How to make clean junctions of line with `\draw`

Question

Here is the MWE (sorry it's not too short)

    \documentclass[border=2pt]{standalone}
    \usepackage[utf8]{inputenc}

    \usepackage{pgfplots} %pour Tikz et pgfplot
    \usetikzlibrary{positioning} 
    \usetikzlibrary{calc,decorations.markings} 
    \tikzset{
        damper/.style={
             decoration={
                markings, mark connection node=dmp, mark=at position 0.4 with 
                    {
                     \node (dmp) [inner sep=0pt,transform shape,rotate=-90,minimum
                        width=15pt,minimum height=3pt,draw=none] {};
                     \draw ($(dmp.north east)+(10pt,0)$) -- (dmp.south east) -- (dmp.south
                        west) -- ($(dmp.north west)+(10pt,0)$);
                     \draw ($(dmp.north)+(0,-5pt)$) -- ($(dmp.north)+(0,5pt)$);
                    }
                },  decorate
            },
    }
    \begin{document}
    \begin{tikzpicture}[thick]
        \node (start) at (0,0) {};
        \coordinate (top) at (1,1) ;
        \coordinate (join) at (3,0) ;
        \draw (start) -| (top) -- ++ (0.05,0); % the last point to make it clean
        \draw[damper] (top) -- ( top -| join) node[pos=0.5,above=0.3cm] {$c$}; 
        \draw (top -| join) -| (join);
        \draw (join) -- ( top -| join) ; 
    \end{tikzpicture}
    \end{document}

The interesting bit is inside the tikzpicture

See, if you use \draw (A) -- (B) -- (C) the junction in B will be clean. if you use \draw (A) -- (B) and \draw (B) -- (C) the junction will be visible, like on the right in the picture.

The problem is, I can't use the first way when only one line has the decoration to make the damper, that's why I kept it in the MWE.

So you can see I patched the problem for the corner on the left using -- ++ (0.05,0) which is more a bandaid than really fixing...

Got an idea ?