Langley Passive House – Part 5 – Door Install

Doors are installed similarly to windows. A 2×4 ripped is offset at jamb and head. The door frame rests on plywood spacers and is glued/sealed with adhesive foam. The frame is over a self-adhered flashing at sill which itself sits above rigid EPS at concrete foundation. The EPS is painted with compatible damp-proofing. 2 layers of rigid roxul provide a thermal bridge free installation at the wall. On the interior the door is taped to the concrete topping at floor and to the studs at jamb & head.

The door install shares the non-conventional details as the wall detail (see Part 4). The exterior insulated strategy shown here is considered the most robust (http://buildingscience.com/documents/insights/bsi-001-the-perfect-wall) is endorsed by the Home Protection Office (https://hpo.bc.ca/r22-effective-walls-wood-frame-in-BC) the same people who insure your home.

Langley Passive House Part 3 – Wall Detail

As mentioned in part 1 of the series this wall detail takes a high vapour permeance or breathable approach in contrast with a more vapour closed system such as traditional 6 mil poly, spray foam insulation, or SIPS panel. In an everyday example it is similar to choosing a breathable Gore-tex or Tyvek jacket over a fully waterproof rubber or latex one.

The sequence of assembley allows for easy access for sealing of the air barrier membrane and the vapour barrier is solid (plywood) avoiding the difficulties in sealing and movement of the traditional 6 mil poly. 1) a 2×4 stud wall is framed on conc. foundation 2) plywood is attached to the stud wall without gaps 3) air barrier membrane is draped over the plywood and sealed at edges with specialized tape 4) two layers of roxul insulation are installed with 5) 2×4 vertical strapping holding the insulation in place 6) fibre cement siding forms the finished cladding 7) Drywall is installed on the inside face of studs

1) 2×4 Stud Wall. The 2×4 stud wall is framed traditionally providing for a common and cost effective installation. 2x4s utilize less wood than the code standard 2×6 while providing adequate strength.

2) Plywood is installed over the 2×4 stud wall and form the vapour barrier and sheathing in a single step. The plywood is sealed at seams with vapour barrier tape. This vapour barrier is much more breathable than the traditional poly and more so than the code requirement. This allows for the wall to dry to the outside and inside should any moisture enter. As a solid sheet product this vapour barrier avoids the difficulties in 6 mil poly construction where care must be taken to ensure proper sealing with sealants, lapping at edges, solid backing at electrical boxes and other penetrations, and post construction movement during pressurization and depressurization due to wind pressure. An inherent property of plywood is its natural tendency to increase its vapour permeance when wetted. This allows it to dry itself out more rapidy if it ever gets wetted through condensation or rain penetration at window openings or other gaps.

3) Siga Majvest (http://www.siga.ch/en/product-overview/majvest-detail.html) is the air barrier membrane which is more vapour open that the code requirement in the BCBC allowing for greater drying capacity. As the air barrier is applied to the outside over plywood the installation is no different that the traditional installation of tar paper or Tyvek. Siga is taped at edges and seams to form a strong air barrier.

4) Roxul exterior semi-rigid insulation is used in two layers. These layers are lapped at edges so there is a lesser chance of gaps between insulation and avenues for water penetration. Roxul is made from rock and slag absorbs less than 1% of water and does not harbour mould according to their website http://www.roxul.com/products/commercial/products/roxul+comfortboard+cis. Partial assembley of the 2×4 strapping allow for install of the Roxul (see construction sequence image).

5) 2×4 borate treated vertical strapping is installed over the rigid Roxul. Long screws penetrate the strapping, plywood, and 1.5″ into the studs. The screws are installed traditionally with a common drill & bit and according to the installation crews are easy to install since the majority of the intervening material is Roxul which takes very little effort to penetrate. The only trick is the inability to pull out screws that miss their studs for fear of introducing penetrations to the air and vapour barrier. These screws are left in place.

6) Fibre cement cladding is to be added over top the 2×4 strapping. Nails penetrate the strapping only so no holes to the air & vapour barrier are introduced and reducing any small thermal bridging.

7) Drywall is installed on the inside face of studs as per typical residential construction.

This and similar exterior insulation systems for passive house are considered one of the most durable due to the solid plywood. It has seen application in Alaska as part of the REMOTE wall (http://cchrc.org/docs/best_practices/REMOTE_Manual.pdf) although this system utilizes an exterior 6 mil poly vapour barrier over the plywood and rigid EPS or XPS insulation (vapour closed).

Double wall is another system used for passive house. Typically this system utilizes a double 2×4 wall with a intervening space between the stud walls. This space is filled with insulation (typically blown cellulose) providing the additional insulation value without thermal bridging in the wall. A 6 mil poly vapour is typically used on the inside face of the inside stud wall with plywood or osb backer at electrical boxes and other penetrations. This is a good wall which utilizes conventional skills the trades already have and has a good track record for high performance with proper workmanship. Because the wall cavity is also used for plumbing and electrical runs the poly vapour barrier must be penetrated many times so the key in achieving the air tighness required here is proper sealing at penetrations. There have been questions on durability of the vapour barrier due to post construction use (picture hanging) and pressure differentials dislodging the poly vapour barrier. Nonetheless, this method is tried and true and has achieve net zero designations. The strongest advocate I’m aware of for this technique is Peter Amerongen (http://habitat-studio.com/?page_id=2).

SIPS panels consist of rigid insulation typically EPS/XPS sandwiched by OSB. These form a prefabricated panel which is often delivered onsite and assembled with a crane within a few days. This system is vapour closed due to the rigid insulation and the OSB. It is considered very durable and has a long history especially with Timberframe builders who have used the panels as infill between posts and beams and more currently outside the timbers as a continuous wall. Services can be run within pre-drilled holes in the insulation or within a backup stud service wall. To my knowledge this system works well but is considered more expensive than other systems. This is a good, durable, vapour closed system that has seen a long history use.

Vapour open exterior insulated wall as in the Langley home is described in the Building Enclosure Design Guide (HPO 2011) and Guide for Designing Energy Efficiency Building Enclosures (FPInnovations 2013) both by RDH. The wall design borrows from the North Shore Passive House in construction by the Econ Group (http://www.econgroup.ca/north-shore-passive-house/) and progress photos of the North Shore home are available at http://www.econgroup.ca/north-shore-passive-house/. This system borrows the durability of the REMOTE wall and other exterior insulation wall types common to commercial and multi-family construction. Its’ durability comes from the ease of installation on a solid vapour barrier and requires little additional skill from typical construction. It introduces an increased vapour permeance that allows the wall to breathe and dry out while maintaining a very tight envelope. The increased vapour permeance is not represented in the Building Code and results in greater reliance on consultants and their expertise.

Each of the wall types discussed above have a long history in construction in various forms each with their advantages and disadvantages. With the increased need for more energy efficient construction the budding popularity of high-efficiency wall types is certainly a good thing. Time will tell if the single family home will latch onto one of these systems to the exclusion of the others as has generally happened in the past or if it will embrace multiple wall types.

Langley Passive House Part 2 – Sunshade

The South facing sunshades on the Langley Passive House are permanent, sized to reject the overheating summer sun while allowing passage of the winter sun through the windows to heat the home, and fit the architectural style of the home. There are two levels of sunshade one at the roof level as an extension of the eaves and the other shades the main level windows and doors as a continuous wall mounted canopy.

The upper eaves are extensions of the top chord of the roof trusses and form an angled soffit with continuous venting. This overhang shades the upper level windows from the steep angle of the summer sun. The lower angle winter sun is not obsured by the length of the overhang allowing the warming rays to play a key role in heating the interior of the home.

The main level canopy is shown in the detailed close-up image and is attached such that it does not penetrate the insulation and create a thermal bridge. The trusses are hung off 2×4 ledgers which are in turn attached to the 2×4 vertical strapping without penetrating the insulation.

Passive House Detail

Langley Passive House Part 1 – In Progress

The Langley Passive house is a ‘split-insulated’ wall assembley pioneered by RDH Building Engineering for the BC climate. This strategy is described in the Building Enclosure Design Guide (HPO 2011) and Guide for Designing Energy Efficiency Building Enclosures (FPInnovations 2013) both by RDH. The wall design borrows from the North Shore Passive House in construction by the Econ Group (http://www.econgroup.ca/north-shore-passive-house/) and progress photos of the North Shore home are available at http://www.econgroup.ca/north-shore-passive-house/.

Passive House Detail
Passive house Wall, Roof, and Foundation design detail

The schematic roof – wall – foundation diagram shows the component parts for the Langley Passive house. The wall assembley consists of a 2×4 structural and service wall with a plywood vapour barrier at the exterior. An air barrier is taped to the rigid plywood backing. Two layers of rigid roxul provide exterior and continuous exterior insulation which in turn is held in place by 2×4 strapping on flat anchored with long screws.

The roof assembley consists of a truss roof with OSB vapour barrier attached to the underside and a 2×4 drop ceiling for services. Blown in insulation blanket the attic space.

A raft slab concrete foundation sits on 2 layers of rigid insulation which abut the rigid roxul of the wall assembley ensuring continuous insulation without thermal breaks.

The Langley Passive house is currently largely framed with roof membranes in, rigid roxul and wall strapping mostly present, and raft slab foundation installed and backfilled. The image shows the blue roofing membrane on the lower granny suite, staging is shown, double layer of rigid roxul at wall, 2×4 strapping, and south facing sunshades at the right-side of image.

The chosen assembley is a relatively vapour open system allowing any moisture that finds its way into the wall from condensation or through gaps in the assembley a way to dry out. The plywood vapour barrier has a permeance range of 115 – 252 ng/Pa*s*m2 above the prescriptive requirement of 60 ng/Pa*s*m2 (BCBC). This in addition to the vapour open air barrier and roxul insulation allows for drying to the outside. Similary the roxul in the stud wall cavity allows for drying to the inside. This contrasts with the relatively vapour closed passive house systems such as structurally insulated panels (SIPS), closed cell spray foam, EPS or XPS exterior wall insulation, and to a lesser extent systems using a traditional poly vapour barrier. The team including the passive house consultant Dale Mueller have chosen this strategy to best contend with British Columbia’s temperate rainforest climate.

Subsequent posts will go into more detail regarding the roof – wall- foundation assembley, exterior window and door installation and their construction sequencing.  There are some nonconventional methods used in the all these areas which may be of special interest

Langley Passive House -Part 4

Window Detail

Triple pane window is installed over sill flashing & weather resistant membrane and then taped.

Then there is a 2×4 ripped to the thickness of 1 layer of rigid roxul around the window offset about 3″. This holds a layer of rigid roxul tight against the window frame and provides a nailing & flashing surface. The second layer of rigid roxul covers up the 2×4 resulting in a thermal bridge free detail. Borate treated 2×4 strapping on flat hold the 2 layers of rigid roxul in place. Also shown here is the wall connection to the foundation. You can see the dimple board drainage layer with a self adhered flashing at the top and the rigid roxul over top. On the left of the lower picture (above) you can see how the rigid roxul is held in place with temporary bracing via leaning 2x4s before the install of permanent strapping and long screws.

You can see the head flashing at the top of window. This is nailed into the 2×4 ripped strip offset above the window. Wood trim is installed at jambs and sill flashing with end dams. What is left is the siding nailed into the strapping (not shown).

On the inside headers are installed at the floor joist level. Air barrier wrap can be seen surrounding the window head and jamb.

The windows are installed through the interior side of the window frame rather than with the common flange. Sill self adhered flashing can be seen with the air barrier membrane properly lapped. Tape from the window frame to the structure and rod & caulk will be provided in future (not shown).

The head and jamb are shown here.

Compared to a typical window installation there are some differences here. The membrane wraps are similar but the air barrier membrane needs to be taped at all seams. The window is flangeless and is mounted with side-mounted screws. There is a 2×4 nailing strip offset at head and jamb and the 2 layers of exterior rigid roxul is a new addition to the conventional sequence of installation. The 2×4 strapping on flat is larger than the standard and the required extra long screws must penetrate the 2×4 strapping, 2 layers of rigid roxul, plywood sheathing, and at least 1.5″ into the stud. This takes some skill as the studs can’t be seen and must be hit. Also, the screws should be angled upward slightly. This is due to the nature of long screws which tend to sag from the weight of the siding if installed horizontally. The angled installation slightly up mimics the final resting ‘sag’ of the screw such that there is no movement of the siding after install. Any screws that miss their mark are to be left in place. This avoids penetrations of the air barrier if these screws were removed.

rockhouse-conception

How to enclose a rock in a living room? – Stories from the Rockhouse

When anyone first enters the Rockhouse, after a moment of disbelief, they invariably ask, “How on earth did you manage to enclose a rock bluff inside a living room?!”
So we decided to share what we learned from this experience in the blog, from the conceptual, practical and technical sides.

 

I have to say that the largest barrier we had to overcome was the problem of perception rather than technical difficulties. Before we could get anywhere with the idea of enclosing a rock inside a living room in the rainy climate of BC, we had to believe for ourselves that it was possible. I will not underestimate the importance of this first step because nothing could have been accomplished without it. This proved to be very challenging at times when everyone and everything around us seemed to suggest that it could not be done. So the next big step was to convince others of our vision. This included everything from having the support of our family and friends, to having the support and expertise of fellow professionals to work with us towards that vision, convincing builders that they already had the skill to do something they had never attempted before and getting their input on how it could be done, convincing municipalities that together we were a competent team that could successfully bring this vision into reality.

Another big part of this learning experience for us was understanding our relationship to the building site. Our first desire was to have the entire back wall of the house exposed to the rock. But there were problems with this idea. Although most of the rock face was smooth and dry, there was a big crack on the lower portion of the rock face we wanted to expose where water was constantly draining out of. We contemplated various ways of dealing with the water drainage problem, including plugging the crack with epoxy. One day we were standing at the construction site already well underway, like two little specs in front of this massive rock bluff surrounded by the footprint of the house foundation, and we understood for the first time our place in the whole picture. We could not impose our will on nature. Plugging that crack on the rock face would likely generate leakage unpredictably elsewhere. To succeed we had to work with what was already there. So we studied the rock face more closely. We observed the parts of the rock that were naturally kept dry and how the water naturally drained. We went back to the drawing board to reformulate our strategy. Instead of exposing the entire rock face we decided to strategically expose only the portion of the rock that already “wanted” to be exposed. From that standpoint, the design evolved smoothly into what came to be a very special “picture framing” of the rock, as well as a cozy seating space where we could hang out by the rock.

The conceptual lesson the Rockhouse taught us was twofold – That it is important to have the confidence to believe in our ideas and to be able to bring others along with our vision. But that it is equally important to be humble in the understanding of our place in that vision – to understand that we cannot impose our will on others and much less on nature. The best we can do is to bring out the full potential of what is already there.

Travelling through Italy last summer we were reminded of Michelangelo’s famous quote: “I saw the angel in the marble and I carved him until I set him free.” Never before had that famous quote resonated with us so deeply. We understood that just as we cannot impose our own will on our clients, we also cannot impose our will on our building sites. Our building sites are in a way also our clients. We have to work with the clients’ ideas to bring out the best in them, just as we have to work with our building sites to bring out the full potential of what we already see in them.

On the practical side, we also had to deal with the nagging question, “But how much is enclosing a rock inside a living room going to cost? And is it worth it?”

This question comes hand-in-hand with other questions like, “What is the relationship between “design” and “money”?, and “Does innovative design need to cost a lot of money?”
Our understanding is that whenever we dive into any project, there is already an existing flow and logic to it. We always have the choice to go with the flow or to go against it, but going against the flow will always take more effort. In the same way, working against the building site will always cost more money. Lots of money could have been spent blasting away the site to impose a pre-conceived design on it, or in trying to control the water drainage pattern of the rock. On the other hand, lots of money was saved by working with the land and what was already there, instead of imposing our will on the site.
If a design becomes prohibitively expensive, we have to pause and ask ourselves, “What are we working against here? And how can we reformulate our strategy to turn this around and swim with the current instead of against it?” If all the options are considered and the design still proves to be prohibitively expensive, it is important to have the courage to ask, “Is this site right for me?” A relationship between a house and a building site is not unlike a relationship between people. If after doing everything to try to make a relationship work it is still not working, letting go may be the best option. On the same token, if the site proves to be not right for the house you envision, it is important to have the courage to either let it go, or to adjust your vision to work with the site. In the case of the Rockhouse, we chose the latter.
Having said that, it is very important to pick a site that works for you. If you are someone who can’t handle too many stairs, don’t pick a steep site to build your house on. If you have to work against your piece of land to impose your own needs and desires on it, it will inevitably cost you more money in the end. Pick a site that resonates with you. A site that already brings you closer to what your needs and desires are, and work along with it, not against it. We have learned that this attitude in itself can not only make the design more affordable, but will also go a long way in bringing out creativity and innovation in the design without prohibitive extra costs.

 

Another side of the relationship between “design” and “cost” worth mentioning is that it is also important to understand that you cannot accomplish something great unless you invest yourself in it. If a creative feature of the design is important to you, if it is something that you feel will really enrich the space and make that space more special and unique to you, understand that you will have to invest some money into that portion in order to express that feature well and fully. In other words, you want that special part to be done right. But this does not mean you need to go above and beyond your means to accomplish it. We often advise our clients to weigh their priorities and put their money where it means the most to them. Perhaps another feature of the design that is not as important can be cut back to make room in the budget to more fully express an important feature. The exposed rock wall was a very important feature of the Rockhouse to us, and to make room in the budget for that we ended up eliminating a few items from our ‘wish list’, such as a wood fireplace, an outdoor tub, and a green roof over the bridge entrance, with the understanding that these features could be added in the future when our budget allowed. In some cases we even made provisions for the future addition of these items.

Finally on the technical side, the solution to enclosing the rock in the living room ended up being fairly simple once we realized that we could take advantage of the dry portion of the rock face. The decision was made to cast a concrete frame around the perimeter of the rockface to be exposed, leaving the crack out of the exposed portion so that the rock could continue to drain out naturally. Within the concrete frame we embedded bentonite rope as a natural sealer. Bentonite is a natural clay material that expands when it comes in contact with water, creating a flexible seal against the uneven rock face. On the top portion of the concrete frame we created a gutter against the rock face to collect and drain the rain water away to one side. The gutter is built up with roofing membrane and metal flashing against the rock face. We insulated the concrete on the inside face with rigid insulation and covered it with drywall, creating a nice color contrast between the grey rock face and the white walls. The inner edge of the concrete frame was skillfully crafted in bamboo, using the carpenter’s technique of scribing to cut the bamboo edges to closely follow the uneven surface of the rock face. This visually created a warm frame around the rock, and also a nice seating space.

The other technical question we are often asked is, “Is the rock face cold?” If we consider the rock as a massive object, it is easy to see that it would take a long time to heat or to cool such a massive object, so its temperature cannot vary much. We find that the rock stays at constant temperature of about 15 degrees Celsius all year long. So it gives a nice cool feeling to hot summer days, and in the winter it is still warmer to stand by the rock face than it is to stand in front of a window. There is in fact a lot more radiative heat loss through windows than through the exposed rock.

On a final note, I have to admit that even though I am used to seeing a rock in my living room everyday, from time to time when I enter the Rockhouse I also stare at it in disbelief… The disbelief comes from the feeling that there is more at work here than anything we could have originally conceived – the confluence of the site’s influence and the efforts of all the people that have believed in the vision and had a hand in bringing that vision into reality created something that is really outside of our hands, it has a life of its own. And again we humbly stand as little specs in front of this massive rock bluff.

rockhouse in constr

Design and Build your Own Home

There is something very visceral and satisfying to conceive, design, and to build your own home.  To me building your own home is the definition of empowerment.  A home crafted to your personality and your needs can become more than a reflection of your personality, it can be a platform that allows you to flourish.  A home can be crafted to give you that pure quiet space from the hectic world where you can meditate, contemplate, and give your creative juices the space to come out.  A home can be crafted to allow you to commune with the natural landscape around it in harmony.

A hammock in our private courtyard is a personal touch from my wife who comes from Brazil.  It is a piece of home that transforms an outdoor space into an amazing vacation retreat right at home.  There is a wealth of peace and quiet that can come from a lazy summer afternoon gently swaying in the hammock with a glass of wine.

Most people think of their home as simply a place to eat, sleep, and relax.  But there is a spiritual cultivation that is missing in this standard conception of home.  To let our personalities flourish we need to cultivate and nourish our creativity.  The quality of ones life and experiences are what is important.  My parents might travel to far away destinations and see all the attractions in just a few days.  Whereas my wife and I will go to one place for a month and try to absorb as much of the culture and way of life as we can.  We think of deep experiences as being more important than multiple experiences.  Home life should be treated similarly as a deep experience.  I am sure there are subtle things in your home that make you smile everyday and although you may not be conscious of it I bet those little things add together and contribute greatly to your general happiness.  Imagine if you wake up or walk into your home after work each and every day and your home gave you a constant reason to smile.

Many people I speak to dream about building their own home but far fewer people actually do it.  I’ve done it and it is a lot easier than I thought it would be.  Oh, it is an adventure and it will keep you up at night but you’ll remember this deep experience forever.  There are quite a few practicalities that you’ll need to address in order to do it without putting your finances in jeopardy and you’ll need to really get your creative juices going and think about what makes you happy in a home.  A hundred years ago almost everybody had a hand in building their own home.  I think it builds character and it makes you appreciate and focus on what you really believe is important in your life.  I’ve had many clients who think of the exercise as a spiritual re-evaluation of what is essential in their daily habits and daily lives.  There is a great joy in taking something you’ve dreamt about and bringing it to realization in the world.  It is a feeling that is basic and real and satisfying and honest.

There are many aspects to consider and I’ll wade through one by one with this blog.  I’ll act as your guide.  I’ve been educated as an architect with a Masters in Architecture from the University of British Columbia (UBC).  I’ve worked for architects, builders, and developers but now run my own design practice.   I’ve also taught estimating, scheduling, and building technology at the British Columbia Institute of Technology and been a teaching assistant at UBC for structural design and HVAC systems.  For a more detailed CV see http://ca.linkedin.com/pub/howard-leung/2a/252/55a

Stay tuned for a piece on ‘affording your new home’.  It is surprisingly easier that your think!