Renovation & Design
Question: My house was retrofitted with a heat recover ventilator (HRV) system a number of years ago. Both of the home’s bathrooms had ductwork retrofitted at the time to connect to the HRV system.
The two bathrooms also have ceiling exhaust fans, vented to the outdoors, that were original to the house. The fans are still in place and functional, but have not been used since the HRV retrofit. From time to time, especially in winter, the air in the bathrooms is noticeably cooler than the rest of the house, as well as having a fresh air scent, as if a window has been opened. There are no windows in either bathroom. The cool air in the bathrooms doesn’t seem to be related to whether or not the HRV is running.
Is it possible that the existence of the ceiling exhaust fans has put the HRV out of balance, resulting in outdoor air being drawn into the bathrooms? Would it be advisable to remove the ceiling exhaust fans and their ductwork entirely? — Allan, West St. Paul.
Answer: Periodic balancing of your HRV is a very good idea, to maintain proper operation, but keeping the older ceiling fans in place may be a more likely cause of the cold air intrusion in your bathrooms. Removing and/or sealing these may help warm the cooler rooms, but regular cleaning, servicing, and balancing or your HRV should be done, regardless.
There may be several factors that are causing your bathrooms to be colder than other rooms in your home. These may include location of the rooms, proximity to the furnace, uneven attic insulation and ventilation, or an improperly functioning HRV. The first item to address, which is quite normal, is that bathrooms do not typically have return air registers or ducts installed. Because these are not present, airflow may be more restricted than other rooms, especially when the door is closed. Because the warm air coming from the heat register does not have a direct path back to the furnace, warm air circulation may not be as good as elsewhere.
Also, most bathrooms have at least one exterior wall, which may be on the north or west side of your home. These are the walls that are typically the coldest, due to the lack of direct heat from the sun, and the prevailing cold winter winds. These two factors combined could make the bathrooms colder than others, even without any of the other variables taken into consideration.
The possibility of the ventilation system being imbalanced may be a factor in colder bathrooms, but other malfunctioning components of that system may also be to blame. Especially with retro-fit units, I often see controls that are improperly used or not proper set up correctly.
In my opinion, the HRV controls should only be used by setting the dehumidistat for a desired relative humidity (RH), and manually when a shower or bath is taken.
The manual controls in the bathroom should be simple, with the HRV turned on by a simple finger touch. These may be automatically set to run for a specific length of time, or have optional timed buttons to select.
The main control, often installed beside the thermostat for the furnace, should have a functioning dial or touch control with variable settings based on RH. These should typically be set around 30 per cent at normal room temperatures, for a typical Manitoba winter. When the RH in the home exceeds this setting, the unit should run until the humidity drops below your chosen level.
Many HRV systems have controls with multiple options, especially newer models. These include timed cycles such as 20 minutes on and 40 off. They may also have several speeds and an option for continuous ventilation. If these are overused your home may be come too dry, or other problems can occur, like uneven room temperatures. If your system is not well balanced, and the HRV is running too often due to a timed setting, the interior of the home could become depressurized.
This can cause cold air to be drawn in through small openings in the building enclosure. The solution to any of these issues is to call a heating, ventilation, and air conditioning technician, who has lots of experience with your particular brand of HRV. They should measure and balance the system, as well as ensuring the dehumidistat on the main control is working3.Once completed, try setting the control around 30 per cent, plus or minus five per cent, and see if the bathrooms warm to your satisfaction.
If the HRV servicing and resetting does make any difference in bathroom comfort, then dealing with the older ceiling fans is warranted. These units became redundant as soon as you had your HRV installed. Because of this, sealing or removing them should not affect anything significant in the indoor air quality in your home. Because these units have not been in use for some time, there could be some damage to the components, which is letting cold air infiltrate your bathrooms.
The first suspect would be the vent hoods, which typically are mounted on the roof or the exterior wall near the bathroom. These have dampers which function to keep cold air from entering the ducts when the units are not blowing air out. These can easily become damaged, warped, or dislodged, which would certainly allow cold air intrusion.
The ultimate solution to this potential problem is to remove the hoods, ducts, and fan housings and properly seal and patch the openings in the ceilings and the roof or exterior walls.
An improperly set up or operated HRV could certainly cause a negative pressure inside your home that would make the bathrooms feel cold and drafty, but abandoned ceiling fans may be a more likely cause, especially if the vent hoods or dampers are damaged. Proper HRV servicing and settings, combined with removal and air sealing of the old fan components should ensure your bathrooms are as comfortable as possible.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
Question: I have a bungalow built about two years ago next to the Red River in Grand Forks, N.D. Last fall I started noticing cracking in my basement and garage walls and ceilings.
The problem continued until mid-November and resulted in significant cracks. Recently, I started to see new cracks slowly begin to appear. There is noticeable heaving in the middle of my basement floor that appears to be causing the issue. I estimate about an inch of movement.
The confusing thing is my sump pump has never run, even though all my surrounding neighbours were running their pumps nonstop this fall and into the winter. I assume the problem could continue, and potentially worsen, as spring approaches.
In your opinion, what is the best course of action to prevent or minimize additional damage in the short-term and what can be done to correct this issue long-term? Any assistance would be greatly appreciated. — Gerald Muizelaar
Answer: The problem causing the cracking in your home is undoubtedly a defect in workmanship in the lower level wall construction and may also be a problem with your weeping tile installation. I would definitely consult the builder to rectify the defects, hopefully under some kind of warranty. If that avenue is not available, you should immediately call a reputable general contractor, with a decade or more of experience, to evaluate the problem and repair the basement walls and weeping tile as needed.
I cannot speak to the quality or experience of homebuilders in your area south of the border, but problems like yours are normally due to a lack of experience and poor workmanship in new homes. I can tell you that heaving and cracking basement floor slabs is a constant problem in both of our areas, especially close to our common Red River. To see a rise of an inch or more in the concrete basement floor is not without precedent, so the basement walls have to be constructed to anticipate this possibility. If they are not, they can easily push up on various areas of the main floor, causing serious cracks and damage to the drywall or other components.
Experienced builders and contractors in southern Manitoba know to install proper slip-joints in basement perimeter and partition walls, often referred to as floating walls. These are simply gaps left between double wall plates, or between the wall and the floor joists or concrete floor. These spaces are essential to allow for the inevitable movement of the basement slab on grade, due to the expansive clay soil beneath.
It appears to me the builder of your home either neglected to install any slip-joints in the basement walls, or left too small a space for movement. The latter may be the case, as your significant floor heaving showed the results of this defect after a couple of years post-construction. Regardless, the situation now calls for these walls to immediately be cut down to prevent further damage and allow repairs to existing areas, once the floor structure has settled back to normal. This may be easily accomplished in an unfinished basement, but yours will require partial removal of drywall and likely doors and trim.
The next item to address is the cause of the excessive basement floor heaving. I would have suggested that it may have been primarily due to condition of the soil beneath the floor slab at the time of construction, but the sump pump observations may be a red flag to something more serious. One reason could be a defect in weeping tile installation. This could range from a simple omission to unblock the ends terminating in the sump, to failure to properly install or connect the corrugated weeping tile pipes. The first place to look is in the sump itself, to ensure that the pump is operational and the weeping tiles are open. There also should be some water in the bottom of the sump, but it should not cover the tops of the weeping tile ends.
Most rooter companies now have one or more technicians who are equipped with a snake camera, which can take video of the inside of the weeping tiles, no matter the length. If nothing improper is seen, and the weeping tiles and pump appear to be functioning as designed, then the excess floor movement is just bad luck.
Problems associated with excessive floor movement in a newly constructed home are often due to poor installation of the basement walls, specifically missing or small slip-joints. The remediation and repairs should fall under a structural defect in most new home warranties, so contacting the builder or the warranty provider is prudent. If there is no warranty, or you are not covered, hiring a contractor to trim down the basement walls and fix any issues with the weeping tile and sump pump system should prevent a troublesome reoccurrence.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to firstname.lastname@example.org. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.