24x40 3-story custom, Stevens Pass WA

Started by knopfarrow, August 24, 2015, 12:27:54 PM

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knopfarrow

This is the inaugural post for a project still in the planning stages near Steven Pass, WA.  Last year I stumbled upon a deal I couldn't pass up on property near Stevens Pass Washington, and purchased it...well let's just say at a *very good* price.  My family has bought seasons passes to ski at Steven Pass for a handful of years now, about a 1.5 hour drive from the Seattle area. We're aspiring to build a family cabin that we can use on weekends, holidays, and vacations, and also rent out to others when we're not using it.  It's proximity to Stevens pass makes it highly desirable because no other properties are available neary this close to the ski area.  It's nestled in a beautiful valley, with peaks to the North and South.










Now the fun part.  The property comes with more than few idiosyncrasies:


  • Over 400" average annual snow fall, and over 100" annual snow pack -- that means we'll have to design for 300 psf snow load on the roof, and make plans to protect the foundation of the building not only from the snow pack, but also from the additional snow that falls off the roof.  This amount of snow also can impede entry to the first floor unless you really plan -- raised foundations and snow fences are a necessity here. 
  • From about November through sometime in April depending on snow fall and snow melt, the property is not accessible by car. Cabin owners are able to park their cars out near the highway, and then either snow shoe or snowmobile the 1+ mile in to access the cabin. 
  • There's ample power, phone and high-speed Internet right in the street, both of which were  upraded within the last year.
  • There's a county-maintained water supply in the street BUT they are not allowing any new hookups to the water supply because the county has determined (in their infinite wisdom) due to seasonal drought conditions they have to protect the use of tributaries that feed the rivers in the Chelan and Wenatchee areas.  So there's water in the street, but I cannot hook up to it.
  • I could drill a well BUT the lot is not large enough to support digging both a well and putting in a septic system, due to required setbacks between the two. I do know from other owners that the soil perks well and septic is not an issue.
  • It's a narrow, sloping lot: 60' x 220'.  Plenty of buildable space at the front of the lot next to the street, but then after about 80 feet a very steep drop off down to a stream (can you say"wetlands" -- a taboo word here in WA state.)
  • There are about 30 cabins that have been built in this little community over the years, and twice as many undeveloped lots. Some of the cabins have been built within the last 5 years, and their solution has been to install a handful of thousand gallon water storage tanks in the basement and have a water truck come deliver water during the summer.  According to one cabin owner just down the street, the water costs about $80 and the delivery charge is several thousand $! And water can only be delivered during the summer months. My hope is that we'll eventually be able to hook up to the water system, but we may have to begin the build planning on water storage tanks.

I've been designing our cabin (it's a little more extravagant than many I've seen posted on the board here) for the last 6 months using Sketchup Make, working with my wife try to accommodate all of the idiosyncrasies noted above along with a desire to have a place that will service our family and friends for many years to come, be as low-maintenance as possible, and provide the potential for at least some occasional rental income.  Of course, my aspirations always exceed my budget, but I've gone through several iterations in planning and am starting to hone in on what I think is a workable design that's getting to the point where I need to graduate on to engineering and schematics.

My designs and aspirations will be my next post. Need to get back to work now to pay for all this.
"One is not a pattern. Two is not a trend." -me

knopfarrow

Here's a great web page that shows the snow conditions I'm dealing with near the build location:  http://www.nwrfc.noaa.gov/snow/snowplot.cgi?SVNW1

This was a light snow year, by the way.  The ski resort gave discounts to all the season pass holders for next season because the snow cover was so light and left relatively early, shortening the season.




"One is not a pattern. Two is not a trend." -me


knopfarrow

Shown below are the current iteration of the floor plans and design.  (Some of the plans are chopped off a little bit.) 

The foundation is a walk-out, daylight basement - designed specifically to allow for easier ingress/egress during high snow-depth. 


The main floor has a mud-room/air-lock along with a WC, a combined kitchen and vaulted great room, and a master bedroom.


The upper floor has a loft, bedroom and bunk room with 6 bunks in it. They share a bathroom with door'd toilet and shower so people can use simultaneously with a bit of privacy.  Sliding, shed doors throughout much of the home, expect where hinged is required to be workable.


It's a basic rectangle with a basic shed roof.  Going to need to hold a pretty significant snow load, and all the research I've done indicate that a cold, medium-slope roof will have less wear and problems with freeze/thaw cycles (think European chalet).  No eves or valleys on the roof at all.  (The plans will likely look a little different after I get the roof engineering completed.)  My intention is to finish it in a simple-modern-mountain-industrial style.  All of the plumbing will be on the interior walls. Electrical runs will be exposed conduit. Planning on a heated, poured concrete floors -- polished but left natural. Combination of drywall and rough sawn lumber for interior walls.  Probably a combination of corrugated aluminum on the lower exterior and concrete fiber board on the upper exterior.








"One is not a pattern. Two is not a trend." -me

knopfarrow

Does anyone have detail or advice on how to design/structure a cold shed roof that is still flat on the underside (finished interior side)?

I want to use tongue-and-groove wood (either knotty planks or plywood) on the underside, but have the roof be highly insulted (~R50?) and hold a heavy snow load each season.  I know there needs to be vapor barriers, a significant space for insulation, and a cold cavity between the insulation and upper, weather-proof roof layer  Pitch will be either 3/12 or 4/12. The roof needs to handle 300 psf snow load.  I figured using something like SIP panels for the insulated portion of the roof would be the right approach, but in order to handle the heavy load, it will almost certainly need engineered beams for the trusses (glulam? i-beam?)

Need to span walls that are 24' apart at a ~3/12 pitch (~18 degrees). Also planning to extend the top and bottom eves by about 10' beyond the walls to protect the exterior of the house from weather. So the roof will be a total of about 44' from the top eve to the bottom eve. Since I'll be permitting the build, I'm already resigned to the fact that I'll need an engineering stamp on the plans, but I'm hoping I can get close to what will be needed on the initial designs for budgeting purposes.

Can someone point me to the detail of the various layers and structures I need to insulate well, prevent condensation, provide ventilation, and support the weight? I'm not sure what the detailed structure should look like. ???
"One is not a pattern. Two is not a trend." -me

midrover170

First off, I really like your bold design. I wouldn't hesitate getting that engineer's stamp though, or at least a consultation if your area doesn't require stamped plans. You'll be happy to have the peace of mind, even if they recommend building it like a cold war era bunker. I am also a fan of shed roofs, but my area doesn't get as much snow. Still, our main roof includes 2x12 rafters, 12" OC with a 5.5"x15" glulam spanning the middle of the cabin.

I've been researching the same topic of ventilation that you ask about, and you have options. But first, I assume you're doing cathedral ceilings? No attic? If that's the case most will go one of the two following routes (exterior inward):

1). Roof, roof deck, air cavity for ventilation (minimum of one inch), batt insulation, vapor barrier, drywall and then wood paneling if you want that. Some will argue that drywall is sufficient and that the vapor barrier is overkill, but hey, why not right? With this style, you need to be really careful with penetrations, especially recessed lighting. Those are basically vapor tubes and have to be installed with caution. I decided to nix this type of lighting from my build. This style of roof is obviously a vented roof and needs adequate openings in the soffit.

2.) Roof, roof deck, closed-cell spray foam (min. of 3"). Since closed-cell foam is a vapor barrier in itself, you don't have to worry about drywall/other vapor barriers. In most cases, this option is an unvented roof.

Great article on the topic:
http://www.greenbuildingadvisor.com/blogs/dept/musings/how-build-insulated-cathedral-ceiling

I don't know enough about SIPs to offer help there, but I'd imagine they're somewhere between both options above. Nor do I know enough to advise on roof structure engineering for your weight load. Good luck and excited to see your build shape up. How is your site for access, i.e. can a concrete truck get up there? I hope so  ;)

Cheers,
D


knopfarrow

midrover170,

Thanks for complimenting the design. It's gotten to the point where I'm also getting very enthusiastic. I haven't read the article you linked, but will this evening.

QuoteI assume you're doing cathedral ceilings? No attic?
Yes, correct.

I've also heard in my research that one of the prime concerns is to make sure condensation doesn't develop between the insulated area and the roof deck.  For that reason, I'm tending towards hanging pendant lights instead of cans in the ceiling.

Thanks for laying out these couple of approaches. I'd thought about spray foam, but dismissed it too early, perhaps.  Knowing that the roof is one of the most likely failure points unless engineered and constructed really well, I'm hoping a few more forum members will weigh in with their hard-knock experiences building and maintaining in snowville.
"One is not a pattern. Two is not a trend." -me

Don_P

 I'd try glulam's there if possible, You'll get a slight strength bump for using 44' continuous rafters over looking at it simply, that's the engineer's job. Crudely, there is a 24' simple span with 7200 lbs per foot of rafter spacing (24' x 300psf). 4' spacing would look good with a heavy timber deck... 4' spacing x 7200=28,800 lbs/rafter.  Hmm, 7x18" rafter every 4' , that's living too large. It looks like there is provision for a mid support beam, cutting the span in half to 12' span carrying 14,400 lbs, a 6x12 works as a rafter on 4' centers. A 4x8 on 2' ctrs at 12' span also works.

How big would that midbeam be is my next question, if there can be supports no more than 16' apart I'm getting a 6-3/4" x 24" beam under the rafters down the center of the 24' width of the building.

Roughly, I'd be looking harder at 4x8 rafters on 2' centers bearing over an 8x24' center beam and the exterior walls, 2x6 T&G decking would probably work. The rafters might work in solid sawn dougfir.

From inside out, I'd cover the glulams with heavy timber T&G decking, layers of 2" foam sheets seams offset, purlins running up and down the roof on 12" centers to create an air gap, 3/4" plywood then roofing material.

knopfarrow

Don_P -- thanks for the "crude" math. Definitely helped me think about it in a more structured way.

You're right that running a support beam down the middle of the building would allow me to split the load and go with more standard lumber for the roof joists.  I had thought of that early on, but it's so much more fun to have wide open spaces (when you're not thinking about cost...)  I was originally thinking engineered wood i-beams to span the complete distance.  If I stay true to my design and add a middle support beam , the middle beam would need to span 22' (if I stay true to my design) to avoid being supported by a post skewering the kitchen and loft.   

Hmmm. What to do.

I think I need to doe some crude math estimates of the cost trade-offs between varying sizes and quantities of standard dimensional lumber and engineered lumber for the several options on the table.  Will probably try to design up the different options in Sketchup, at which point I'll chime back in on the forum with my findings and for feedback.
"One is not a pattern. Two is not a trend." -me

Redoverfarm

Not to get into the engineer portion of your build but with that much snow I would be inclined to put larger soffit area and overhangs on the front and rear.  Large snow fall area houses seem to go with at least 4 feet soffit on the sides and the same or a little more cantilever the fronts and backs or gable ends.  Another thing that might help is a little steeper pitch roof. 


knopfarrow

Redoverfarm - Yes, it may not be apparent from the design pictures I posted, but the roof overhangs the walls (front, rear, top, bottom) by 10 feet.  In addition, the roof extends even further on the back/north side to cover the deck.  Having talked with a couple neighbors, unless you have an ample roof over the deck, you have maintenance every year on it or you just replace it every couple of years.

Do you think 10' is sufficient? overkill?
"One is not a pattern. Two is not a trend." -me

Redoverfarm

10 feet may be a little overkill.   I would think that 4' would be ample unless there is a particular area that needs more such as entrance areas or areas which you intend to use year round to keep the snow from accumulating.  If you plan on using metal for your roof remember that the snow will slide off on the low side.  Not much chance for guttering to last unless you use some type of snow guards.

This was relatively a lighter snow but it will give you some idea.  Wish I would have had my camera on the deeper accumulation.  There was only 18" clearance between the soffit and the snow top once it slid off. Not to mention that it shot away from the porch some 15-20 feet into the yard.


knopfarrow

You're definitely correct on the gutters: None planned as they'd be ripped off first season.  I was thinking a larger overhang because a number of the homes actually put snow fences at the beginning of the winter to prevent the snow from resting against the side of the house for the entire winter.  I've been thinking a larger overhang would prevent the snow from piling to close to the house.  Many of the homes first floors are built 10 feet above ground during the summer, which becomes ground-level during the height of winter.
"One is not a pattern. Two is not a trend." -me

nailit69

I saw some interesting gutters on a mountain "cabin" the other day... more like a fortress.  I'm guessing they're 3"x3" steel angle with 3/4" standoffs welded on at  about 4'-0" o.c. and were bolted with 4 ea. lags into the beam ends and open ended to allow the water to spill out of either end [cool].  Although we've had a couple of mild winters, they've been in service for about 3 years now and have not come down yet and this place is just east of Snoqualmie Pass in the mountains.

Redoverfarm

This is what I used to save the gutters on my cabin.  It is commonly know as "witches hat".  Has done exceptionally well.  I mounted mine about 18" above the gutters. It can be color matched to the roofing color. 







The shorter pieces were doubled and installed as steps to gain access to be able to clean the wood stove/fireplace flue out.


MountainDon

I have the same thing on our home. I did a similar thing on our cabin using pipe. Pipe or even timbers have been used for a very long time in the European Alps. Of course the roof must be built to hold to weight, but that should be done anyways.

In Switzerland....

Just because something has been done and has not failed, doesn't mean it is good design.

knopfarrow

I've been busy over the last month (in my relatively limited spare time) doing a "virtual build" in Sketchup of the design I published early in this thread. Even though it's far from finished, I've got the framing completed and figured it was time to share.  The pictures below are in progression from the footings through framing and then to the roof.

I did all of this in Sketchup Make - incredibly useful for helping me work through how to execute design details. As a result of virtual "building" this in sketchup, I changed a few things like upper floor layout and a few windows sizes and placement.

Appreciate any comments or feedback.

Footings:


Foundation:


Basement framing:


Main level subfloor framing:


Main level subfloor decking:


1st floor framing:


2nd level subfloor framing:


2nd level subfloor decking:


2nd level framing:


Exterior sheathing:


Rafters and perlins:


Roof insulation (tentatively planning on SIPs):


Roof ventilation layer:


Roof cap:



Having done this design using standard dimensional lumber along with glulams where necessary, I'm beginning to wonder if it might be easier (and cheaper?) to build the skeleton with metal ibeams and the shell with SIPs.  I may virtual-build it again using that method and price it out to see which pencils better.

I'm planning a day trip soon over to Chelan county the building department to get the lay of the land on their process and what they're saying about my specific piece of property so that I can get the engineering requirements and figure out if any progress has been made on the water supply situation.

"One is not a pattern. Two is not a trend." -me

John Raabe

Nice work modeling a rather complex house. Sketchup is a great tool to explore options.
Make sure you have a good thermal break on any metal framing. SIPs on the outside will take care of most of that, I expect.
None of us are as smart as all of us.

Don_P

Just little stuff for the back burner I'm seeing as I roll thru;
>Main subfloor sheathing changes direction with the change is joist direction... lay it with the long axis perpendicular to the joists.
>1st floor tall walls, these need engineering, they will be 2x8's or better, there will need to be something heavy behind the exterior roof support timbers. (steel in the window corner?) I'd design a wall shackle and pin assembly for those timbers to further accent the design.
>2nd floor framing, diagonal and catwalk are probably LVL's, check size with the rest of floor framing
>Exterior wall sheathing is typically run vertically, it is stronger running horizontal but all edges need to be blocked, I'd rather not run blocking every 4', it looks like the difference would be 3 rows vs 6 rows of blocking, all the way around the building.
> Porch roof sheathing runs perp to rafters with seams offset.
> You can (and I believe should) attach metal down to SIPs, or to the sheathing, unvented, follow manufacturer directions there.
> I'm missing the reason for the spot footings under the slab?

knopfarrow

#18
Don_P, thank you truly for the insights on some of the framing nuances. Exactly the feedback I was hoping for.

I'll make the changes you suggest. Yes definitely going to need engineering on this structure and the tall walls. Exceptionally heavy snow loads in this location.

Can you reply with a picture link to what you're thinking on the "shackle and pin assembly to further accent the design"?

The spot footings are my uneducated attempt to accommodate a gaggle of 1,500 gallon water tanks -- a likely necessity unless I can get the county to relax their ban on new hookups to the existing water system. I was just figuring I better put something down there to shore up the added weight on the bottom floor. Appreciate any guidance there.
"One is not a pattern. Two is not a trend." -me

waggin

Fascinating project that I'll watch with interest.  I too am a fan of the single pitch/shed roofs.  300# snow load certainly makes for a bit of a challenge!  Stevens Pass is a great area, and I hope to be playing in the snow there this winter at least a few times. 
If the women don't find you handsome, they should at least find you handy. (Red Green)


UK4X4

Spot foundation's separate post and then just a perimeter support too, have you spoken too local owners , seen other builds in your area ?
with just the snow load  the weight of just the snow is huge,  add in snow run off, , I presume mountain side, is the area stable ?

I was just a 90# snow, and the area has water run off issues with sands silts and clays, reacting every spring..."mud season " as the snow pack on the hill above melts and drains down..

We went with a waffle pad and did a monolithic pour to insure the whole thing stays in one piece , plus a 4 ft compacted drained sub surface pile of crushed rock,
The deck, the porch, everything is all on the one foundation.

Have you had a soil report or the site surveyed ?

Kris


knopfarrow

Quotehave you spoken too local owners , seen other builds in your area ?

Yes, there are about 30 cabins in the area, most have been there over 20 years. There are a few newer ones within the past 5 years.

QuoteI presume mountain side, is the area stable ?

Yes, the soil is quite stable. Our lot is flat on a low ridge line between streams the flow year-round. Everything drains well, and I think some home owners had to use pressurized sand (?) in their septic design because drainage was a little too good.

QuoteHave you had a soil report or the site surveyed ?

Not yet, but I have talked to one of the neighbors who built about 5 years ago. They didn't mention problems with soil. A trip to the county is planned in the coming month, and a site survey in the Spring after snow melt.

You are right, it's a huge snow load to plan for. Going to require some solid engineering and thoughtful design to keep it workable. I expect to be tweaking plans throughout this winter as I gather additional information and get the experts involved.
"One is not a pattern. Two is not a trend." -me

knopfarrow

Posting a refined set of floor plans I developed over the Thanksgiving holiday.

First/Main Floor


Second Floor


Basement/Ground Floor


I'm still planning to move the entry/airlock interior door so that the WC is "inside" -- but haven't gotten around to it yet.

Wish I had more to report, but still in the dreaming and planning stages (and hoping for a good year end sales and a bonus to kick things off).
"One is not a pattern. Two is not a trend." -me

knopfarrow

Sorry. No pictures in this post, but I've made some progress on planning for the build over the last few months.  A quick summary:

1. I've modified the cabin plans so that this is now a 16x32 3-story custom.  Taking it down a notch in size will allow me to build sooner, and I think I can still meet most of the usage goals.  I'll post the updated floor plans after I get through the frenzie of marrying off my first daughter this weekend.  The plan is to get the septic, foundation, framing, sheathing and roofing done next Spring/Summer, then rough-ins and finish work the following Spring/Summer.

2. I've talked to the county planning department and gotten the following information about my site and the requirements for building.
   * Roof Snow Load - 320 psf (The plans will need to be fully engineered.)
   * Ground Snow Load - 457 psf
   * Wind Speed (nominal) - 85 mph
   * Wind Speed (ultimate) - 110 mph
   * Exposure - "B"
   * Seismic Design Category - "D0"
   * Frostline Depth 24"
   * 2015 International Building Code (IBC)
   * We will need to get a geological assessment done by a Qualified Geologist to check for any known slides, erosive soils, avalanche zones, etc.
   * The county uses Lot Depth Averaging (Code 11.78.140) to constrain placement of a building on the site with a creek running through it.

3. This last fall a culvert washed out limiting access to our property to foot traffic. The snow hasn't yet melted off this year.  At the ski resort just up the road, there's still a 60" base, although it's melting quickly.

4. I'm shooting to get all the planning and permitting done by the end of the year so that I can begin the build as soon as the snow melts in 2017.  I have engaged a friend who's a certified geologist to do my lot/land assessment and help me begin the paperwork required to get permits -- I'll go up to the property with him as soon as the snow is melted.  Septic plan and engineered drawings come after geology is done.

Filing a residential online application takes about 2 weeks in non-peak season (before April), so I plan to do that in January 2017.
"One is not a pattern. Two is not a trend." -me