Renovation & Design
Renovation & Design
ASK THE INSPECTOR: Fresh-air intake will help balance air-pressure differential
QUESTION: I reside in a 60-year-old split-level home in North Kildonan. The home has a crawl space beneath the first level, about four feet high. The crawl space has a heat duct providing warm air to the space.
When I purchased the home in 1984, the original crawl space had a gravel base with tar paper on top. Over the years, I insulated the walls with blue foam-board insulation bonded to the concrete walls. Plus, on top of the board I used bubble/aluminum insulation wrap bonded to the foam-insulation board, then filled in the spaces where the joists are with panels of foam board.
I covered the gravel floor with poly and went up the walls about five inches, then I placed fibreglass reinforced poly tarps on top of the poly and sealed all seams with duct tape and aluminum metal tape. Where the floor poly met the walls I used 12-inch-wide aluminum backed with sticky black rubber to bond on the floor and the wall, thus sealing the envelope. This sticky aluminum/rubber tape is the type used for valley flashing on a roof and I thought that it would be the ideal seal between the floor and the wall, which it is.
The floor tarps billow upwards, indicating air entering through the gravel base. How can air enter from below the home with enough force to cause this billowing? This has become more apparent once I completed the seal with the valley flashing material.
I placed a hygrometer in the space, and it remains fairly constant at 35 to 37 per cent. What do you think is going on with the "billowing"?
Thanks, Dave Magrel
ANSWER: Initially, I want to commend you on the excellent job you have done insulating and sealing your crawl space from the living space. While it's a bit of overkill in some areas, that is often a good idea when it comes to moisture prevention, and your RH readings confirm that. Unfortunately, the excellent job of sealing the poly and tarps is part of the reason for the strange billowing of these covers.
The main reason to install plastic sheathing over the floor of a dirt crawl space is to prevent the heated air of the home from warming the cooler soil and drawing moisture from that soil into the living space.
A secondary reason is to prevent soil gasses, such as radon, from entering the home where it can harm the occupants.
Your double-layered air/vapour barrier appears to be accomplishing that task remarkably well. The diligence you have shown in sealing every seam, especially at the floor to wall junction, is preventing small gaps or holes in this membrane.
It's quite common for these to occur during installation, or later, due to storage or traffic on top of the polyethylene sheathing. The secondary layer of plastic tarp is likely preventing any physical damage to the poly, while adding another well-sealed layer of protection against air leakage.
While your high-quality air-sealing methods are preventing air from infiltrating your heated living space, they can do little to prevent air flowing into the soil beneath this area. There is a chance that you have weeping tiles installed around the foundation of this part of the home. If they have interior connections to a sump in the crawl space, this may be where the majority of the air is coming from. You have not mentioned a sump pit, but there still may communication between the soil in the floor of the crawl space and outside weeping tiles even without it.
Even if there is no weeping tile system for the crawl space, air can easily gain access to the sub-membrane soil from outside. The soil outside your home is quite porous and is not much of an impediment to airflow. In recent years, with very dry summer weather, significant gaps are often seen between the shrunken soil and the outside of the foundation. These gaps can allow a larger than normal amount of air infiltration to the soil under the shallow grade beam foundation of this part of your home.
Why this air causes the membrane to billow upwards is a more technical question. The reason for this can be explained by discussing air-pressure differentials. While this sounds very complicated, it's a pretty simple concept.
Air will always migrate from an area of high pressure to one with lower pressure. Because the building envelope of your home may be quite airtight, especially in the crawl space that you have super-sealed, there may be little chance of air infiltration. When you run your bathroom or kitchen exhaust fans, dryer, fireplace or older heating equipment you are drawing air out of the home and mechanically forcing it outside. This may cause a drop in air pressure inside the home, which tries to compensate by drawing in replacement air from outside the building envelope. If this is too tightly sealed, with no fresh-air intake for replacement of the vented air, negative pressure will be maintained. This will cause the higher pressure air outside the home to be drawn into any area where there is a small gap or opening to the exterior environment.
In your case, this air is being drawn into the soil underneath the crawl space membrane, but is not able to penetrate due to your excellent sealing methods. Because the membrane is very light, the high pressure air can cause it to lift up as it seeps into the voids beneath.
While it may seem to be a defect, the only concern with the lifting membrane is that is likely showing us a significant low pressure situation in your home. To prevent the membrane from lifting, covering it with a thick layer of sand or pea gravel may do the trick, but I would also explore installation of a fresh-air intake duct or HRV to help balance the air-pressure differential this is illustrating.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors - Manitoba (www.cahpi.mb.ca). Questions can be e-mailed to the address below. Ari can be reached at (204) 291-5358 or check out his website at www.trainedeye.ca.
trainedeye@iname.com
Renovation & Design
Have fun decorating in psychedelic '60s style
Dear Debbie: I have a medium-size office at home that I would like to redecorate with a 1960s theme. Any suggestions you have to get me started would be helpful. Thank you, Janice
Dear Janice: The '60s were an iconic, forward-thinking period that heralded bright, bold, sweeping changes in all aspects of living. Fifty years later we are loving it all again, celebrating the Beatles everlasting rock 'n' roll, sporting short skirts, soft floppy bobs and the tie-less dressy look for men. We love to hear it, wear it and decorate with the same brave style. It's pure fun.
I can envision your '60s-style office with clean-lined furniture and fabric or wallpaper that showcases the era's eclectic mix of geometric designs and bold colours. I would start by checking out some wallpaper companies that have revamped '60s wallpaper for today. Graham and Brown have a good selection, including Carnival by Hemingway Design shown here. This daring print of lozenge blocks in black, white and zesty orange would set the mood as a focal wall -- the rest of the room painted white.
Moulded plastics came into the spotlight in the '60s, showing off sculpted chairs with no hard edges and colour galore. Vernor Panton's plastic, cantilevered "S" chair is a classic, as is Pierre Paulin's little tulip chair. These space-age styles transformed homes and offices 50 years ago and are still doing so now. Teak furniture was all the rage in living room and dining room sets. See if you can find a slim-lined Danish desk, but whatever you choose keep the desk design simple.
Good lighting is an essential element for any office. You can stay with your theme with pendant lights that have either brightly coloured or metal globes and hang directly over your desk. Or choose a banker's lamp with a lamp that swivels, or an adjustable desk lamp in a space-age-shaped globe.
Furniture stores are capitalizing on the Retro style and offer new pieces that copy or complement the '60s. There's lot of vintage stuff on eBay and secondhand stores. You can mix and match what you have with a few new purchases. The wallpaper alone makes the statement. Have fun, and enjoy your work.
Dear Debbie: I have a '60s antique brick fireplace that takes up an entire wall in my step-down family room. The bricks are various shades of pink. I have read conflicting views about painting the brick. I'd like to update the room and it doesn't get much light. What do you suggest? Benita
Dear Benita: There are always many solutions to the same decorating dilemma, so it's up to you to decide which suits your needs and taste. Since you are planning to update your room, think about the overall mood and style you would now prefer. Check out rooms on the Internet that have painted brick fireplaces to get some ideas. Once the bricks have been painted, it is very difficult to return them to their natural state. But, because there is little light in the room, I suggest you paint the entire brick wall matte white. Your family room will take on a brighter aspect as the brick wall will no longer appear heavy.
Debbie Travis' House to Home column is produced by Debbie Travis and Barbara Dingle. Please email your questions to house2home@debbietravis.com. You can follow Debbie on Twitter at www.twitter.com/debbie_travis, and visit Debbie's new website, www.debbietravis.com.
Renovation & Design
ASK THE INSPECTOR: Solving the mystery of the frozen lock
QUESTION: My son and his wife have a relatively new house, about five or six years old, and every winter their front door lock freezes so you cannot put a key into it.
This winter, the door itself has even frozen, so it's almost impossible to open the door from the inside, which obviously is dangerous. They've been using the garage-to-house door of the attached garage, but this winter that door has had problems freezing, so they don't lock that door. Using lock de-icer doesn't do anything.
On a very sunny day the lock on the front door will thaw, but when the sun goes down it freezes again. I have since heard of a couple of other people in newer houses having this same problem.
One locksmith was called and said it was a cheap lock and replaced it with a Weiser, but the problem persisted. My old wooden door on an old house has never had this problem.
Could the problem be the newer steel doors on new houses? You can't see water leaking anywhere near the door or lock, so it must be something internal. Thanks, Kathy Youngson
ANSWER: It seems simplistic to say the root of all home maintenance problems can be traced back to water, but in most cases that is true. Moisture can damage many building materials, whether from precipitation or from human activities, but can also lead to other issues. Your son's problem may appear to be with the doors, but you are correct that the true culprit is much more insidious and coming from within their house.
The scientific explanation for the frozen steel insulated doors in your son's newer home may be a little tough to swallow, but the cause is obviously from freezing moisture. While it may seem like the source of the moisture is a mystery, I can safely say it is not coming from outside the home. The fuel for the ice is water, in the form of vapour that is dissolved in the air inside the home. The problem occurs when water vapour leaks through the exterior door, causing ice to build up in the locks and inside the jamb.
Moisture present in the home will normally only cause problems like the ice buildup if there is too much or it is allowed to cool. The amount of moisture in air is known as the relative humidity (RH), expressed as a percentage. The higher the RH, the easier it is to cause condensation because it requires less of a temperature drop for the moisture to reach its dew point. If this dew point is reached in an area where it is very cold, condensation can quickly freeze before it has a chance to evaporate or be manually removed.
This is what is occurring inside the locks and door jamb of the home. You must either lower the RH, raise the temperature or prevent any air from leaking from the house into the door locks and jamb.
To prevent excessive condensation on the steel exterior door of the home, we can only attack the variables we control. The only one of the three items we can't control is the outside temperature. The only possible way to warm up the exterior of the steel-encased door in the dead of winter is to install a storm door. This may succeed in warming the door slightly, but may not be enough to prevent the ice formation. The attached garage also acts in this manner, but obviously is not sufficient to warm the door enough in the coldest months.
The next item to address is the air leakage. While it may seem like most modern exterior doors are well-sealed, there are a few areas that can be quite the opposite.
Check the weatherstripping around the door to make sure it is contacting properly. This can wear out or tear over time and require replacement. If the backset in the door knob is loose when the door is closed, adjusting the striker plate may pull the door tighter to the jamb, sealing it better. With the house lights turned off at night, shine a bright light or flashlight at the door from the exterior and look for gaps. You may be surprised to find there are a few areas where the light easily penetrates the weatherstrip or threshold. You may also notice small pads near the top and bottom corners of the door jamb, designed to plug small gaps, which can wear out and require replacement.
If any of these items are lacking, replacement or adjustment may be the first step to preventing a frozen door. Since the problem originally occurred with the lock, installation of a small foam gasket where the lock contacts the door should help. This can be made from material designed to prevent air leakage at electrical boxes, with some modifications.
The main item to deal with is the RH inside the home. Go to an electronic supply store, home centre, or Canadian Tire and buy a decent-quality portable hygrometer. This small device measures the RH and should be placed in a main living area within the home to get an accurate reading. If the RH is approaching or exceeding 40 per cent, at normal indoor temperatures around 20 C, it needs to be reduced.
This can be addressed by operation of bathroom and kitchen exhaust fans, or a central exhaust fan or HRV if one is present, for a longer period of time. Setting the furnace fan on continuous low speed, using natural gas fireplaces, or installing a fresh air intake for the basement or furnace return air ducting can also help.
While there could be a problem with the newer doors due to poor installation, mis-adjustment, or deteriorated weatherstripping, the issue that is causing the ice buildup is likely excessive RH in the air that is leaking around the door. Attention to this, as well better air sealing of the door, should prevent the problem.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the president of the Canadian Association of Home & Property Inspectors - Manitoba (www.cahpi.mb.ca). Questions can be e-mailed to the address below. Ari can be reached at (204) 291-5358 or see his website at www.trainedeye.ca.
trainedeye@iname.com
