Useful Tips for Buildings

Kitchen Stacks and Pipes Clogging

Letter: My board asked me to follow-up with you about the progress we have made since you helped them requisition a meeting last year and get a better board and manager. I am the new manager and the previous one had "something" for the plumbers and the board was very worried because these plumbers were asking for new clean outs in the basement and the ground floor and they did this, but then they wanted about 25 clean outs in units and they were cleaning the stacks at least twice a year and this is too aggressive and will deteriorate the pipes too quickly. Our building is only 7 years old.

Just to tell you that we followed what you suggest in your website but we did it with a new twist and our new plumbers just can't believe how well this has worked out. First, we post notices asking people not to throw grease and cooking oil and kitty litter down the drains and we explain why, just as you suggest. We do this at least 3 times a year, one time just before Christmas.

Second, 4 times a year, we post this other notice about combining baking soda powder and vinegar and we buy huge amounts of these. On a predetermined Sunday, the super, janitor and myself come to the building and we distribute the stuff to all the residents that come and get it downstairs. So about two thirds of the people come and then go to their unit and do it in their kitchen sink and then in their toilet sinks. We keep a list of the units that do it and then we go upstairs and for two hours we go into units that have not done it and do it for about 25 of them, with a prior proper notification.

So it means that on the same day, all the stacks are flushed by mostly the residents with baking soda powder, followed by hot vinegar, flushed down with hot water, all units within a few hours. We haven't even had to have the plumbers come in to clean the stacks this year so far.

I should also say that when I arrived and because we also changed plumbers to get honest ones, it was difficult to figure out where the clean outs were in the building. We have since made a list and designed plans that show exactly where they are so that if there is another change of management, plumber or board, the new people will know where things are. his is saving us thousands of dollars each year and it is much less disruptive. As the president says (the one that wrote you), this also helps us do some "community building" by engaging all the residents at solving a costly problem together. Some residents now do this every week in their units.

-- January 2012, Ottawa

Balcony Deterioration

The information below was provided as a courtesy to a question I had about balconies. I am reproducing it here because it provides very useful information, especially for boards and managers.
— A.-M.A.

Balcony deterioration is a poorly understood issue. Condominium Corporations are sometimes spending hundreds of thousands of dollars on repairs which do not address the root cause, due to a lack of understanding of the failure mechanism.

Steel embedded in concrete is immune to corrosion, except under two key circumstances: exposure to chlorides and carbonation.

  • Chlorides (salts) usually get into concrete from application of de-icing chemicals, but also salt-water spray from oceans, and in older buildings salt that was added to the concrete during winter construction. Salt causes embedded reinforcing steel to lose its immunity to corrosion.
  • Carbonation is a process where carbon dioxide in the air reacts with the moisture in the concrete, forming carbonic carbonate in a process that reduces the pH of the concrete. It progresses in from the outside surface, penetrating deeper into the concrete over time. With a reduced pH, embedded reinforcing steel loses its immunity to corrosion.

The primary cause of highly disruptive slab-edge concrete repairs is usually related to the simple drip slot at the edge of the slab. Drip slots are the small grooves at the outside edge of the balcony slabs. Their purpose is to intercept water running off the edge of the balcony so that it does not dribble back onto the balcony soffit, thereby preventing damage to soffit finishes and keeping water from dripping onto people on the balcony. An unintended consequence of the drip slot is that it reduces the thickness of the concrete covering the embedded reinforcing steel. This makes the reinforcing steel directly above the drip slot more prone to corrosion than any other steel in the balcony slab (because the rest of the steel has a thicker layer of concrete over it).

The primary failure mechanism for balcony slabs is carbonation. The layer of carbonated concrete typically only reaches 10 to 25mm deep, largely on the underside of the slab (not the topside, because the wetting related to rain reduces the depth of carbonation penetration). In most areas of the slab, 10 to 25mm of carbonation is not an issue, because the steel is typically protected by 25 to 40mm of concrete. However, right at the drip slot, this cover may be reduced to 10 to 15mm, allowing carbonation to advance to the depth of the embedded steel, making it free to corrode. The reinforcing steel right above the drip slot corrodes; the corrosion product is bigger than the steel; the expansion causes the concrete to crack (typically along the drip slot); air and water get in the crack, increasing the rate of corrosion. Eventually the outer edge of the slab works loose and needs to be repaired.

This failure mechanism is characteristically different from a chloride-induced failure. If there are chlorides in the concrete, or applied to the topside of the concrete, there will be slab edge concrete deterioration (similar to carbonation-induced damage), but there will also be topside damage and/or soffit damage away from the drip slot.

To properly repair a slab it is important to understand the underlying failure mechanism. Concrete repairs must be designed to avoid recurring damage by selecting an appropriate extent of removal, appropriate materials, and applying features which protect the adjacent concrete (which remains in place beside the patched areas) from suffering the same fate. Many buildings are waterproofing their balconies during repair as a preventative measure. Waterproofing a balcony that is failing due to carbonation may be a waste of money as it does not address the underlying failure mechanism, while waterproofing a balcony that is failing due to chlorides can sometimes be an good investment if the extent of remaining chloride contaminated concrete is known and managed through proper repair techniques.

We typically recommend a balcony condition survey, sampling at least 15% of balconies, when condos are about 15 years old, and about every 10 years after that. The evaluation budget should allow for chloride testing, carbonation testing, hammer-tap sounding and visual review. This can usually be done from within the suites, so outside stage access is not typically required.

Note that some balconies are reinforced by joist chord extensions, rather than conventional reinforcing steel. Their failure mechanism is somewhat different from that described above.

Sally Thompson, P.Eng.
Halsall Associates Limited

Swimming Pool Environment-Friendly Initiative

Over the years, we have had our share of complaints about the chlorine used to purify the water in our swimming pool and whirlpool, for the cloudy water, the unpleasant smell (a constant even down the ground floor hallway), eye irritation and skin concerns. Several residents refused to use the pools due to the presence of chlorine.

The building's Club Sommerset Committee, which focuses on the quality of our recreational facilities, has spent some two years discussing, studying, researching the solution. Salt water was considered, then rejected on expert advice (due to its corrosive effect on the pipes). Then our property manager received information from a pool maintenance company about this new and better way: the UV 254 Sanitizing System.

The Committee invited several experts to brief them and learned that it:

  1. destroys 99.99% of bacteria, algae and micro-organisms (including chlorine-resistant bacteria such as cryptosporidium);
  2. significantly reduces the need for chlorine and bromine;
  3. destroys the chloramines that cause red-eye, chlorine smell and skin irritations;
  4. requires minimal maintenance (15-20 minutes a year);
  5. provides significant reduction in dependence on chemicals; and
  6. uses technology proven in sanitizing drinking water.

In June 2007, the Committee formally recommended the installation of the UV system, and the Board approved. The cost was $3,187.95 and $1,859.89 respectively for the swimming pool and the whirlpool. The maintenance required involves the annual replacement of a UV bulb for each pool, costing under $500 for the two. To our knowledge, we are the first Toronto condo to have UV-treated pools.

What a difference: the water is crystal clear; you can read a dime on the pool floor. The smell is gone. Real estate agents have started using our pool as a major selling feature.

After the installation, our corporation applied to the City Public Health department for permission to eliminate or reduce the required use of chlorine and bromine. With the help of our City Counsellor John Filion, the officials took us seriously, and relied on World Health Organization (WHO) data to give us written permission to reduce the chlorine in the swimming pool by 75% to 0.5 mg/l = parts per million, and the bromine in the whirlpool to 2 mg/l.

Andrew Simon,
President, MTCC 1273,
Toronto (Willowdale)

Added February 2011: Two years later, Andrew Simon reports that "this system still works as it did at the beginning and it's a delight to swim in (almost) unchlorinated water. The City reduced our requirement for chlorine by 75%, so we still have  25%."