insulate and seal... insulate and seal!

I would check the fire retardent used in the insulation that you buy. Borax may be the best.It would probably ward off carpenter ants also. Some of the dodecacane fire retardants(if my memory serves me well)may be hazardous to your health. You should be able to get an MSDS beforehand on the particular fire retardent in the insulation that you are about to buy.

J Shaw

I'll do that. The River Dale NetZero Project guys are pretty diligent, so I have confidence that they've thought of this. Still, I'll check it out.

I'm adding an addition to my house right now and am trying to find the best product for insulating. All the contractors I am talking to say that fiberglass has a better R value than cellulose, but the soy foam would be best (or some foam/fiberglass combo? Recently, I have also seen a foil that you can place between the drywall and insulation to block radient heat. I haven't seen any mention of soy foam or the reflective barrier, what are your thoughts?

Yeah, insulate and seal- it seems to be the right thing to do under the current circumstances. All of your tips amazed me, I never seriously considered this aspect and now that I read about it I got a whole different perspective. I'm definitely in. I also did dome internet research and and I found a double glazing company UK that might do some good work with what I need. Thanks for everything!

With using spray-in-place foam, you not only air seal the building, it's a vapour barrier as well. It can be applied at 3-4in thick with an R-20 Value. It doesn"t matter how high your R-value is with cellulose insulation, it"s not completly air tight, therefore losing alot of energy.

With an air change rate of 0.5 air changes per hour at 50 Pa., this house will be as air tight or more airtight than almost any other, spray-in foam or not. With Peter Amerongen's special vapour barrier detailing, the airtightness is there.

Given that, an R-56 wall vastly outperforms an R-20 wall.

Do you have an airtightness numbers for the spray-in insulation? I do like that you get the vapour barrier and insulation in one go.

It's crucial to never underestimate the importance of an airtight seal for this type of insulation, otherwise a lot of energy is lost.

Thanks for the advice. Peter Amerongen has special detailing techniques for sealing houses. I hope to publish a piece on them later this year.

Need advise on insulating a large old type commercial building (Super Valu Store), which does not have a vapor barrier in the attic but has the insulation attached to the attic ceiling. The old insulation is now falling down and has to be removed which is another issue. Also, a large portion of the store has a four foot dropped ceiling and again the insulation is falling off the rafters. I have pictures. I need some professional advise. Can you help. Thank you.
Ken

Hi Ken,

I can't provide professional advice. Sorry. All I can do is urge you to insulate as much as you can afford once you do get a contractor lined up.

Conrad

Hi Conrad,

Back at the design stage did straw bale ever cross your mind as a possible alternative? Similar to the insulation levels you will be getting but much different in regards to the 'seal' aspect. Seemingly uber-ecofriendly so I'd be curious to hear your thoughts.

Thanks.

Hi Brad,

I initially wanted to build with straw bales. The bales have such a low embodied energy that it was compelling for that reason alone. As I kept researching though, I began to realize two things: 1) there is no vapour barrier in a straw bale wall. Everything that we know about building science tells us that by the end of the winter that wall will be full of ice. 2) The R-value of a 16 inch straw bale wall would be closer to R25 than the R56 that we are definitely getting from our wall system. Furthermore, Peter Amerongen (who knows as much or more as any builder in Canada about building energy efficient houses) has told me that it's very difficult to seal a straw bale wall properly. So it wouldn't be as air tight as our wall.

Take care,

Conrad

Just curious why you didn't use spray foam for insulation?

We'll achieve an excellent seal without it, avoid the much higher cost versus cellulose insulation, and avoid the higher environmental impact of foam versus cellulose.

Hi, Conrad.

I own a 1400 sqft bungalow in the Edmonton Mill Creek area and as with many houses in the area, mine is starting to show it's age, some 50+ years. When it is cold outside, my walls are cold to the touch and I can feel a cold draft around many of the exterior wall outlets. I have been considering having my house re-sided so that I can add a layer of insulation and possibly replace the windows.

As a first time home owner I am at a loss as to where to start.

How do I go about finding a contractor that can manage the work required in a manor that will be environmentally friendly, cost effective and last for another 50 years?

(PS: Great job with your site, plenty of good information and discussions.)

Thanks for the straw bale feedback Conrad. We have a family friend who has a bale house just east of Edmonton and every time we go there we fall in love with the idea. Did you find some studies, etc. that led to your concerns about the moisture freezing in the walls or was that a result of your own reading and/or discussions with others? It seems to make sense (in my layman's mind anyway) but I guess I'm still holding out hope there is a solution for our climate.

Also regarding the 'plastic bag' and HRV approach - I haven't read up on HRV technology much but it seems to introduce a single point of failure into the system. Is there any real concern with this (i.e. do you have to check it constantly to make sure it is functioning as intended) or not so much?

Thanks again.
Brad

Hi Brad,

I have no particular studies in mind. With regard to the HRV, it is a single point of failure, but there are many emergency back up solutions: the windows. I think that the building science is pretty solid in asserting that cold air moving into a house is undesirable.

I know what you mean about falling in love with straw bale houses - they are very beautiful.

Conrad

While I can't help you with a contractor, I suggest that you think about using larsen trusses on your outside wall. The advantage is that you can take off your existing siding, then apply and seal a vapor barrier and then add the larsen trusses(2" x 3" joined with 1/4" plywood), creating whatever width of space that you want (I would suggest a minimum of 14" to give R42), put on siding and or plywood and fill space with cellulose insulation. Obviously you want to replace windows at the same time and increase overhang to accomodate wider exterior wall. You might also have to do something with roof to increase space for attic insulation. Another thing to do at the same time would be to insulate the exterior basement wall to 3' or 4' below grade. You can use styrofoam insulation and cover it with plastic stucco. While expensive and complex it is best solution that I have been able to devise.

Larsen trusses were created by John Larsen of Edmonton in the mid to late 1970s.

Hello there Rob I live in Alberta and we just bought a home that is 3yrs old it has a "bonus room over the garage" and we find it very cold in the winter months. it has two heat registers underneath the window which faces north. The exterior of the home is siding. and the real estate fellow who sold us the home advised that there is a house wrap on the underside of the siding all around the home.

The garage is insulated and drywalled but not heated. Do you have any ideas on how we can get this room warmer in the winter. Ohh yeah and in the summer months the room is alot warmer in the house.

Thanks

T

Antonio,
If the siding is nailed through the house wrap, then the house wrap no longer acts as an air barrier. Here's a page that describes different air barriers:
http://www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/98109.htm

I had a master br over garage in a previous house; similar problems to you. Not much you can do about the energy efficiency; it's a design problem. A typical room in a house has 2 cold surfaces (i.e. 1 wall & the ceiling). The bonus room has 3 cold walls & a cold floor & cold ceiling.

It would be good to learn more about the techniques PA uses for detailing the insulation installation.
Are you also recommending insulation firms?
MikeG

On Feb 16, Conrad wrote
"1) There is no vapour barrier in a straw bale wall. Everything that we know about building science tells us that by the end of winter that the wall will be full of ice."
Although I am not a proponent of straw bale houses, I could not let the above statement go unchallenged. It is actually quite easy to add a vapour barrier to a straw bale wall by giving it a coat or two of latex paint on the inside. Air sealing is a little more difficult, but doable. As far as the ice in the wall...simply untrue. I am including a link to what I regard as some real building science regarding straw bale construction. The author is fellow Canadian, John Straube.
http://www.buildingscience.com/documents/digests/bsd-112-building-scienc...

I do agree that the R value of straw bale walls (Straube reports values ranging from R26 to R30) is probably too little for our climate, but it is still twice what today's building code allows as a minimum. (whole wall R value of 2X6 wall filled with batt insulation is about R 13)

Hope you don't mind my challenge of your statements. I really enjoy your blog and hope to read more soon.

Considerate comments such as yours are always welcome here.

I guess that I was jumping to conclusions a bit with that statement.

However, the three strawbale houses that I've toured were finished with unpainted plaster on the inside, and the owners were practically boasting about how their houses "breathe". One person's "breathe" is another's "leak". They were explaining how air moves in and out of their houses as if it was a good thing, and they couldn't answer questions about that same air carrying moisture into the walls in winter.

Thanks for pointing me to a school of strawbale building that follows the rules :)

hello Conrad
having had some experience with cellulose over many years I would have some concerns with it settling in walls. Any thoughts?

Hi Les,

Rob Dumont built a similar house to mine (16" walls filled with cellulose) in 1992. Fifteen years later, he measured the temperature at the top of his outside walls and compared it to the rest of the wall - he found no difference. That, along with the fact that the manufacturer puts a binding agent in the cellulose and the assurances of my builder Peter Amerongen, lead me to feel very confident that there will be no settling of the cellulose insulation.

Conrad

In the picture I see light through cracks between 2 sheets of OSB. Were these later sealed?

-Ralph

I don't think so. The cavity would have been filled with cellulose, and then the exterior covered with tar paper and stuccoed.

And the vapour barrier installed on the inside, of course.

Conrad

My house has the same gaps in the walls. I assumed, but never did confirm with the framers, that this is to allow for expansion of the OSB if it gets wet. Almost everyone who visits the house comments on this. These gaps are covered from the outside by either tarpaper or Tyvek so the insulation can't leak out and water can't get in.

B.

Conrad: I think your stucco finish is a big help for air infiltration.
Bob: the mfr recommends 1/8" space between panels. If this is done over blocking then air won't get in through the gap (not important for a stucco finish like Conrad's but very important for Vinyl siding)

I am an insulator in Alberta. What do you feel about the current code, and do you expect it to be changed much for 2010?

Hi Dave,

I think that the current code should enforce much higher R-values. As for how much it will be changed, I haven't the foggiest clue.

Conrad

I wouldn't count on the current code changing any time soon. There's lots of pushback from spec builders trying to build as cheaply as possible. Where's the support for higher standards? Only a few "wingnuts" (to quote the leader of the province of Alberta during the "bozo" years). The general public would still rather spend their money on hot tubs and granite countertops than be forced to spend it on more insulation. Besides, natural gas is dirt cheap and will be for at least another year so why worry? Remember the controversy over changes to the fire code requiring better fire protection under vinyl siding? That likely went through only because it was related to safety (and probably had the support of the insurance lobby).

B.

I think a double 2x4 wall with offset studs 24"OC, 10" thick with R12 & R20 fiberglass batts gives the best bang for the buck.
I've just posted details on my issues with dense-pack cellulose to my blog.
http://ecoralph.blogspot.com/

Has anyone tried to upgrade a ~25 year old building to airtight/superinsulation from the inside? I'm thinking I'd like to have the drywall removed, add 2x4s and perhaps a space and insulate with cellulose or fiberglass. My biggest concern is about integrity of the vapour barrier.

I used to teach an "energy and fuel science" course in the '80 an have been a huge fan of the Dumont style house ever since. I guess that makes me a "wingnut" retired physics prof. I've wanted a factor 9 home for some years now, but live in a four-plex that is administered as a condominium. I'd only be modifying the two outside walls and seeing if I can improve on the attic insulation.

Margaret in Thunder Bay

Conrad,

I'm trying to get my mind around how the actual double 2x4 framing was performed on site. Was it essentially a duplication of each wall layer on the deck, and the outer level lifted up and nailed to the 16" top and bottom plates before both were tipped up? Did you tip up the outer wall first and then the inner wall before attaching to the top plate? Was it a combination of both?

Thanks in advance for your reply.

Conrad,

On the same note for framing, conventional framing is done with 2 top plates, making a 3" thick bearing surface for the upper floor joists. With your method of a 16" wide OSB or plywood sheet on the top, what provisions are made to support the joists?

Hi Gordon,

Conrad is very busy right now so I've offered to answer your questions as my house (Belgravia NetZero) has the same 16" double-wall system.

Each wall is built horizontally as a complete double wall on the subfloor, then raised into place. From bottom to top, a wall consists of a 3/8" bottom plate, 1x4 spacer (3/4"), stud (7' 8 3/4" for a nominal 8' wall or 8' 8 3/4" for a nominal 9' wall), 2x4 (1 1/2"), 3/8" top plate and finally another 2x4 (1 1/2") giving a total wall height of 8' 1 1/4" or 9' 1 1/4". So yes, there are two 2x4's at the top of the wall with the OSB top plate between them.
Here are some pictures to illustrate how a wall is built and erected.

First, lay out the top and bottom plates side by side. This allows you to mark stud positions in the same location on both plates.

Position the bottom plate for horizontal assembly and toe-nail into place. The inside edge of the bottom plate will be the axis of rotation when the wall is erected.

Position the top plate and full-length studs.

Attach the full-length studs to the top and bottom plates

Frame in windows with 2x4's

Add OSB sheathing to the outside wall

Add caulking for the outside edge of the bottom plate

Erect the wall


Done! Repeat for next wall

Another view of erecting a wall, showing 2x4's on top of the top plate. This being a second-floor wall, the roof trusses will rest on these 2x4's.

Here's a SketchUp model illustrating how the 2x4's on the top plate tie walls together. The east wall (on the left) has been displaced 20" to the east. 2x4's that extend past the end of the OSB top plate are added after the wall is erected. In this example, the 2x4 on the outside of the south wall is 16" proud of the east end of the OSB top plate, while the 2x4 on the inside of the south wall is 3 1/2" proud of the east end of the OSB top plate. The 2x4 on the outside of the east wall is 3 1/2" shy of the south end of the OSB top plate, while the 2x4 on the inside of the east wall is 16" shy of the south end of the OSB top plate.

B.

Excellent pics Bob.

In these and other pics of the double wall construction, I don't see headers for the window openings. Is that stage added later, or am I missing a framing trick?

Al

Excellent question Al.

No tricks - headers are certainly required. The short answer is that the headers are in the interstice (joist space between floors). But I'm not partial to short answers so allow me to elaborate.

Here's the south main floor wall of Belgravia NetZero. There's no way you could lay joists directly on that top plate - there's nothing to transfer the load around the window openings.
BNZ Main Floor South Wall
So the headers go on top of the wall and the joists are attached to the headers with joist hangers. Header size depends on the size of the window opening. For the large living room window on the left, the header consists of 3 microlam beams, the dining room room window requires only 2 microlams and the kitchen window only a double 2x10.
South Wall With Headers
Here the joists are attached to the headers.
South Wall With Headers And Joists
Here's a view from the northwest showing how the joists attach to the headers.
View From Northwest
Here's a photo. Sorry, this is the best I have.
Photo From East
On the second floor, the windows go right up to the top plate so there's no room for a header in the wall even if you wanted to place it there.
BNZ Second Floor South Wall
In this case a full-width triple 2x10 header is used.
Second Floor South Wall With Header
Here's how the roof trusses were designed to tie into the header.
Header And Trusses
Finally, a photo of the header and trusses.
Photo Of Header And Trusses
B.

This is excellent information, Thanks Bob. One more question: It appears that you will have very little in the way of a roof overhang. If possible, could you post a picture that shows what the final overhang will be?

Ken

Hi Ken,

Thanks for your question about overhangs. I'll try to put a response together soon.

B.

Bob,

Clearly I had used the wrong terminology, and should have said 'lintel'. However, you addressed exactly what I was curious about, and the framing technique used here is excellent info. Thanks. Al

In all the research I have examined regarding ‘building envelopes’, the evidence is clear that a well sealed home is necessary for energy efficiency. A solid vapor barrier and well constructed air barrier creates a best case scenario for insulation to do its job. For wall construction, these practices are relatively simple to complete.

However, I have not found any reference (in building codes or best practice recommendations) that the same effort should be made for ceiling insulation. It seems to me that the efficiency of the top (significant depth) of ceiling insulation is negated by the opportunity for air movement. Given that so much more insulation is recommended for ceilings, it seems to me that at least some effort could be made to improve the efficiency of that insulation.

I appreciate that due to the webbing nature of rafters, a solid air barrier would not be possible. It would also make sense that a (vapor permeable) barrier would need to be secured sufficiently to prevent ‘fold over’. And, clearly there would be more labor involved. But I believe in some ceilings it would be possible to cover a large portion of insulation for improved efficiency.

Does anyone have any experience with such an installation? Or, does anyone know a reason why such an air barrier should not be contemplated?

Great site, I appreciate the work it takes to keep it current, and the opportunity for discussion about the ‘common good’. Thank you.

Al

Bob, I'd like to add my thanks for the drawings and photos.
I also thought of putting lintels above the top plate, but your way of doing it is better since it doesn't seem to require hangers (or were hangers added after you took those pictures).

Bob,
Did you consider going with a single 2x4 top plate instead of a double?
Part9 allows single top plates when stack framing is used.

Al,

The drywall is the best air barrier in an attic. Cellulose insulation performs very well in an flat attic without an air barrier on top.
http://www.gwscientific.com/cchrc/rtf_data/roof/roof.html

For walls an exterior air barrier is the best. It is easier to detail and it protects insulation from wind washing while an interior air barrier does not.