Adding Stone Stairs Against Siding; What to Avoid

Lots of people want to upgrade those builder grade temporary steps or perhaps upgrade what is already existing to stone or paver stones.  One of the improper installations that I see quite often is when the landscape contractors who install this type of stair just slap it up against the side of the house.  In the photo above, you can see how the steps overlap the siding.

So here's the inside view.  Not too unusual.  But as a home inspector, whenever I can access the rim joist beneath a sliding door, I remove the insulation to have a look.  Most sliding doors leak and cause unseen moisture damage.  

Here's what's behind that rim joist insulation.  Wet wood.  This is still in the early stages, the seller of this house had these stairs recently installed.  Remember that we're looking at the good side of the wood.  The exterior side will have more moisture.  With the moisture comes rot, mold and wood destroying insects attracted to damp wood.  

The vinyl siding doesn't serve as protection for the wood.  The siding should have been removed and proper flashing material rated for contact with masonry installed (common aluminum flashing will corrode when in contact with masonry due to the lime content).  

So what happened here?   The seller requested that the buyer make repairs.  The buyer had the original contractor come out (why would you want the guys who didn't know how to do it right the first time fix it?) and they took some blocks out at the area of the dampness and stapled some tyvek house wrap over the wood.  Not a proper repair, and they didn't address the other areas where the pavers were in contact with the siding.  

Work of this nature takes more than a landscape contractor to install.  A skilled carpenter familiar with drainage planes or a roofer who does chimney work should be able to properly prep the siding, and even then there should be barriers between the stone and the flashing to prevent the above mentioned deterioration from lime content.  Have a look online, there are some excellent drawings of how this type of installation is properly done.  If you're not doing the work yourself, be sure your contractor is doing it right.  If you do some reading online, you may be far more knowledgeable than you contractor.