Knitting Nancy

Here's Cait with her new knitting nancy, which she got for Christmas. She's a great knitter!

Moonlight surveying

Here's a picture I took a couple months ago in the light of the full moon. Note the orange line, indicating the eventual height of the deck, which will be an inch or so lower than the floor inside the house.

One silly mistake

Just a moment of impatience and you're cooling your heels and paying the tow truck to pull your ride from the ditch.



I wish I'd been there to see this take place, Volvo drivers at a Marin horse training ring can be highly entertaining.

You know, given all the horsepower and cowgirls standing around and a few tree branches there must be a way to lever the car up the 6" or so it'd take to get the rear wheels over the berm. Shame I was in a hurry, we could have had a fine time engineering a solution.

Landfill

Here's an example of the junk that I unearthed from the yard while excavating for the wall. This was what the previous owner used to fill in the brick steps from the house to the patio:



Wood, brick chips, old concrete, any junk he could lay hands on. (I presume the fly was just visiting.) The patio was a lumpy, wet mess since it was largely build right on top of dirt and roots. I'm looking forward to walking on the deck with 12" of airspace to the ground.

Steel

Interesting comparison of the steel used in my brother's recently-built slab house foundation in Albuquerque and the steel required by my upcoming wall. The house uses wire mesh while the wall uses rebar. Concrete really doesn't like to be put in tension.

Here's the wall schematic, and here's the house:

Geotech non gratis

I got a bill from the geotech for $350 -- two hours of work to

- check out the back yard and
- write a memorandum saying my yard is built on a landslide of clay just waiting to turn to mud and
- take on legal liability for the work done subsequently based on his opinion

so I can't fault the guy.

Expedite!

The first rain of the season came early yesterday, but it was impetus for us to get moving smartly on the wall project lest the excavation succumb to gravity and water. I've hired a contractor with some experience building this sort of wall, and while it won't be cheap it won't be ridiculously expensive either, about $30K including the drain to the street and ancillary work. A bit more than half of that is labor cost. The wall will have 5/8" rebar every 12" horizontally and vertically, so it should stop the mud just fine.

Here are pictures of a similar wall form system that the contractor built for another client. What's interesting about this is the wall is poured all at once, foundation plus vertical. This is accomplished by suspending the vertical forms from hangers that run from the hillside down to inside the walled area. The forms themselves are made of 2x12 douglas fir with 2x4 walers (backing stiffeners).





We start work on Monday.

Power stump removal action

Removing a 4' diameter eucalyptus stump is tough. It's tougher when it's on a hillside and, despite exposing 6 feet of the roots, you can't chainsaw it apart because it's full of dirt and rocks. Here's what it looks like after chomping off all you can with a 28" chainsaw above the dirt.



Driving a stump grinder up to it won't work, because the grinder weighs 300lb and has a reach of only 2 feet.

So, build a ramp to the top of the stump with the handy Bobcat!



Then, after chewing off 2 yards of stump chips with much noise and great effort, remove the ramp and excavate the remaining root bits. And you now have a big hole in the ground.



And a big pile of dirt.

It's looking like a wet stamp job

One of the bits of jargon I've picked up from talking with landscape contractors is "wet stamp design." This is a design, plan, or schematic that is known to be vetted and pre-approved by the local building & planning department. Using a wet stamp means you don't have to hire a structural engineer to create a custom design for the job, which saves money and time.

There is a seriously overengineered wet stamp CMU retaining wall design for the County of Marin that Novato approves of that looks to me like it could hold back a hill of mud. I didn't like it: it specs that a 4.5' wall needs a 4.5' wide base, with lots of rebar and a keyway (I'll try to post a drawing later). But after going through the custom design process for a poured concrete retaining wall with a geotech and a structural engineer, it turns out I practically do have a hill of mud to deal with.

Dry clay is rock hard, with a load bearing capacity of 8000 pounds per square foot (psf) or more. But wet clay is only 2000 psf and likes to slide. A design that will safely withstand the pressure of that wet clay is nearly as hefty as the wet stamp design. Since I don't have to pay for ~$1500 of engineering to use the wet stamp design, it's starting to look attractive.

I can put off a final decision for another week, since this weekend I'll be removing a massive eucalyptus stump for our hillside with chainsaw, 25hp self-propelled stump grinder, Bobcat (to build a ramp to the stump for the grinder) and excavator (to pull out the roots and ground up bits.) If I have time left over I'll start the excavation for the wall footing.

Here's David last weekend, having at the stump with the chainsaw to cut vertical grooves. It was my plan then to pull the stump apart at the grooves with the excavator. This was a complete failure, since the stump is massive, strong, and full of dirt that dulls the saw blade in seconds. The pros cut off the wood and grind up the stump.

Designing for the ice age

I spoke with the geotech who stopped by my place around lunchtime as planned. He says it's just as he thought, my yard is part of the landslide material that started at the top of the mountain and stopped a couple miles away in the valley. I'm about in the middle, on the foot of the mountain.

The soil in my yard is "landslide deposit junk" of clay, boulders, and everything in between. The slide happened about 20,000 years ago at the end of the last ice age.

The geotech says that the soil is rock hard now but will turn into mud a few weeks into the rainy season and slide into the yard. He also said he'd give me a "great cat rate" because our cat Hirame stalked him around the yard so much that he was delayed getting back to the truck where his wife took Hirame's picture. He's a cat person himself, among his cats is a 16 year old Siamese that they take camping and horse riding.

His quick spreadsheet calculation says a 5' wall needs 18" piers on 6' centers, 6.5' deep. That's doable, especially if I don't hit any boulders...

Geotechnical

After a lot of dialing I found a structural engineer with a bit of free time to design a pier wall for me, but he needs a "geotech" (soils engineer) to "write a memorandum" (technically describe the soil stability parameters) first. Fortunately there's a geotech who lives close by my house and rides his horse along the fire road right behind our lot a couple times a month! He told me yesterday he watched us build the playhouse (he liked the framing).

He'll be stopping by today to glance at the site to form an opinion. I think he might even do this gratis!

I've told both engineers that my goal is to drill the pier holes this weekend, but given that it's already Friday morning, I don't think it's gonna happen. I'll be installing baseboard moulding inside instead.

Update: I dropped by the equipment rental yard this morning to check out the 18" drill bits for a Bobcat mounted drill rig. They tell me I can swap from bucket to drill and back myself with no tools. Awesome.

Timid concrete DIYer?

One of the structural engineers I spoke with advised me to reconsider a CMU wall built on top of a pier foundation, for two reasons:

1. I'll have to bring a concrete truck to the site at last twice: once for the piers, and again to fill in the CMU cells. The truck trip is as expensive as the concrete, he implied.
   
2. It'll probably be a lot easier overall to build forms for the wall and do one big pour than build a big CMU wall.
   

The subtext of #2 was that I was being a big weenie, should get over my fear of five foot high concrete forms (think of the hydrostatic pressure at the bottom!), and just build the thing properly. He pointed out there were several good ways to screw up a CMU wall, too, like dropping mortar into the cells and closing them off, or simply building it crooked.

Engineering

Before I can rent more heavy equipment and get on with this wall, I need to know exactly what kind of wall I'm building. The City says any wall over 2' in height must have a building permit, and they have only two pre-approved designs for walls between 2' and 5' 8". One of those is a cantilevered CMU design that for my 4' 8" wall would be 4' 6" wide at the foundation. That's a freakin' sidewalk, it would stick 2' into the usable yard space and require massive amounts of excavation and backfill.

The other is a wooden wall that uses piers sunk 4' into the ground, which I like a lot better because being only 18" wide it saves space and materials. But the wood will only last 10 - 15 years around here and can't be covered with a nice stone finish, so I'm not building one of those.

I went back to the City building permit troupe* today to plead my case for a hybrid wall that use 18" rebar & concrete piers sunk 5' into the ground, tied to the wall with top to bottom rebar. Robert, the building permits guy, looked at my drawing and agreed it's great idea! Narrower, more efficient with materials than the cantilever, easy to build.

"So can you approve this design?"
"No."
"You had me going there."
I wasn't really surprised, it was a fool's hope anyway.

The City must have a professional structural, civil, or soils engineer's signature on the design before they'll approve it. "That way when the mud flows into your neighbor's yard, we've all got someone to point the finger at." Ah, liability avoidance, the second great purpose of planning departments (after revenue generation).

I called around to a dozen or so local structural and civil engineering guys / firms. Three answered their phone, and one actually agreed to take the job for about $800. I was expecting to pay $2000 for this engineering, so that's a bright spot in this diversion.

(* They have hired a new code enforcement guy, about 55 years old, who thinks he's the comic relief for the planning department. The place felt like a continuous amateur improv show today.)

A different kind of CMU

We've designed a great new backyard and started the excavation. I rented a Bobcat, Takeuchi TB-16 excavator, and 3 yard dump truck for a couple weekends, and Frank did a great job as truck driver and dirt load cleaner. Fifty cubic yards of dirt, three trees, and a brick patio have been removed so far.

I got bids from licensed landscapers for 100 feet of 4.5' retaining wall and miscellanenous other work. Each came in at about $48K, or about $400 per foot of wall. Tanya researched wall costs for elsewhere in the country and found $35 per foot is typical. Welcome to Marin.

So, it's time to learn about DIY retaining wall construction. "Concrete Masonry Unit" is the term used for what I used to call "cinderblock." You pour a sidewalk-like foundation with lots of rebar in it and sticking up from it. Then you stack courses of specially shaped cinderblock and more rebar. The cavities in the wall run top to bottom and get filled with concrete to complete the CMU wall. Don't forget to put a french drain behind the wall, and get a city inspection at every stage or you'll be jackhammering it apart later. No problem.

No PV at this time

Here's why not:

• PV technology is improving rather drastically these days. A system like this might cost a lot less in a few years.
  
• Our actual energy cost is about 12¢ per kWh right now, making this system take practically forever to pay off unless we start consuming lots more energy. A similar argument explains why I don't grow corn.
  
• The vendor/installer is unclear how many roof membrane penetrations it'd take to install the array on our flat roof, but it's a whole lot. This will invite leaks and make future roof replacement much more complicated.
  

40 x 12 of dead south

Tanya and I really want an A/C for our place to make the house bearable on those 10 - 14 days each summer where the temperature goes over 95°F. Turns out a little 3 ton unit bolted on to the existing furnace will do the job, so maybe we'll get one this season!

But really, the expensive thing about A/C is the electricity. So I got to thinking: flat roof, southern exposure, acres of SiO2...sounds like photovoltaics are in order!

I contacted a local PV system installer (this being the Bay Area there are more than a few to choose from) and here's what he said:

I looked at your house on Google, I believe it is the tan roof facing hillside, no pool. If it is you have 40 x12 ft of dead south. Looks like an excellent site!

The economics of Solar work out in a couple of ways. 1) An excellent hedge against inflation. This works on the same principle as home ownership. You stop paying rent and start paying

down your loan to capture the free sunlight. The cost of electricity for a typical 3 kW system is 8.3 cents per kwH when you factor in the cost over the life of the system. You will get at least 428 kwH on a 3 kW system per month, 153,360 kwH over the 30 year lifespan. There are other factors such as tax deductions and the fact that the system adds more value to the home than it costs to put it on the home, iepeople pay more for solar homes when they are on the market.

A system like this cost about $18,832, after all rebates and tax incentives. The state pays about 25 percent($7,822) of the bill and the Federal government gives a bottom line tax credit of $2,000. The $2.50 rebate is almost gone. Do not delay! It will drop to $2.20 very soon.

If you are paying 32 to 38 cents per kwH in tier 4 and 5 you can see that solar really pays off fast and big. There is no end in site to electric rate rip-offs so protect yourself with a solar system.

If you are paying an average of 36 cents on the 428 kwH you would save $155 per month. $1,860 per year, $60,000 over life of system IF rates do not increase further. At the current 10% per year your bill doubles every seven years!

Let me know if you are ready.

Playing webmaster

Tanya and I have multiple volunteer positions, generally in support of our kids' interests and activities but sometimes they overlap with our (as James would say) jobby-jobs. Here's a website for our son's swim team that I just redesigned, and here's the logo that I didn't design but did turn into vector art sometime last year:

Splining the Miter

Tanya designed and largely single-handedly built a really nice redwood fence in our front yard last fall. But the gate never got built until a couple days ago. Here's the (almost) final product:

Creating the joints at the corners of the hexagon was interesting. I didn't want to have any exposed hardware (screws, metal plates) so I used a technique called "splining" that Tanya found for me on the web. It's pretty simple, you just cut a notch in the back of the miter and glue in a strip of wood:

It's a lot trickier to do the spline notch in a fence post that's already standing. Here I am up on the fence, using a circular saw as a router:

It was lots of fun, redwood is really pleasant wood to work with.

No argument from me

Snapshot of a bumper sticker in the parking lot at work. Check it out, but don't feel badly if you can't handle it either.

Playhouse in Sketchup

Before we built the playhouse we first modeled it in a 3D drawing program called Sketchup. This free program has a fairly steep learning curve, but for projects like this it's absolutely invaluable to help visualize the interior and exterior of a building concept. Here's a snapshot from Sketchup of the playhouse schematic. (We didn't actually build it quite this way; I only used four of the five 12' roof beams and haven't added the porch yet. But otherwise this is an accurate model.)
I can send you the original Sketchup file if you like; just drop me an email.

The new kitten

Here's Colby the kitten from back in early February. Tanya picked him up at the local Humane Society since he was the bestest kitty in the place. Colby was rescued from the Sonoma Landfill where he was living with his family until 8 weeks old. He's a great kitty, but he roughs up our five year old boy cat Hirame quite a bit. Our 15 year old girl cat Jadzia won't have anything to do with him.

Cam's island cake

Cameron's last Cub Scout Blue & Gold dinner with Pack 186 was in March. He competed in the cake contest in the "tropical island" category. Here's Cam decorating his island; note the blue jello ocean and candy cigarette lean-to. The latter are hard to find these days, being politically incorrect, but Novato recently got a real candy store that carries candy cigarettes and other items I haven't seen since I was ten.

Playhouse

Tanya had an idea about a month ago that we build a playhouse for the kids on an otherwise hard to use part of our yard. Here you see the framing, which has since been covered with plywood & painted "watertank green." Many thanks to David and Jason for their help with the framing and sheathing.

Big trees, hale hikers

I came across this photo of three hikers in Muir Woods from August 2006. That guy in the middle -- where can I get a shirt like that?


And here's Cait, another cute chickie photographed the same day.

Hammer and spade

About 14 months ago our hot water supply line from the garage to the house started leaking. I discovered this in the middle of December when I noticed moss growing on the cedar shingle siding of our house above two foundation vents. It was a fast leak, about three gallons an hour, and it's a testament to our foundation drainage that the whole crawlspace wasn't flooded over the three months or so that this leak was going.

We hired a plumber to repair the leak and replace the old iron supply pipes with copper. (I was more than happy to pay a professional to do this, since it involved torch work under the house, in an 18 inch crawlspace, in what must've been six inches of sticky mud.) The plumber rented an electric jackhammer to tear up the garage floor where the pipes passed down through the slab, then he used the hammer and a clay spade to dig up the trench in the clay between the buildings.

This latter innovation is something I hadn't seen before. It took the plumber maybe 10 minutes to dig a trench that would've taken me two hours with a pick and shovel. Since then we've rented a Hilti 25lb. hammer several times to break up our hardpan clay in preparation for patio building, garden bed amendment, and post hole digging. It turns two-weekend jobs into one-morning jobs all by itself, and that's worth the $70 rental.

In the picture below you see a model holding the hammer we use for yard work. This picture illustrates a nice fiction that a 25lb. hammer can be used to break up a large slab, when in fact holding the hammer the way illustrated will wreck nothing but your lower back. When I use this hammer for clay work I hold it by the loop handle at the top with two hands and let it work itself in with its own weight. When we do concrete demolition I usually rent a 60lb. Bosch hammer and a chisel point.

Cam parallel parks

This spring break we stayed at the Manchester KOA, which featured pedal cars for those with more energy than sense (they were rather heavy). Here's Cam practicing his parallel parking skillz.

Manchester Beach

Here's Ellie, the cutest little chick on (windy) Manchester Beach, CA.