Java (OpenJDK 8), 178(削除) 178 (削除ここまで) 177 bytes
(w,h)->h->{int i=0;String t="",m,r;for(;i<w;)t+=i++%3<1?"+-":"-";r=t+="+\n";m=t.format("|%"+(t.length()-3)+"s|\n","");for(i=0;i<h;)r+=i++%2<1&i>1?m.replace("|","+")+m:m;return r+t;}
-1 byte thanks to @KevinCruijssen
Java (OpenJDK 8), 178 bytes
(w,h)->{int i=0;String t="",m,r;for(;i<w;)t+=i++%3<1?"+-":"-";r=t+="+\n";m=t.format("|%"+(t.length()-3)+"s|\n","");for(i=0;i<h;)r+=i++%2<1&i>1?m.replace("|","+")+m:m;return r+t;}
Java (OpenJDK 8), (削除) 178 (削除ここまで) 177 bytes
w->h->{int i=0;String t="",m,r;for(;i<w;)t+=i++%3<1?"+-":"-";r=t+="+\n";m=t.format("|%"+(t.length()-3)+"s|\n","");for(i=0;i<h;)r+=i++%2<1&i>1?m.replace("|","+")+m:m;return r+t;}
-1 byte thanks to @KevinCruijssen
Java (OpenJDK 8), 178 bytes
(w,h)->{int i=0;String t="",m,r;for(;i<w;)t+=i++%3<1?"+-":"-";r=t+="+\n";m=t.format("|%"+(t.length()-3)+"s|\n","");for(i=0;i<h;)r+=i++%2<1&i>1?m.replace("|","+")+m:m;return r+t;}