With this type of installation, you will also create a space in which you can run wiring or plumbing if you need to. The furring strips provide a secure fastening point, to which many materials can be affixed. The foam insulation will moderate the inside LQ temperatures, and you should be very pleased with the results.

Gard

This one will not work with the slats, as you won't have anything to attach them to.

Either one of these ideas will work as you will have a solid backing to attach the beadboard slats too.

I attach furring strips with the foam board insulation between them, and then put the beadboard (or slats) over that? 

That is the route I chose and we also used the space to run wiring across from one side to the other.

I don't know if the wording I chose to copy was correct.

I placed the foam type insulation board in between the existing wall braces. I attached my furring strips to those braces and then I attached my wall boards (?slats?) to the furring strips.

Let me see if any of my pictures show it more clearly...

It does make sense and it should work, but I used more strips horizontally. I spaced them like 12 or 15" apart and just used as many as necessary...not just where I "thought" something would attach. That way, when I attached my wall paneling, it was really secured and bowing/sagging/any other negative issue was less likely to be a problem later on.

I was wondering about the space for the wiring. Thanks for the clarification on that. I'm doing this in spurts while using the trailer. So some things are out of order, just trying to allow for the future additions. Does the electrical wiring run through anything for protection or just run it behind the walls?  I have no intention of doing any electrical stuff myself. But just trying to educate myself so I don't have to re-do anything.

If you cut notches into the back of the furring strips before they are installed, it will leave a gap between the original wall and the strips, in which you can run your wiring or plumbing. This also places the wiring behind the foam.

If you plan on using any plumbing in freezing temperatures, make sure to place your PEX plumbing between the insulation and the interior wall covering. If the plumbing were placed directly against an outside wall and covered with insulation, it could freeze, even if you had interior heating.

It is important that when you install your interior wall covering , whatever hardware you use doesn't penetrate the furring strip and contact the wiring. This could result in an electrical short. For the best protection, a piece of sheet metal can be installed on the face of the furring strip opposite the notch, covering the wiring chase. This will protect the wiring from damage. If the wall covering is attached with construction adhesive, this is not a problem.

It was mentioned that additional strips should be added to prevent the new interior wall covering from flexing. This can be tested by laying some furring strips on the floor, lay the new covering over them and press down between the strips. If it is too flexible, try moving the strips closer together, until you get the right spacing. Use that measurement when you mount the strips on the wall. It's better to have them too close together, than too far apart.

When you finish the furring strips and the plumbing and wiring are installed, it's an ideal time to take some photos. Stand a ruler in the picture for a reference, and shoot all of the structures as they are constructed. File these away, and later you will know exactly where each strip is located, if you want to install something extra or do some trouble shooting. It's very easy to forget exact locations after the job is finished

BOL   gard