Archive for July, 2012

council crest update

July 27, 2012

from yesterday:

exterior and interior progress continues.

architecture by bohlin cywinski jackson

construction by don tankersley construction

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notes on placing an exposed slab on grade

July 22, 2012

Here are some quick notes on our Exposed Slab on Grade (placed on top of continuous 15mil vapor retarder and 4″ of eps insulation):

Placing concrete on a continuous vapor retarder definitely ups the degree of difficulty when it comes to finishing and curing the slab.  Water in the slab can only move out the top, meaning the slab can dry unevenly, crack, and even curl.  To compensate we are trying a wet “flood” cure.

We decided to use fiber mesh reinforcing and eliminate the steel reinforcing altogether from slab.  Apparently the fiber can make finishing trickier, but it typically results in strong slab with less cracking and for a bit less cost.

The type and location of joints is always a question – we even considered for awhile not using them and letting the slab crack more randomly (it will crack).  In the end we decided to use a tooled joint (in this case made with a custom tool from another project) and to place them strategically under walls so they are barely visible.  Tooled joints can be made almost immediately before cracking can happen whereas sawcuts have to wait until slab is firm enough to handle the saw, and potentially after random cracks have already occurred.  Saw cuts also have a risk of spalling, but when they are executed properly they certainly look best.

After knocking around options for curing the slab, we decided to go old school and use a wet flood method.  The idea is to cure the slab slowly and evenly by keeping it wet and cool, allowing it to gain as much strength as possible before subjecting it to the stresses that occur when it dries out.  The slab edge formwork was already above the top of the slab, so it was relatively easy to keep the slab underwater.  It uses a fair amount of water as there are minor breaches in the perimeter formwork dam, but it eliminates the use of expensive chemical curing compounds.

So far we have kept the slab wet for 5 days (flooded most of the time) and we’re still babysitting it.  It’s time to get set up for the last small concrete pour (a plinth for the stair which doubles as a landing), so the wet curing will come to an end. Only time will tell what the result will be, and we’ll never know if our methods were better or worse.

breaking ground on skidmore (passive) house

July 15, 2012

After many many months (years really) of scheming and planning, we finally broke ground on our new house.  A lot has happened since our last look at the project in passivhaus progression.  It took us a bit of time to get our house ready for sale, but we eventually sold it, found a great house to rent complete with chickens, moved, and are getting settled in our temporary digs.

First up was getting our delinquent and non-responsive tenant out of the house.  We got our first (and hopefully last) taste of the eviction process.  A few checks and a couple of weeks later we took possession and had a close up look at the sorry state of the house.  Next we removed some of the existing trees.  A few were unhealthy, a few were in or too close to the footprint, and a couple were creating massive shade.  While we struggled with this decision and upset at least one neighbor, in the end we decided it was best in the long run to remove the largest Oak in the backyard.  It was sad to see it come down but the lot has been transformed back into a sunny paradise and we hope over the next decade to develop a well designed and much more beautiful landscape.

While the first bank we approached about construction financing had favorable rates and seemed easy to work with, the process quickly turned sour as they began to question first the green roof, then the single ply membrane, separate structures, and finally the lack of a garage.  In the end it became apparent that they didn’t get it and it was time to try another route.  At the same time, we decided that the separate structures created some domestic challenges in addition to lowering the value of the property in the eyes of the bank, so we quickly redesigned the house to incorporate the space between the buildings as interior living space.  Although it adds more square footage and cost, it does make for a better surface to floor area ratio and had a favorable impact on our PHPP calculations.  We then approached a local bank with our revised design complete with green roof, no garage, and modern aesthetic, and it was basically smooth sailing right up to the loan closing.  Aside from their annoying tagline, so far I have nothing but good things to say about my experience with my local bank.

The permit process went a little more smoothly.  After responding to a simple structural checksheet, answering some questions from the plans examiner about the Passive House specific details, filing a required Operations and Maintenance agreement for the ecoroof with the County, and smoothing out some internal confusion at the city about an existing cesspool tank and drywell, we got our new building permit as well as demolition permits for the existing house and garage.  Next up was testing for Asbestos; the demolition contractor was required to have paperwork certifying that the debris was free from Asbestos.  Somewhat to my surprise, Asbestos was found in a number of unusual places including window glazing, caulking at the roof penetrations, and drywall compound.  Another check and about a week later the Asbestos was abated and demolition could finally begin.

Here’s a quick progression of what’s happened over the last 2 months:

Trees are cut and asbestos abatement in progress.

House and garage are gone!

Old tanks are decommissioned and building area is stripped.

Building pad is prepped with compacted gravel.

Footings are formed, EPS placed and moisture barrier taped.

Concrete is placed in footings.

Gravel backfill is placed and compacted underslab.

Underslab EPS insulation is getting set on sand bed.

Now that we’ve started, there’s much to talk about.  Some possible ideas:

– A better way to build an insulated slab on grade?

– PHPP calculations and optimization of systems

– PH certification:  PHIUS+ vs PHA

– Passive House Windows

There are many people to thank for their help (directly and indirectly) in getting us to this point.  Here are just a few:

– Aaron and Mike at Brute Force Collective

– Dan Whitmore at Blackbird Builders

– Florian at Zola European Windows

– Don Tankersley Construction

– John Russell (Concrete) Construction

– Matt at Zehnder

– Skylar at Hammer and Hand

– Ryan at Earth Advantage

All for now.  Check back soon.

Jeff

www.insituarchitecture.net