Category Archives: building

Finnish footing foam…

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One of the ideas behind ShopHouse is “healthy”.  Things like indoor air quality are important to us.  We’re spending a lot of time on HVAC, but even the materials in the overall construction are important decisions and opportunities to make sure our indoor environment is the best if can be, as well as making sure that we at least try to choose environmentally decent materials.

Additionally, we’re incorporating a split footing design, where 2 halves of the footing are thermally isolated from on another, and also insulated from the ground (more on THAT project shortly).  So – we needed a source for 4″ xps foam to get the R values we needed AND it needed to have sufficient compressive strength to hold up the house (minor detail).  The search started with the usual suspects – Dow, and other companies that seem to be more chemical that insulation…

And… then we find out that all the foam insulation that appears to be available in the US contains HBCD (Hexabromocyclododecane – there will be a spelling quiz later – so pay attention) – a bio accumulating chemical that is banned in Europe and in the process of being phased out globally.  It’s a flame retardant and blowing agent.  Read the link for a more detailed discussion on why this is bad stuff.

Why would we want THAT all in the ground around our house and under the slab?  It doesn’t need to be flame retardant, and we’re anti – nasty chemical. So intrepid husband starts the search for happy foam to make our footings.

The US companies’ answer for removing HBCD is just to find a better chemical and make everything flame retardant.  Sigh.

Enter – FINNFOAM!

In northern Europe, apparently what we’re doing isn’t all that odd, and Finnfoam complies with the stricter chemical regulations of the EU.

So we’re now experts in importing Finnish Foam by the container.  Interestingly enough the cost was equal to the “blue foam” even including ocean freight.  We paid for the foam to be delivered and then unloaded it all into our trailer and basement.

not quite...

not quite…

Another round of my personal slave labor.  That was an entire 40 foot – high cube container…..

Now – on to the form making!

The Big Dig

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Great googely moogely we’re moving dirt.

Ground rising!

Ground rising!

Despite what appeared to be the wettest winter (and spring) since weather was invented, it FINALLY dried out enough to start the cut and fill work required to level the site inside the retaining walls.  And in my lack of knowledge, or extreme positivity, I hoped this would only take a few days! Ha!  Between building up a site 8-9 feet in places, crappy non-draining clay soil, glorious trees that block the drying sun – EVERYTHING takes longer than you expect.

Luckily, our GC decided that he’d bring his tractor and disc up the soil allowing things to dry faster, and then moving the dried soil for the next lift.  And then, the soil testing.  Who the heck knew the soil testing involved a radioactive testing device that uses 2 nuclear isotopes and has to be calibrated using their respective half lifes (lives?). Proctor testing involves taking soil samples and drying them in the lab, and determining dry density and then the level of moisture allowed and compaction required (both measured by the nuclear machine).  Passing grades mean the next lift can commence, failing grades mean more compaction.

Crazy radioactive machine measures density and moisture content.

Crazy radioactive machine measures density and moisture content.

The “good news” is that since we are compacting to the retaining walls, there won’t be an “spread” and loss of compaction and we can march on to footings.  Assuming the heat wave continues, and the pop up thunderstorms miss 15 acres in northern Wake County – we’ll be done with set prep this week.  Onward!  (finally)…

Sheep's foot compacts the lift

Sheep’s foot compacts the lift

Green rating hell.

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I spoke about this in a previous post regarding the high performance home.  I am becoming increasingly disillusioned with the possible rating systems.  And I am beginning to wonder if it is worth spending my heard earned money to meet what appear to be rather arbitrary standards.  And the overall process seems to be painstaking in its detail and appears to be straightforward, but inflexible in the execution.

what rating system is right for me?

what rating system is right for me?

Here’s some observations of a few of the green ratings:

LEED – probably the most comprehensive scoring system for both energy efficiency, quality of life issues and social responsibility.  Between the HERS index and other points for things like solar panels, they have this area pretty well covered.  Testing is required, too, so that’s good.  Guidance for issues like water conservation, VOCs, avoiding indoor air contaminants gives this a good “healthy home” foundation.  And lastly – points for things like using infill lots and access to public transportation, and even points for an electric car charger add the social responsibility aspect into the mix.  Of course with us building a pretty large house on 15 acres, in the country and driving a variety of non-earth friendly vehicles – we’re not racking up the points in those areas.. That being said – while you have to meet prerequisites, you can get your LEED certification by focusing on the areas that are the most meaningful to you.  I wish it was as generally recognized as some other programs.  It also seems to be the popular “architect’s choice” and is much more popular in commercial building.

National Green Building Standard (ICC 700) touted by the home building professional association as the only standard certified by ANSI (the American National Standards Institute) seems to be a way for the building industry to capitalize on the green bandwagon.  My scientific observation that any home that can be certified to a “bronze” level isn’t that green.  But – I downloaded the spring template and it’s A LOT like LEED.  Everything from site location, solar preparedness, formaldehyde free cabinets and no VOC finishes matches nicely.   So while Bronze appears to be an easy deal (you can get Bronze by being Energy Star in their HVAC section) if you did get to Emerald – there’s at least a bunch of paperwork that needs to be submitted.  My guess is that this is the preferred certification of the more production builder.

Passive House, or – for the more Euro flair – PassivHaus….  Besides trying unsuccesfully to navigate and understand the Passive House Institute US (PHIUS)  and the Passive House Alliance US (PHAUS) differences, so far it’s been painful.  Requiring a consultant to pre-approve or at least “pre-score” your project, then to put this project / register it with the proper organization, and also to hire a rater (usually the LEED raters are cross certified – and the stuff they are checking is about 80% overlapped, so it’s not that big of a deal) it’s costly.  We started considering Passive House late – mostly because it looked like we were headed towards building something that would meet it – so perhaps the next comment isn’t fair – but we’d hoped that we’d have enough feedback from the initial certification assessment that we could make building decisions (cost benefit, etc) based on the calculations.  We’d also hoped that we’d be able to take that info and perhaps help our HVAC contractor best design a system that will perform and keep us comfortable.  So far – that’s not happening.  And with the cost, if we can’t offset some of that by either savings from not having to hire engineers or other experts in the HVAC field, or perhaps being able to reduce some insulation or switch from using geothermal to going solar and   generating more electricity – then it’s going to be hard to justify continuing.  It also seems that many just say “built to the Passive House” standard – and don’t go for the full certification – and I wonder if the cumbersome nature of the process isn’t driving that…

Maybe it’s just a brag anyway, since there’s no marketing “value” for us – but I am still searching for the perfect “green” rating…

People…

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people banner

A house is made up of glass and concrete and steel and wood (well, not ours) and a host of other materials.  You assemble the pieces and you “build”.  But it’s the people involved in the project, that can set it apart.  The people either rise to meet the challenges or they produce the minimum they can to get by and don’t inspire others, and likely don’t garner a lot of personal satisfaction from their “job”.

Think Big!

Think Big!

We’ve been very fortunate on this project to have met some incredible people.  People who’s skill and caring have helped us realize this crazy dream.  People who took at little extra time to understand what we’ve been trying to do, and figured out creative ways to help meet the goal.  They’ve stepped outside their personal or professional, comfort zones and took us seriously when we asked ‘why not?’.

We hope that we can partner with some of these folks as we move through the process and at project completion when we do “the fun stuff” – like the open house tours with NC Modernist Houses, or open house required by LEED, or maybe the Green Home Tour (although no sure I’ll be spending the money to put our house on the tour…)

The house is “stuff”, but the process is people.  And continue to be pleased and comforted by the folks who are passionate about what they do – and strive to differentiate themselves against “the rest”.

LEED for Homes 4, Passive House, Energy Star, DOE Challenge Home, and and and…

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There seems to be a decent amount of alphabet soup or certification “choice” when it comes to energy efficiency and measuring your “green-ness” – but realistically, what does it mean and what is it worth?  We’ve already established that the mortgage industry and the appraisal system doesn’t give it a hoot, and since we’re not a builder – what the heck does any of this stuff MEAN to us?  Overall, nothing.  Well, that’s not entirely true – it should result in lower operating costs and a “better” home.  But at what cost?  What’s the payback calculation?  There’s no way in Hades that we’ll ever pay for our uber windows in energy savings with anything close to the current rates for power in the US. So why do it?

Maybe we’re looking at this wrong.  It’s not about the certifications, (although we believe they DO have value for both builders and suppliers of the materials for the project) it’s about building the High Performance Home.  THAT’S my new personal certification – HPH.  Everyone else seems to have a certification program – why not me?  HPH fits a theme here – we have high performance “stuff”.  My daily driver car is a 469 HP station wagon.  It’s not the highest HP car out there – but in it’s class, it’s top of the heap.   Henry drives a Dodge Cummins diesel dually pickup.  All the wheels and all the torque – a high performance towing machine.  We have a little vice in that we drive Dodge / SRT Vipers.  Very high performance American muscle.  This level of high performance may not be necessary, but it’s pretty cool when you can achieve it.  And ultimately, that’s what we want for our house: quite simply, a house that performs to the level of the rest of our lives.

But- since HPH is not a globally recognized certification (yet), what are our options?

LEED can be regarded as being a little prescriptive  and judgmental (after all – what the hell would we do with an electric car charging station? Unless I get a Tesla) and there’s a lot of focus on stuff we can’t control – we’re not an infill lot and our “walkability” score is pretty low.  But then DOES cover things like Indoor Air Quality which we believe to be a real benefit to living better.  LEED incorporates this measure, and also Energy Star into its rating system, so you are getting a little more bang for your buck here.  And maybe feeling that you are looking at your home’ performance from a multifaceted approach, and building a High Performance Home.

But then you look at Passive House – I call this the Engineer’s certification.  It’s VERY much performance based and focused on energy usage, and not wasting energy.  This certification becomes very much a numbers game.   Without being all that smart on Passive House – it’s close to saying that your energy usage is about 10% of something “normal” for your home’s size and location.  It also says that you take advantage of passive means to heat (and cool or avoid heat) the home – so using solar warming of a slab concrete floor, for example.  In this regard, Passive House is right up our alley.  They are VERY interested in building envelope performance- with requirements for multipoint blower door tests and other more stringent qualifications.  The other good news is that Passive House seems to be “flexible” in how you meet the requirements – and for an out of the box project like this – that’s GOOD news.  So – this very much works with the High Performance Home theme.  Passive House also incorporates the Department of Energy’s Challenge Home criteria – so again – more recognized certs as part of a higher level program.

With this in mind, we’re going to see if we can meet Passive House without any major design or building plan changes, as it’s highly regarded as a standard for PERFORMANCE.  Once we know if we can pre-certify – we’ll show you the numbers and talk about it more and see if it really makes sense to got for the full certification process or just “built to the Passive House standard” that often gets used instead.  In the meantime – let’s hope we can nail a high performance BUDGET…

If all goes well, we’ll be able to move to submit for our building permit this week – another milestone we need to make.  Onward!

P.S.  What do you think of the new rendering???

Deep dive – everything you possibly want to know about concrete sandwich panels

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So at a more detailed level – what are concrete sandwich panels??  Basically they are panels consisting of concrete as the “bread” of the sandwich with insulation as the “meat” of the sandwich.  In the case of the panels offered by International Precast they consist of 3” thick high psi reinforced concrete wythes of concrete with either 2” or 4” of Polyisocyanurate insulation as the interior.

IP_Sample

A surprising and very important differentiator of the International Precast concrete sandwich panels is that International Precast claimed that they could deliver panels where the interior and exterior wythes are not connected by any thermal bridging material – they would be completely isolated by the interior insulation.  We quizzed them at length on this claim but they were able to demonstrate to our satisfaction that they could indeed deliver on this claim.  This opened up the possibility of completely isolating the interior and exterior of the house from one another with insulating material and eliminating all thermal bridges.  There would be no through concrete in the panels!!  This started the thought of the house as a cooler – more on this later.

The concrete wythes would be connected via non-conductive cast-in wythe to wythe fasteners.  These are described by their suppliers as being made from “high performance heat and alkaline resistant engineered polymers” or “high-strength, low-conductivity, not-corrosive and chemically resistant” polymers.   These are spaced at defined intervals in the panels per well tested engineering specifications.  They are poked through the insulation at the center of the sandwich panels and have heads that end up being embedded in the concrete with a very small diameter high strength fibrous material connecting the heads together.  These connectors work in tension to prevent any wythe movement under load – basically keeping the exterior concrete surfaces from moving relative to one another under loads and enabling bending loads to be shared between the 2 wythes.  To be 100% technically correct these panels are referred to as “structurally composite concrete sandwich panels” because both the interior and exterior wythes act compositely to carry the external gravity and lateral loads.

 

The concrete itself is high psi concrete with reinforcing wire and rebar embedded in each of the wythes to enable the concrete wythes to carry structural loads.  Both the interior and exterior wythes are reinforced so both can carry structural loads – this would turn out to be a key factor in enabling thermal isolation for other parts of the house such as the roof.

Why concrete sandwich panels for our exterior walls? Part 3 – Step 2 toward concrete sandwich panels – the interior walls

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Having bought into the concept and design aesthetic of concrete exterior walls we started brainstorming about interior walls surfaces.  Out initial thoughts were to use wood to warm up the interior of the house and avoid the dreaded sheetrock as a wall material.  We bounced around a lot of ideas on how to execute interior wood walls while keeping with the evolving design aesthetics.  We came to the conclusion that it would be better to use wood as warming / accent material via furniture, cabinets, doors, etc. where it made logical sense to use it.  This then led to the crazy, wild assed idea of using concrete on the interior walls – an idea that grew on us after initially us being skeptical about it.  So why not??

In parallel with our discussions on interior wall materials we had continued our internet search for precast concrete wall manufacturers.  And during this we stumbled across a company that claimed that they made concrete sandwich panels – panels that had both a concrete exterior surface (known in the trade as a “wythe”) and a concrete interior surface or “wythe”.  And it turned out that this company, International Precast, was fairly local to us – offering the ability to meet with them in person, see their facility, etc.  The fact that they were local also helped from a LEED perspective as it minimized the environmental and cost impacts of shipping the finished panels.

So our next steps were an initial telephone call and then a visit to International Precast.  IP_SampleThe net out of these discussions and site tour was that it appeared that they could do exactly what they claimed they could do – deliver concrete sandwich panels that could form the outer walls for both buildings for our project.  So our crazy wild assed idea to use concrete on our interior walls was actually possible.  Not only was it possible – it seemed that properly executed concrete sandwich panels would deliver both our interior and exterior finished walls in a single product.

Why concrete sandwich panels for our exterior walls? Part 2 – Step 1 toward concrete sandwich panels – the exterior walls

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In considering the wide variety of exterior materials that we could use I half jokingly made the statement that I wanted a house built of concrete, steel and glass (design aesthetic #1).  Note that all of these are lousy insulating materials.  So why these materials??  From my personal perspective these were part of the commercial / industrial / modernist design aesthetic (we can call this design aesthetic #2) that I like.  So we asked ourselves why not a concrete exterior to the house??  Properly mixed and cured concrete certainly is a very durable, low maintenance cost material that does not require any exterior finishing as is proven in the millions of commercial buildings that are built out of concrete.  And if it is used without trying to make it look like something that it isn’t then it meets a design aesthetic of “truth in materials” (design aesthetic #3) – it is what it is so don’t try to hide this.  And if we use it this way we get the bonus of not having any additional cost for exterior finishing.

concrete exterior

So how could we execute concrete exterior walls??  Certainly we could do poured in place walls – but these required lots of work in on site forms, dealing with all of the quality issues caused by weather, variations in concrete batches, etc.  Our architect / builder had done poured in place walls on a previous project so they were very aware of the issues with using them.  In particular the waste material from building custom wood forms was an issue.

The next thought was precast walls that could be cast in more controlled conditions that would then be set in place on site.  We looked at these fairly closely and even visited a factory where they were manufacturing walls that had a concrete exterior and were fitted with various materials to serve as studs in conventional walls.  We were convinced that we were on the right track on finding a material and method of making walls that met our exterior requirements – the panels would be “cool” as a way to meet our evolving design aesthetic and accomplish the our exterior durability / minimal maintenance goals  .

Further analysis showed that these panels that we had found still had some issues that we needed to consider.  First, they would still require insulation and interior finishing.  In that sense they solved our exterior goals but not our interior goals.  And they did not achieve the goal of thermally isolating the exterior and interior surfaces – we would still have to accomplish this.  They were clearly a big step away from conventional 2×4 construction – but were they a big enough step away??  Another concern was with this particular company’s ability to execute the panels to the detail and precision that we expected our project to require.

Coming up next – Why concrete sandwich panels for our exterior walls? Part 3 – Step 2 toward concrete sandwich panels – the interior walls

Why concrete sandwich panels for our exterior walls? Part 1

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This is the first post from the engineering geek guy for our ShopHouse project.  I will be explaining some of the more technical reasons for the design and material decisions that we are making as a couple for this project.

So why build using concrete sandwich panels for our exterior walls??  There are a  variety of reasons but this decision started as a desire to find a better way to build a house and shop.  And a better way to achieve our goals of having the lowest possible operating cost and the lowest possible maintenance cost.

wood framingI look at conventional 2×4 construction as “lowest common denominator” construction – while it is cost effective I find it to be incredibly wasteful and sloppy.  It also has a fundamental problem that we needed to avoid to achieve our “cooler” concept of thermally isolating the inside of the house from the outside as much as possible.  Every 2×4 creates thermal paths between inside and outside surfaces, thus creating thousands of holes in the thermally isolated “bucket” that we are trying to achieve.

There are certainly a number of ways to reduce the thermal  paths or bridges between the inside and outside surfaces but these add complication and cost to the building process.  One way is to build 2 separate walls so that there is insulation between the inside and outside surfaces.  Again this can give a good thermal result but essentially you are building 2 separate houses, one inside of the other.

Another factor with conventional 2×4 construction is that exterior wall surface materials must be added to project the exterior surface from the elements.  The exterior sheathing, typically plywood or OSB, must be covered to prevent degradation from rain, sun, etc.  There are obviously a very wide variety of materials to use but most are susceptible to damage from the elements and require some level of maintenance.  Brick can be used as an exterior material but you are again essentially building multiple walls in order to achieve the desired end result.

In almost all cases conventional 2×4 construction assumes sheet rock for the interior wall surface.  I find this to be another “lowest common denominator” construction material.  It is very forgiving of construction errors, easy to find people to install and finish, etc but I personally find it to be a material that I would like to avoid if at all possible.  It is messy to install and finish, susceptible to damage from everyday household activities (and especially damage from dogs!), and difficult to hang items from the walls because of its low structural strength.

The net out of wanting to find a better way to build a house is that I challenged the architect/builders that we considered to design a house with no 2×4’s and no sheetrock.  Needless to say the reactions were interesting.  I think that most didn’t believe that I was serious – but at least one took it to heart and embraced the philosophy that this challenge required.

Coming up next – Why concrete sandwich panels for our exterior walls? Part 2 – Step 1 toward concrete sandwich panels – the exterior walls