Plywood Crickets – A Report

When roofs or decks can’t drain along an entire edge, or towards a central point; when run-off needs to be gathered or concentrated, crickets are required. This report describes building one type of crickets.

There are two ways to build a cricketed roof; first is the traditional stick-framed way where the slopes of the roof are built into the framing. The roof sheathing just follows the framing. The second way is what’s called a “California” cricket.

In a California cricket, the main slope of the roof is framed and sheathed entirely. Ripped sleepers are nailed on top of the main slope sheathing, and the cricket plywood is nailed to the sleepers.Ripped Sleepers West (We used Pressure treated lumber here to make the sleepers simply because the they’re adjacent to concrete block.) There are several advantages to this:

  • If the roof plywood is being used as part of the seismic system, the diaphragm is un-interrupted at the peaks and valleys of the crickets,
  • There is less fussy calculation during framing, and the carpenters can quickly roll the joists, shake out the plywood, and get the building temporarily dried-in,
  • The carpenters can check heights, snap lines, and determine the run-off flow while standing on solid decking.

There are several disadvantages, the main one: cutting a long, slow taper where the cricket plywood meets the main slope plywood. Here’s how it’s done.

Cutting Ply on Edge

Get an idea of what it’s going to take for the taper. In this case, a 1/4″ in 12″ cricket slope met a 1/4″ in 12″ main slope so the taper for 3/4″ plywood was about 12″. Mark which side is the top, and where the taper runs out.

After the cricket piece is cut (generally it’s triangular) stand it on edge with the side to be tapered pointing up and level.

Set the Skilsaw at maximum depth, and eyeball the angle. My 7-1/4″ saw only cuts about 2-1/8″ deep, so that’s what I cut it.

After the long careful rip on the edge of the sheet, I put the piece down on the sawhorses. In 2-1/8″ depth of cut, it tapered about 1/2″, so I set the foot of the saw to 1/2″ for the first cut.


Reference Grooves

I snapped and cut a series of increasingly shallow reference grooves, 1/2″, 3/8″, 1/4″, and finally 1/8″. The grooves are about 2″ to 2-1/2″ apart. Then comes the tricky part: with the depth of the saw set at 3/8″, my right hip touching the piece, my right hand holding the weight of the saw and the guard back, my left hand on the trigger, I pulled the saw sideways, grinding out the plywood to the correct shape. Note that the saw motor is always between my body and the blade, and if the saw kicks, it’s going to kick towards the left out in clear air.

Skilsaw on Scarf Joint

I used the reference grooves to tell approximately how deep I was cutting, and the plys in the plywood give a visual cue as to depth. Sort of like a contour map.

It’s important to keep the right edge of the saw brushing sideways on un-cut plywood to keep the cut smooth. If it runs over the bumpy part, the cut becomes correspondingly bumpy.

The cut can be surprisingly accurate, the limitation for me is just physically holding the weight of the running saw.
Planer on Scarf JointFinally, I took the little planer to knock the high spots off. A good question is why I didn’t just use the planer for the whole operation. The answer is speed. The Skilsaw has a 13 amp motor concentrated in a kerf of an eighth of an inch and is unstoppable, the Makita has a 6.5 amp motor spread over 3-1/2″ inches and is helpless.

Note that I had to take the spring out of the planer’s height adjuster to crank it down enough to get it to cut. I set it for about 1/8″ depth of cut. The planer did leave a nice flat taper.

 

CricketsFinally, I installed the 3/4″ cricket plywood pieces on top of the ripped sleepers – glued and screwed. In the photo, you can see that the slot in the concrete block wall for the scupper has not been cut yet.

 

Finished Cricket DetailHere’s a detail of what the finished cricket edge looks like. An even 1/8″ all along. Note that the cricket plywood is carefully glued and screwed to the main slope plywood.

The roofer will be able to add a couple of layers of felt to make a smooth transition at the bottom of the valley.

 

Wrinkly Tyvek – A Report

East wall tyvek2

This is DuPont Tyvek Drain Wrap commonly know as “wrinkly” Tyvek. In previous installations, we’ve used regular smooth Tyvek and battens to create the drainage plane behind the siding. This wrinkly product promises to create the drainage plane without the battens.

This post reports on what we encountered:

We wrapped Bituthene around the framing before the windows were installed. Some of the windows had nail fins, and some didn’t. The windows that didn’t got fabricated sheet-metal pans sloped to drain. DR window flashing2Note the sheet metal is Rezi-Bond, galvanized metal coated to promote paint adhesion.

We foamed the gaps between the windows and the studs. Where the foam oozed out, we trimmed it off carefully with a serated kitchen knife. The Tyvek carried over the Bituthene, over the foam, and turned out at the window. Then the trim boards and corner boards were pre-caulked and nailed over the Tyvek.

It’s hard to get it to lay flat! Wrinkly means wrinkly and the installation looks amateurish; it fans out, won’t stay level, and won’t lay down nicely. All that said, it shouldn’t make any difference to how it performs.DR window tyvek3

We’re installing Hardie plank in the 8″ Colonial pattern. You can see the slight indentation that transforms regular Hardie siding into “Colonial” siding. We had to order it in smooth in lieu of wood-grained and it costs slightly more,  but it’s worth it; when it’s painted, from fifty feet away, if you squint, it almost looks like the original wood siding.

The story board is tacked onto the trim. Note that the marks on the story board control the top of the siding which is hidden by the succeeding layer.starter strip

To get the first course of siding to lay at the same angle as the succeeding courses, we use starter strips. These are cut from 4×8 sheets of cored poly-styrene that we get from the sign shop. The cores allow the drainage plane to drain, but keep the bugs out.

Knauf Eco-Seal – A Report

Knauf Eco-Seal in Richmond
We’re working on a little house on Terrace St. It’s a 1902 railroad worker’s cabin on the hill looking out over the Richmond train yard. photo from wall touchedBoards nailed to boards, no studs, with a layer of newspaper to slow down the wind blowing through. Saturday, January 4, 1902 was when the old guys built that particular piece of wall. (Note: the Walla Walla actually sunk on Thursday the day after New Years day, but it wasn’t reported in the papers until Saturday.) The original work is so rough, the little house may have been an amateur weekend project, hence the Saturday paper!

It’s a duplex, the upper half is fairly intact as the original cabin, the lower half is getting a complete remodel; as energy efficient as we can make it on a limited budget.
Bucket IIWe couldn’t afford the $4.00/s.f. cost of spray-in foam, so we decided on a compromise between foam and newspaper: a product from Knauf called Eco-Seal. The claim is that Eco-Seal will stop the air infiltration, and fiberglass batts or blow-in will provide the insulation. The advertising says “Simple airless equipment”, as opposed to specialized equipment for spray-foam costing $20K or more.

Well, we’ve got an airless, so we bought a bucket of the Eco-Seal – $225.00. One thing for sure about Eco-Seal; it’s blue! We put the intake in the bucket and fired up the airless. Nothing. The intake wouldn’t begin to pick up the thick blue material. When we finally read the fine print, it says the airless has to be a “Graco 695 or equivalent”. This is a one gallon-per-minute machine, and none of the rental yards in the Bay Area have one that big.
Kelley Moore in SSF came to our rescue; it’s a long trip from Richmond to SSF, but worth it?
Intake tubeThe intake tube on the 695 wouldn’t pick up the heavy material either. We finally took off the tube and set the machine right in the bucket.

 

 

Airless in bucket

We blocked the bucket up so the intake was picking up off the bottom. Even so, it tended to suck wormholes in the blue material and cavitate the pump.

 

 

 

 

Moving goo to pickupWe had to take a shingle and keep pushing the Eco-Seal material over towards the pump intake.

 

 

 

 

All this manipulation in the open bucket made a mess and caused extraneous bits of material to fall in, so the spray tip kept clogging. It took two hands to run the gun, one hand on the trigger and the other on the tip to reverse it every two feet or so to blow the clogs out.Reversing tip

This was a pain in the neck, we never would have gone to this much trouble, but we’d spent the $225.00 for the Eco-Seal, if it works, it will do what nothing else will. When it works, it foams up just enough to make a nice bead, and it looks convincing as an air infiltation stopper. Only the blower door test will tell.

The silly part is that the airless may be unnecessary. The folks that build log homes have miles of gaps between the logs to caulk neatly. They’ve developed a set of manual tools to install bulk caulk out of five gallon pails which I’ll bet would work very well for the Knauf product. It’s what we’ll try next time.

Here’s the company video:

Demand-Responsive Parking in San Francisco

Demand-Responsive Parking in San Francisco

 This article first appeared on the website THINKPROGRESS

By Matthew Yglesias on Aug 11, 2010 at 1:44 pm

People generally understand that there were shortages and long lines for things in the Soviet Union because goods weren’t priced according to supply and demand. And people generally understand that, in general, price controls will tend to lead to either gluts or shortages. And yet few people understand that this same principle applies to on-street parking. In many places, it’s hard to find and that’s because it’s not priced properly. San Francisco is trying to change things with its SFPark initiative:

SFpark will charge the lowest possible hourly rate to achieve the right level of availability in both garages and at metered spaces. This project is not about raising parking revenue; it’s about making parking easier to find. SFpark is designed so each block and each garage maintains have about, an average, 20% availability. [...]

SFpark will use demand-responsive pricing to even out parking availability and reduce the need for circling. In pilot areas, meter pricing can range from between 25 cents an hour to a maximum of $6.00 an hour, depending on demand. During special events, such as baseball games, hourly prices may temporarily increase beyond the $6.00 ceiling. Parking rate changes will also affect City-owned garages and lots in pilot areas. Since many City-owned garages are currently underutilized, the prices are likely to decrease, which will attract more parking demand to City garages.

A nice next step would be for the city to get out of the garage-owning business. In a city where street parking is priced in a demand-responsive way and developers are not subject to regulatory mandates to construct parking, one assumes that parking garages and parking lots will still be constructed. If you want to drive somewhere then you’ll need to park your car, and since people often do want to drive there’s money to be made charging them for the privilege. But regulatory mandates and city-owned garages tend to ensure that parking is oversupplied.

 

System Overview

SIMPLE BUILDINGSM

Uncomplicated. By design.
From a downtown loft touching property lines, to a multi-story, multi-familydevelopment, to a second back-yard unit or even emergency housing, the Simple Building begins with a steel frame and a unique foundation that is suitable for any terrain. A customizable kit of panels and other components are added as the design dictates. The Simple Building has all the benefits of pre-fabrication with none of the cookie cutter aesthetics.Together with outstanding cost efficiency, the Simple Building has it all.

THE INTEGRATED APPROACH


The technology of the Simple Building is borrowed from a wide array of disciplines: the electric utility industry, commercial refrigerated food storage, industrial metal buildings, state-of-the-art “green” products, and a number of proprietary innovations, all of which carefully interlock.


The Simple Building is not modular, nor are the shapes of the buildings constrained by shipping distances, dimensions, or weights. We don’t ship large boxes filled with air. Simple Buildings fit in standard shipping containers which enable them to travel long distances secure from weather and vandalism. And, once they arrive, special truck or crane access is not required.

Most Simple Building components, such as the frame, the mechanical core, and the panels, are pre-cut by suppliers. Others, such as flashing and the interior walls, are cut and fitted in the field. The connections between the parts are coordinated with detailed shop drawings.

This hybrid approach means that the labor-intensive parts can be delivered to the site in a semi-finished state, and the large simple areas can be closed in on site. This allows for a high degree of flexibility at all points of the design process.

THE FOUNDATION

Simple Buildings typically have insulated concrete slab foundations. The concrete foundations provide “thermal mass” and are a critical piece of the energy-efficiency.

In steep or adverse conditions, or where concrete is not available, the Simple Building system uses helical piers for a foundation. These are essentially galvanized steel pipes with welded flights which screw into the earth.

In many areas, resistance to uplift is as important as gravity loads. In the West, uplift is caused by earthquakes, in the Midwest it’s tornados, at the Southeast coast it’s hurricanes. Helical piers resist uplift loads equally as well as they resist gravity loads, making them inherently safe. Where flooding is a concern, braced ground floor columns can be used to elevate the living floor above the flood plain.

The Simple Building system uses a proprietary system for connecting the helical piers to the structure.

THE PANELS

The floor, walls, and roof of the building are pre-finished sandwich panels, consisting of a steel inner face, a foam core, and a steel outer skin. The panels fit together with double tongue and groove joints. The panels are carefully caulked at the joints making a very tight and efficient envelope.

Depending on the location or application, various thicknesses are available ranging from 2” with an R-16 rating, to 6” rated at R-49. The inner steel face and the outer face do not touch, so the entire wall assembly can achieve the tested R value, without subtracting for the typical thermal bridging through studs. Additionally, since the inner and outer faces do not touch, there is no path to transmit sound, making the panels inherently sound-reducing. Since the panels are composed of Kynar coated, galvanized steel, they are rot-resistant and termite proof.

Fire-rated panels are available with a mineral wool core in lieu of foam core. With FR panels the buildings are suitable for urban infill, zero-lot-line, (property line) construction.

“INTEGRATED FRAME”

Since the walls (panels) are not load-bearing, the building requires a separate frame. Our “Integrated Frame” is composed of galvanized rolled steel “C” sections bolted together. There is a continuous, bolted path of connection from the foundation through the roof, including the covering skin, making the building extremely resistant to earthquakes and other natural events. In addition, with our proprietary fittings, the frame provides the pathways for wiring and piping for the building.

Above three stories, wide-flange steel beams and columns with braced frames or moment-resisting connections are typically used in lieu of the rolled section frames. Photo shows a four-story steel-frame building in San Francisco with fire-rated sidewall panels being inserted edgeways into the six inch slot between the new steel frame and the adjacent buildings. Our  proprietary temporary hoisting/trolley/panel installation mechanism is visible just above the panels.

Both types of steel frame are non-combustible, making the building envelope suitable for fire-rated, or zero-lot-line, construction.

 

 

As an alternate to steel, in single story construction, the frame can combine wood Glu-Lam beams with our steel columns. With careful detailing, Glu-Lams can be a handsome alternative to steel and can be fire-rated as well. The open-beam ceiling with the steel panels give the interior a clean mid-century-modern look.

THE “WET WALL” MECHANICAL CORE

Our proprietary, patent pending, mechanical core is a thick wall manufactured off-site which contains typical plumbing and mechanical systems carefully fitted into a pre-fabricated unit.

Depending on jurisdiction and budget, the Wet Wall is available with a range of options from ABS plastic waste lines and PEX water piping, to cast iron waste lines and copper water piping.

WINDOWS

The Simple Building can be built with any specified window system. State-of-the-art R-5 windows with foam-filled fiberglass frames are recommended. The combination of the tight wall and roof panels, and this high-performance glazing, makes a very efficient building envelope which can achieve Passive House standards.

The high-performance windows also have a high STC (Sound Transmission Coefficient) which makes the Simple Building suitable for adverse acoustic environments – next to busy streets, bus lines, train tracks, etc.

INTERIOR WALLS

The interior walls are built on site with conventional wood or metal studs and are available with various wall coverings. The interior walls have most of the plugs, switches, and lights which are difficult to locate in the sandwich panel exterior walls.

HEATING

Simple Buildings typically have radiant heat with PEX tubing cast into the concrete floor. This photo shows an elevated slab with the concrete poured over steel pan deck.

When the building is small, it may not make sense to install a separate heat source for space heating. Our proprietary “Radiant Core system uses a conventional water heater as the radiant heat source and is perfect for small spaces.
SUSTAINABLE BUILDING

Steel is the single biggest component used in the Simple Building. The steel used to make the frame and panels contain approximately 35% recycled material and is 100% recyclable.

One of the principal advantages of the Simple Building is that hybrid pre-fabrication minimizes on-site waste, minimizes on-site construction and thereby worker trips to the jobsite, yet retains the flexibility to adapt the design to any particular context. Almost all sustainable systems are available with the Simple Building, and with the Photovoltaic option and all-electric cooking, water heating, and space heating and cooling, the Simple Building can achieve true net-zero energy, net-zero carbon (CO2), and very high marks from the various rating agencies.

Simple Building embodies the three sustainability goals of Malpas Sustainable Design:

  • Obvious – The selection of sustainable or green materials
  • Less Obvious – An efficient process to fabricate and install
  • Non-Obvious – Elegantly engineered so each component is working at its optimum

 

THE END RESULT

With the designer free to configure the final product to match the client’s program and the geographic conditions, the Simple Building is the most flexible, general purpose platform on the market.