Energy Revolution in a Brooklyn Townhome
Monthly Archives: November 2009
Yes, even more discussion about spray foam! When we are using spray foam as our air barrier and not just for insulation, the quality of installation becomes that much more important. The company that we are using is doing a good job working with us to come back and do multiple stages of spraying so that we can move forward on testing our side walls for infiltration while we wait the 3 months for the windows to come in, but their initial pass was not very careful in terms of coverage or depth.
The areas to look for when reviewing a spray foam job are:
- Rim joists: Were they all covered or are there gaps? In this case the rim joist in the entire house were missed on the first pass.
- Overall depth of spray: If you have purchased 3″ of spray foam at $1.50 per in/sq ft, then you want to make sure that you get what you paid for. Spray foam is difficult to “eye” how consistent the depth is, so we use a simple method. We purchase small bamboo skewers (sold for grilling), cut them to the 3″ and then stick them every couple of feet or where the spray looks low to determine the depth. The good thing about the bamboo, vs. using a nail is that the bamboo does not act as a thermal bridge and can be left in place for the next pass of the spray foam to go right over.
- Wall intersections interrupting foam: When I was inspecting the property after the initial spray, I noticed some areas where a partition wall ran perpendicular into the exterior wall framing, creating an area of a lot of wood and no spray foam. We remedied this by removing those studs and after the spray foam is filled in, we can put back a nailer for our drywall.
The common thread that I have seen with the four spray foam companies that we have used in the past is that they will not do quality control on their own. They tell their guys to spray and wait for you to either accept the work or make a complaint. While this is frustrating and not how their companies should operate – we expect it now and can work to get a good quality product regardless.
Passive House BKLYN is featured in the November 13th Daily News Article, The Passive House: European energy- (and money-) saving building standard catches on in New York. Check it out!
We have spray foam – the first phase of it anyway! Most of the front and back walls, as well as 3 feet of the party walls on either side, were covered with 3.25 inches of foam yielding a 23.4 R-value. After 3 months, that R-value will drop to 21.5. An R-value of 21 is the specification set by the passive house consultant. The windows cavities were left un-sprayed for now. We will have a second phase of spray foam when the frames for the windows are installed. Every opening of our 23 windows are a different size, some by as little as an 1/8 inch, so it is best to wait until the windows are in before adding the foam to those areas.
We found a nifty, inexpensive way to deal with airsealing the electrical boxes in a retrofit capacity – Lessco boxes. We simply cut out the sheetrock around the box location and install the Lessco box – into which the electrical box can be installed. Any penetrations made through the box can be caulked before the sheetrock is replaced, and if there is still some leakage after everything is put back together, this box can be filled with spray foam right through the sheetrock.
More to come in the next 2 weeks as the windows are ordered, the solar hot water system is installed, the ventilation system is installed, the plumbing inspection completed and a blower door test to indicate how well the house is sealed thus far. After these elements are complete, we can begin closing up walls and moving forward with the finish elements of the house.
We have created a Passive House Meetup group because we are interested in raising awareness in the Passive House movement. We believe that the ideas behind Passive House can revolutionize the way we build in NYC. Are you interested in renovations, building, or the “green” movement?…You should join!
Go to www.meetup.com
Register or Sign in if you are already a member (it is free) and then look for our Meetup Group – Passive House NYC.
This week, we put a lot of focus in preparation for the spray foam installation. There is no turning back after this phase. Anything in the way of the foam as it expands will either move or be buried, so special attention was given to protecting our framed walls. The carpenters installed a lot of bracing on the studs of the framed walls to keep them from moving out of plumb and or level during the foam expansion.
The roof (new, durable SBS membrane) was installed this week (minus the new skylights.) The roofers removed many attic ducts intended for venting the interior space. This concept of attic venting is outdated and contrary to the passive house concept. Since we will have mechanical ventilating systems in place, we will be able to control exactly how much fresh air enters the home. Open holes in our air barrier aren’t needed and are avoided at all costs. We can now move forward with our solar panels installation for the hot water system.
Early next week, while we continue to work out the particulars on the ventilating system and windows, the house will be cleared of the contractors so the spray foam can be installed.
Currently, a lot of our effort is being put into sizing the windows just right to place the order. Since the frames of our new triple pane windows are much thicker then the old ones, many details need to be worked out so that the old interior window shutters and casements can be re applied appropriately. A number of dimensions can’t be compromised so that our landmark and insulation requirements can be maintained.
Much of the plumbing sewer and supply lines are in place and we should be ready for an inspection in another week.
However, in order for a plumbing inspection to pass, tubs need to be installed, which will block access to walls that need spray foam. To avoid a delay we are forced to phase the insulation application. In the approaching week, we will be preparing for this. Key areas will be sprayed now, leaving out the window areas for a second phase after installation.
This week, we will also prepare for duct work installation. The ducts are currently being fabricated at the shop. Our Heat Recovery Ventilators (HRVs) are en route from Europe, and we want to have everything ready so they can be installed as soon as they arrive. An area of this passive house construction that differs from conventional construction are the soffits around the duct work. The carpenters will need to pay special attention to the way the soffits are sealed so they don’t become chambers for air movement. This means that the walls within the soffits need to be finished and air sealed, the ducts can then be placed and the soffits built. Duct work tests will need to be conducted after installation making sure the ducts are air tight. We will likely have to cover the seams with mastic several times to pass these tests.