Test, test and test

It is so very important to keep trying structures against other structures as you go along.  It is extremely unlikely if you kit-bash anything you will get away with not making some mistake but clearly you will want to avoid it if you can.

One of the biggest mistakes is moving interior walls without considering the windows.  Now you have read that, it will seem glaringly obvious, but I have seen several finished projects where someone didn't do this.  There is nothing more 'distracting' than seeing an interior wall divide a window when the house is closed up.  

marks showing position of windows

At the planning stage you need to do a lot of measuring of this and that and transferring those measurements to the 'box' part of the project to check the relationship of one thing to another.

right hand door in place to ensure the new walls are OK

When you think you are ready to glue in the walls do another 'dry build'.  Put them in without glue and stand the door fronts of the building in place and check that doorways and windows all make sense.

If, like mine, the front of your house also includes some sort of pavement or basement frontage that also needs to be thought about in relation to the interior of your house and what could and couldn't be accessed from where.

In my case for example there with be a 'dead' area under the entrance hall (middle floor in this picture) which I would like to access from the servant's hall as some sort of storage area.  You can see from this photo that the dead area which runs in line with the entrance hall walls is not neatly where I would like it to be.  In this instance that's fine and can be 'got round' but that may not have been the case.

The servant's hall (bottom floor in the picture) only gets one off-centre window which is also OK but, again, it could have looked odd in another room in the house.  All my other rooms have windows in an appropriate position.  So far, so good.