Sep 247 min read

Water & Mold Damage Prevention in Residential Design

Designing for occupant health is a trending topic in both commercial and residential construction. One of the biggest concerns is preventing mold growth in our homes, which can lead to many chronic health concerns and allergies. We're going to go over some strategies and tools you can use to mitigate interior water leaks and mold growth that are implemented in the design phase to ensure occupant health is a priority from early design conception.

Strategies for Water and Mold Damage Prevention

Many of the below topics are not considered to be 'standard' or 'conventional', no matter how simple they may be, so do not assume that they will be included in your project by either designer or contractor unless they are explicitly discussed and noted in the plans.

Plumbing Manifold Systems
Access Panels
Air Quality Monitors w/ Humidity Readings
Leak Detectors / Monitors
Shower Waterproofing Systems (Schluter, etc.)
Exhaust Fans with Humidistat Switches
Drain Pans with Trench Drains at Clothes Washer & Dishwasher
Shower Dryer Systems

These strategies can easily be integrated early in the design and construction document process, but many are difficult to retrofit once construction has begun

Plumbing Manifold Systems

This is a strategy for organizing and controlling the plumbing supply lines in your home. It can be done (2) different ways - a central manifold or distributed submanifolds. Fine Homebuilding has a great article here. The benefits to using a manifold system include more efficient water use, faster hot water, and control over water flow to each fixture from a central location in case of leak, damage, maintenance, or disuse. The only major downside is that is requires a lot more piping as each fixture (or submanifold) is piped all the way back to the manifold, water heater or supply location. The alternative and more traditional system is called trunk and branch, where there is a single hot and cold supply line that makes its way around the whole house and branches off at each fixture - meaning when you want hot water, you have to wait for it to pass by every fixture connection between the one you turned on and the water heater.

This is an entire plumbing strategy and should be indicated on plumbing plans long before construction begins as it influences the entire plumbing installation. If you would like a manifold system, discuss which type works best for your situation with your architect and then confirm that approach again with your contractor to ensure the project is bid with your preferences.

Access Panels

Concealed Access panel — Image from https://bauco.com/

This one applies mostly to second floor fixtures, but can be used for any fixtures where access may be a concern if there is a leak. There are access panels available today that are drywall faced and blend quite well with walls compared with the conventional plastic or metal ones that may come to mind. Installing an access panel in the first floor ceiling to access the plumbing lines going to second floor fixtures may save a lot of headache later on in the case of a leak or a suspected leak. Instead of having to rip out and then replace the drywall each time, you can simply open the access panel and assess the situation before causing any damage. Its the difference of a couple hundred dollars up front or a couple thousand later on.

If you would like access panels installed on your project, let your architect know early on so placement can be carefully considered and coordinated around lighting an other ceiling mounted items. The styling of the access panel should also be confirmed with the architect and the contractor to ensure you don't end up with a cheap plastic or metal one that stands out like a sore thumb.

Air Quality Monitors w/ Humidity Readings

There are a number of new products available that monitor your indoor air quality for quite a variety of important markers. These are just wall mounted or countertop monitors that can be placed where ever you are most concerned. Keep one in your wet rooms to monitor humidity levels so you know when to open a window or keep your exhaust fan on.

Carbon Dioxide (not to be confused with carbon monoxide) - which can cause headache, fatigue, brain fog, and similar symptoms when found in too high concentrations. High CO2 can easily be resolved by opening a window or otherwise bringing fresh air into the home
Volatile Organic Compounds (VOCs) - These are what you smell when you bring home new furniture or put up a new coat of paint. VOCs are found in paints, building materials, furniture, household cleaners, and similar products and high concentrations of these chemicals can lead to headaches, nausea, kidney and liver damage, and potentially cancer.
Particulate Matter (readings are usually looking at the PM2.5 microns or smaller and PM10 microns or smaller levels) - This is your dust, dander, pollen, pollutants, smoke, and the like. High PM levels lead to many health concerns, especially related to the lungs.
Radon - A naturally occurring odorless gas that is emitted from the soil in some locations.
Humidity - This is what is critical for managing mold. High indoor humidity creates the perfect environment for mold growth.

Below are a few options that we've seen, in no particular order. I personally have the Airthings monitors, but I have heard excellent reviews of the Aranet monitors and would likely purchase those if I were looking today.

Airthings IAQ Monitor
Aranet IAQ Monitor
Amazon Smart Air Quality Monitor
Awair IAQ Monitor
Inkbird IAQ Monitor
Temtop IAQ Monitor

If the system / devices you select are wireless, they don't need to be included in your construction documents. However, if you go with a hardwired system or chose to hardwire a system for EMF reduction, please let your architect know which system you'd like to use, and where you'd like them placed so they are included on the electrical plans.

Leak Detectors / Monitors

Whether it is the nightmare of coming home from vacation to a flooded home or the slow unknown drip of a dishwasher leak, indoor water damage often leads to mold and sometimes structural damage. For peace of mind and prevention, there are whole house Leak Detectors on the market now that learn the standard water usage patterns of your home and notify you when something is off. These monitors are installed on the main water supply line to the house and allow you to remotely shut off the water supply to prevent damage to your home. There are also stand alone water sensors that are placed on or around water using appliances to notify you if a leak is detected.

The whole home leak detector should be included in your plumbing plan and fixture schedule so it is installed and working during construction. The sensors can be installed in the finish stages just before or after your appliances are installed.

Here are a few systems we've heard of, in no particular order:

Moen - Flo Smart Meter Shut Off + Smart Water Detectors
Flume 2 Smart Home Water Monitor
Phyn Smart Water Sensor
Orbit B-Hyve Smart Flood Sensors
D-Link Water Sensor

Shower Waterproofing Systems (Schluter, etc.)

This topic will be self evident for some, especially those using a well experienced contractor. Wet rooms require careful planning and detailing to ensure their long term water-tightness. One of the best and most straightforward strategies is to use a comprehensive system that includes all the components required and provides training and direction on how these components work together.

By 'system' we mean a group of products that are designed to work together and include the substrate boards, the joint tape, the penetration seals, the drain, the tray, and the curb (where applicable). All of these components can be sourced separately and carefully installed by a knowledgeable contractor, but when in doubt, specify that you'd like it to be a complete waterproofing system.

Another little detail to keep in mind is to not have the shower head pointed at a horizontal surface (bench or shelf), as this with create a lot of wear and tear on that vertical to horizontal joint that is constantly exposed to pressurize water. And where you have a bench, shelf or niche inside the shower, use a solid material (like stone) on the horizontal surface. Slope that surface away from the wall, and include a slight overhang with a drip edge to prevent the water from running back to the vertical surface.

There are many alternate configurations to the one shown above, and other companies with their own proprietary systems.

Exhaust Fans with Humidistat Switches

Now, this is actually a code requirement in California, but I thought I'd include it here to help clients understand why they have a funny looking switch on their bathroom wall that automatically turns their exhaust fan on mid-shower. A humidistat is the smart sensor-switch that runs your exhaust fan any time the humidity reaches an established threshold. They are required in all bathing rooms and, when paired with a good quality exhaust fan, are one of the best lines of defense against mold growth in and around your wet rooms.

These sensors should be indicated on your electrical plans and will be checked during plan review.

Drain Pan with Trench drains at Clothes washer and Dishwasher

Washing machines and dishwashers are two of the most common sources of water leaks in the home, and they often go undetected for long enough to cause significant damage and mold growth. One sound strategy for managing this risk is to simply put a lipped drain pan under each of these appliances. Take that drain pan one step further and have it sloped to the front so you are alerted to a leak right away. Make this strategy nearly foolproof by installing a drain pan with a trench drain under each of these appliances. The trench drain will be connected to your waste water line, just like a shower trench drain, so any water mess immediately drains away while still alerting you to the problem by the visible presence of water at the front of the machine. Anyone with a front loader who knows the pain of cleaning the filter will immediately thank me for this mess-saving option.

All images courtesy of Killarney Metals

Shower Dryer Systems

A shower dryer? What? This may sound far fetched, but there is a newer technology available that uses carefully placed small nozzles to blow air throughout your shower for several minutes after a shower to dry all it's surfaces. At first it sounds crazy - but imagine never having to squeegee your glass or scrub mold or mildew from slow drying surfaces, or worry about mold growing because the bathroom just always feels moist. It is a real technology by a company called Airmada.