Low Poly house exercise

I found using the Modeling toolkit very useful when creating the house as it holds all the tools i used in making the house and more such as: Vertex,Edge and Face selection

This exercise was helpful to me as it taught me to use different selection tools to manipulate the model in different ways, which can be more appropriate then others in different instances.
Some issues that I have encountered while doing this exercise sometimes Faces or Edges may seem to act unpredictably when moving them as they are connected to the Faces and Edges around it and sometimes end up disconnected.
This may lead to faces becoming inverted