How to Size an Air Purifier for Your Home: Calculate the Size of an Air Filter Needed

If you are wondering what size or how "strong" of an air purifier you need, these two calculators will help.

To properly size an air purifier or filter for your home or room, the main value you are looking for on an air purifier's specs is how much air it moves. This will be provided by the company as the CFM (Cubic ft/Minute) value. Think of this as the fan size.

The First Calculator: Calculate What Size Air Purifier you Need 

In the first calculator you will find out what CFM value you need for your room size. You need to add your desired or ideal Air Exchange Per Hour (ACH). This is how many times you want the unit to overturn (and filter) the air in the room per hour.

This calculator will tell you what (minimum) CFM value you are looking for and then below is a list of air filters that meet that requirement.

Air Purifier to Choose based on Result of Required CFM from the Calculator:

PCO Models Best for Mould Reduction:

Airocide CFM 14
Molekule CFM 80
GermGuardian AC4825 CFM 125
Vornado PCO300 CFM 145
Vornado PC0500 CFM 184

Here is the Post with Detailed Comparison of These Models

High Carbon (and other Sorbant Material) Best for High Offgassing: 

Amaircare 3000 225 CFM
Austin Air Healthmate Plus CFM 250
EnviroKlenz CFM 250
IQ Air Multigas CFM 300
E.L. Foust 400 Series CFM 380
AllerAir AirMedic Pro 5 Ultra CFM 400
Airpura C600-DLX 440 CFM

Here is the Post with Detailed Comparison of these Models

The Second Calculator: Calculate How Effective Your Air Purifier is in Your Space (How Much Air is it Cleaning)

Below, the second calculator can tell you how many air exchanges per hour you are getting from an air purifier you already have, or one you are looking to buy, based on the size of your room.

Most experts recommend a minimum of 4 ACH. ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends a minimum of 4 ACH for patient rooms in hospitals, 5 for intensive care units and 25 for operating rooms.

Hopefully these two calculators helped you find out your ACH to CFM calculation and your CFM to ACH calculation.

Free Location Effect Sabbatical E-Booklet

Sign up for the email list for a free 15 page e-booklet on the Top Six Spots for a Location Effect Sabbatical, 2019

This includes the top 6 American locations in: Arizona, Nevada, California and New Mexico. These are campsites for RVs and tents (some have cabins, but not vetted) where experienced mold avoiders have found a lot of healing within the last year. Many of these locations are tried and true for many years, but I make sure I have recent reports on all of them.

The brochure covers the basic information you need to decide on which one will be best for you, including:

Location, elevation, basics on the campsite (hook ups, bathrooms etc), how spacious they are, costs, proximity to stores, WiFi and cell coverage, temperatures (and other weather related details).

This post on the Locations Effect goes into more detail on what a sabbatical entails (and also what to bring!).

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Linseed and Tung Oil: A Comparison of Chemical Additives and Offgassing

This article is a comparison of linseed and tung oils: are they non-toxic, what types of chemical additives are used in the different oil types, what compounds do they naturally offgas, and when do they cure and become safe for the chemically sensitive.

I review the following oils: Tried and True polymerised linseed (pure and with a stain), 100% Tung oil, Rubio Monocoat (plain and a blue colour), and Odies Oil.

This post contains affiliate links. Upon purchase, I earn a small commission though affiliate links at no extra cost to you.

The video compliments the post:

Linseed and Tung Oil - Chemicals and Offgassing 

Linseed and Tung Oil are the traditional natural finishing oils for wood - some forms can also work well as stone and concrete sealers. Both of these oils are drying oils which polymerise in the presence of oxygen forming a durable and elastic finish. They do not go rancid like semi drying or non drying oils.

While all of these oils, the pure ones and ones with additives, claim 0-VOC (a legal term), they do give off natural VOCs, whether these are enough to be considered toxic depends on you and your tolerance. The term "non-toxic" means that the toxins are not at high enough levels to do harm to the average person. During oxidation (curing) of these oils, aldehydes and hydrocarbons are produced. Peroxides, alcohols, ketones and acids may also offgas during oxidation (1). I could pick up this odour very acutely. In low concentrations these compounds are not toxic for most people. For those who are comprised, aldehydes especially, can be harmful or cause symptoms.

If you are wondering if linseed and tung are suitable for you and your sensitives be sure to test both in the 100% pure versions, as well as Rubio Monocoat and see how you do. For those who like pure natural finishes and who are not bothered by the natural aromatics of plants and oils, both 100% linseed and 100% tung would be great options. I wasn't expecting to like Rubio Monocoat, the modified linseed, because of the lack of transparency of ingredients, but I explain why it turned out to be my top choice in many ways.

The finishes produce slightly different looks and you should also check the application procedure for the oils you are considering, as well as upkeep

I'm going to compare tung and linseed (including Rubio Monocoat and Odies Oil) in terms of the chemicals added as well as what compounds they naturally give off when curing.

100% Pure Tung 

When choosing a tung oil you are looking for 100% pure tung oil. Not the danish oil mixes from the hardware store or anything premixed with a thinner. My top brands are Real Milk PaintThe Hope Company and Heritage. We want to start with something pure that does not have additional chemicals added.

Tung oil can be applied without a thinner to weathered wood, new wood floors as well as some old wood floors and concrete. Check to see if your application requires a thinner before starting, because the thinners are chemical compounds that may not be tolerable or desirable.

Common thinners for tung are citrus solvent, mineral spirits, or odorless mineral spirits. The thinners can be very hard to tolerate. I describe the citrus solvent as “brutal” - it wipes me out and makes me very sick, it does not dissipate quickly. Just because it's natural does not mean it is safe. If I had to pick one I would use odourless mineral spirits which should dissipate (offgas) quickly, in theory. However, whenever you are applying something yourself things get more tricky. If a non sensitive person is applying the oil you may opt to use an additive that will dissipate quickly and wear protective gear.

100% tung oil is food safe on butcher block, cutting boards, wooden counter tops, concrete counter tops and wooden toys once cured. (To err on the safe side, wait 30 days for it to be cured).

Apart from wood, tung oil can be used on raw slate (slabs or tiles), it should not be used on marble, whether you should use it on granite is up for debate - do a test first on raw granite. It can be used on concrete counter tops as well as concrete floors.

You can use it on metal, in fact cans for food used to be lined in tung. A coat on some types of steel helps prevent rust.

The companies say it normally takes 30 days to a full cure. This means you may be able to pick up the offgassing odour for 30 days if you are sensitive. However in my results at the end of this post I compare all the oils at 30 days to see if I can still pick up the offgassing. Companies claim 95-98% cured within 7-14 days and depending on conditions, it can take up to 90 days for a full cure. There is a statement on wikipedia that tung comes to a full cure whereas linseed continues to polymerise for years. I was not able to confirm that statement about tung after looking through all the scientific literature on tung that I could find, and talking to many companies. In fact my results after 30 days does not confirm this (comparison at the end of the post).

In the literature I did see lots of reference to the idea that tung oil has a superior ability to polymerise due to its a-elaeostearic acid (77–82%) content. In theory this gives it a greater chemical reactivity and excellent ability to polymerise (cure) (2, 3). However, my sniff test at 17 and 30 days revealed more offgassing of tung than all of the linseeds I tested.

The offgassing odours of tung are a little different from linseed. In my assessment, tung is not as pungent when in liquid form, but they both offgas similar VOCs while curing. During oxidation aldehydes and hydrocarbons offgass. Peroxides, alcohols, ketones and acids may also offgas during curing. (1). At the end the two had reversed in my assessment: tung was the strongest at 30 days.

How to apply it instructions here.

Linseed Oil

Linseed comes in three types:
1.  Raw, which is pure, not usually used for wood, as it takes a long time to dry and is often cut with a thinner.
2. "Boiled" which has driers, usually metals like colbalt, or petroleum (which I would want to avoid), this version could be considered toxic if it has toxic metals.
3. Polymerised/stand oil which is pure, food safe, and faster to dry. This oil does not require a thinner. Polymerised is the type you want to use. I like the brand Tried and True because it's pure 100% linseed, and because of their total transparency with ingredients and additives.

The odours of these oils (and the citrus solvent) comes from their naturally occurring VOCs (4). For the chemically sensitive, these two oils have odours that are stronger than some other finishes. The solvents/thinners should be tested separately, are not always tolerable (or needed). The pungent smell of linseed comes mostly from the aldehydes (5). You should see if the pure version works for you. I prefer to use this on applications that do not require solvents/thinners.

Linseed will dry within a few days. But according to the literature, the drying reaction of linseed oil continues for many years even when the oil film seems to completely dry in a few days (7).
You can speed up the offgasing by increasing temperature and decreasing humidity. Raw linseed might be different in this regard compared to modified oils with driers.

Tung oil has milder offgassing compared to polymerised linseed in my assessment at first, but at the end of the 30 days tung had a stronger odour left. Rubio Monocoat (modified linseed with driers), was the exception, it was far less pungent than either polymerised linseed or tung.

Other areas to use linseed - it should not be used on marble or granite. Odies Oil has been used as a concrete sealer which I am quite certain is linseed based, but the ingredients are not disclosed. In the video I discuss why I think Odies Oil is linseed based.

Here are the instructions for application of polymerised linseed oil.

Is Linseed Mould-Prone?

Woodworkers having varying opinions on the two oils, each camp preferring one over the other with some noting caution to linseed as being less mould resistant in certain conditions. Outside in high humidity linseed does not do well. For indoors with regular humidity levels, linseed will work just fine, and I have no trouble recommending it. Tung oil has the advantage of holding up well to water and mildew outside

Brands of Linseed:

Rubio Monocoat

Rubio Monocoat makes linseed based finishes (natural and modified) that smell like honey or lemony incense. It contains a wax component (natural and modified) as well. They claim zero-VOCs but you should test any linseed product before using it. The accelerator which is a part B drying agent, lists hexamethylene diisocyanate as an ingredient (0.5%), but not all ingredients are listed. Because part A (without the drier) takes a very long time to dry, it sounds like part raw linseed to me (though it does not smell like raw linseed). This means Part B is unknown driers and hexamethylene diisocyanate.

It does contain non-aromatic hydrocarbons, I could not get the company to claim no metallic driers, but they do claim no solvents. I will always prefer brands that disclose all their ingredients.

Sensitive folks reporting that they really like this brand is important and caused me to seriously consider it. It turned out to be my top pick based on odours, offgassing level as well as personal tolerance. I was surprised by how mild it was from start to finish, though I did still pick up an odour at 30 days in the plain colour. I was very impressed with Sapphire which I found cured to my nose at 30 days.  Because it's easy to apply, easy to touch up and seemed to have the least offgassing, much lower than I expected, I have to say it is my top pick. Though with reservations, since we don't know everything that is in it.

I would personally be reluctant to use this on large products like floors since it has unknown ingredients and I might not be picking up all of the offgassing with my nose. I would however feel more confident using this on cabinets or furniture, since it tested so well for me personally. I would like the company to confirm no metals, since metals are a major health problem for many of us.

This brand offers unique colours in their stains that no other natural option offers (greys and white). Be sure to sample both Part A and Part B as well as different colours, which for me tested quite different. I tested plain and sapphire.

Rubio Monocoat (Part A & B mixed) takes one week to cure, they say. You could use just part A which takes 3 weeks to dry.

Although I say in the video it is approaching offgased at 48 hours, at one week my sense of smell ramped way up (due to a reaction I had to something else), at this point I could still smell it very noticeably. So the time that it cures will very much be dependent on you and your level of sensitivity.

Tried and True - Polymerised Linseed

Tried and True Java
Polymerised Linseed
Tried and True is my top recommendation for pure linseed with a stain because it is pure linseed and because of their disclosure of ingredients. No driers are used. This company can claim that metals are not a component in their pigments other than what comes naturally from the soil. I really liked the look of the Java stain (pictured), it went on beautifully even though I did not prep my wood properly. That’s going to give you a high quality stain/finish in one. I was really impressed with how the stain looked after my disaster trying to mix my own pigments with hemp oil.

They offer versions with waxes and resins as well, check out the different formulas to see which suits your project.

Other Brands

Fusion is a similar oil and stain in one but they don't reveal all the siccatives (driers). This brand does have other products that I am a fan of, but unknown driers is not one of them.

Oils labeled as teak oil or danish oil from hardware stores are usually a mix of oils like linseed or tung, solvents, and possibly resins, UV inhibitors and mildewcides.

Odies Oil (Universal Finish)

Odies Oil (the Universal Finish) is another oil I tested in the video.

I suspect this to be a linseed based finish. The ingredients are listed as: lubricating oil, drying oil, natural waxes; essential oil. They claim solvent free, that it contains UV inhibitors, and it has the warning for spontaneous combustion (which is seen on almost all drying oils).

I made the following mix which came close to the odour of Odies: mineral oil, linseed, beeswax, carnuaba wax, lemon and orange oil. I did not get the exact match but it seemed pretty close. There is still is another essential oil I think, lavender or similar, something flowery. And there is a different mix of waxes I think, compared to my guess. But I got quite close to their mix, according on my nose.

This tested quite strong to me at first, with the essential oils being overpowering for me in the first 24 hours, but at 48 hours that had faded significantly, and what smelled to me like linseed was then dominant. Those who are reactive to essential oils will likely have trouble with this one and might not find it fades as quickly as I did.

As always, I’m not a fan of using products that I don’t know the ingredients of, we don't know if there are toxins in here, but it did cure faster than some of the others.

They claim 2-3 weeks to cure.

My Test Results

My test results at 24 and 48 hours are in the video.

My testing at 17 days 

  • Rubio 1st place 
  • Tried and True Java 2nd place
  • Odies Oil and Tried and True still quite noticeable odour, 3rd place
  • Tung actually the strongest at 17 days, last place

My testing at 30 days when they should all be "cured"

  • Rubio plain - I can pick up the Rubio plain at 30 days though it is very light. My nose is unable to pick up any offgassing from the Rubio Sapphire - this is the only one that seems totally cured to me at 30 days 1st place.
  • Rubio plain is in 2nd place
  • Odies oil - very slight odour in 3rd place for offgassing levels
  • Tried and True Java in 4th place very slight odour
  • Polymerized linseed - Tried and True plain still offgassing 5th place
  • Tung oil - strongest one. I do not agree that tung oil cures in 30 days, at 30 days I can still pick up the odour of one coat. I kept it at 30C and about 50% humidity. I cannot say it is 100% offgassed. Last place.

Other Options

If these two don't work for you, try hemp oil. I was really happy with pure refined hemp oil. If you want a totally natural purist option, hemp is a good choice. It's not as strong of an odour as the others.

Other finishing oils reviewed in my main post on finishes are coconut, walnut and rosewood. That post is also is also a comprehensive overview of water based 0-VOC and non-toxic finishes for wood as well as stone and masonry.

Non-Toxic Windows, Blinds, Curtains

Updated Summer 2019

This post covers non-toxic Curtains, Blinds, Shades Blackout options, Window Frames, Window Flashing and Caulking.

I recommend all of the products here, some products have affiliate programs and some do not. Upon purchase, I earn a small commission though affiliate links at no extra cost to you.

Non-Toxic Curtains and Blinds

Source: Blinds Chalet

Fabric curtains are usually treated with wrinkle-free chemicals and flame retardants. Natural fabrics do break down in UV light but are a healthier option. Look for Oeko-Tex or GOTs certified fabrics to guarantee no chemical treatments.

Blinds and Shutters

Green versions include bamboo roll down blinds that are not treated with chemicals like those from Earthshade and Blinds Chalet.

I have not found wooden blinds with a 0 VOC finish since this is so hard to accomplish with something that holds up to UV.

Aluminum blinds used to use powder coated metal which was very safe. You can find some older blinds like this. But currently all metal blinds in North America, Asia and Europe are made with a polyester based baked on enamel finish that does offgas. I have also seen additives, for example, Hunter Douglas ads an anti static additive to the coating. This may be something like Teflon, which would offgas as well.

You can find brushed aluminum blinds with no paint or coating, like those from Earthshade. At some retailers, brushed aluminum does have a coating.

Between the Glass

Between the glass is a really cool option that eliminates the worry of offgassing. Here is an example.


Conventional screens are very smelly at first. They can be left outside to offgas, or aluminum screens can be used instead. Marvin is one brand that makes aluminum options.

Non-Toxic Blackout Shades 

Bamboo Shades

Blinds Chalet blackout liner on the bamboo shades is PVC- free and they claim that it is environmentally friendly.

Polyester Curtains

Polyester with No PVC will work for many. If you can wash and or air them out first that will help:
West Elm 100% polyester curtains still have that new fabric toxic smell but will offgas.
These Eclipse polyester curtains from Amazon do not contain flame retardants, can be washed and aired out and should be tolerable after washing and airing for most people.
These Sleep Well polyester curtains do not guarantee no flame retardants or fabric treatments, but they are 100% polyester and free of PVC. They are washable. You can remove that new fabric smell by washing. Some have reported these having no smell and others more sensitive still can pick up the new fabric smell.

100% Black out Shades

Earthshade makes eco blackout shades and rollers that are probably the safest ready-made option on the market. The blackout roller shades do contain 35ppb formaldehyde which is produced when pressing the polyester sheets together to laminate them with heat. The shades have also been processed with bleach. Those are the only two treatments of the fabric. Generally my recommendation on formaldehyde (as long as it's not urea) is to give it 3 months of offgassing. When installed with a proper blackout system these will get you the most light blocking of the list.

Something Simple for Lightblocking:

Another option to consider is this paper black pleated shade - the company claims in an email they do not give off any hazardous chemicals (I bought the natural colour version of this - it has a slight toxic smell and needs to be offgassed only for a short while). They are not that great at blocking light compared to the other options and you will need to double them up to make a bigger difference. But these are super inexpensive, easy to install quickly, and worked perfectly in my tiny house.


Another really safe option (truly the safest) would be to make your own blackout curtains with pesticide-free hemp fabric.


IKEA curtains made with 100% cotton are somewhat light blocking. They should be washed or aired out before using.

Avoid: vinyl roller shades and vinyl mini-blinds, PVC and conventional blackout curtains.

Non-Toxic Window Frame Options


Aluminum windows are the healthiest, safest option. It is what I used in my tiny house (pictured left). On the interior, they are framed out in wood so they appear to be wood framed windows. You can also use decorative moldings around the windows. I used DYG from Canada.

What is used in the windows as a thermal break is blocked by the glass and metal so there is no need to worry about much offgassing. The most extremely sensitive clients can pick up the seal, PVC glass stop and some glues used.

The finishes I have seen on aluminum windows are baked on enamel, resin paints, powder coated and anodized. Some baked on enamel finishes and paints can offgas, the other two are considered safe. The gaskets are made out of rubber or PVC.

I have seen some companies (like Alpine), replace the PVC stop with aluminum. More details on Alpine and other low toxin "High Performance" windows in this post on Passive Houses (in the window section).


Wood windows are usually treated with fungicides. You could use a sealer that seals in VOCs like AFM Safe Seal, AFM Transitional Primer or Zinsser Shellac.

Accoya wood used in some window brands use a non-toxic process called acetylation to naturally provide rot resistance. They contain no chemical fungicides or mildewcides and claim less shrinking and swelling that most solid wood windows. Loewen is one of the brands that uses Accoya and allows you to choose your paint brand.

You could go with custom wood windows to avoid fungicides, but they are more expensive and you still have to consider what kind of sealer you can tolerate on the inside and outside. For an exterior sealer see my post on paints and sealers.

All wood (through and through) windows are not a good idea as they do not hold up well to moisture in the long run, but you can consider ones that are wood on the inside and a more weather resistant material on the outside. Consider also the glue that is used in conventional wood windows could be irritating for the sensitive person.


Fiberglass offgasses VOCs and some sensitive people do report reacting to it. Though it may be tolerable for some. Some types and brands are better than others (in terms of offgassing) and this could result in a preference of fiberglass over vinyl or vice versa.

Marvin's Ultrex was not tolerated by the very sensitive though other fiberglass types by Marvin have been tolerated (especially if only used on the exterior side).


Vinyl is generally not healthy, but since this is a hard plastic, many very sensitive individuals report tolerating it. I did not pick up any offgassing on the vinyl windows I tested (and used in a little camping trailer). I can pick up the offgssing in some of them used in apartments under one year old. Others have reported reacting with new ones. Personally, with a bit of time to offgas, I find these to be good. Better than fiberglass but not as good as aluminum.

Fibrex is a PVC and wood composite made by Anderson which sensitive folks have reported being high in offgassing.


High Quality Window Companies Include: Marvin, Kolbe, Anderson, Pella, Wasco. Alpine for High Performance windows.

Are Gas filled Windows Non-Toxic? 

Windows filled with argon or krypton gas have a higher insulative value and both gasses are considered non-toxic.

Are Low-E Coatings Non-Toxic?

The two main types of Low-E coatings are both non-toxic. The"soft coat" which is a mechanically applied silver coating that is within a double pane window system. You will have no exposure to the silver. A "hard coat" is a layer of tin oxide that is applied while the glass is still hot. The tin is a more integral part of the glass in this case, and is therefore not a risk.

Sealing Windows


My top choice for caulking was Eco-Bond (which is out of business as of late 2018). The first two I would test out are AFM Caulk and silicone. Silicone caulks all have different odours/offgassing and rates of curing. Try Chemlink and GE. I have a post on caulking that goes into more detail.

Sealing around windows and doors

Plastic backer rod (polyethylene) can be used. This is non-toxic and odourless. Many people do tolerate the canned spray foams after some offgassing (give it 24 hours to cure or more).

Window Flashing

For zero-VOC window flashing use TYPAR AT. They do not recommend this being used in the rough openings, and it doesn't fit all building codes.

Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

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Non-Toxic Grout and Thin-Set Mortar

Updated summer 2019

This post contains affiliate links to relevant products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you.

For individual help on choosing the best products and materials for you and your home, you can schedule a consultation with me here.

Non-Toxic Thin-Set Mortar

Non toxic underlayment with chemical free grout
DITRA over the first layer of thin-set
I used Custom Building Products Thin-Set Mortar which is zero-VOC (and mildewcide-free). It had a bit of a smell when wet but seemed fine once dry. You want a water-based thin-set that is not mixed with latex or acrylic additives. The unmodified one is recommended for floors and may not be suitable for all applications. Schulter also makes an unmodified thin-set mortar.

These non-toxic thin-sets are more prone to cracking than ones with more additives, and you have to check if you application requires polymers. Thin-set mortar is also known as dry set and drybond. 

Avoid the toxic epoxy thin sets. Avoid toxic mastics as well. Although there are some safe and tolerable tile glues like AFM 3 in 1.

Non-Toxic Tile Membranes / Underlayments

non toxic no offgassing odourless underlayment
Schluter Kerdi 
Over the first layer of thin-set I used Schluter DITRA (polyethylene with a fleece backing), an uncoupling membrane that will help prevent cracking when my tiny house moves (it worked well and did not have a odour to me). Polyethelene is a very safe plastic.

If you just need a waterproofing membrane use Schluter Kerdi (a modified polyethylene (PEVA) core with non-woven polypropylene).

For a tiled shower, the Kerdi shower system is recommended by architects to create a mould preventative shower. Be sure to test all parts including Kerdi Fix sealant if you are sensitive to chemicals (though you can use your own thin-set, as long as it's compatible).

Instead of using the membranes over backer boards, you could use Kerdi boards or Wedi panels. Test for tolerability before proceeding, they are not odour-free. These simplify things by replacing concrete backer boards and membranes with one layer that is does not contain mould food. The panels are non-toxic 0-VOC polystyrene with a membrane already integrated.

Concrete Based Non-Toxic Grout

non toxic tiles with non toxic grout and grout sealer
My completed tiled bathroom!
I used this Custom Building Products grout, the same brand as the thin-set, which is also 0-VOC and contains no mildewcides or antimicrobials. It comes in sanded and unsanded and in different colours. (Unsanded is for marble and certain tiles). It barely had a odour, though it does have polymers which may not be tolerable to some.

If that one is not tolerable, Hydroment is also recommended for people with sensitivities. However, it has a small amount of latex additives and contains mildewcide.

If you need to avoid all additives, you can make your own with Portland Cement (no additives) mixed with sand, lime and water for a totally chemical-free grout. Here are the ratios from Craftsman's Construction Encyclopedia. To mix your own chemical-free grout it is a ratio of portland cement to sand, 1:1 for 1/8th joints, 1:2 for 1/2 inch joints, and 1:3 for over 1/2 inch joints. Adding up to 1/5 lime increases workability.

Laticrete also makes a number of 0-VOC grouts and thin-sets that may work for you. It's a matter of finding out which additives work for you and if additives are required for your application. Before planning out the project (especially shower walls, make sure you know which kind of grout and mortar are required and if they work for your health concerns).

What are Grout Additives and are They Toxic?

Those who are sensitive will probably want a concrete-based grout (like those above) and then see which if any additives can be tolerated. Since additives are trade secrets and polymer is a word that can mean a variety of chemicals (there are over 10,000 polymers that can be used in cement) you will probably have to test them. Common polymers in grout include: latex-based, Acrylate copolymers (acrylic eg. PVA), Styrene Butadiene Rubber copolymers (SBR), and Vinyl Acetate-Ethylene copolymers (VAE), and Ethylene-vinyl acetate (EVA).

They might come mixed in or you might mix them in yourself. Mixing them in yourself has the advantage of being able to test the additive against your sensitivities in a more concentrated form, on the other hand, you may not want to test the grout until it has cured. Polymers are added to improve chemical resistance, reduce porosity, improve flexibility, and freeze/thaw stability (source).

You will have to find out when and where you need additives, which depends on your project.

Are Thin-Set and Grout Safe - Why do They Have the Prop 65 Warning?

is thin set, grout safe? why is there a prop 65 warning Sanded grout and thin-sets contains silica (the same substance as glass) which is harmful to breathe in when in dust form; you will see a Prop 65 Warning on every product that contains silica dust. Use a N95 mask (or better) when mixing it until it is fully wet. This is completely safe when it is no longer in dust form. There may be other minerals in there that are a problem in dust form like aluminum oxide, which can result in a high health rating on the SDS and other warnings.

Some cements contain fly ash and others don't. Otherwise, plain Portland Cement does not have any other harmful additives.

Non-Toxic Thick-Set /Thick-Bed Mortar 

Thick-Bed mortar (also called thick-set or mud set) in it's most basic form is simply portland cement and sand. Custom Building Products makes a mix of 1:3 that is unmodified, it contains no chemical additives like polymers. 

Alternative to Concrete-Based Grout

For something more waterproof check put QuartzLock; this won't be tolerable for everyone. It is a urethane based grout, not cement, and provides more waterproofing.

Non-Toxic Tile Types

I used concrete tiles from Morocco in the picture above. For more info on choosing non-toxic tile types see my post on bathrooms.

Non-Toxic Grout Sealers

If just sealing grout (and not tiles) you can use AFM Grout Sealer (0-VOC, one of AFM's most tolerate products), Custom Building Products grout sealer that many people do well with, less than 1 g/l VOCs. ECOS, a well-liked brand has a stone sealer that can be used on grout. If you don't do well with any of those, you can check out more concrete sealers (which can work on grout) in the last section in the post on sealers.

Sodium silicate (aka water glass) is an idea that gets mentioned a lot among the chemically sensitive. When I spoke with a company that makes sodium silicate they recommended against using this on tiles in the shower. This brand Conkrete-Seal, has been used by someone very sensitive, she said it was somewhat waterproof and she was happy with it in the shower. Technically it's a densifier, and not a sealer, and normally it doesn't claim to make concrete waterproof. It is used in concrete polishing systems like Retroplate and as radon sealers in concrete. It is very benign.

Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

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Non-Toxic Glues and Caulks

Updated in winter 2019

Testing glues and silicones was the hardest part of building my tiny house since I did this when I was highly sensitive. This post covers low VOC, non-toxic options that are suitable for the chemically sensitive or the health conscious.

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Non-Toxic Wood Glues

It's difficult to extrapolate a small jar of dry glue to a house filled with it. (In retrospect I would have tested a much larger dry sample.) I smelled them wet because I got a clearer sign of their relative effects on me. Since I have not figured out a better way to test materials, that's what I'm working with. It is often a better idea to sniff something dry as the rate of offgassing and curing can vary greatly between chemicals.

Here are the contenders:

Gorilla Glue - Got pretty dizzy, not good, but not terrible. Seems OK when dry. (Easy to find at hardware stores and on Amzon.)

Elmer's Wood Glue - Not good for me. Didn't test dry. (Carried at hardware stores and on Amazon)

safe healthy 0 VOC wood glues
Roo Glue was the best of the wood glues
Roo Glue - White and wood glue - Not great when wet, but not terrible. Seemed totally benign when dry. This is my top pick and what I ended up using. (Available in the US and it ships to Canada).

Titebond - This is a brand that is recommended for chemically sensitive folks. I had already picked Roo Glue before I got a chance to test it. I do know people that build for the chemically sensitive who use this brand. (Easy to find at hardware stores and on Amazon). I would start here since it's inexpensive and easy to order from Amazon and find in stores.

ECOS Wood glue - ECOS makes extremely tolerable products, and while I didn't get a chance to test this one. I would expect it to be quite good.

Hide Glue is the most natural glue option for wood. It is a strong glue with no VOCs but it is not waterproof. You can mix it yourself from beads or flakes for the most natural option, or you can buy it ready made which does contain additives.

Non-Toxic Caulks

While silicone itself is not toxic, chemicals are added to keep caulking in liquid form are. These chemicals offgas at different rates until the product is fully cured. For silicone caulk, look for 100% silicone, but each brand has different additives which affect people differently and offgass at different rates. 100% silicone is not really 100% silicone, but the chemical additives are not listed.

The replacement silicones can be much more tolerable, EcoBond was a top pick before they went out of business.

All caulks have a chemical odour when wet. I tested them at 24 hours, 48 hours and one week.

I would recommend getting a non-sensitive person to put them in jars and only testing them after they have dried. Note that caulks labeled bathroom or mildew resistant contain a mildewcide. Currently GE I is mildewcide free, GE II contains a mildewcide and DAP makes an aquarium caulk that is free of mildewcides. Any caulk labeled aquarium safe is free of mildewcides.

are aquarium caulks safe and non toxic, no offgassing
Aquarium caulks I did not do well with
AFM Safecoat Caulk - Not the best when wet, not the best at 24 hours, but the best at one week. I used this in my bathroom. It comes in white and is generally a replacement for silicone.

GE Silicone II Clear Caulk - This may a better choice for the exterior. It was not as good at one week as AFM or Ecobond. We used this on the underbelly of my house and on my windows. It is low-VOC. I find that after a couple weeks it is fine for me.

ChemLink DuraSil - This type of silicone caulk is highly tolerable. This company makes great products that you can find at the Green Design Center. I have not tested this one myself but I would expect it to be up there with the most tolerable.

Aquarium Caulks - I have read that aquarium caulk is the least toxic because fish are exposed to it and they can't handle chemicals. I tested two brands, Aquarium Silicone Caulker and one called Marina from a local pet food store, they were much more expensive than brands for home use (for no reason), and they were both the worst of the worst. So bad I would not recommend testing or using these brands. One super sensitive person preferred the Aquarium caulk Aqueon to GE and Ecobond.

Chemlink also makes an elastomeric caulk for sealing concrete and masonry called NovaLink35. I haven't tested this one, but again it's a great brand.

Non-Toxic Adhesives

The best adhesive I have ever tested is AFM Almighty Adhesive. I had absolutely no problem and no reaction to smelling it while it was wet. This was a pleasant surprise after all the other glues and silicones. It is a highly tolerable very low chemical multipurpose adhesive. Insider tip, this is the same formula as Build Secure by Chemlink. I used Almighty this to install my shower, on subfloors, countertops and really anywhere this can be used since it's the healthiest adhesive I have found. It has many applications, I always use this one if it works for the project, or start here first with testing.

Liquid Nails subfloor adhesive is also well tolerated by many.

Ecotite is another good brand liked by the chemically sensitive. Their ET 5500 is an adhesive that works on a number of surfaces. The 9500 is used for windows, doors and some kitchen applications. These links are to a Canadian store but you can find this product in the US as well.

Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

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Non-Toxic Wall Boards & Natural Wall Systems

This post covers:

1. Non Toxic Wall Boards and Drywall
2. Non-Toxic Joint Compounds
2. Non-Toxic Wall Systems
3. Natural Building Systems

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For individual help on choosing the best products and materials for you and your home, you can schedule a consultation with me here.

1. Non-Toxic 0-VOC Wall Boards: Drywall, Gypsum, Cement Board


National Gypsum makes natural gypsum boards that are VOC-free (the paper backed ones). It's not always easy to source and I would rather not have paper-backed drywall.

For easy to source wallboards that are GreenGuard Gold certified, try DensArmor plus, and Georgia-Pacific Gypsum board are all GreenGuard Gold Certified (Densshield tile backer not Greenguard gold).

CertainTeed Gypsum boards and USG Sheetrock claim no VOCs. Research that a very sensitive client did reveal that USG was the cleanest gypsum on the west coast. Some gypsums synthetic and some are mined, and there are different additives used by different brands. For the super sensitive USG Firecode X is recommended (it does not contain a flame retardant, it does contain glass fibers).

AirRenew which is also GreenGuard Gold, claims to soak up formaldehyde. However, it contains a biocide which is likely not healthy. It is a little harder to source than the ones above and some have reported an odd smell with this one that indicates an additive used to soak up formaldehyde might not work for everyone.

Cement Boards / Baker Boards

Magnesium Oxide Board claims to be VOC-free, but not all of them turned out to be. This is a cement board that is more prone to cracking than regular drywall. Many people have reactions. There are many new brands trying to fill the gap for well-controlled production, but there are also many problems coming to light. I list the brands out in the post on bathrooms.

Cement backer boards as well as specialty foam based baker boards for behind showers are also listed out in the bathroom post.

Joint Compounds / Drywall Mud

For regular drywall, drywall mud (spackle) that are zero-VOC are USG Sheetrock Brand Lightweight Setting-Type Joint Compounds – EASY SAND 20, as well as 30, 45, 90, 210, 300.

Proform drywall mud is extremely low VOC (considered "zero").

There are many 0 or extremely low VOC drywall muds available at regular outlets. The powder form is lower in VOCs than the pre-mixed. Even pre-mixed can be found in extremely low-VOC formulations but the most sensitive should use the powdered form.

I used Murco as a joint compound and found it totally tolerable but it is not compatible with MgO board. It has cracked at the joints which is something other builders have noted as well. This compound is compatible with MgO.

2. Non-Toxic Wall Systems

The following are concrete and earth-based wall systems that do not offgas toxins and are suitable for the chemically sensitive. Something a little different from the standard timber frame, fiberglass and gypsum boards.
Pumicecrete Walls

A mix of pumice and concrete are poured into forms to create these non-toxic walls. They can be made load bearing with a concrete beam. Test pumice for radioactivity and for odours that it may have picked up prior to installation.

An interesting material making a comeback, HempCrete is blocks made of hemp and a lime-based binder. The blocks are used to form the walls and act as insulation. They are not load bearing so are used with a timber frame. HempCrete claims to not mould, but a natural fiber in a breathable wall is not something I would consider mould proof. Consult with an architect to make sure this is right for your climate.
Wood Insulated Concrete Forms

Forms are made of a mix of remineralised wood and concrete. Inside, rebar is used as reinforcement and then they are filled with concrete. Insulative fibers can be added or they can be filled with part concrete and part clay or a non-toxic insulation. Brands include Durisol(Nexcem) and Faswall. Faswall currently the only brand available in the US (2017).
Aerated Autoclaved Concrete (AAC)

Concrete based blocks made from quartz, lime or cement, and aluminum powder. Test thinset mortar for sensitivity. Hebel is one brand in the US. It's not approved in California (2017).
Insulated Concrete Form ICF

Nudura blocks (US and Canada) and Fox Block (US and Canada) are the most popular brands right now. ICF could mean different types of foam with concrete fill, but typically it is EPS. See my post on Insulation for a detailed review of EPS. Nadura has a dye. Both have flame retardants.

Is Concrete Non-Toxic?

Portland Cement should be used and it should be confirmed that it is free of admixtures such as air
entrainment and water reducing agents, accelerants and retardants, and super plasticizers. 

Ceramic Cement (Magnesium Cement) is also generally a non-toxic option.

 Which Concrete Aggregates are Chemical-Free?

Natural non-toxic mineral aggregates should be used. Toxic aggregates include crushed brick, crushed 
sandstone, concrete slag, fly ash, cinder, and volcanic materials other than pumice. (Source: Prescriptions for a Healthy House).

3. Natural Building: Earth Based Walls

Cob, Adobe, Light Clay-Straw, and Straw Bale and Rammed Earth

Adobe house from
These are all different types of walls made of clay, straw, and sand. But instead of giving a comprehensive overview I will comment briefly on the suitability of these building materials for the chemically sensitive. Houses made of all natural materials feel great to be in and there is no need to worry about any offgassing. However there are precautions that should be taken to avoid mould. These types of builings might be best suited to dry climates so that there is no chance of mould forming. Some people seem to be doing very well in adobe houses in the south-western US.

If straw is used in the walls it should be carefully sourced to be free of mould and pesticides. When building with cob, adobe or light clay straw there needs to be a dependable dry season of three months for the walls to dry out properly. They are particularly suited to be heated with wood stoves as that dries out the walls well in the rainy and damp seasons (source: Econest). An above grade stem wall and proper drainage around the house is also very important to keep the walls from getting damp.

I'm hearing some bad stories of mould forming on cob and straw bale homes in cold climates.

Rammed Earth from

Another natural wall system worth mentioning in a little more detail, Rammed Earth, uses sand, gravel and clay and has had an interesting development recently. Foam has been added for insulation and steel for support, and 5-10% cement is added to the clay mixture. It's called Stabilized Insulated Rammed Earth.

Water does not penetrate the walls, however concrete, especially when not climate controlled is extremely prone to mustiness.

Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

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