New Tiny House Plan

We at Istockhouseplans have been busy developing a cadre of tiny house plans.  Not every one makes the cut to be web-worthy.  Most of them do however become inspiration for other plans.  We are proud to introduce our latest plan, the Wilsada 1416.

Several things inspired this plan.  One was simple lines.  The plan is a simple box with one tip out and three ridges.  Generous light also came into play.  A sliding glass door provides entry on one side while a bank of windows opens up a view on another side.  The third was tiny bathrooms.  We first introduced a complete wet room in the Carver cabin series.  We continue the idea in the Wilsada.  Finally, we have been recently enamored with the idea of sleeping nooks.  Rather than a formal bedroom, the Wilsada contains a very cozy bed nook.  Visualize curtains over the opening and a little bookcase at the foot.  And of course it's elevated allowing for storage underneath.

A kitchenette, sitting porch, and vaulted ceiling complete the look.  Despite our generally craftsman motifs, we could easily see this one decked in white beadboard.  Somewhat of an East Coast beach theme.  Probably not appropriate for a mountain retreat.  Or maybe that's just the kind of irony that you go for.

IKEA Loves Small Homes

If you've received your copy of the 2012 IKEA catalog, you may have noticed a theme. We at Istockhouseplans were thrilled to read the phrase on the front: "A HOME DOESN'T NEED TO BE BIG, JUST SMART."  Bravo IKEA, bravo!


The first couple of pages immediately show some ideas that the IKEA design team put together.  They created a space for 6 friends to live in within 430 square feet.  The solution consists of curtained bunkbeds at the edge with a large table in the middle.  All other space is communal.


Their second challenge was a 75 square foot kitchen.  IKEA was able to get an island and plenty of storage in the small space. Other layouts are shown starting on page 112.  If these still aren't inspiration enough, you can go to IKEA's website and use their kitchen design software.


The next challenge was a 118 square foot living-slash-bedroom-slash-playroom.  The central feature is a loft bed for the grown-ups.  Another variation is shown in a 107 square foot living room that is essentially a showcase room for a chaise lounge.


The final design involves a 29 square foot bathroom - with laundry space and a spa tub.  There must be some smoke and mirrors here because no good ol' 'Merican spa tub would be less than 29sf itself, right?


To see videos showcasing all of these ideas, visit IKEA-USA.com/smallspaces.


The coup de grace of all of this for us was the new Lillangen single bowl sink.  One of our favorite things is to make secondary rooms (powder baths especially) as small as possible.  Building code dictates some minimum sizes needed around fixtures.  At some point to get smaller, the fixtures need to shrink.  We can specify a smaller sink only to have the contractor turn it down because of cost.  (Why are smaller appliances, fixtures, and doodads so much more expensive anyway?)  IKEA's previously mentioned sink is less than 11" in depth with a side faucet (faucet sold separately).  Price for the ceramic, $49.99.  Price for faucets starting at $39.99.  Less than $100 to reduce the size of the house, or give that space to another use.


Of course this is all good news for our line of tiny homes.  If you try to design a tiny home as a mini-McMansion you will fail.  But with IKEA and a little ingenuity you can make anything happen.


*Full disclosure: IKEA has no idea I wrote this blog post.

Calculating Even More Heat Load

Welcome back to the third and final installment of calculating heat load.  In Part I we looked at the envelope of the home.  In Part II we looked at air infiltration and how it works.  In this part we will look at internal loads and finally deciding what heat source to add to a home.

We realized that we should have been giving a real world example from the start.  In light of that, let's do some quick review using our plan The Belmont #3232.  If you recall the equations:

1. Afloor x Ufloor x ΔTfloor = Btu/hr floor
2. Awall x Uwall x ΔTwall = Btu/hr wall
3. Aceil x Uceil x ΔTceil = Btu/hr ceil
4. Awindows x Uwindows x ΔTwindows = Btu/hr windows
5. Adoor x Udoor x ΔTdoor = Btu/hr door

This translates to:

1. Floors: (32x32) x (1/38) x 25°F = 673.68 (1024sf insulated floor, R-38 in joists)
2. Walls: (32x18x4 - 339.33) x (1/21*.8) x 45°F = 5262.51 (four walls minus windows, 32'L x 18'H, R-21 with framing factor)
3. Ceiling: (32x32) x (1/49*.8) x 25°F = 522.45 (1024sf ceiling, R-49 with framing factor due to edge pinch)
4. Windows: 339.33 x 0.30 x 45°F = 4580.96
5. Doors: 40 x 0.20 x 45°F = 360

We've taken a few liberties but not much.  The end result won't be too drastic.  As you can see, walls will have the highest heat load followed closely by windows.  This is because the wall area is large; for windows the R-value is poor.  Envelope load comes to a grand total of 11399.6 btu/hr.

For air infiltration, recall the formula ΔT x ACHnat x Volume x HC = BTU/hr.  Our ΔT=45°F, volume is 18432 (32x32x18), HC = 0.022, and we'll assume ACHnat to be based off of a blower door test of 5.0ACH, ergo .25.

• 45°F x .25 x 18432 x 0.022 = 4561.92

Again, not small.  Add up all the bold numbers and this gives a base load of 15961.52.  See, now you're a back of envelope engineer!

Now for the good news!  You will have several internal loads that will help to heat your house, that is, they will make this number smaller.  The biggest source is the occupants.  General convention assumes that there will be 2 people in the master bedroom and one person for each of the other bedrooms.  The Belmont is a 4 bedroom home but practically we could assume four occupants living upstairs.  Occupants put out anywhere from 200 to 300 btu/hr of heat load.  We are preferential towards 275 btu/hr.  For four people, this is a reduction of 1100 btu/hr.  You can also figure in incandescent lights, the kitchen oven, hair dryers and other such pieces.  These don't make a huge difference unless your heat load is so low that you are in PassivHaus range.

Our final result for heating this home in this scenario is 14861.52 btu/hr.  Now what?  Now we need a heat source.  Our first choice might be the typical forced air gas furnace.  A quick look at manufacturer catalogs will reveal that 40,000 btu/hr is the smallest one available.  Even at a low 90% efficiency this will put out 36,000 btu/hr.  But if you have an attached garage, you can always place the furnace there and lose about 40% of your heat bringing the load down to about 25,700 btu/hr.  Let's not.

Another option might be electric wall heaters.  Each 1kW wall heater = 3412 btu/hr.  This calculates to needing 5 heaters.  Reviewing this plan shows that there are up to 10 rooms that would need heat.  Perhaps several 500W units would be more applicable.  Don't forget to install them on an interior wall.

Another choice is a ductless heat pump.  You are limited to a max of 4 heads per unit.  More heads requires another unit which doubles the price.  Or you could get a splitter for some of the heads and share the heat load between rooms.  To outfit the Belmont 3232 you would need one head for the dining/parlor, one split head for the office/bath, another for the master and bath, one more for the auxiliary bedrooms.  The kitchen, utility room and bathroom would need a 500W electric heat source.

Another option might be radiant heat.  In floor hydronic heat puts out 18-25 btu/sf.  Assuming 20btu, you could cover 743sf of the floor with tubing.  But how do you cover 743sf in a 2000sf house?  If you stick to just the walk areas you could make it happen.  But unless you are doing an onsite DIY approach, this option can be super expensive.

The final choice would be to increase some insulation in the walls, try for better windows (U-0.025 is reasonable) and tighten the home to 2.0 ACH or less.  Resulting calculations reduces to 10519 btu/hr.  Then install an HRV in the utility room to cycle fresh air and attach a small heating unit to it.

Any other ideas?

In the very near future we'll refine our simple spreadsheet calculator and make it available for your use.  The calculator does most of the math for you but we made this guide available so you'd know what's going on in the background.  Happy calculating!

Calculating More Heat Load

Last week we looked at how to calculate your heat load based on the envelope of your home.  This week we'll take a look at air infiltration and the effect it can have on your home.  The caveat should be given that the tighter you make your home, the more you should be concerned about vapor barriers, retarders, and other management.  Indoor air quality also becomes a concern.  We won't address these issues in this post.

Air infiltration is not something that can be assumed or calculated.  Just as a nail can't be driven by estimation, it needs a tool.  The most common tool used is a blower door.  This is a device that attaches into your front door frame and accepts a large industrial fan.  After closing all other doors and windows, the fan is turned on (generally pointing out) until it is removing 50 cubic feet per minute (CFM) from your home.  Some places in the world aim for 25 CFM.  For a visual, imagine 4 regulation basketballs.  This is 1 cubic foot.  So turning the blower door on to 50 CFM means that you are throwing 200 basketballs out your front door every minute (or more than 3 every second!)

Why in the world would you do this?  A couple of reasons.  First, this is a great opportunity to walk around your house with a smoke stick and see where air is leaking in.  These are places that need to be plugged.  Get your caulk, foam, whatever and fill it up.

Second, since there is diagnostic equipment hooked to the blower door, a technician can determine how much air will blow through your home on a windy day.  The result is a standardized answer that can be used for comparison.  Generally it is in the range of 0-20 air changes per hour (ACH).  This means that with the blower door running, the volume of air in your home could be changed out 20 times an hour.  Every 3 minutes you're getting new air.  This air is coming from outside, the attic, the crawlspace, and the attached garage.

Most newer homes fall around 6 ACH50.  Older homes will be much higher.  It takes some determination to lower a new home from 6 ACH50.  No one accidentally builds a tight home.  With some simple effort we have seen homes approach 4 ACH50.  A bit more effort and change in building methods results in 2 ACH50 which is very good.  The lowest we've ever seen is 0.22 ACH50.  This was a home built to PassivHaus standards.

So why does this matter for energy calculations?  Warm air can be blown out of your home and replaced with cool winter air through leaks.  We need to calculate for this for the furnace to be able to keep up.  Otherwise your home will get cooler and cooler until it equalizes with the outdoors.  This could occur with a 3000sf leaky home and a 40kBTU furnace.  Bad news.

Less talking, more computing.  This is one single formula that has a lot of lead up.  There are four numbers in the formula.  The first is our friend ΔT.  The second is the result of your blower door test in ACH50.  We need natural ACH so divide by 20.  The third is the volume of your heated area.  The fourth is the convective heat transfer co-efficient (HC).  This number has a general range around 0.018 to 0.022:

ΔT x ACHnat x Volume x HC = BTU/hr

Example:  A 1500sf house has a blower door result of 3.5ACH50.  Assume HC to be 0.022 (Marine Cold).  What is the heat loss through infiltration?

Answer: ΔT from last week is still 45°F.  ACHnat = ACH50/20 which is 3.5/20 = 0.175.  Volume is approximately 1500sf x 9' (ceilings) = 13500cf.  HC is stated.  So the formula is 45 x 0.175 x 13500 x 0.022 = 2339 BTU/hr.  Note that we gave a tightness that is half of typical.  Were it 7 ACH50 this load would double!  Don't think air tightness matters?  It's the biggest factor in heat load.

Add this to your envelope load and come back next week for part three, Interior Loads!

Calculating Heat Load

How many times have you looked at a house plan or a house and wondered how much heat it was going to use per year, or need at peak times?  There are several good programs out there that will allow you to do this with a few mouse clicks.  Maybe you don't have access to such a program and want to make an educated guess.  There are several simple calculations that you can do to figure out the answer.

What we are figuring out is the amount of heat that is lost from the house in several ways.  One way is by conduction through the envelope.  Another way is by convection through leaks in the house.  Most factors are known but several need to be looked up.  Once you know those values for your area, you can use them again and again.

Let's establish those values.  First you will need to establish your highest desired indoor temperature.  During winter this might be 62°F or 65°F or 68°F.  We'll use 65°F for this guide.  Next you'll want to establish the coldest outdoor temperature that might be experienced.  For the walls this might be 20°F or 0°F or -20°F if you're in Alaska.  We'll assume 20°F for this guide.

Beware however that your crawlspace and attic will have different cold temperatures.  If your insulation is in the ceiling plane instead of the roof plane, your attic will enjoy the comfort of being enclosed even though it won't be insulated.  Therefore in 20°F weather the attic may register at 40°F.  The same situation is present in the crawl space, especially if it's vented and any walls adjacent to a garage.  We'll use 40°F for these three locations.

Using these temperatures establish a difference of temperature known as ΔT (delta-T).  This is simply subtracting the coldest outside temperature from the desired indoor temperature.  Using our established values the walls, windows, and exterior doors will have a ΔT of 45°F and the crawl space and attic will have a ΔT of 25°F.

Next you'll need to gather the areas of each of the parts of your building envelope.  This includes floors, walls, ceilings, windows, and doors.  Rather than figure the exact wall area, imagine there are no windows or doors.  Then when you do the window and door areas, you can subtract them from the wall area to get a more accurate reading with less calculation.  If you want to be especially precise, you can note the amount of wall against the garage, second floor walls against first floor attics, etc.  We'll skip that precision.

The other thing you'll need to gather is the U-value of those components.  U-value is the inverse of R-value.  U-value should also take into account the whole assembly and not just the insulation itself.  An R-21 batt does not equal an R-21 wall.  A typical R-21 wall will end up at about R-16, that is, a U-value of 1/16 or .0625.  A simple true R-value conversion can be had by multiplying your insulation R-value by a factor depending on quality.  For a standard average build, assume 75% of your insulation value.  For good construction (24" o.c. R-30 wall for example) assume 80%.  If you're using exterior foam, figure your percentage value and then add the foam.  For instance, an average R-21 wall works out to about R-16 but adding 1-1/2" of XPS foam adds R-7.5 for a total of R-23.5, U-value of .0426.  More precision is better but don't go crazy.

Let's put it all together:

The general equation for each element is area x u-value x ΔT.  You should write down the following:

1. Afloor x Ufloor x ΔTfloor = Btu/hr floor
2. Awall x Uwall x ΔTwall = Btu/hr wall
3. Aceil x Uceil x ΔTceil = Btu/hr ceil
4. Awindows x Uwindows x ΔTwindows = Btu/hr windows
5. Adoor x Udoor x ΔTdoor = Btu/hr door

Now add all of these together to get your envelope load.  Simple!


Next week: Infiltration!

Istockhouseplans Gets Greener

As more and more companies are beginning to do a life cycle analysis of their products, Istockhouseplans feels that this is a worthwhile study to pursue.  Generally we will send you a half dozen sets of plans.  Most of those will go to the permitting jurisdiction for approval; some of those you will give out to subs to do their work.  What's left is a few sets around the jobsite that get muddy, or a couple extra sets that get stuck under the seat of your F-350.  We've compiled this list of how you can safely, humanely, and environmentally end the life of those plans.

• Recycle them in the paper bin.  Duh.
• Ship them back to us for proper disposal.
• Shred them for landscaping mulch.
• Shred them for attic insulation.
• Shred them for party confetti.
• Sweep up your wood dust and roll it up into a set of plans.  Smash the ends in and leave a few next to the woodstove or outdoor fireplace for the new homeowner to burn.
• If you have a nice set leftover, present them to the homeowner.  Possibly even in a frame.  Or take the time to mount them over the fireplace yourself.  Build the frame out of scrap wood from the site.
• If a set gets too muddy to use, wrinkle it up good, re-flatten it and set it in front of an exterior door for a shoe mat.
• Cut strips to use if you run out of drywall tape.
• Separate the sheets and fold them into origami for the children who are pressing their faces into your cyclone fence.
• Let your kids color the elevations.
• Use the backs as large blank sheets for your kids to color on.
• Make holiday cards for your subs/supers/suppliers using the elevations or details as the front picture.

Other ideas?  Please feel free to share in the comments.  Want to employ some of these ideas yourself?  Visit our plan catalog and purchase your own set.

Lumber Sizes

Ever notice that a 2x4 isn't really 2"x4"?  What's with that?   Fact is that the piece of wood started at 2"x4" but is called "rough sawn", that is it has unfinished faces.  The stick is then sent through a planer to smooth the faces and reduce serious splinter casualties.  About 1/4" is shaved off of each of the four faces resulting in a lesser dimension than you would expect.  Besides, who would want to say "one-and-a-half by three-and-a-half"?  Mind the twist at 2x8 and beyond...

Now pay attention as we mention dimension convention:

1x:

• 1x2 = .75" x 1.5"
• 1x3 = .75" x 2.5"
• 1x4 = .75" x 3.5"
• 1x6 = .75" x 5.5"
• 1x8 = .75" x 7.5"
• 1x10 = .75" x 9.5"
• 1x12 = .75" x 11.5"

(5/4 material is similar but is 1" thick)

2x:

• 2x2 = 1.5" x 1.5"
• 2x3 = 1.5" x 2.5"
• 2x4 = 1.5" x 3.5"
• 2x6 = 1.5" x 5.5"
• 2x8 = 1.5" x 7.25"
• 2x10 = 1.5" x 9.25"
• 2x12 = 1.5" x 11.25"
• 2x14 = 1.5" x 13.25" 

3x: (for those odd structural plates that engineers like to call out)

• 3x4 = 2.5" x 3.5"
• 3x6 = 2.5" x 5.5"

4x:

• 4x4 = 3.5" x 3.5"
• 4x6 = 3.5" x 5.5"
• 4x8 = 3.5" x 7.25"
• 4x10 = 3.5" x 9.25"
• 4x12 = 3.5" x 11.25"
• 4x14 = 3.5" x 13.25"

6x and beyond follows typical pattern as above.

And while we're at it, how about some typical engineered wood sizes.

I-joists are created by standing a piece of OSB or plywood upright and capping it with a 2x flange.  The result looks like a capital serif 'I' hence the name.

I-joist flange widths (varies by manufacturer):

• 1-3/4"
• 2"
• 2-5/16"
• 3-1/2"

I-joist heights (total height):

• 9-1/2"
• 11-7/8"
• 14"
• 16"
• 18"
• 20"
• 22"
• 24"

Laminated Veneer Lumber (LVL) beams are created by gluing several sheets of 7/8" thick plywood together.  Installation is by standing them on edge so that the profile looks similar to |||

LVL widths:

• 1-3/4" (2 layers)
• 2-5/8" (3 layers)
• 3-1/2" (4 layers)
• 5-1/4" (6 layers)
• 7" (8 layers)

LVL heights:

• Any height possible though generally intended to match I-joist material.  Can match dimensional as well.

Glu-lam beams are created by gluing and compressing several layers of post milled dimensional lumber together.  The whole beam is then planed again to create an even surface.  For this reason, glu-lam beams are slightly narrower than dimensional lumber.  *The industry has recently changed to also offer Gle-lams in full 5-1/2" widths as well.  Heights are always in multiples of 1-1/2" due to the size of the plies.  *The industry has recently changed to offer heights that are consistent with solid sawn and engineered lumber as well.  Due to general engineering practice the height should always exceed the width though rare exceptions always exist.

Glu-lam widths:

• 3-1/8"
• 3-1/2"
• 5-1/8"
• 5-1/2"
• 6-3/4"
• 7-1/4"
• 8-3/4"
• 9-1/4"
• 10-3/4"

Glu-lam heights:

• 6"
• 7.5"
• 9"
• 9.5"
• 10.5"
• 11.875"
• 12"
• 13.5"
• 14"
• 15"
• 16.5"
• 18"
• 19.5"
• 21"
• 22.5"
• 24"

Glu-lams can be used as posts as well.  A 3-1/8"x6" glu-lam post is sturdier than a 4"x6".

Free Plans part 4

As we wrap up August and the month of free, we offer one more plan for your enjoyment.  Last week we promised two new plans but the dog ate part of our homework.  So we're left with one final flagship plan to introduce.

The Ramapo is 12' long and 8' deep covering 96sf.  It sports a single shed roof with clerestory windows on the tall wall.  This was originally designed as a bunkhouse for a rural property.  It's big enough to get a bed and bathroomette and closet in.  Or loft the bed and increase the floor space.

This may be the last of the free blitzkrieg for a while but it won't be the last of the free plans forever.  There are a few variants on the current plans that we would like to add, plus some new ideas.  In the meantime we need to attend to some other business.  If you have a particular idea that you would like to see, post it here or send it to us and we'd be happy to give it a go.

Free Plans part 3

More free than you can shake a stud at!  The third of our free plans, the Watson 88 has been released into the public.  The Watson is a simple 8'x8' building that anybody could build in a week.  We've kept the 2x3 wall studs but 2x4 would be perfectly appropriate at this point.  Some gridded windows and a small front porch create an appeal that's hard to pass up.  The uses for this building are as vast as your imagination.  At this size we're bordering on the edge of playhouse and small house.  Istockhouseplans has two more basic sizes to offer and... oh shoot, there's only one Tuesday left in August.  I guess our back to school special includes our flagship free plan.

We better get cracking.  In the meantime download the plans, build the shed, and give us your feedback.  Maybe we should have a contest with the most innovative use of materials in one of our sheds...

Free Plans part 2

A couple of weeks ago we introduced you to our new free plans.  We've added another to our portfolio and are thrilled to share with you.

Following the theme of defunct stops on the Springwater Trolley line in Portland, the Kendall 84 is named for the stop that was at 82nd Avenue.  This is similar to the Bell 66 we launched prior except that this is in a more expected straight line format rather than an L shape.  More like a backhoe loader, if you will.  In fact that gives us another idea for decorating the structure.  Lose the porch, slope the roof from left to right and add some extra wood to the front and back.  Paint it all yellow and be the dirt digger you always wanted to be, all from the comfort of your 5-point office chair with lumbar support.

As long as our hosting provider doesn't freeze up again, we hope to release one more each for the remaining Tuesdays in August.  Expect two more free plans from us and then more sporadically through the rest of the year.

Built this?  Link to your picture in the comments and share with us!

Free Plans!

We may be a day late but if you are a dollar short you are no longer up a creek.  Istockhouseplans is proud to introduce our first free plan.  Now granted you probably couldn't live in it but it does at least provide some quiet space for you to work, read, meditate, or pursue a hobby.  Named for a defunct station on the old Springwater Railroad Line, the Bell 66 is small and could be a ticket booth as well.  Post office?  Dry goods?  Vault?  Almost too many options.

Plans can be downloaded directly from our website in 11x17 pdf format.  Full wall framing details are included.  Some cut lists and guides should help even the most ham-handed builder to at least kludge together a reasonable facsimile in a weekend or two.  You may notice on the plans that the wall studs are 2x3 @ 24" o.c.  The obvious reason should be in order to increase the usable space as much as possible.  If you were really creative you could use 2x2 framing.  Our suggestion would be to tack a 2x2 onto a 2x4 for the corners.  Maybe you could even consider 1" plywood edge screwed to each other but then you lose insulation and effective window installation.

"Are these plans really free?  What's the catch?  Will you harvest my IP data and spam me?"  We may look at your IP data but our only motive is to encourage you to visit our site and see what other great stuff we have to offer as well.  We also plan on releasing some other small free plans over the next several months.  Something you'd like to see in the 100sf and less range?  Let us know and we'll do something with it!

Built this?  Link to your picture in the comments and share with us!

Addition vs. Addition

Spy vs. Spy with a twist!  The English language is such that two phrases that sound very similar can mean very different things.  In this post we will be exploring the differences and similarities of the phrases "A New Addition to Your Home" vs. "A New Addition to Your House".

I think most folks understand that a house is a structure and a home is the entity that dwells in and among the house including the occupants, behaviors, and the structure itself.  We've recently experienced a new addition to our home (which explains our radio silence for the past month).

A new addition to your house is:

• Noisy
• Costly
• Invasive
• Bulky
• Sleep depriving
• Time consuming
• May include some screaming in the process
• Requires lots of planning
• Requires several professionals
• Requires a permit and/or license
• A lovely thing five years later
• Can pay you back when you move to the next stage of life.

Whereas an addition to your home is:

• Noisy
• Costly
• Invasive
• Bulky
• Sleep depriving
• Time consuming
• May include some screaming in the process
  
• Requires lots of planning
• Requires several professionals
• Strangely, DOES NOT require a permit and/or license
• A lovely thing five years later
• Can pay you back when you move to the next stage of life.

Further, an addition to your home may necessitate an addition to your house but not vice versa.  We have already taken pains to design an addition to our house should we feel we need it.  However the cost of the addition to our home may delay costs available for the addition of our house.  Nonetheless the addition to our home will receive all the necessary attention for the payback when we move to the next stage of life.