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Building a mold free house

Messages
39
I am in the planning process of building a completely mold resistant and healthy house to live in. For this, one would probably need to build with only non organic materials like glass, steel and plastics. This was the original intention.

However, after investigating Styrene (a common plastic for insulation and an alternative to concrete) a bit more, it seems to be toxic to humans. Both harmful to the endocrine system as well as being carcinogenic.

Then I researched concrete/cement, and this too seems to be toxic.

So, what can you use? Steel by itself does not insulate enough. Stone perhaps?
 
Messages
15,786
Then I researched concrete/cement, and this too seems to be toxic.
Concrete is the normal material for house construction in many (most? all?) European countries. The variety used in building houses shouldn't have any negative effects upon health.

A steel house would probably be incredibly expensive. Stone probably isn't allowed as a primary structural material (versus outer surface), due to not being stable enough, without a lot of reinforcement from other materials (concrete and/or rebar).
 

IThinkImTurningJapanese

Senior Member
Messages
3,492
Location
Japan
I am in the planning process of building a completely mold resistant and healthy house to live in. For this, one would probably need to build with only non organic materials like glass, steel and plastics. This was the original intention.

The perfect is the enemy of the good.

Conventional housing is remarkably mold-resistant when kept clean and dry. Many years and intelligent people have resulted in efficient and healthy housing for most.

As you are seeing when you try to improve upon current housing, you often run into problems.

No housing is completely mold resistant.

Unless, perhaps you keep people out of it. We exhale significant amounts of water, daily, which condense on structures that have cooled to the dew point and will then mold if they fail to evaporate this moisture back to the surrounding air.

If you want an alternative, this is a good place to start.

 

sarah darwins

Senior Member
Messages
2,508
Location
Cornwall, UK
One of the most important things you can do is install at least one air exchanger. These take the humidity out of a house with minimal heat loss. New builds in Canada require them because modern insulation and draught-proofing are so good that moisture can't get out any other way. Eliminating moisture is the key to preventing mould, which will find a way to grow in any house without excellent ventilation, regardless of the materials used.
 
Messages
2,391
Location
UK
We used to live in a house that got pretty damp in one corner and prone to mould (we lived near the sea and it was very exposed to the weather), and found that a decent dehumidifier (the portable ones you can buy anywhere) made a lot of difference. There was a bit of wallpaper peeling off the wall, and after a few days it started curling the other way - sure evidence the air was drying out. Definitely became much less prone to mould.

Also found that a good damp-seal paint applied to the wall before other decoration also helped a lot.
 

geraldt52

Senior Member
Messages
602
Having built a "healthy house", I can tell you that it is an endless series of compromises. What is perfectly healthy for you, might be unhealthy for me (wool carpet for instance). There are many books written on the subject and my best advice is to read as much as you can, with a skeptical mindset, before you begin. Buy small amounts of questionable materials and test your reaction to them before building them in.

As to mold, "dry" is more important than materials. Mold will grow on aluminum frame windows if they are constantly moist. The design should have adequate overhangs on the roof, with gutters and drains to get water away from the foundation. Be certain that the foundation walls are sealed and the crawl space or basement "floor" has plastic barrier underneath the gravel or concrete...no bare soil. Be especially sure that there are more than the required number of crawl space and attic vents for constant air circulation. Also be sure the framing is dried out before it is closed in, and it doesn't hurt to spray framing members with a bleach solution before closing in. As was suggested earlier, a dehumidifier, especially in the first year, will be a great help in keeping moisture levels under control.

FWIW, we were meticulous about the design and materials in our house, but it didn't improve my health or my wife's health at all...but at least it didn't make us worse, which is all too common in new homes.
 
Messages
74
Location
Toronto, ON
Beware of simple answers to questions that are more complex than they at first appear.

As someone that used to be "in the biz", my answer is 1) thoughtful, intelligent design with 2) construction from a knowledgeable, experienced contractor. As said previously, mold as about high moisture content and food source. Dry clean wood is not a mold risk. Concrete without admixtures is similar. But dust/pollution will accumulate on any surface with access to air, so yes, you can get mold on glass/metal. Also, it is not just whether it will get wet (must assume it will), but how long it stays wet. Wetting happens quickly, and you want things to dry before you get spore germination and propagation of the fungi.

Climate is one of the first considerations (part of world, sun exposure, mm/in of rain/snow, number of days with precipitation, degree days heating/cooling, wind exposure, desert/lakefront/oceanfront/forest, etc.). What the climate is will change my answer as to what will work. Experience has proven that the answer to 'what works' is 'it depends'. I admit @Cheesus, I too am partial brick-cladding and vented/drained cavity walls (with a nice overhang).

Dehumidifiers, air-to-air heat exchangers and other HVAC equipment can be key to performance, but cleaning and maintenance of these devices is also key, as they can easily be sources of mold themselves.

As @geraldt52 notes, there will be numerous compromises and trade-offs among: cost/time/sustainablity(material, energy, etc)/IndoorAirQuality/Thermal Comfort/Ventilation Quality-rate/Visual comfort-daylighting/life-cycle cost/longterm performance/maintenance requirements/resale value/ etc etc etc
 

boohealth

Senior Member
Messages
243
Location
south
The material you use depends on your climate. Hot/cold, dry/moist, or alternating. A good person to consult is Merrell Holley, he's an environmental builder.
 

junkcrap50

Senior Member
Messages
1,330
You should check out and thoroughly research these websites to start:
www.greenbuildingadvisor.com
www.buildingscience.com

The key here to building a mold free house is "building science," basically the science of temperature, moisture, and air control in wall and roof design and construction. Then, proper and leak (air and water) free window installation. Also, the climate or geographical location your house is in makes a differene. Strategies for New England vs Midwest vs marine like Seattle vs Texas vs Georgia are all different.

Also good for introduction to building science is this guy's youtube videos and blog: https://www.youtube.com/user/MattRisinger/videos His blog is less up to date than his videos. He specifically asks building scientists how to build a mold free house because he has had clients come up and ask for him to build mold free houses in a set of videos. So, check out these interviews: https://www.youtube.com/playlist?list=PLDYh81z-Rhxj07xJbCiNJ9AQKbHq5Y7X8

ICF - Insulated Concrete Forms are something to look up. They've been used in homes for people with highly sensitive asthma and multiple chemical sensitivity.

Unfortunately, the only people knowledgeable in building science and proper mold free construction are those contractors that build extremely air tight homes, ie: passive houses, zero energy, pretty good house, green homes, etc. You have to be very conscious of small details from the very beginning through the end, at all stages of construction, with all sub contractors, to avoid mistakes that can lead to mold or failure of your design. I've research this topic thoroughly and would use passive house architects and builders to build a conventional style house for myself.
 
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boohealth

Senior Member
Messages
243
Location
south
[Unfortunately, the only people knowledgeable in building science and proper mold free construction are those contractors that build extremely air tight homes, ie: passive houses, zero energy, pretty good house, green homes, etc. You have to be very conscious of small details from the very beginning through the end, at all stages of construction, with all sub contractors, to avoid mistakes that can lead to mold or failure of your design. I've research this topic thoroughly and would use passive house architects and builders to build a conventional style house for myself.[/QUOTE]

I disagree with this part--Merrell Holley is a genius, and George Swanson pretty dang smart too ("Breathable Walls"). And they don't necessarily build air tight homes.
 

geraldt52

Senior Member
Messages
602
Another thing I would caution on is considering that so-called "green" houses are "healthy" houses. As a for instance, recycled plastic products are considered "green", and encouraged in green building, but I would definitely not consider them "healthy" in a lot of applications. "Green" has come to be about "sustainability" in building, and the health of the occupants of buildings is not given the priority that chemically and environmentally susceptible people require.
 

junkcrap50

Senior Member
Messages
1,330
I disagree with this part--Merrell Holley is a genius, and George Swanson pretty dang smart too ("Breathable Walls"). And they don't necessarily build air tight homes.

I've looked at George Swanson's website and he seems to be consistent with those builders I recommend and seems to take the most logical building science approach if mold is your top priority. (However, I may have been overly inclusive with "air tight," including builders who are bad and don't know anything about building science.) Being airtight and George Swanson's definition of "breathable" (which he means to be vapor open/vapor permeable; breathing moisture but not air) are not in conflict. You can have a house/structure 100% air tight and 100% moisture proof. Air permeability =/= vapor permeability. He evens says so often including "(hygroscopic)" after "breathable"

However, I don't understand why he uses the term "breathable" then. It's not technically correct and further confuses the issue. He must do it to differentiate himself and his approach. "Breathable" is usually used by builders who purposefully avoid air sealing. You still want to air tightness even if you are 100% moisture open, because air leaks bring warmness/coldness and moisture to conditioned or unconditioned areas, which can then lead to mold build up (think hot, humid, exterior air leaking into cold home, condensing, leading to mold. Or vice versa).

I couldn't find anything on Merrell Holley, but I would assume his approach would be compatible with passive house builders/designers. The science is the science and will always win out. So, if he's successfully designing mold free houses, then his approach would work too.
 
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Messages
74
Location
Toronto, ON
@junkcrap50 link to BuildingScience.com is a good one. They have papers available, and "Dr. Joe" conveys material in an understandable way to many levels. There are two "Building Science Insights" in particular that I recommend.
BSI-001: The Perfect Wall including the " the 500-year wall".
Also, when talking about foam, it is interesting to hear his rant.
BSI-096: Hot and Wet but Dry - a perfect wall where? "New Orleans or Galveston. Hurricanes and humidity." However, I must disclose my bias for plywood over OSB.

And it is true that unintentional concentrated air leakage through walls or roofs can create very big problems.
 

Sean

Senior Member
Messages
7,378
Obviously house design and materials can play a big part, but if you really want mold free then move to a dry climate.

I live in the seasonal monsoon tropics, and mold is unavoidable during the monsoon season. Even if I kept my house 100% mold free (impossible, but even if I could,) the entire environment around me is still heavy with mold for up to 6 months of the year.
 

boohealth

Senior Member
Messages
243
Location
south
Dry climates have as many moldy houses as wet climates. Very few dry climates have the kind of year round air temperature where at no time do you want to heat or cool. As soon as you have a temperature/humidity differential btw inside and outside because of heating or cooling you have condensation possibilities in the wall cavity. Breathable walls allow diffusion, rather than trapping the condensation.

Old houses were build with breathable materials. Woods used were resistant (not completely of course) to mold, far more so than plywood or OSB, which mold in two secs. Plaster was breathable and durable. Old houses can get mold but it tends to be more benevolent, more like the outdoor mix in any given environment. New tight houses built with crappy materials get really bad molds that are virulent and fester.

YMMV...
 
Messages
39
I appreciate all the inputs so far, thanks.

Some comments and replies to some of you:

Cheesus: Bricks are probably good, but it seem that cavity would be terrible for mold. It sucks moisture into it. It looks like a breeding ground for mold. Correct me if I'm wrong.

Junkcrap50: ICF is something I've been looking into. My only concern is that it's made of plastic. When heated, who knows what kind of outgassing it does? Styrofoam (which is in ICF) has been proven to be a carcinogen and a xenoestrogen. Should it be cause for concern?

By the way, I just spent 3 months in the dry SW, and 90% of the hotels, apartments and houses I stayed in had mold issues. All buildings there are made out of wood and drywall and usually have bad ventilation.

Here's where I'm at currently:

1. Will build it in Nevada or Arizona
2. Frame will be made out of steel
3. Walls and flooring will be pure, thick concrete, with lots of glass windows
4. The whole house will be raised about 2-4 feet from the ground (hence, never comes into contact with it, and has no basement or crawl space)
5. All rooms will have small openings to the outside to ventilate 24/7
6. No HVAC system. For heating will use convectors.
7. Air conditioners will be portable ones and will be cleaned on a weekly basis, never turned off for more than 12 hours at a time during the warmer months.
8. Kitchen and most furniture will be made out of tile, metal or stone
9. No paint will be used
10. No water pipes will go inside the walls, but either outside

I'm trying to not just eliminate mold, but also eliminate all kinds of VOCs.

Any inputs on the above set up, or does it look more or less bulletproof?

By the way, this is a pretty cool house, made out of shipping containers:
http://www.homedsgn.com/2011/06/16/containers-of-hope-a-40000-home-by-benjamin-garcia-saxe/

As it is also raised from the ground, it should be very mold resistant.
 
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boohealth

Senior Member
Messages
243
Location
south
It's hard to say, because AZ and Nevada are very different...Nevada is drier. AZ has a high-ish risk of valley fever, from the whole Tucson to Phoenix corridor, for instance, partly because it is actually more humid and has monsoons. High altitude is a far different situation than low altitude, as well. The heat at 1-2000 feet is very intense; while the cold at 6-7000 feet can be quite extreme. So again, it depends on your climate.

You can use passive solar in either place, as well as active...
You can use minisplit a/c, they don't tend to mold.
 

antares4141

Senior Member
Messages
576
Location
Truth or consequences, nm
I
Junkcrap50: ICF is something I've been looking into. My only concern is that it's made of plastic. When heated, who knows what kind of outgassing it does? Styrofoam (which is in ICF) has been proven to be a carcinogen and a xenoestrogen. Should it be cause for concern?
I like this stuff:
http://www.homedepot.com/p/Owens-Co...sulating-Sheathing-37L/100320340?N=5yc1vZbaxx

Doesn't seem to outgas at all. I've used the more conventional styrofoam which is half the cost. And before I get de-sensitised to the smell it is noticeable. And as you say when heated, much more so. I made a camper for an old truck of mine with the stuff (Fomular) and covered it with visqueen which doesn't outgass much, like can't smell it at all when it's not heated but quite a bit when it is.
http://i185.photobucket.com/albums/x74/antares41_41/truck02_2.jpg
http://i185.photobucket.com/albums/x74/antares41_41/truck01_2.jpg

Also made a building out of what probably was Chinese drywall. It took about 5 years for the "drywall" smell to go away. I painted the inside twice hoping to make a vapor barrier nothing worked except over time it gradually went away.
http://i185.photobucket.com/albums/x74/antares41_41/house1_2.jpg

If I were going to do it again I would have used the foamular panels and made a much lower ceiling.

Actually I was thinking what would be interesting to do is make a 40x60 metal building on a cement foundation and build 12 8x16 foot units that would be cramped but might be worth the tradeoff for someone who want's to escape conventional housing. Most people can't afford to go it alone but if 12 people pooled funds it would be much more obtainable of a goal. And relatively cheap. A 40x60' metal building would probably only cost around 30 to 60 thousand maybe? You could make the individual units out of fomular and metal drywall studs.
Course you would have other expenses depending on where it's built. And you would maybe have to put in a communal kitchen, restroom, and storage facilities. Which could be added to the sides of the 40x60' building, by adding maybe 12' overhangs on each side. Face it east and west so you have passive heating on the south side.

Say the whole setup costs 100k, by the time you include running electric utility to it, a well, sewer, and things like that. Might add another 50k for the land in some remote location, with 20% down that could be financed by each member for around $800 a month maybe.

And it could be even cheaper if 2 people shared 1 unit.

Probably wouldn't be appealing to many, depending on how desperate they might be for safe mold and chemical free housing.
 
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antares4141

Senior Member
Messages
576
Location
Truth or consequences, nm
I

Say the whole setup costs 100k, by the time you include running electric utility to it, a well, sewer, and things like that. Might add another 50k for the land in some remote location, with 20% down that could be financed by each member for around $800 a month maybe.

And it could be even cheaper if 2 people shared 1 unit.

Probably wouldn't be appealing to many, depending on how desperate they might be for safe mold and chemical free housing.

Actually I fudged that, it would be $66 per person & roughly $800 for all the members combined. Which seems awfully cheap. Might want to double that just to make sure you account for any other things I might not have taken into account. Like maybe an air conditioning system. I was thinking out here in the desert you could spray water into the air, or make a simple "cooling tower" like some power plants do. That might reduce the temperature of the water to maybe 20 degrees below the ambient. So if it were 100 out here in S. C. NM it would be 80 inside. But you wouldn't be generating any condensation on the unit inside the building cause it wouldn't be cold enough for that. And because it would be just circulating water it would be easy to inspect and clean. Because nobody makes this kind of system the cost might be prohibitive though.