Stucco siding and your roof replacement

Stucco is durable and reliable siding material.  90% of houses that have stucco will have areas where the roof meets the wall.  In these locations there will be metal flashing, which we spoke about a couple weeks ago on our blog about the long term function of metal flashings on a Calgary roof installation.  The approach to installing the shingles during the roof replacement will change depending on the age of the metal wall flashings and step flashings, and various aspects surrounding the metal.

Stucco can be affected by various issues during replacement of your roof installation

  -Clearance between the roof and the bottom of the stucco (weep screed or casing bead) of a wire lath stucco system 
On older installations it was common to bring the stucco right down to the roofing surface.  This is problematic in several ways:

  • Water will wick up the cement and will corrode the metal lath over time
  • Water is held against the roofing product, increasing the effects of the freeze-thaw cycle, and promoting wood rot
  • Removal of the old roofing system is nearly impossible without damaging the stucco
  • The flashing is covered and replacement is very difficult
  • Hail damaged stucco is already cracked
  • Discolouration where the roof installation meets the lath stucco

-Water draining onto the stucco
If your roof installation is technical or complex there may be a few areas where water is not channelled away from the cement siding properly.  These areas show up from the ground as staining or discolouration around corners or where the eavestroughs meet the wall, or where clogged eavestroughs are causing overflow  Strategic placement & configuration of flashing is required in these areas to avoid long-term damage.  If the step flashing or valley flashing is no longer in good shape we must install new product.  Our actions are decided by the roof to stucco clearance

  • Greater than 1″ clearance and we can often slide new pieces in with the old
  • Less than 1″ clearance and we will install new flashing flush with the stucco and then add counter-flashing (caulk-lip) over the top of that, finished with a bead of silicone
This roof had a leak in the flashing around the chimney and as a result was completely rotten

This roof had a leak in the flashing around the chimney and as a result was completely rotten

Improper stucco flashing can end up with a situation as shown to the right, where water drained behind the stucco for years and literally turned the wood into dirt.  This is extreme, but any problem is a problem that must be solved.

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