Do I need a building permit?

Generally, no. Check with your local municipality, but for the most part playhouses and other non-inhabited single story structures under 200 square feet are exempt. In very urban settings, such as Seattle, it can be less, while in rural counties this can rise to 400 square feet. However, if you're looking for something that is 20' x 20' and we start talking about bathrooms, multiple bedrooms, and a place to put Mom, then you should probably contact a licensed architect or your local general contractor.

How much does a playhouse cost?

Asking how much a playhouse costs to build is like asking how much a house costs to build. I don't have cookie cutter models. What I build is more akin to custom homes, writ very small, and like the construction of any custom home, the cost will depend on many factors.

First of all, how big are we talking? Is this a 5' x 8' children's playhouse, or is this a 12'x16' artist studio with a guest loft?

Do you live down the street from me, or do you live in Florida?

Am I going to spend three weeks carving a life-sized mermaid who's supporting the eaves with her wave-swept arms?

You get the idea. 

There is very little we buy anymore outside of custom home construction that is commissioned, so it may seem odd to you when I turn the question around to you. Tell me what you're dreaming of and what you're budget is, and I'll tell you what's possible.

But if you want numbers, I can tell you what I've built in the past.

I want to build you what you can afford. I don't mark-up materials. I don't have employees. I have very little overhead. Considering that the average lumber package for a building which I can tow down the highway costs between $3,000 and $7,000, I think you'll find me quite affordable when I give you a (no cost) bid.

How long does a Magical Playhouse take to build?

A playhouse can take anywhere between 4 weeks to 4 months to build, depending on its complexity and size.

Do I need a foundation?

Most people don't have perfectly level yards, so some kind of leveling is often required, but for the size of structures I build, a simple post/pier foundation is more than enough. I use pressure treated joists, so theoretically if you had a level yard, it wouldn't need anything. Where's it going to go?

The only reason I would pour a full foundation would be if your local municipality requires one, or your site's topography demands it.

What size buildings do you build?

To me, a Magical Playhouse is something less than 200 square feet. Structures more than that start to feel like ADUs to me.

For children's playhouses, I usually build them in my shop here in Port Townsend, WA because they are small. I can legally trailer a building down the highway that is 6'8" feet wide at the base, 8 feet wide at the eaves, 12'6" feet tall and 16' feet long. This is the size of The Dragon, which I exhibited at the Bellevue ARTSfair. When I was there I watched thousands upon thousands of children play inside it and I heard ONE boy (about 10 years old, I'd guess) say it was 'small.'

Delivering children's playhouses fully assembled is particularly fun because they can be dropped off in during the afternoon and abra-ca-dab-ra! alakazam! its there when the kids come home. Plus, I'm not there for weeks in your backyard making sawdust and noise.

But I want something for myself and you can't drive into my backyard...

Bigger structures are usually panelized, delivered and assembled onsite.

Smaller structures that I can tow down the highway, but not into your backyard can still be delivered fully assembled. Hiring a crane or a boom is more affordable than you might think. In my neck of the woods, it costs $150/hr. Compared to on-site assembly, this is a much cheaper option for small structure that just needs a "boost" to clear your landscaping/fencing.

Do you charge sales tax?

I collect sales tax for playhouses delivered in Washington State.

Does the price on your 'for sale' building include installation?

It does if the installation is simple, meaning I show up beforehand, prepare a level space on your yard (pressure treated beams, or a compacted gravel surface) and am able to drive my trailer into your yard. If you want a concrete foundation with a facade of fossilized ammonites, that would be extra.

How far will you deliver?

If a Martian wanted a playhouse and was willing to pay for shipping, I'm sure SpaceX would be thrilled to hear from me.