Asphalt Roof Maintenance

It may be getting a little late in the year for this but I wanted to talk a little about roofs and roof preventative maintenance and repair.  While inspecting in southern Wisconsin, I commonly find roofs that are in disrepair or have major deficiencies in the penetration flashings and wall flashings.

First off, tar, asphalt cement, and caulking should not be used as a means to flash or seal


roof penetrations, wall steps, or chimneys.  Sealants are prone to cracking and separating during freeze-thaw cycles.  We all know how harsh it can get in southern Wisconsin with summer temperatures in the 90’s and winter temps. below zero regularly.  These temperature differences cause building materials to expand and contract.  Differing materials will move

at different rates causing any sealant to become ineffective.  The most effective flashing materials will move with the expansion and contraction.  A stepped aluminum flashing is most effective at chimneys and roof step sidewalls.  In the diagram you can see at each course of shingles the aluminum steps down with the shingles.  This allows for the expansion and contraction and makes it impossible for the water to penetrate the

Roof-Asphalt step-flashing

transition.  Wall siding is generally used as the counter flashing, if the wall is brick a counter flashing should be incorporated into the mortar joints.  The aluminum flashing should never be located above the shingles, as water runs along the flashing it can work its was under the flashing leading to leakage.  If your home has an incorrectly installed flashing it may be a good time to have a qualified roofing contractor replace your flashing before you end up with moisture staining on your ceiling and walls.  Annual inspection of wall and chimney flashings should be conducted for areas of damage and/or separation.  The use of urethane sealant is considered a temporary fix, but can be utilized to make it until spring when an appropriate flashing can be installed.

Another area where we find deficiencies is at plumbing vent, mechanical system vents, and electrical mast penetrations.  The mechanical vent pipes generally come as a package with a storm collar.  Minimal sealant is sometimes used at these transitions.  I regularly see these flashings installed incorrectly as well.  The upper side of this flashing


must be located beneath the shingles while the lower side is exposed above the shingles.  This may seem elementary but, you would likely be surprised how often they are either located completely on top of the roofing or completely beneath the shingles.  Electrical mast locations are also often found with no flashing at all with asphalt cement or tar gooped all over the penetration.  This would only likely last a couple of years before leakage occurs.  A rubber boot flashing is recommended for the electrical mast as well as plumbing vent flashings.  These rubber members should also be inspected annually for cracks or other damage.  If cracking happens these flashings are easily replaced.

An area of maintenance that is common is keeping the roof clean and free from debris, lichen, and moss.  Lichen is the light green crusty moss that grows on shaded areas.  1540992496780Lichen has a small root and does extensive damage to the shingles.  Cleaning these areas is recommended to prevent premature failure of the shingles.  A cleaning solution and lightly brushing of these areas generally works well.  Keep in mind that brushing shingles with a stiff brush or brushing hard will generate granule loss and should be avoided if possible.  In these shaded areas this cleaning will likely be necessary on an annual basis.

Of course many of these tips would be different for different roofing surfaces, but I am concentrating on asphalt shingles as this is the most common roofing material in our area.

One last thing, be sure to check your gutters and downspout locations for obstruction.  I have seen gutters that were half full of shingle granules, this can cause low flow and Downspout-extension-too-shortoverflowing of the gutters during periods of heavy rains.  I recommend cleaning of gutters each fall.  If you have a lot of trees in the area, cleaning of the gutters may become necessary a few times per year.  Another common issue that comes up on home inspections is the lack of downspout leaders.  These leaders should direct water runoff a minimum of 6 feet away from the foundation.  This defect is probably the single most cause to foundation seepage issues that we come across.  When you collect all of the water runoff from the roofing surface and dump it in one location right by the foundation it’s hard to imaging that area would stay dry in the basement or crawlspace.

To summarize, it is always a good idea to check the exterior of your home in the spring and fall for any changes that may have occurred in the previous season.  While I do not recommend climbing on and walking your roof as a general rule, monitoring the conditions of these items can be done from a ladder at the eave, and/or with binoculars.  If you need further assistance or would like advice on the monitoring your roof condition, we’re here to help, let us know if we can be of assistance.



Aaron M. Zuehlke is the owner and inspector at Zuehlke Inspection Service, LLC, a full-service home inspection company serving Southern Wisconsin. Specializing in Home inspection, Radon Testing and Residential Thermal Imaging.

If you have a home inspection or home maintenance related topic you’d like to read about please send your suggestion to me via email at

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