Just a little double entendre in the title to start you thinking.
Every now and then roofs need cleaning.
A simple Google search of companies that pressure-wash roofs in the Seattle area, reveals that there are literally HUNDREDS of companies out there willing to “hose” your roof. While there are some roof coverings that hold up well under pressure-washing–like concrete tiles and metal–composition shingles and wood shingles/shakes do not hold up very well. Many years can be taken off a roof by pressure-washing, as the granular coating gets blasted away.
The pressure-washer, in the hands of someone who does not know what they are doing, can do immediate damage to the roof–not just shorten the roof’s life over time, as would be the case if they DO know what they are doing. Below is a series of pictures, all from the same house, of what typical pressure-washer damage to a roof looks like. In this first picture can you see the “decorative” wand marks from the pressure-washer?
Notice all the roofing granules in the gutter–those are years of the roof’s life headed out to the city sewer or into your perimeter drains–which, in one way or another, will cost you money. Your taxes will pay to maintain the sewers or the granules many cause issues with your drains that you will have to pay for directly.
This next pictures shows more wand marks.
Here is a close up of the surface blasted away exposing underlying layers.
This next picture shows more damage in one of the valleys.
Keep in mind that the areas that are “black” are where all the granules have been blasted away.
As a side note, all of this roofing material can end up in the perimeter drains of the home reducing the effectiveness of the drains. So when considering the cheaper cost of installing these shingles, don’t forget to add the other costs when they plug up your drainage or have to be disposed of at the end of their useful life. As a builder I have dug up old perimeter drains completely packed with roofing granules and one can see every color of roofing that was ever on the roof.
It is also worth noting that none of this damage could be seen from the ground and most could not have been seen from a ladder at the eaves.
Please take a moment to view this pressure-washing of a roof. Pay attention to how the force of the water lifts up the shingles–especially at the very end of the video. This means that the tabs are no longer sealed down and are vulnerable to wind damage. I frequently find shingles lying on the ground around homes–evidence of having the roof pressure-washed prior to putting the house on the market.
Why aren’t these pressure-washing companies held accountable for the damage they do to roofs? Because no one ever goes up to check and see–and even when someone does find the damage, the culprits are long gone.
Whenever I trash pressure-washing companies, the first thing people usually ask me is: “So how DO I clean my roof?” The simple answer is that in most cases more frequent gentle sweeping of the roof with a stiff broom will be less damaging to the roof–especially if done during the dry season. There are also relatively safe chemicals that can be sprinkled on the roof to discourage moss and lichen growth.
By far, the best solution is for the consumer to stop buying the types of roof coverings that cannot be pressure washed.
The fact that as a country, we still support the oil industry with the creation of asphalt shingles says a lot about how real or unreal any oil crisis might be. Roofing materials consume over 10 million barrels of oil every year–and this is just for asphalt type shingles. The fact that they could be recycled to the tune of about 1 barrel of oil per ton (if there was the will to do so) still would not justify the initial waste. A square (100 sq ft area) weighs between 200 and 250 lbs per square. The average roof size is about 2200 square feet–or 22 squares of shingles. That makes the average roof weight somewhere between 2.2 tons and 2.8 tons. Each ton of roofing can yield about one barrel of oil if it was recycled. Multiple layers on the roof would yield more.
But why not avoid the whole issue?
There are all kinds of metal roofs that weight less, last longer and can be recycled easier–and that can be pressure-washed as well. There are of course also the various tile type roofs that can be installed–which also last longer and can be pressure-washed.
Some times it might be better to leave them covered with moss.
Also, don’t be conned by the new kids on the block that will attempt to convince you that “air-washing” is even better than water pressure-washing. It may even be worse as can be seen in the following video.
By Charles Buell, Real Estate Inspections in Seattle
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