UPGRADE YOUR HOUSE Part 1: Is Your Home Slowly Killing You?

Updated: Jun 11

rot and mould in an abandoned prison

As much of the white-collar world - me included - gradually turns to working from home either part-time or completely, we are forced to confront both the intrinsic deficiencies of our homes and the ways in which they're not suited to quite the range of activities which they're now hosting. The home's function as a space for eating, sleeping, and sitting around to engage in mostly sedate recreation has been expanded for many people to include office work, videoconferences, virtual classroom learning and study, daycare, and more. Pressed into more sustained, intimate contact with what should be unwaveringly be a place of respite, you may now need to consider the question: is your home slowly killing you?

Over the course of this three- (or perhaps four-) part series, I will present the unseen hazards, the unrecognized failures, and the solutions to improve the quality of your experience at home and the impact of your home on your health and well-being.



In Canada, basically every occupied building has thermal insulation in the exterior walls. The insulation helps keep the building warm, of course, but it's almost a guarantee that the insulation is not doing its job as well as you need or even as well as the Building Code requires. Here are several reasons why.

1800s-1940s: THE CEREAL BOX

First off, the way that almost every thermal insulation works is by trapping many small pockets of air. Without trapping the air, a convection cycle within the wall turns warm air into cold air by releasing heat to the exterior. Many homes in central and Western Canada - including the greater Vancouver area - were built before the 1940s. There were no regulations governing how much insulation was put in the exterior walls, so builders often used wood shavings or crumpled-up newspaper - when they used anything at all - to limit air movement in the walls. However, over time, the shavings or papers settle and become a pile at the bottom of the wall just as you find happens in a bag of potato chips or box of bran flake cereal. Convection above the pile means it was a wasted effort.

colour gradient exterior thermograph of a 1930s house

For those who live in character houses, this is why even a mild winter can feel bone-chillingly cold and drafty. That 80-year-old house may have been renovated once or more during its lifetime, but it's almost guaranteed to have the same type and amount of insulation as it did when it was built. In the thermograph to the left, the yellow-orange-red area shows where heat is leaving the house through the walls and windows instead of being retained inside. The walls are losing nearly as much heat in most of the rooms as the single-pane windows.

1950s-1960s: FILL IN THE BLANKS

The middle of the twentieth century brought an upgrade to the crumpled paper and wood chips with the introduction of fibrous batting -- poofy wads that fit snugly between the wood studs. During the 1940s, the batts were made of fibreglass, by the 1950s batts were also fabricated from cellulose, and by the 1960s batts were available made of mineral fibres. All these batts were a large improvement and are still the primary form of thermal insulation used today. Since the late nineteenth century, exterior walls of wood-framed buildings were generally constructed of 2x4 studs (3-1/2" or 89mm wide) as that size suited typical structural requirements. Correspondingly, the batt insulation between the studs was 3-1/2" thick regardless of what the batts were made of.

1970s-1980s: BEEF IT UP

The 1970's oil embargo crisis and subsequent energy conservation movement caused American and Canadian builders to thicken the exterior walls to 2x6 studs (5-1/2" or 140mm wide) solely to provide more insulation. If you live in a residential detached or small multi-family building, that's what is in your exterior walls: 5-1/2" thick batt insulation. Generally, that's been good enough for decades. Or has it? During a cold snap, nearly any Canadian house will feel cold next to the walls and down at the floor even when the heat is turned up.

The insulation batting works where it IS; it won't work where it ISN'T. A wood stud transmits far more heat than is lost through the insulation; we call this a thermal bridge because it bridges the flow of heat from interior to exterior. The thing about wood-frame construction is that there are a lot of wood members in the walls. Averaging an entire house or apartment building, the actual overall insulation value of the walls is about 60%-70% of the value stamped on the insulation's packaging. Consider that at every window, every door, and every corner, there are extra studs; sometimes there is virtually no space left over for the insulation. In the thermograph below, the red and purple areas are where the surface is cooler; this is where the wood framing sits inside the wall and is transmitting more heat to the outdoors.

side-by-side comparison of room interior photo and colour thermograph

Structural studs aren't the only thermal bridges.; piping and electrical wiring all are often in the exterior walls, and there is little to no insulation at these locations. The last point to make here is that insulation batts must fill the stud cavities completely and fit snugly to perform well. Whether due to inexperience, haste, or just sloppiness, where the batting is poorly cut or fit, there are gaps that lower the overall insulation value.



scanning electron microscopic image of dust

Fresh air isn't just nice to have; it's a necessity. Fresh air replaces exhaled carbon dioxide, food odours, bathroom gases, body odours, and cleaning product fumes with oxygen. Fresh air supply also flushes out an accumulation of chemicals, dust mites, and... dust. Consider what dust is comprised of: dirt, dead skin, and hair but also fine, abraded particles from plastics, upholstery, hard furniture, clothing, glassware, wall paint, carpet, your shoes' soles or anything you walked through. The shed skin cells in dust also carry with them traces of personal care products, cosmetics, pollutants encountered outside the home (e.g. tobacco smoke, industrial fumes, vehicle exhaust, tire dust, ink), pollutants encountered inside the home (e.g. food particulates and fumes, cleaning products, heated plastic of any appliance or consumer electronic), and any of the plethora of things you touch over the course of a day, such as metal door handles and faucets whose finish wears off (onto people's hands) over time.

That's just what YOU brought into the building yourself. An even wider range of undesirable compounds and organisms exists outside, and they can and do find their way into your building. You obviously do not want to be breathing all those things into your lungs and inviting them into your bloodstream.

But that's exactly what's been happening.

I go into more detail about this indoor air pollution in my article How to Improve Your Home's Air Quality.


Let's go back to the middle of the twentieth century. Many office buildings were built as the trend of urbanization increased after WW2. Most of them were constructed of aluminum, steel, and glass instead of brick and timber as the International Style was the dominant architectural vernacular at the time. This construction shift allowed the buildings to be more airtight than the drafty buildings built a couple decades earlier. Unfortunately, ventilation calculations were hitherto based on higher ceiling heights and less airtight buildings. Ventilation advancements mid-century were focused on cooling spaces inside the buildings which now featured far larger windows. Occupants increasingly reported poor health as a result of inadequate airflow. Thus began the phenomenon called "sick building syndrome" - the pattern of complaints that started in the 1950s and is still poorly understood despite continuing to late in the twentieth century.

Apartment buildings built after WW2 also were constructed in the International Style and consequently were more airtight. If you're familiar with one of these three-storey walk-ups built during the 1950s or early 1960s, you'll note that there is no exhaust fan in the bathroom nor exhaust hood over the range in the kitchen.

The air inside the building is pulled out by one, centralized exhaust fan that draws a small amount of air in through the grilles in the kitchens and bathrooms from all the suites. The resulting negative pressure draws some fresh air in through the windows (whether closed or open), doors, and even the walls. There is no direct, forced supply of fresh air to the suites, and quality of the interior air is often quite poor as a result.


Newer, mid-rise and high-rise apartment buildings are still designed with basically the same concept but turned around. An exhaust fan in the bathroom, another in the range hood, and another from the laundry dryer pull air out of the suite directly to the exterior, and another, central fan - called a 'make-up air unit' (MUA) pumps fresh air into the building to try replace the air lost from all the individual exhaust fans. However, the walls are still generally not really airtight. Depending on wind conditions surrounding the suite, the exhaust fans may not be able to overcome low air pressure trying to pull air through the walls; the result is stagnant air inside the apartment. Even when the system does function as intended, the air coming in through the MUA is hardly filtered and the air coming through the walls or open windows is not filtered at all. Taller apartment buildings are usually located in more dense, urban areas where air pollution is higher. While the filter on a MUA is designed to remove larger particles such as pollen, some dust, and mold from the air; it is not designed to stop smaller particles such as smoke, allergens, and viruses.

How does all this relate to a house? Houses that use electric baseboard heaters or water-filled radiator cabinets have the same problems. A house built before 1940 - usually heated by steam-filled radiators - relies solely on its air-leakiness to provide ventilation. The radiator pipes or fireplace chimney induces a small convective current upward. A house or apartment building built after the 1950s - one heated by electric or hydronic baseboards - relies on the kitchen, laundry, and bathroom exhaust fans pushing air out and the fresh air coming in through open windows and gaps in the walls and roof. Some houses and condo buildings use in-floor radiant heating provided by electrical resistance or heated water, but the basic premise is the same as the fireplace stove of the 1800s: hot element inside the building heats up the air. Air that enters the house is entirely unfiltered. The accumulation of contaminants indoors worsens the air quality further. Heat distribution in a home that uses radiators - electric, steam, hydronic, chimney, or whatever - is non-uniform; air is warmer only near the heat source. Further away and in corners of rooms or windows, the air is damp and cool; condensation occurrence is more frequent, and the likelihood of mould growth is higher.

black mould growing around a white window frame

Old buildings that leaked heat were wasteful and drafty, but the constant loss of warmth and air kept the walls relatively dry. When more insulation was added, the relative humidity indoors went up. Remember the explanation of thermal bridging above? Those thermal bridges create spots where the surface temperature is cooler. When it's lower than the dew point, water vapour condenses on the surface; if the movement of air is too low to dry out the condensation, mould - a type of fungus - has a greater chance of forming. It can develop on the surface, but it also sometimes develops inside the wall. The fungus releases spores and typically is believed by most to cause health problems for the occupants. It correlates well with occurrences of "sick building syndrome". The buildings were arguably making their users sick.


The common method of heating houses in Canada since the 1940s is a forced-air furnace -- the giant, often-gas-fueled firebox with a large, noisy fan, usually in the corner of some small, dark room that nobody goes in unless the pilot light has gone out. The furnace has a fan that draws cool air in from outside, heats it, and blows it through the house. Some air is pulled out through the exhaust fans and some returns to the furnace to be reheated. While this is a more reliable way of getting fresh air into the house than a static hot element, there are two disadvantages. First, during the approximately six months of the year that the furnace isn't required and therefore not pulling in fresh air, ventilation is as poor as it is in a house with no furnace.

Second, the amount of dry, outside air being pushed through the house to meet the heating demand during the worst times of the winter brings the relative humidity indoors down below the healthy range. Below 40% relative humidity, occupants report a drastically higher frequency of respiratory issues. The quality of the mucosal lining of the respiratory tract decreases and diminishes the ability of the body to trap airborne contaminants and pathogens. Additionally, dry air typically leads to dry skin that may crack and bleed, and dry skin is a less effective barrier against bacteria, viruses, and other pathogens and against many harmful chemicals.



Once people began to realize that mould growth was related to an increase in the number of health problems, building science expanded to study indoor air quality (IAQ) more closely. The middle of the twentieth century brought new synthetic materials to building construction. As buildings were constructed to be less leaky, the gases - volatile organic compounds (VOC) - given off by these products were accumulating indoors and contributing to the sick building syndrome. The response was a two-fold change in approach to building design.

First, systems such as Leadership in Energy Efficient Design (LEED) required the use of materials with a lower VOC content. The success of this strategy was initially hampered by a drop in performance by new low-VOC products but was gradually resolved by continued product research and development. The second change in building design was driven by the building codes' new requirement for a barrier in the building envelope (the walls, roof, and floor) to limit the amount of water vapour and air moving through the assemblies.


plastic sheeting and construction netting enclosing a Vancouver leaky condo building during repairsbuilding

In theory, an in-wall barrier to air and vapour movement is a great concept. However, these barriers - technically called retarders since they restrict the flow of air and vapour instead of stop it completely - as they were implemented eventually created problems bigger than those they were intended to solve. Almost two decades after the introduction of proper insulation in the 1930s, everyone's paint was peeling off. Building regulations by the 1950s required a barrier to water vapour from moving through the exterior walls. By the 1960s, the use of a clear, plastic sheet called polyethylene as an approach to achieving a vapour AND air barrier in residential construction - single-family homes and apartment buildings of all sizes alike - was common, and today is still nearly universal on new residential construction in North America.

Polyethylene sheet is non-porous, waterproof, and has a very high resistance to water vapour. When placed on the interior side of the thermal insulation, it prevents warm, moist air and water vapour from the indoors from migrating through the insulation to the cold exterior where the moisture would condense... so long as it's continuous - but more on that later.

During the 1980s, advances in polymers yielded a product system called Exterior Insulated Finish System (EIFS). The EIFS could be installed on large areas of a building face under construction in a short period of time; hence it was relatively inexpensive. The product has a stucco-like finish - suitable to the California aesthetic popular at the time - and is comprised mostly of expanded polystyrene (EPS a.k.a. "Styrofoam") and therefore provided more insulation for the wall. The EPS panels were adhered to the building wall with newly-developed sealants and sealed to each other with more new sealants. It was viewed as a bit of a wonder-product. I'll interject at this point to say that EIFS is a great system when configured, detailed, and installed correctly.

bench in the rain viewed through window covered in raindrops

However, the EIFS was not configured, detailed, and installed correctly in the vast majority of buildings. The product system is nearly vilified, but it would be fair to point out that inadequate detailing and installation caused the failure of other cladding systems at the time also. Without getting too technical, the failures resulted in rainwater entering the walls. Vancouver Island and the Lower Mainland of BC are in what is classified as a temperate rainforest region, so there's plenty of rain for much of the year.

Before the 1930s, the warm air escaping from the interior would simply dry out the wall. From the 1950s to the early 1980s while polyethylene prevented most of the warm air from escaping, there was still some warmth radiating outward and drying out the wall to the outside. However, the EIFS was designed to prevent water from getting through it. Water that did get through gaps and cracks became trapped. It pooled near the bottom of the walls and in areas where the adhesive was not properly applied. It was prevented from evaporating to the outside by the moisture-resistant EIFS panels. It was prevented from evaporating to the interior by the lovely polyethylene sheet. Moisture lingered and accumulated. And accumulated. The wood framing rotted. (Before you suggest steel studs, they had their own scandal in Eastern Canada around the same time, rusting out to leave chunks of brick wall to fall off the buildings.) Buildings failed, and people died. Less dramatically but far more costly to the entire development and construction industry in BC, the moisture in the walls gave rise to large amounts of mould that turned large portions of the insides - and sometimes outsides - of walls black. In worse cases, the water was driven via osmosis to the interior of the building - previously-accumulated water migrating even on a sunny day.


Building codes continued to require greater amounts of insulation. Concurrently and since the 1970s, governmental campaigns urged homeowners to invest in sealing drafts. However, the two streams of advocacy failed to merge until the mid-2010s and then only in some jurisdictions. Remember that the polyethylene vapour barrier works effectively if it's continuous. There are invariably gaps and unsealed penetrations; they're all inside the wall, so a homeowner generally cannot fix the defects. Heated, moist air from the interior will be pushed or pulled - whether by local wind conditions, by furnace pressurization, or just by diffusion - into the wall cavity. The moisture moves outward until it reaches a cool enough surface upon which to condense.

Residential construction is inherently leakier than commercial (office, retail) and institutional (schools, hospitals, civic) buildings. Even most luxury homes are built no differently regardless of the beautiful material finishes, high-end appliances, state-of-the-art controls, and building size. The building code still does not really require the thousands of leaks to be addressed. A house built in the past year almost certainly is feeding moisture into the wall, and small amounts of mould may be developing.



The building industry is still chasing technical correctness in the design and construction of the building envelope and pursuing good indoor air quality, but the experience upon which it is basing its strategies may be becoming obsolete for many cases and will likely become less valid as time goes on.

2020: The Rise of WFH

overhead photo of man at home workstation with multiple computer devices

People in office occupations have increasingly been working from their homes. Many households were until mid-2020 emptied of children and one or two adults during the day. Those adults and children previously were spending 8h or more of every weekday - half their waking hours - in environments designed to address the lessons learned in the second half of the twentieth century.


Problems and design weaknesses that have existed in residential buildings - houses, townhouses, rowhouses, and apartments or condos - but gone unnoticed may begin to present themselves as people spend all day at home. We could easily expect to see an increase in reports of occupant illnesses for the same reason as was determined in the 1950s - inadequate fresh air. The situation is not quite the same though. A home is generally less crowded with people than is an office, so the rate of carbon dioxide buildup is lower. On the other hand, a home may have a greater diversity of contaminant sources; food is cooked in the open, the bathroom is closer to the area in which one works, and all of the household cleaning supplies and personal care products are just below the sink. Many of those who would have gone out for lunch while at the office or gone out for supper are now making lunch at home or are ordering in from a food delivery service. A greater amount of household activity combined with doubling the amount of time spent in that environment is a stress test for the home's ability to provide adequate fresh air. Recent updates to building codes are increasingly requiring airtightness testing as a construction requirement to help reduce wasted energy on heating or cooling indoor air.


indoor photo of pendant light fixtures over an old kitchen counter

Another element to consider in the suitability of the environment for the additional roles of office work, videoconferences, virtual classroom learning and study, daycare, etc. is lighting quality, and that includes natural daylighting. The discussion on this topic is manifold, but each facet is fairly easy to understand. First, you need to have the right amount of light so that you can see what you're doing and so that you're not straining your eyes. Required light levels in offices is based on paperwork tasks. Your kitchen lighting is generally suitable, but lighting levels elsewhere in the house are much lower; that level is comfortable for other uses but not for paperwork. Second, the location of the light needs to provide appropriate illumination of the working surface; that bedroom light or living room floor lamp does not give the same diffuse lighting as is designed in an office or other public space. Third, the type or quality of the light source impacts one's comfort level. Office spaces generally feature fluorescent lighting but increasingly are outfitted with LED lighting. While LED lighting is far more available for home fixtures and provides a higher-quality white, the diffuse lighting in an office has a 'softening' effect on the light that reaches your eye since it first bounces off of and 'picks up' the colours of many things in the room. A lamp in a room at home is usually sending its light untempered straight to your working surface, and that can make things look a little 'off'. Fourth, you may be coming to terms with unshaded sunlight or other sources of glare interfering with your work. Maybe you can't see your screen, or the sun's reflecting off of it right into your eyes. Office buildings have been slowly adjusted or designed to prevent this glare, but you weren't staring at a monitor in your living room to know that the same thing would have happened there. For those that want or need to present themselves well on videoconferences (i.e. no blue-face nose-cams), lighting quality of the face is difficult to achieve when there's a small amount of blue daylight coming from one side of you and yellow light from that task lamp on the other side. In conclusion, the lighting requirements and consequently lighting strategy in your home is entirely divorced from your new working needs.


Another, less significant but not irrelevant consideration is acoustics. Again, the office space has been learning lessons for decades. T-bar ceilings are ubiquitous and attenuate sound reflected off of them. Your drywall ceiling at home does not. Many offices have an open plan - some of them with full-height or low cubicle or 'pod' walls that interrupt and reduce that amount that sounds travel. In contrast, your voice is echoing around that little home office of yours to your zoom audience and anyone calling in must be wondering if you've fallen down a well.


The last aspect of a healthy indoor environment is the psychological one. Many people have been working off the kitchen table, a corner of the bedroom, or maybe a windowless den. Instead of seeing an assortment of visitors and couriers come to the office, you're now lucky if birds are flitting about outside your window. Your co-workers are no longer physically present to chat with or provide painfully colourful distractions, but your cat - probably annoyed that you haven't left the house - isn't willing to take up the slack (except when you actually do want to get work done). Even a small office has a variety of spaces even if they aren't particularly comfortable. Your 1-bedroom suite hasn't suddenly developed a new and interesting hallway to get to the bathroom, and there's only so much a new set of hand towels can do to revitalize a space. If you have a house, the garage might be a nice change of pace, except the WiFi there sucks. The time has come to re-evaluate the quality of one's experience at home; it's being asked to do something for which it was not intended.



In my next article "The Solution to Your Sick Home", I will continue my ramble by showing how we escape our new prisons and how the home can be a place to thrive - not just a box in which to survive.