must be designed for this use. Inappropriate insulation may compress or disintegrate over time. In America, proper insulation boards are rated for “direct burial,” and are generally referred to as “blue boards.”
- Make sure any gravel trucked in is clean. It is not unusual for such a load to be contaminated with oil spills or other contaminants. Make sure it comes directly from a gravel quarry, and inspect each load.
- Decide in advance what to do with any leftover concrete. The driver cannot take it back, it has to be dumped or used somewhere on your property. One option is to spread it on the driveway, where it turns into gravel.
The company, Termimesh, came while the slab was being poured so they could install a special type of mesh, which will protect our house from termites without using poisons; but more on this, as promised, soon.
Dan is the builder of the house, it’s his actual responsibility to get it right. If this house doesn’t work, we will need to sell it and go back to Mt Macedon Ranges but for now, like ten years or so, we’ll have to live here. We need to get this project done right. Also, even though I buried Ganesh in the backyard for good luck, asking him to bless our digs and remove all obstacles placed in our way, however, I still wanted to follow the Greek tradition of putting a coin in the slab for extra good luck. This didn’t happen because there was just too much action going on at the house during the concreting process; instead, I’ve jammed a 50 cent piece Anzac coin under the side front door part of the hardwood frame (post coming up on the frame soon).
I can tell you about some old-school Macedonian stories related to mythology and luck when it comes to ‘blessing’ a new house that would make your vegan (if you are one) head spin:
But instead, I’ll leave on this note from Latman 100 from the Coin Community:
“I am a builder, and people still to this day request to place coins either in the slab or in some other part of the house. The strangest thing I have ever seen was a goat head placed in the slab of a house we built for a Macedonian family. Something to do with an old tradition.”
But I’ll save the details on this particular mythology for another blog post.
EI Wellspring: Building a Concrete Foundation for a Healthy House
Toxipedia: Dangers in our Home, Mould and More
The Labyrinth: DuPont’s Worst Nightmare
The Labyrinth: Reece Plumbing
The Labyrinth: KLM Plumbing
The Labyrinth: Modakboard
The Labyrinth: How Long Does it Take to Create a Safe Home
The Labyrinth: Building a House with Ganesh (Yes, I do love mythology.)
The Labyrinth: The Steps to ‘How to Get a Low-toxic, Water-tight Slab’
The Labyrinth: The Steps to ‘How to get a Termite Proof Slab with without chemical-irritants with Termimesh’
The Labyrinth: More Research on ‘How to Avoid Slab Moisture Ingress’
The Labyrinth: Passive-Heating and Cooling in Eco-House Design
The Labyrinth: How to Test for Chemical and Natural Compound Tolerance to Building Materials and Products
The Labyrinth: Pristine Carpentry
The Labyrinth: Calco (low-toxic, chemically-irritant wood building supplies)
The Labyrinth: A Hardwood Frame
The Labyrinth: Shoji Doors
The Labyrinth: my up-and-coming book: Freedom: an allergy-free, eco-friendly house