The Most Toxic Materials to Avoid in a New Build

1. Spray Foam

My number one priority material to avoid is two-part spray foam, this could be referred to as polyurethane, SPF, or “soy foam”. (“Soy foam” is still polyurethane).

Sometimes they try to obscure what it is by not mentioning it’s a polyurethane, by only mentioning the soy, castor, or other oil component.

I have found that it offgasses far more in real-life conditions than the perfect small sample the companies can make in a lab for the official testing.

You can use one part canned spray foam around windows and other openings that have to go through walls – that is usually acceptable for most people.

Sometimes two-part spray foam can go terribly wrong in the installation and that is an even bigger nightmare (Google: spray foam insulation lawsuits), but even with most average installers, I have found it offgasses noticeably for 2-3 years. 

Two-part spray foam also contains toxic flame retardants which is a priority chemical to avoid.

(Rigid foam also contains flame retardants but this is used on the exterior or under the slab. You can avoid rigid foam too if you like. See more insulation options here.)

You do have to consider avoiding spray foam early in the planning stages because it can have a major impact on your design (especially the roof, in some cases).

Any other insulation next to this is better, in my opinion. My top pick for most walls is Rockwool, my insulation post goes through all the healthy options.

2. High Offgassing Flooring

Sheet Vinyl 

Sheet vinyl resilient flooring is a high offgassing material compared to other options. I always avoid this.

You can use other sheet flooring, even plastic ones like polyurethane if you like, or Marmoleum to go all-natural.

LVP (luxury vinyl plank or tile) is much much better than vinyl sheet – the VOCs are really low (or even 0 in one brand). It does contain plasticizers though.

I would avoid phthalates (a plasticizer that we know is harmful to health according to mainstream sources).

The replacement plasticizers used in LVP are, so far, thought to be much safer, but I would prefer not to use flooring with plasticizers if that is possible (which would mean avoiding almost all vinyl floors).

Other vinyl products with high offgassing include mass-loaded vinyl which is used for soundproofing, vinyl roll down blinds and vinyl shower curtains.

Rubber flooring 

Used in gyms, this is really high in offgassing in my opinion. It’s one of the few floorings that can come in higher than 0.5 mg/m3 in VOCs.

If you are creating a home gym I have a post on non-toxic gym flooring.

SBR rubber is really only used in gyms, garages, and outdoor playgrounds.

Conventional Nylon Carpet

This is usually a high offgasser too, though most brands have been improving with time. Nylon carpets tend to be the carpet textile treated with the most chemicals (compared to polyesters and wool).

There are many synthetic carpets that are low in offgassing, especially the PET and PTT polyester varieties – though many contain stain guard chemicals which are usually poly and perfluorinated compounds (PFAS) – a high-priority chemical to avoid in most experts’ opinions. There are now many options free of PFAS.

Wool carpet, in a few of the specialty brands, is the best of the best.

Low and zero-VOC carpets are listed here.

Non-toxic area rugs can be found here.

You can greatly increase the VOC level by gluing down the carpet and by the use of some of the higher offgassing polyurethane carpet pads.

Epoxy Coatings

Epoxy coatings are, as a general rule, really harsh at first. However, they do come to a complete cure with time. This would be something I want to avoid if it’s new but not necessarily a problem when well-cured.

My top flooring picks are outlined in my Guide to Non-Toxic Flooring.

3. Certain Adhesives

Drywall Glues

I would avoid “glue and screw” drywall in most cases – that is gluing every piece of drywall to the studs.

That is usually a polyurethane glue which is quite strong and slow to offgas.

If they are doing this because it’s a high-performance house then you could still consider this, but look closely at the adhesives and safer alternatives.

(On the topic of drywall, the extremely sensitive may want to avoid premixed drywall mud, especially if they are skim-coating the walls. Use dry mix mud, it’s the same thing but without added chemicals which can really add up when it’s all over every wall). 

Subfloor and Decking Glues

Another place where polyurethane glues are used is in subfloors, especially Advantech subfloor (and roof decking) because the warranty requires it.

That is a good quality product, so if you have a good builder it would not be unusual for them to specify Avantech. But if you can, I would avoid these polyurethane glues.

You can use a plywood subfloor and decking and less potent subfloor glues like AFM Almighty or Lepage PL 400 which will work for most cases – talk to your builder about that.

Glue Down Flooring

I would avoid gluing down flooring (of any type) mainly because there are so many great non-toxic floors you don’t need to glue down, so this is an easy chemical source to eliminate.

(Though there are 0-VOC glues for many flooring types now, but some of those glues are slow to cure, even when they claim to be 0-VOC).

Countertop and Shower Stall Adhesives

Look at the adhesives used for the countertop and shower installation. This is probably going to be fine anyway, but it’s worth checking.

They usually use silicone to attach most countertops as standard procedure. But waterfall types need a stronger adhesive (and the standard kinds do offgas).

Many showers – depending on the material, are attached with silicone. AFM Almighty could be used in most cases if you prefer it. Both are good options for a healthy home.

Be sure to check the installation instructions and the warranty.

4. MDF & HDF

Medium-density fiberboard (MDF) and high-density fiberboard (HDF) offgas formaldehyde and at much higher levels than other engineered wood products. There is formaldehyde-free MDF but it’s rare.

The priority level at which I would place avoiding it depends on where it is used and how much of it is used.

I would put larger amounts of MDF higher up on this list and very small amounts pretty low. 

• I would avoid new furniture made with MDF and HDF. The bedroom is the highest priority to keep “clean”. My furniture post has lots of good options, many affordable.
• Avoid baseboards and other trim made with MDF, because that is an easy one to eliminate (use solid wood).
• Solid core doors almost always have MDF. They can have quite a bit of MDF (basically the whole door) or very little. Some solid-core doors use particleboard in the center. Hollow core doors are healthier due to a thinner layer of HDF and are much cheaper. 
• Cabinets – I would avoid MDF here and HDF if you can. The next step up is particleboard – less formaldehyde and most of it blocked with melamine and laminate finishes – but still, it does have formaldehyde and is not perfectly blocked. Depending on how sensitive you are/how far you want to go with avoidance (and your budget) you could save money here by going with cheaper cabinets like IKEA which are particleboard. Even better would be solid wood doors and drawer fronts with plywood boxes – Kraftmaid is the obvious brand to go with here. Their paints and clear finishes were really good too. Midrange prices (of course more money for the upgrade to solid wood/plywood). My cabinet post goes into more detail on IKEA materials, Kraftmaid, and even more “eco” brands.
• I would avoid flooring with an HDF or MDF core unless it’s formaldehyde-free and ultra-low VOC like Mohawk brand for example.

5. Certain Countertops

I would avoid laminate countertops since they are usually made with an MDF base and then the laminate is glued on top. If you have to go with laminate, here is a video on how to seal in the offgassing.

With real stone, you just have to test the sealers first. With light stones there are only two options I know of that are 0-VOC and PFAS-free. Mainstream sealers are PFAS-based. On darker stones, you can use walnut oil.

Or, make it easier for yourself and go for a countertop that doesn’t need a sealer. Quartz is a great choice for almost everyone, easy.

My main countertop post goes through all the options including non-toxic sealers.

Another post covers the costs of the most affordable non-toxic countertops.

6. Other

I would avoid conventional oil-based paint – still used on trim and doors in many homes (though not the norm anymore).

Water-based alkyd paints, also used on trim, are more potent than regular acrylic latex paints but far better than oil-based paint. My top zero-VOC paints are listed in that post. Trim paints are listed here.

I would avoid certain wood floor finishes like conventional oil-based solvent-based finishes and some specialty varnishes.

Your basic water-based polyurethane is fine for most people (if you are healthy or not particularly sensitive). Another good option is the natural oils. If you are very sensitive you want to dig into the least toxic brands.

Interior furnishings I would avoid:

• Furniture with flame retardants – not used much anymore but this was commonly used in foam furniture until recently. You could still find these chemicals used in window treatments.
• I would also avoid textiles with poly and perfluorinated compounds whenever possible. Safer upholstered furniture is listed here. Safer carpets here.

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Those are the top areas to avoid. If you are healthy and not chemically sensitive you could end the list there.

If you are chemically sensitive then you want to look at your individual sensitivities and your priorities on what you would most like to avoid.

For many of these items you don’t need to spend more – of course, a few are upgrades, but a few are actually downgrades (ie marble to quartz, and solid core to hollow core doors).

Related Posts

A related post covers ways to save money on a build while still building a healthy home. The emphasis is on where you can cut back so that you do have the money to spend it on areas that really matter to you.

Corinne Segura is an InterNACHI-certified Healthy Homes Inspector with certifications in Building Biology, Healthier Materials and Sustainable Buildings, and more. She has 10 years of experience helping others create healthy homes. You can book a consult here.

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