Spahaus Design

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Spa enclosure plans. . . . major


We were calling this the tub room, but now we call it Spahaus.  There's an existing hot tub spa on a concrete pad in the big backyard of these folks in need of spa enclosure plans to build a room or two, enclosing the tub and some adjacent space: the room will include the tub, an open area, and a full bath.  Lots of windows.  A door or two.  There are several elements to this building that provide interesting opportunities and challenges to spa enclosure plans in CAD designs.   You can see various aspects of this set of CAD design home drawing spa enclosure plans elsewhere in this website in

Builder HOME Drawing,

Plans & Elevations, Foundations For Home Building, Continuous Stem Wall . . . unusual

Schematics, Home Plumbing Layout, Roughed

HOUSE PLAN Details, Foundations For Home Building, Continuous Stem Wall . . . unusual


MODEL HOME DRAWING, Home Design, Spa Enclosure Plans

Where has the Autocad Granddad been?  Figuratively, in the rain forest.  Humidity its containment and control provides the biggest deal in this home design spa enclosure plan -  over grade, i.e., the framing.  The AG has gotten hold of an expert in the field Dectron to guide the old man to go where the old man has not been before.  Nor, for that matter as it turn out, have many others.  

Think about it.  You've got about 80 cubic feet of water round about 102 degrees Fahrenheit, evaporating all the time faster in drier ambient air or when folks are splashing around, more slowly with the lid on and rainy days.  Covered.  Uncovered.  Always evaporating.  What do you do with all that water airborne?  Building up?  (No pun intended.)  You can let it ebb and flow around the Spahaus (new name, sports fans) to warp wood, grow mold and fungus, rot structure, distort sheetrock,  peel paint, separate laminates, rust and corrode, foster allergy and infection.  Or control it.

Controlling it is where the AG has been.  Learning about how it's done, then thinking over the consequences to home design.  Dectron's the pro at air control, though they recognize two competitors more or less at parity.   Feed them a half-dozen or so basic inputs, e.g., water temp and surface area, window square footage, r-values of insulations, interior volume, etc.  They tell you what'll it take to control indoor air quality.

So, what about the home design spa enclosure plan implications?  Lots.  Start off by understanding that the air management is enabled by home design and affects it, too.  Let's see now . . .

  1. Create a vapor-proof interior.  We've already vapor-proofed the slab.  The walls and ceiling must be sheathed on the interiors with a continuous layer of some water-impermeable material.  Insulation counts, but in this southern site, it doesn't count for nearly as much as it would up-continent.  It's the ceiling that gets tricky.  Why?  Because of two different building imperatives in this structure.  One is that the exterior face of the ceiling the roof will be by necessity water vapor-proof.  Now, so will the interior.  So, the challenge come in getting the rafter bays to breathe.  Conventionally, that the job of soffit vents and the like at the low end; rafter bay vents along the length of an insulated roof's rise;  and gable or other kinds of roof vent materials and mechanisms at the top end.  Swell when we gable the long wall roof lines.  But at the ends of our elongated octagon, we're going to have three triangular roof sections each, hardly amenable to bay and top-end venting.  The AG's hot on the trail of a work-around.  Structurally sound, creative, different.  Let him pin it down better before writing anymore about it.

  2. Hide the interiors conduit.  It is yet to be determined just how big the air management conduit will be interior to the structure, but it will indeed be there.  The AG is provisionally prone to some valence-like structure rimming at least those parts of the interiors where the conduit will run.

  3. Support the air management equipment that goes inside the structure.  Unless air control pros determine otherwise, it will most likely be that some smallish gear goes inside, say 2' or so by 3' or so by a foot or so high and a couple hundred pounds or so.  The area over the bath would be ideal, and the joisting  and possibly other structural and functional elements would have to be amended to support the gear's presence.  (Again, provisionally, we're in the neighborhood of a small breakfast table-sized mass loading around 30# per square foot continuous dead load plus some slight, operating vibration.  Double joisting, 3/4"+ plywood platform fitted with an antivibration pad is where we're headed, it would seem.)

  4. Energize it.  It's too early to be specific about energy supply to the interior and exterior equipment to control the air, but it will be only electrical power in two-pole, roughly 40A supply.  This, too, will harden up once we've fed the pros what they need to size the air management needs and mechanical replies.

Time to draw a floor plan for the pros, and answer their questions about some key particulars.

There could have been a slight change in plans.  The Autocad Granddad's clients prefer no bigtime air management system.  The AG is not influenced by that preference, noting that he will home design and draw the Spahaus as though the bigtime system would be installed, and highlight those elements of home building that relate directly to the system.  However, no specific system would be identified, sized, and otherwise specified.  You see, this is a free-will society, and the AG's client can freely and willfully amend or omit any facet of the AG's home design.  The only effort the AG can make in these regards is the very best effort of home design that he can.  And that effort must include a sophisticated, extensive, and expensive air management system on the level of Dectron's product offerings.

More news:

The ceiling really, the break between the wall line and the interior roof line will begin about 10' over floor level.  Four reasons

  1. The topography can accommodate a tallish structure without major amendment.

  2. The owners prefer a tallish structure as they look upon their site, and appreciate the perspective a "looming" Spahaus brings to the pool area which the Spahaus will border.

  3. Good building practice all but demands a higher ceiling height at least in one area of the Spahaus the deck area.  Our deck will set about 2'-6" to 2-'8" over the floor level, i.e., the existing concrete pad and up-set  abutting pour.  Good building practice comes to play in that generally 7'-6" is considered the right minimum ceiling height for areas inhabited by people or otherwise through which they pass.  There are a few exceptions to this rule kitchen ceiling heights at 7'-0" minimum, for example but our deck area is not one of them.  So, let's do the math:  2'-6" + 7'-6" = 10'-0".  Now, if the Autocad Granddad home-designed a hard ceiling at 10'-0" or strung beams at the level in the Spahaus deck area, he'd be pushing it some.  Mostly because he's pretty sure we'll turn in a deck height closer to 2'-8" than 2'-6".  The saving grace here is in an owner preference not only for an open ceiling, but also one trussed at angles rising from the rafter tail or wall top plate elevation to heights in the roof line even higher, say, just about collar beam height (roughly one-third of the roof line rise as measured from the ridge pole).  That's all the height clearance anyone can reasonably expect for a habitable structure, and satisfies the AG's need to home design the best, notably for the safety of his clients and their guests.  Based on the clients' own statements in reply to the AG's queries, the AG will carry that higher interior height throughout the structure.  (There will be a couple other shifts to the direction in which the AG was home designing, based on this encouragement to height or at least a loftier look.  Stay tuned.)

  4. There's no way we can header over a door that's over 2' over grade without a 10'-plus wall height without modifying the roofline inappropriately.

We'll start by labeling the exterior walls all eight of them and the one interior wall in plan view.  Our nomenclature will be W1 through W8 on the outside, beginning the count at the north wall and moving clockwise.  So the three short walls by the tub are W1, W2, and W3.  The long wall with the two big doors is W4.  The three short walls by the bath at the south end are W5, W6, and W7.  The long back wall is W8.  The interior wall for the bath will be W9.  Pictorially, this is what we've done.

Time to see the walls in elevation.

Wall four, or W4, is first.  It's the most complex.  Two doors, one up to enter at deck level; at least a window, maybe two; asymmetrical heights of wall amendments, some sort of symmetrical placement.

There isn't the strength in the AG to go over how often this wall got jerked around in order to get things to work out just right.  The French door's centerline is on-center to the face of the tub's concrete pad closest to and horizontal to W4.  (All wall elements are to Andersen specs, identified separately in the building plans.)  Note how the top plates are set downward to let the ceiling joists for the bath, in elevation.

The centering is made clearer in this note included with the framing plans overall home design instructions and guidelines.

That more or less introduces W8, in elevation.

Surprise!  It's W4 flipped with all windows and one missing element that's where the shower backs up to.  Note that all these windows and all the others are set at the same height over floor level.  Symmetry is king!

W1 and W3 are identical, in elevation.

W2 may look identical to W1 and W3, and it is not.  The difference is in the header.  Instead of right over the window as in W1 and W3, this header is hard to the top plates.  Why?  In short, we need an escape hatch if ever the tub needs replacing.  That hatch is to be W2.  Interior deck framing to the north and west of the tub and all the framing and finishing to W2 will be fastened with screws, not nails.  All, that is, except the high-hat header in W2, which will stay put to hold up its end of the Spahaus when the rest is temporarily removed in the escaping process.

At the other end of the Spahaus, we must cope with the lowered ceiling, in elevation.  These windows are tall.  Almost but not quite too tall for application at the south end of the Spahaus.  Here are W6 and W7.  Note the modification to the header.  The flitch is to build out the header in lieu of a nailer.

There's no point to showing W5 or W9 in elevation.  Both are modified in height to let the bath ceiling, and have 3'-0" doors.

But let us  digress to W9 not in its structure, but in its placement.  Initially, the AG though that choosing the shower depth on the W8 face chooses the site of W9.  Not by a country mile.  There is a balancing act here, a balancing act that took several passes to pull off to the Autocad Granddad's satisfaction.  These are the main considerations to siting W9:

  1. The owners want a corner shower bath triangulated.

  2. There are hard rules on rules about how large that corner shower must be in various horizontal line dimensions, in floor area overall, and in a specific circular orientation (none of which we'll go into here, but all of which conspire to a fairly hefty corner shower footprint).

  3. There is the need to make the W4 window area of the bath big enough to hold the window itself and its trim without looking crammed in there.

  4. There is the need to allow sufficient space on the north side of W4's joint to W9 so that the slider has room for a casing, and the decorative wall post for that corner does not become obtrusive to either of the proximate passages, even if that post has a 6" or 8" interior reveal.

  5. The slider itself and the bath window on W4, as with the other two wall elements of W4, must be in some symmetrical relationship which, while not necessarily recognizable, must be proportionately pleasing to the eye.

  6. The W8 wall elements must be mirrored on-center to the W4 elements.

The thigh bone's connected to the . . . .

What truly inspires the old geezer to keep at it is, in part, to see his work in 3d home design color.  Here are a couple of in-perspective CAD designs to brighten his day and, hopefully, yours.  These are only foundations and walls with windows and doors, nothing else.


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