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Building Principles: Getting Ready for Winter
Every facility has, or should have, a checklist of items, issues, and procedures to get the property ready for winter. Many times, though, there are procedures which are not based on smart management, but on the seven deadly words, “That’s the way we’ve always done it!” This issue, we’ll look at a couple of items our engineering practice encounters pretty regularly. Perhaps, together, we can break the cycle, and do some things a little differently.
Beyond draining sinks and toilets, facility caretakers tell us that they spend weeks, and sometimes even more than a month, draining the water lines which lay on top of the ground. Otherwise, the water remaining in the lines freezes — cracking the pipes. The best solution to this issue is to bury the water line below the frost line. Many organizations have the predisposed notion that it will cost too much. However, that idea can be quickly tested by comparing the underground installation costs with the cyclic costs of draining, refilling, and sanitizing every spring the water lines that lay on the ground. That’s correct! Each time that the line is emptied, standard health code procedures require that it be chlorinated, sampled, and tested before it’s allowed to be used for potable water distribution.
Another common practice is the addition of automotive (green) antifreeze to toilets and sink traps. For those facilities on septic systems, know that ethylene glycol is a DEADLY POISON, not just if you ingest it directly, but to your septic systems as well. Neither your septic tank, nor your septic field is capable of digesting this chemical. After it has destroyed the organisms which denitrify your toilet waste, it then percolates into the ground and works its way into the groundwater from which your neighbor (or you!) draws drinking water.
Make the switch to propylene glycol (PG), the pink, more expensive product. Used and diluted as prescribed, PG is not harmful to people, animals, or the microbes in your sewage systems. It’s often labeled as “RV antifreeze,” and it is listed as safe for potable water systems. Remember to read the label and mix it according to the directions for the temperatures you expect to encounter. Undiluted PG actually freezes at a warmer temperature than watered down mixtures. Again, the additional cost of the PG is easily justified when compared to the cost of replacing a poisoned water supply or failed septic system.
Often, we encounter structural problems with swimming pools that have not been properly winterized — sustaining significant, sometimes irreparable damage as a result. For our purposes in this article, we’re speaking about in-ground pools. Many organizations completely drain in-ground pools to avoid “cracking the sides.” While there is some merit to this thought, there are other considerations which are often overlooked. Remember that on the other side of the pool wall is dirt and usually ground water. The ground water pressure can be significant enough to cause the walls to crack and leak, breaking buried piping along with it. The best means to counteract this pressure is with water inside the pool, pushing back on the wall. The same idea applies to the floor of the pool also — since there is often groundwater attempting to push the floor up. By keeping water in the pool, its weight will push back against the water underneath.
Let’s recall a bit of basic water chemistry. As most materials cool, they contract. The lower the temperature goes, the more the material shrinks. Water is peculiar because just below the freezing point, the “green” ice actually swells and occupies more space than it did as very cold water. This is why the ice cubes in your plastic trays pop out — often before the tray is flexed. The same sequence happens in your pool at the water surface — and this is why many organizations drain the pool. But as the ice temperature continues to fall, the ice begins again to shrink. The force of the expanding ice, while potentially very destructive, can be dissipated by surface floats which are compressed as the ice expands with the temperature changes.
A better means of winterizing your pool is to lower the water level just below the filter returns so that those pipes can drain or be drained. Once the skimmers have been cleared of water with compressed air, weighted floats are put into the swimming area with the idea that they will be crushed by ice expanding and compressing them, rather than expanding out and pressing on the walls of the pool. The number and size of the floats your pool requires is dependent on the surface area of the pool.
Lastly, remember that water/ice also insulates (think about igloos). With a layer of ice on top, the water beneath is less prone to freeze. As long as there is liquid water present beneath the ice, the damage associated with freezing is reduced on both sides of the wall and floor.
Another point of discussion is whether a cover for the pool is really a cost-effective addition or only aesthetic. Most fences will not keep out small rodents or other climbing animals which may be attracted to the quiet water surface. Decomposing animals, leaves, sticks and other detritus can make the already arduous chore of opening the pool that much more difficult and unpleasant. These materials often release stains which are difficult if not impossible to remove from the sides or bottom without repainting.
Finally, whether your pool has a liner or is painted, the biggest enemy to its interior coating is ultraviolet exposure to the sun. Covering and uncovering the pool daily during the summer is impractical, but to cover it during the six months (or more) that it is closed could extend the life of the pool surface coating by as much as two times! A good quality pool cover is an investment which could literally pay for itself!
Remember those enormous glaciers of ice on roof edges last winter? That came about when heat from inside melted snow on the roof. When that very cold water encountered the uninsulated roof eave, it refroze in layer after layer. These ice dams cause all sorts of damage to the entire roof system including the shingles, the underlayment, and even the sheathing and supports. Ice like this can be extremely heavy and can cause the trusses to fail from being overloaded.
The first solution that may come to mind may be to insulate the whole roof — preventing or at least slowing the melting process in the first place. That, too, can have repercussions since the snow can build in depth just like the ice. Other solutions may include heating wire systems on the shingles themselves (or sometimes in rain gutters) to prevent the refreeze. Improperly installed, these may present a significant fire hazard.
Ultimately, the best solution is to ventilate and insulate the eave and roof as a combined system in which neither is warmer or colder than the other. This can be an extremely difficult prospect but should be a consideration when the roof needs to be replaced on a building that has this ongoing problem.
Another risk involves gutters and downspouts that are fouled with leaves, sticks, bird’s nests, Frisbees®, and other foreign objects. Gutters should serve to divert roof drainage away from the foundation. (Here’s a hint: If your downspouts point straight at the ground at the corner of your building or if the water runs right back at the foundation, you’re not getting your money’s worth!) Invest in the time to keep all of the components in good repair. Any component which isn’t installed properly will prevent the whole system from working as it should. Gutters should have a continuous slope — with no places where water ponds. The joints should be caulked to prevent leaks, and the hangers should be secure to the fascia. Gutters with heating wire installed will send the water to downspouts (which are typically not heated), and the freezing will happen there instead. Eventually, the system will overflow and icicles will freeze on the face of the building. The ice dam has only been moved.
In every season at camp, there are always too many chores and neither enough hours in the day nor hands to get it all done. You’ll start spring off on the right foot if you look at your fall procedures now. Maybe looking at things in a new way now will make opening camp a little easier when the snow is gone.
Rick Stryker is a professional engineer with Camp Facilities Consulting, providing study, design, permitting, and construction consultation services to the camp and conference center community. Camp personnel may contact him at 570-296-2765 or by e-mail at email@example.com.
Originally published in the 2003 September/October issue of Camping Magazine.