There are two principles at work in dancing back and forth between painting and gluing when building a dollhouse.  The structural strength of a dollhouse requires gluing to un-painted surfaces, but the tidy look of clean paint-lines requires that the parts are painted before they are glued together.  How can you do both?

The short answer is to plan ahead – to assemble before painting where the colors are the same, and to paint before assembly where they are different.  Well, like most short answers, that’s not always true. 

Two kinds of “housebody” assembly:  Most houses are either

“continuous” or “Balloon” construction (the outside walls go all the way up from the foundation to the roof, and the floors are suspended on the inside [all New Concept, JM401, JM907, all lilliput])  

or “stacked” or “layer-cake” construction (each floor of the house has a perimeter of walls that sits on the floor, then the next floor sits on top of the wall set [all Batrie, JM860, J1033, Queen Anne])

And, some houses are a combination of styles [JM1065, JM975, 4500, LH100]; the dance is different for each of these construction styles.

The first coat:  No matter which kind of construction you have, the first coat is easiest before construction.  One coat to fill the grain and stabilize the surface before the walls are sanded, filled, primped, or even touched very much (this is especially true of the “Milled Plywood” houses that are made of plywood and have a clapboard profile machined into the wall-surface). 

The first benefit of painting before assembly (one-coat) is that it is the easiest time to do a really thorough job of sanding after painting.  The difference between a heirloom-grade finish on a dollhouse and a “I-was-in-a-hurry” finish is most often the quality of the sanding, and it’s hard to sand into the little hidden corners of an assembled dollhouse, but it’s easy to sand the flat panels layed out on a workbench. 
For you “MP” or “MM” (clapboard profile) house builders, the statement “one clapboard course at-a-time” means to fold the sandpaper and hold it on your finger-tips, then sand back-and-forth across one clapboard’s suface two or 3 Times, then move up to the next clapboard.  “One at a time”  is what makes it smooth and “Heirloom_great”.

The second benefit of the first-coat before assembly is that it makes the panels so much more robust.  I don’t have to be so worried about being gentle with the parts when I stack them in groupings for assembly.  I don’t have to worry about how I take off the tape after an assembly sequence (I use a very sticky tape, and it sometimes will peel off the surface of a wall, and it will always peel off the wood-look finish on a JM401 or JM907 floor, but one coat of paint on the wall or clear acrylic urethane on the floor and I’m worry free), and I don’t have to worry when I wash a glue-smear or dribble, the panel is much more protected from water-damage.

The first-coat is all about what penetrates and fills the wood.  There is no expectation that more than a hint of paint will be on the surface, and this is what makes it so neat.  After sanding, there is ample wood exposed on the surface for a perfectly strong glue joint.  You get the benefit of easy-sanding and of good glue joints!  OOhhh, AAhhh

On Continuous Construction houses, now it’s time to build the house.  After the housebody is assembled (the walls and floors), second-coat the walls.  Everything that is attached after that should be fully-painted.  Groups of parts that are pre-assembled before attaching them to the housebody should follow the same logic we’re developing: same-color parts painted, sanded, assembled, then second-coated; different-color parts first-coated, tested to identify the glue-surface (which won’t get second-coated), second-coated, then assembled.  When parts that have to be strong are attached (Roofs!), trace for the glue-joints, then paint to just cover the tracing.  That will leave a crisp paint-line and will still give a strong glue-joint. 

On Stacked Construction houses, everything must be painted before it is glued on.  I’ll use the porch section of a Victoria’s Farmhouse as an example here:
The walls are painted, sanded (one clapboard course at-a-time, naturally!), then re-painted.  If I am painting the inside, I set up the walls on the house (dividers too) and mark the glue-spaces.  The marks get just-barely covered with paint, leaving an un-painted space for glue.  I also test and mark the floor of the Base Assembly (base floor and foundation) and the underside of the second floor, and then paint to just barely cover the mark. Now, I assemble the walls and floors.  The painting is done. Each floor is a repeat of this process 

 

Now, there’s the question of what to do with glue joints have to be strong, but the parts really must be painted beforeassembly… things like porch rails and posts.  The Rails themselves, I one-coat, sand, assemble, and second-coat.  The posts are pre-painted, then a little spot of paint is scraped off where the rail will attach.  The rail has no paint on the end, and the scraped-spot gives a paint-free glue space.  In the same way, I scrape a spot for the post on the porch floor and ceiling. 

For the non-structiural things like window frames and shutters, I glue directly to the paint.  These parts are not subject to knocking and pulling, and they have large glue-surfaces.  They will be just fine without bare-wood for gluing.

 

Well, that’s the dance.  Sometimes there are a lot steps, sometimes it’s a waltz.

All the best
Gary