Multi-layer roofs are the goto solution for house “flippers” and people that need a new roof surface but would like to do it as inexpensively as possible.

The edge of the roof is the best location to determine if you have a multi-layer roof.

There are some benefits and some problems with this situation:
The main upside to going over the top of an existing layer of shingles is cost. The labor that it takes to remove the old roof and the dump costs can be directly subtracted from the cost of the new roof. In general this savings equals around 10 to 20 percent of the cost of the new roof. If you are planing to move in the near future this saving may seem like a good deal.

Now lets look at the downsides. Wear and tear: Multi layer roofs are usually not warranted by the shingle manufactures and they will not last as long. How much shorter the new shingle’s life will be depends on many variables but two thirds to three quarters the life is a safe bet. Also multi-layer roofs will have more issues with nail pops, or fasteners that poke through the surface of the new shingles. This condition is due to the fasteners not being long enough to penetrate through the old shingles and in to the wood sheathing properly.

As a local Salem, Oregon home inspector I see these type roofs often and it is important my client understands what a multi-layer roof actually means. Most shingles are at least 20 year products (if they are installed correctly!) so even on a multi-layer roof you should have at least 12-15 years of relatively trouble free roofing.

Multi-layer roofs have some upsides and some downsides….

One of the areas that moss is a concern on homes in this area our roofs. Depending on the roofs exposure moss can grow most of the year.  If sections of your home’s roof are shaded throughout the day and stay moist these are likely areas to grow moss.

Over time moss can damage your shingles if left un-checked. As the moss develops into a larger and larger colony more and more moisture is held against your roof. The colonies will also develop root systems that will dig in to the surface fibers on your shingles. As the colonies grow larger, they can actually lift the edges of the shingles. This can leave the shingles vulnerable to wind damage.

There are lots of ways to kill moss. Most of the good techniques involve some sort of the heavy metal application usually copper or zinc. Some really bad ideas involve laundry detergent and or power washers…..

In general the more trees you have around your house in the steeper your roof the more applications of moss killer you’ll need.

1.  The best way to control moss is with an annual or biannual application of a powdered or liquid name brand moss killer designed for roofs. For steep roofs I have found a hose end attached shrub and tree sprayer to be a handy tool.

2. Another option for continuous moss control are some new

shingles that are actually impregnated with copper

granules. I have only seen the shingles used on two

different roofs and the major issue with these is the fact that

the ridge shingles were not impregnated in a still need to be

treated for moss/algae growth.

3. Mechanically removing the moss is also an option.

This option is really only for the very worst conditions.

It envolves a paint scraper, screwdriver, putty knife or

something similar and trecking across your roof slope and very

carefully removing the moss growth.

This technique is very prone to damage of the asphalt

composition shingles and should be used as a last resort.

4. Zinc or Copper strips- These may be ok for preventing

algea growth but moss looks at the little strips and laughs.

You may have noticed some homes around town that have

clear sections of shingles under metal roof vents.

What is going

on here is the

zinc in the

galvanized steel

is leaching on to

the roof every

time it rains.

This has lead to

people thinking that they could install little strips or even

sections of wire to kill moss and algea, but this is not

usually an effective technique.The difference is all

about-surface area.The roof vents have a rather large

amount of exposed surface and therefore a good amount

of rain hits the vents. Compare this situation to a 2 inch

wide strip of zinc and you

can see that there will be far less leaching occurring off

of the little strips.The strips usually are effective for 2 to 3 feet,

and I have seen the strips added every 2 or 3 feet down

an entire roof slope. This installation appeared to be

effective but I have only seen this once.

5.  Power washing, scraping with brooms, or laundry detergent. Unfortunantly I see the aftermath of these steps to control roof moss on far too many Salem area home inspections. If you are reading this post you probably have educated yourself enough to know that blasting or scraping the surface off of your aspahlt composite roof is a bad idea.  The folks that commit these heinous crimes are usually the people that already know-it-all and they maintain their homes the way they see fit.

-There may be some contractors who use power washers to clean roofs, but these individuals are licensed and bonded and have the experience to know which nozzle to use and how far to hold it away from the roof surface. Power washing should be strictly limited to the driveway and walkways surfaces around your home.

-Brooms and other mechanical abrasion are also techniques that should either be left on the ground or for qualified professional contractors. The removal of the surface granules on the asphalt shingle also removes the ultraviolet resistance and of the shingles.

-Laundry detergent, although will kill moss on your roof, is full of degreasers. An asphalt based composite shingle is a petroleum based grease compound. Do not put degreasers on your greasy roof.  (Thanks Joe Ocilia for educating me on this fact!)

Those are my 2¢ on how to control moss. Being a Salem, Oregon home inspector, I get the chance to see various maintenance techniques. By far the best one to use is the first one, which is a chemical, powdered or liquid, commercially available moss killer applied at annually or biannually.

The worst part of this issue was the fact that she had paid roofers to find and repair this leak multiple times.

This last summer she even had the drywall repaired under the leak
figuring that the roofers had actually done what they had been paid to
do.

By the time she got a hold of me she had reached the end of her
rope and was on the edge of tears. I told her that I would be happy to
come do an inspection to locate the leak and hopefully give her some unbiased answers.

When I got to her home she showed me the areas of concern. I crawled up
in her attic and there was little doubt as to the source of the leakage.
The valleys were soaking wet.

Roofing like other construction trades is relatively basic but just
because it’s basic does not mean that it should be slapped together any
old way. The installation guidelines must be strictly followed.
Something as simple as an additional bevel cut into the end of a shingle
can be the difference between proper installation an leakage.

There are many different ways to do a proper valley installation. Each style has their own particular guidelines.

This particular home had a “Closed cut valley.”

-1. The first part of this installation is the lining of the valley
with an additional layer of building paper or metal liner. This layer
serves to be a ‘last line of defense’ if all of the other layers of
protection fail.

-This step was likely neglected on this particular
roof.

-2. The next step is that one entire roof slope (the smaller section of roof or lower slope) of shingles should be
installed completely and extended past the center line at least 12
inches.

-It is difficult to determine if this guideline was followed.

-3. The next step is to roof the other adjoining roof slope.  Along with this step the top edge of the shingles must be cut-back and beveled to prevent water infiltration. The acute angle that is at the tips of these extended shingles may
act as a scoop and funnel if they are not provided with an additional
cut to bevel this edge.

-This step was neglected on this roof.

-4. When all of the shingles that are close to the valley are fastened to the roof it is important to hold the
fasteners away from the center line of the valley at least six inches.

-This step was also not adhered to precisely.

The bad news is that my client has some work ahead of her.  She is not quite ready to sell and the rest of her roof has at least 5 more good years of service.  It is not a great financial decision to properly repair the valleys since the rest of her roof will need replacement in the near future. So what kind of patching options are there?

Since the valleys are the issue it is possible to seal the leaks with a generous coat of tar.  However most tar (flexible asphalt based sealers) are recommended to be installed when the surface is dry.  With a little research I found this stuff:

http://www.dewittproducts.com/catalog.asp?prodid=627618&showprevnext=1

This product claims that it is specially formulated to be installed upon wet surfaces! Sounds pretty good to me!

I also discovered a great little post from someone in a similar situation about how to apply the goop: http://www.hammerzone.com/archives/roof/patch1/tar/temporary.htm

The person in the above post makes it pretty clear that the tar is a TEMPORARY SEAL!!! This is an important point and as long as a good layer is reapplied in the summer my client should be leak free until she is ready to replace the entire roof.

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Your gutters need attention

We all know that the parts that are exposed to the elements (and leaves) are important to keep clean but lets not forget about the underground pipes as well. These pipes are low and out of sight and are easy to forget about. Those underground pipes are probably the most important part of the system as they will collect, concentrate, and (hopefully) remove the concentrated storm water from around your house.

In Marion and the surrounding counties, the underground pipes are usually where things are going wrong and unless inspections or unusually close attention is paid, things can go wrong for months or even years.   It really is all about the way we receive rain.

The rains in the Willamette valley, in Salem and surrounding parts of Oregon show up in mid October and things stay moist until the middle of May.  We don’t necessarily receive a lot of rain, it is just steady and the clouds do not usually part long enough to dry anything out.

The gutters, downspouts and underground pipes are the wettest points around our home.  If there is water in your crawl space or basement the gutter and downspout system is usually the main culprit.  

A great test for the underground system is to shove a garden hose in it and see where the water comes out.  If water bubbles to the surface in the area you are testing…….you have some work to do.

A few years ago I was on a roof and the agent asked me how old the roof was. I told her that I couldn’t really tell, but that I guessed that it was maybe 1 or 2 years old. She asked me why didn’t I look at the date stamp on the flashing boot?

………….(•blank-home-inspector-look•) The wha…….?

Yup, every so often even the know-it-all home inspector has something to learn. Right there, stamped for all whom know where to look, is the date that the flashing was made. Of course this is not an exact date of roof installation but it is usually within 6 months.

Pretty neat little trick.

Now, you are going to be in charge of an ENTIRE house!!  It can be intimidating, especially after a good home inspection!  Not to fear you first timers, there have been lots of people in your shoes and many with even less technical understanding of the maintenance issues that plague your new home.

In the Salem, Oregon area one very common issue that will require attention is moss growth on your roof.  To be fair, this is not a life and death issue, however with less than a few hours of attention a year this issue can be effectively controlled.

Moss tends to grow in the shady sides of the home.  Mostly this has to do with the 8 months or so that your roof will stay wet in these areas.  This constant moisture creates an ideal location for algae population.  If moss is allowed to flourish unchecked it can create little pockets that catch and hold moisture.  Also the moss can actually begin to lift the shingles.  All of this catching and lifting will slow the water that is running down the slope and the longer water is on your roof the shorter the life of your roof will be.

Ok, we know that moss is not good but how do we control it?  Moss killer.

Moss does not like reactive metals like zinc and copper.  Commercial available moss killers like, “MossOut“ or any of the other sprays or powders are best.

• The moss control measures that do not work or maybe work too well, at the expense of the life of your roof are: Strips of zinc that claim to leach onto the roof and kill moss continually.  These strips are good only in theory and only tend to protect about two feet of the down hill roof surface.
• Also, moss will die if treated with laundry detergents, however laundry soaps have surfactants (read: de-greasers).  Composite shingles are made of asphalt (read: grease!).  These detergents can quickly chew holes in your roof!!
• Power washers.  Please, please DO NOT power wash your composite shingle roof.  The idea behind killing moss is to prolong the life of your roof.  You will quickly shorten the life of the roof you are trying to prolong by blowing it to smithereens with a well meaning power washer.

While most people complain about our recent downpours they have been providing me with much-needed rain to make leaks light up.  One of the biggest benefits having a thermal image camera is the ability to see things you can’t see with your visual senses.  A recent inspection on a home on Sesame Street and no I don’t need you to tell me how to get there, I found a leak that wasn’t showing through the finished surfaces yet….

Although advanced in age the surface of the roof did appear to be satisfactory.  On initial scans from the kitchen and family room there did appear to be an interesting cool spot in the family room and upon further investigation this cool spot did in fact turn out to be a current wet spot. This was roof leak.

Although no Big bird or other Muppets could be noted during my investigation, I did provide some much-needed information for my clients.   Thermal Imaging again proved its value and ensured my client’s home would be a safe and dry place to live

I love my job.  Above and beyond me finding problems with my client’s new homes, my job is to educate them on how their home works.  Most people who are willing to climb on a roof could notice that this roof vent is out-of-place but explaining the vital function of the roof vent is my job and I love it.

Home inspections are more than just a check list of the “problems” in a home.   They are a great start in the educational process that we as homeowners need to actively pursue.