How Proclima, and Laros Fixed Our Slab/Frame Overhang

The Slab Overhang Issue

How did this happen? Is slab overhang a common happening? How do you avoid a mess like this? Well, the Surveyor, contracted out by the builders, came out twice (over a six month period) to measure up, placing painted sticks and ties about the property for both house designs. We can’t work out what happened exactly. Except maybe…

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Take your own measurements, folks

…the kangaroos jumped the fence and moved both sets of sticks about. Yep! The first lot were left in; and the new ones were added to mark out the slab boundary.

The other thing could be that we downsized the house therefore confused our measurements. We’ve still not gotten to the bottom of it all but it really doesn’t matter now. The way the situation was handled by our carpentry team who alerted us and by our concreting team, who found the right people for the job, it’s such a small issue in retrospect!

If you accidentally design a McMansion and decide to downsize, beware!

Oh the #kangaroos this morning made my #heart sing I know why I live where I do. #grateful #wildlife #vegan #loveanimals

A photo posted by Michellina (@michellinaoutofthelabyrinth) on

Because of this mishap, the slab (due to the pegs and measurements) was made to the incorrect dimensions—the frame on the south side, the cold side of the house, was too short by 40 ml, and another 40 ml in two other places on the northern side, leaving our custom-built, excellent Calco hardwood frame hanging over—not precariously so but, according to engineering good practice: It wasn’t safe to build a second story on.

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And to answer the question: How common is this? People in the industry told us this happens a lot. Many builders don’t go to the trouble that we all went to. Life has been very stressful for him lately. He has to do so much. I can’t get government help for Oxygen or CIRS medications (some of them, but most, no!), testing cost a bomb. I’ve got my uni and my plans for a career from home but I don’t feel the disabled are given a fair go. Unless a fair go is just laying in bed getting sicker by the year!

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This piece was expertly sliced off by a concrete cutter

Plus, another section on the north side (the sunny, warmer side, which is our passive heating side during Melbourne winters!) and the western side (the hot side where the sun sets) were too big by 40 ml, which meant the concrete had to be wet cut with an electric saw by a concrete cutter.

These are the drawings our engineer drew so that we could get a clear picture of the solution to the slab overhang:

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Basically, we had a steel beam bolted onto the 3 edges of the slab to support the frame. However, right away from a building biology standpoint, it bothered me to think that some builders and owner-builders would construct a building straight over this  because of the condensation issue that most likely would develop: basic building-biology science says that if you have metal that’s cold on the outside while warm on the inside (as most houses are in cooler weather) then condensation will occur… then mould! could follow.

Being concerned about the health of the building envelope, condensation for the above reasons and, for a mould sensitive person with CIRS, this is a nightmare of a mistake to make.

In my brain fog, attached to oxygen, I contacted Thomas at ProClima in New Zealand (whom I found out about from Building Biologist, Rapheal at EcoLibria at Torquay, who I found out about from Lucinda at Eco Health Solutions). Thomas then put me onto Andreas at Laros Technologies, here in Australia.

Thankfully, Andreas understood my concerns! I have CIRS

The irony of writing a book on how to Build and Eco-Friendly, Allergy-Free House that is mould free and having to deal with these issues aren’t lost on me. As far as my book and blog go, this is a fantastic event to document because, thanks to ProClima and Laros, we fixed the issue. (I have a whole chapter on mould and happenings that can and did! go wrong and how we overcame these issues.) Dan and I inserted this thermal break ourselves. Now, 12 months later, my thumb still hurts from holding the beam while Dan wedged that low voc, non-toxic ‘thermal break’, between the slab and the metal beam.

Other ProClima products we plan on using:

Intello Internal Airtight Wrap (post coming up on that)

And, hopefully having our house and cottage roof windows’ supplies (flashing and tapes) supplied by them. I’m trying to book Kale in from KLM plumbing to do the job. He’s the perfect plumber: on time; does what he says he will. We’ll be sure to get good instructions for our plumber from Andreas [check] at Laros!

An Energy Efficiency Weakspot

From an energy efficiency point of view: this would be a weak spot that would suck out heat from the building during winter. So although the solution from our engineer was a clever one that saved our house and budget, it didn’t take into account that, Melbourne, being a colder climate, that has such *lovely cold weather, which would keep the piece of steel cold on the outside and warm on the inside each time the house was heated: this would cause condensation given those conditions, which is a great way to end up with mould!

The solution was to create a thermal break along the piece of steal. This would be a guarantee against condensation because there wouldn’t have any heat conductivity of the steel leading to it in the first place!

The galvanised steal beam which is called a ‘RHS’ (Rectangular hollow section) bolted to the slab edge. The RHS had the dimensions of 150 X 50 mm; and was placed On the 3 sections under the overhang of the hardwood frame&msash;Southside and Northside.

Again, the slab was too big by 25 ml: the whole west side length of the house, jutting out with no purpose but to leach heat out of the house by poking out into the cold like that.

The slab jutting out by 25 ml along the length of the westside, a potential heat leak in a passively heated house.

The slab jutting out by 25 ml along the length of the westside, a potential heat leak in a passively heated house. We had this saw off by (update coming)

So then the builders and Dan found a concrete cutting mob to came out to the build. Whew! They bought with them a special saw and expertly cut the excess slab of by 25 ml, exactly!

Our frame was then nailed and glue together by Pristine Carpentry the ones who rang us alerting us to the fact that the house frame was too too big for the slab. When you take into consideration all the bricks, tin and metal that need to make up the house, that’s still only 40 ml hanging precariously over the edge of the slab. Earthquake anyone? Hyperbolic catastrophes aside:

The problem was: because of the steals temperature conductivity, it was a potential, most definite with time. Mould problem caused by condensation, which would have rose up the wall.

We could have used a hairdryer to meld the shape of the material to the beam but, we realised the pressure of the house would do this.

It was a hard lesson.

Note: It’s best to check yourself.

But it’s all taken care of one thanks to Laros and ProClima: sell truly environmentally-friendly and people-friendly products made for New Zealand weather.

Our solution to slab overhang came from Laros.

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People and Places where we Received Assistance in Relation to Building Biology for People with MCS and Mould Illness (CIRS)

 

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.

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!

Download (PDF, Unknown)

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

More

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.

D&C Fear Concreting

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.

Daniel Fear concreter: House slab, garage slab and cottage slab for the 'Build and Eco-Friendly, Allergy-Free House' project

House slab, garage slab and cottage slab

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:

DC Fear Concreting: tradespeople used in the book 'Build an Eco-friendly, Allergy Free House'

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.

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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.

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Dan the Vegan Eco-Builder Man

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.

More

EI Wellspring: Building a Concrete Foundation for a Healthy House

Green Home Guide: Is concrete flooring eco-friendly? What’s the best way to finish it—stain, paint, polish?

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.)

Coming up

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

 

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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