Blower Door Testing up-date #3I have previously made blog entries regarding blower door shell testing on new home construction to locate and address air leaks within the building envelope of conditioned space. These tests are conducted by an independent energy auditor once a new home is tight to weather and (typically) after it has been insulated.
Recently we conducted such a test on a new project which was constructed and insulated similarly to other projects that we have tested.
The test resulted in 0.85 ACH/50. Pretty good numbers!
Other similar homes tested somewhat higher and as I think about differences between these projects the one item that I can identify that could be the reason for an improvement is that on this recent test every window in the house is either a casement window or a fixed window where as the other homes we have tested had a mix of casement, awning, and double hung windows (the window manufacturer (Andersen) and model (A-Series) were the same in all of our test homes).
Some of our homeowner clients have voiced their preference for not having any casement windows in their new homes but for those that are not opposed the casement window style does have an energy performance advantage when a house is under negative pressure (windy weather).
LED lighting and new home constructionLED lighting is helping to make our new home building projects more energy efficient than ever before. As LED lighting options have become more abundant and affordable it is being utilized almost exclusively throughout our new home building projects in a variety of applications.
Whether selecting LED bulbs for lighting fixtures, LED bulb/trim inserts for recessed lighting, or LED "ribbon" accent lighting for under cabinet and display applications, whole house LED lighting can make a significant impact on energy costs.
In my own all LED house, one string of incandescent Christmas tree lights consumed more electricity that the remainder of the house lighting combined (we will have LED Christmas lights this year)!
As seen in "Maine Home + Design" magazineOne of our recent projects has been featured in the Architecture issue of "Maine Home + Design Magazine".
Please follow the following link to review the article: Maine Home + Design article
ARCHITECTURE: BY DESIGN
Construction: Greg Fitzpatrick, Custom Home Builder
Structural Engineering: Becker Structural Engineers
Landscape Architecture: Terrence J. DeWan & Associates
Photography: Randolph Ashey
A cure for thermal bridgingWe have utilized a number of strategies to combat thermal bridging, the heat loss/transfer that occurs through the connection between conditioned and un-conditioned space by framing lumber.
A relatively new product that we have recently utilized is the ZIP R-Sheathing from Huber Wood the maker of Advantech floor/wall/roof sheathing.
ZIP R-Sheathing combines the popular ZIP System sheathing and continuous foam insulation available in 1" which includes 1/2" R-3.3 foam, and 1-1/2" which includes 1" R-6.6 foam.
Some advantages of the ZIP R-Sheathing is a one step installation of wall sheathing and foam envelope insulation, tight to weather walls as soon as the proprietary "ZIP" tape has been installed on the seams, and a reasonable balance of cost to build and energy efficiency.
We will definitely use the ZIP R-Sheathing again on upcoming projects and recommend it as a consideration for your future new home construction project.Another new product that we have recently utilized for the fist time is "ZIP system Liquid Flash". Liquid flash as the name implies is a liquid flashing material for sealing sheathing seams and preparing window and door openings. It is applied with a caulk gun and plastic spreader. The applied product is very tough and durable and looks to be an improvement to some previously widely used weather management techniques. Wear rubber gloves when applying liquid flash!
Blower Door Test Update #2A second blower door test was recently conducted on our current new home construction project. This test was done after the completion of insulation installation to ensure that we had sealed the shell adequately.
Our initial test result was 1.89 ACH/50 prior to air sealing and insulation completion. The second test result was 1.62ACH/50.
My first reaction was of disappointment having utilized hundreds of dollars of spray foam and a bit of my time sealing every inside sheathing seam, panel edge and penetration. This was in addition to the insulation contractors efforts which were substantial.
A smoke generator utilized during the test showed that the weak links in the air tightness of this structure are the double hung windows, doors, and zero clearance fireplace flue and combustion air supply.
There is nothing that can be done about the windows (other than utilizing much more expensive euro windows and avoiding double hung windows (we have utilized Marvin windows which are very good windows). The doors should get better with the permanent hardware and corner pads installed which will be done after we paint. There is nothing that can be done to further seal the fireplace.
A final blower test will be done after drywall installation and the permanent door hardware and corner pads have been installed.
My expectations are for some additional but modest improvement on the final test result and as I think about things I have made the following conclusions:
- The ZIP sheathing with ZIP taped seams do a pretty good job at sealing the shell and probably do not require further air sealing on the interior side
- The 1" DOW foam that is applied to the exterior with seams taped helps air tightness as well
- The Protecto Triple Guard sill seal is more effective than traditional sill seal products to seal the foundation wall/sill plate joint
- The cost to upgrade windows and decision to forgo the fireplace in an attempt to achieve a test result of less than 1.0ACH/50 is probably something that many homeowners are not willing to do given the significant added cost of the windows and lifestyle choice of having a fireplace
- Our test result of 1.62ACH/50 (and maybe a bit better after our upcoming final test) represents a very well air sealed home which will be very efficient to heat for its occupants.
Update on Blower Door TestingI had previously written about Blower Door Testing to measure how well a completed home is air sealed (which is now a requirement in some of the communities that we build new homes in as a condition to receiving a certificate of occupancy).
Recently, we performed a blower door test on a new house that we are building as soon as the house was tight to weather (but prior to the insulation being installed) to help us determine how we could better air seal the building shell while it is still accessible.
This particular home includes the popular "ZIP" wall and roof sheathing and has all seams properly taped. It also has 1" DOW Tuff -R polyiso foam board applied to the outside of the sheathing with all seams taped as well.
The windows and door perimeters were foam sealed, but no other wall sealing efforts had been completed prior to the testing.
Our test results were 1.89 ACH at 50 Pascals. Not too bad, but, we have a pretty strict final target established of 1.0 ACH/50 that we would like to achieve.
The test results have determined the need to air seal 38 square inches of leakage to achieve our target goals.
As the test was being conducted we utilized an inferred camera to identify temperature changes in the building shell which could be caused by air movement. When we found these areas, we used a smoke generating device to check if it was indeed air movement causing the differential, and if so, made a paint mark to identify the need to air seal that area.
We will conduct another blower door test after completing air sealing and insulation installation to see how we did.
So far we have sealed all identified areas as indicated by our test, and went ahead and sealed the inside sheathing seams, top and bottom plates, gable rafters, and around window and door headers and studs which had not indicate leakage, but are areas that we would typically seal anyway.
I will follow up with the results of the next blower door test after it has been completed.
Make up air in tight house constructionNew home builders in Maine have often included dedicated make up air supply for fireplace and wood stove locations, but as houses get tighter and tighter in an effort to conserve energy, make up air for other devices that exhaust air from the building envelope such as kitchen exhaust fans should be considered.
Unfortunately however, the manufacturers of these items are not typically prepared with recommendations and provisions to help homeowners and contractors determine what is best to do.
An excellent article on this subject: Make up air for range hoods can be read here.
Solutions to consider are to either select low CFM devices, re-circulating devices, or provide make up air to avoid the pitfalls of high CFM air exhaust and a tight building envelope.
Depending on total square footage, even houses with whole house air exchange systems may require additional make up air if the CFM volume of air exhausted exceeds the exchange system capacity.
Of course you could always open a window a little bit as many people have done for years to avoid back drafting stoves and fireplaces, but with a little thought and advanced planning that can hopefully be avoided.
Blower Door TestingAs Maine home builders strive to enhance energy efficiency in new home construction, blower door testing is being utilized as a valuable tool to measure how effective we are at air sealing to eliminate unconditioned air from entering the building envelope
A simple concept: with all windows, doors, and other pathways for outside air to enter closed, the blower door temporarily seals itself into an exterior door opening, blows air out of the house at a controlled rate, and measures how much (or how little) replacement air is entering the houseOften, a test may be conducted before the installation of insulation so that air leaks can be identified and corrected while there is access to areas that will be inaccessible after insulation has been installedAn additional test may be conducted after insulation and drywall have been installed to measure the final resultsSome municipalities in Maine are now requiring blower door testing as a condition to receive a certificate of occupancyWhile test results can vary widely depending upon the goals and construction details of the project, blower door testing can benefit all new home construction in Maine
Geo-Thermal heating in MaineWe are currently working on a project that is utilizing a ground sourced Geo-Thermal Heat Pump HVAC system.
I am a big fan of these systems as they are unmatched for efficiency of operation. Geo systems are about 400% efficient as compared to the best LP systems which are about 95% efficient. In other words, for every dollar of energy purchased to operate the system (electricity for a Geo system) a Geo-Thermal system delivers four dollars worth of heat (the LP system delivers .95 cents worth of heat for every dollar of LP purchased)!
This system was designed and installed by Elco Geo-Thermal Heating of Bangor ME.
It is an "Open Loop" system which utilizes the existing domestic supply well for its heat exchange source. Simply, water from the well is pumped to the heat pump, heat is extracted from the water, and then it is returned to the well.
The system delivers heat and air-conditioning via a ducted forced air delivery.
As an added benefit, whenever the system is operating it also pre-heats domestic supply water as a free by-product which is then held in a storage tank until required which further reduces energy costs.
We have also added a Heat Recovery Ventilation (HRV) system which works in concert with the HVAC system to provide a continuous fresh air exchange into the building envelope while capturing much of the heat from the exhaust air being removed from the house.
These systems do cost more than typical Oil or LP boiler/furnace systems, however they currently enjoy a 30% Federal Tax Credit (through 2016) which makes the installed price very competitive and the return on investment time relatively short.
I am a big fan of these systems and we are specifying them in several upcoming projects, including our own home!
Energy efficient constructionNo matter what house style, no matter what budget, energy efficient building techniques should be utilized to enhance ongoing home energy performance.
The following photographs of a current project in New Gloucester Maine highlight a few details that will have a dramatic positive effect regarding how comfortable this house will be, as well as less expensive to heat.Intersecting wall framing techniques that allow full insulation to be installed in the outside wall cavity which eliminates an area of potential thermal transfer from conditioned to unconditioned spaceInsulated window and door header assemblies with continuous rigid foam insulationWall corner construction that allows our blown in insulation to fully insulate this often neglected areaEven though we utilize foam sill seal gasket between the sill plate and foundation wall,we also caulk this seam with silicon caulkWe will foam seal all sheathing panel edges as well as both sides of any wall stud where two panels meet and at the top and bottom plateIt only takes advanced planning, a little extra time and a few cans of DOW Pro foam to make a big difference.
Build new houses tight, tight, tight!I sometimes hear people say things like "new houses today are being built too tight".
I might share this opinion if I were a home heating fuel salesman, but as a Maine home builder with a focus on saving my customers money through energy efficient construction, I say that it is better to understand building science, specifically moisture management, and build new homes as tight as you are able.
Years ago, fuel costs were low, and moisture management not well understood. Houses that leaked air were not much of a concern. They would get wet, but with an abundance of air moving through the walls would dry avoiding moisture damaged assemblies.
With rising fuel costs houses had to become better insulated and tighter, and fortunately within the past decade or so, building science case studies have shown new home builders the way to build structures that are not only tight, but also properly manage bulk moisture from external sources and moisture vapor from internal sources.
Today's home builders are fortunate to have the availability of a wide variety of excellent building products as well as the educational resources to build new homes that are both energy efficient and sustainable.
Products such as "Greenguard Raindrop house wrap" which facilitates a drainage plane between exterior cladding and wall sheathing, "Advantech" brand roof and wall sheathing which is highly resistant to moisture damage, "DOW" "SIS Structural Insulated Sheathing", "Styrofoam" extruded insulation panels, and "Thermax" insulation panels, "DOW" "Weathermate" construction tape and "DOW" "Great Stuff Pro" expanding foam insulation just to name a few.
Fiber-Cement Siding: Worth considering for your new homeIf you are interested in a durable, low maintenance, clean finished look for your new home construction project, Fiber-Cement siding is an excellent choice to consider.
Available in horizontal lap, vertical panel, shakes, and trim, it is a green product known for durability and beauty.
A wide variety of factory applied finish colors are available which will remain beautiful long beyond that of a typical site applied finish product.
We have utilized CertainTeed "WEATHERBOARDS" horizontal lap siding on a recent project and have specified it again for several upcoming projects as well. In addition to all of the previously stated benefits, "Weatherboards" has an industry leading realistic wood grain appearance as well.Proper installation techniques are critical when utilizing fiber-cement siding. A drainage plane should be incorporated into the wall system to assure that moisture can not be absorbed into the back side of the siding, and industry best practice techniques should be followed for flashing, sealing, and bulk moisture management.As an added benefit, Fiber-Cement costs compare favorably to other available siding choices.I look forward to exploring with you how Fiber-Cement siding could be a good consideration for your new home project.
Energy Efficient Wall ConstructionThere are many choices to consider when designing wall assemblies that will be energy efficient and provide homeowners with a comfortable home that is economical to heat.But which is the best balance of performance and cost to build?We have been utilizing a method that combines advanced framing techniques, insulated sheathing, diligent wall sealing, and high performance blown in insulation to achieve these goals, and are happy to see that in a Building Science comparison of high R-value wall assemblies, this method scored quite favorably.The Building Science study can be viewed here:
Additional details and construction photographs can be viewed here:
The wall system, balancing efficiency and cost.
We look forward to exploring with you how these construction methods could be the best choice for your new home construction project.
Radon resistant constructionA requirement of the new Maine Uniform Building and Energy Code (MUBEC) is Radon resistant construction techniques.
Radon, a soil gas that is prevalent throughout Maine has been linked to lung cancer.
We have previously partnered with the EPA to incorporate Radon resistant construction techniques in all new construction and believe that including it in the new building code was the right thing to do.
Many of the techniques were already included in our standard specifications, so it was fairly simple and inexpensive to comply with the remaining requirements and made sense to do so even before it became required by code.
An overview of the techniques follows:
- Utilize perforated pipe for drainage/venting below basement concrete floor
- Back fill below basement concrete floor with clean gravel or crushed stone
- Utilize a poly vapor barrier above the gravel/stone and beneath basement concrete floor sealing the edges and penetrations with silicon caulk. Seal any foundation penetrations or cracks with silicon caulk
- Connect a PVC vent pipe to the below slab drain/vent piping and run vertically within the building enclosure and through the roof deck to vent soil gasses
- Add an electric outlet location in the attic space for a future vent fan if ever required
Together with appropriate building enclosure ventilation practices, these construction techniques will help assure homeowners of a healthy home living environment.
New Energy Codes in MaineIn an effort to achieve conformity throughout the state, Maine has adopted the "Maine Uniform Building and Energy Code".These new codes are now in effect in many cities and towns, and will be enacted statewide by July 1, 2012.We welcome these new codes. We have always had a strong focus on energy efficiency and have typically exceeded code in an effort to achieve tight, well insulated houses that are easy to heat.Some of the required changes however will add cost to a building project. As an example, foundation walls will now require continuous R-15 insulation, and concrete floors will require R-1o.There are minimum U-Factor requirements for windows and skylights as well.The following summary details the requirements by building enclosure element for Maine zone 6 ( all of Maine is zone 6 except Aroostook county which is zone 7).Fenestration U-Factor: 0.35Skylight U-Factor: 0.60Ceiling R-Value: 49Wood Frame Wall R-Value: 20 or 13+5(R-13 cavity insulation plus R-5 insulated sheathing)Mass Wall R-Value: 15/19 (the second R-Value applies when more than half of the insulation is on the interior of the mass wall)Floor R-Value: 30Basement Wall R-Value: 15/19(R-15 continuous insulation on the interior or exterior, or R-19 cavity insulation on the interior)Slab R-Value and Depth: 10, 4ftCrawl Space Wall R-Value: 10/13There are a number of strategies to achieve these new requirements. If you have questions about how these changes might effect your future project and which solutions will best balance performance and cost please contact me as I look forward to speaking with you further.
"Advanced Building Materials"As advancements are made in building material development, quality home builders must continue to remain educated regarding construction methods and techniques that work in synergy with these advanced materials to eliminate potential future problems.
An excellent article by Building Science Corporation explores this topic in detail and can be found at the following link:http://www.buildingscience.com/documents/insights/bsi-039-five-things?topic=doctypes/insights
- "Winkumpaugh Cottage"
Building science case studies are educating Maine home builders on the importance of properly managing moisture in new building construction.
It is unsettling that practices which were considered acceptable for many years are now being questioned as ineffective and even potentially damaging regarding proper moisture management.
Our goals for moisture management are:
- To prohibit bulk moisture from entering the building envelope from the exterior by effectively weather sealing the structure
- To regulate how moisture vapor on the interior of the building enters wall assemblies
- To provide an opportunity for any moisture within the wall assembly to be able to dry to either the exterior or the interior
Best industry practices should always be utilized for weather sealing to prohibit bulk moisture from entering the structure.
This includes proper installation of roofing materials and flashing detail, weather barrier wrap installation and sealing, window and door installation, and exterior cladding installation and detail.
The following photographs detail proper window installation.
Wall systems should be designed so that moisture vapor within the conditioned space is regulated from entering the assembly, yet able to dry either to the exterior or to the interior if it does enter an assembly.The first strategy to keep moisture vapor from entering the structure is extensive air sealing all gaps, joints and seams in the frame as air movement from conditioned to unconditioned space is the principal cause of moisture entering insulated assemblies.A few cans of DOW Professional foam and a little time effectively seals all sheathing seams, plate joints, window and door perimeters and mechanical system penetrations.
Our current project, "Winkumpaugh Cottage" utilizes DOW "SIS" structural insulated sheathing which has a perm rating of 0.03 (twice as impermeable as 6 mil poly). This requires that wall systems be allowed to dry to the inside of the structure as it is nearly impossible that any moisture could dry through the sheathing to the exterior.
But how can we prevent moisture vapor inside the structure from entering the wall system while at the same time allowing moisture vapor to dry to the interior? By installing a vapor retarder.
Building science case studies have determined proper vapor barrier/vapor retarder recommendations for all climate zones based upon average heating degree days and projected dew points within wall assemblies built to a variety of specifications.
In our climate zone, and with foam sheathed walls (the DOW SIS sheathing is continuous foam sheathing of R-5.5) it is recommended that a class III vapor barrier be utilized (class III requires permiance of less than 1.0 perm and greater than 0.1 perm).
An excellent choice to accomplish these parameters is Sherwin Williams Vapor Barrier Primer. It is a latex based product and applied as recommended has a perm rating of 0.9.
By any standard, this type of construction is both energy efficient and "tight", so measures must be taken to ensure ongoing indoor air quality that is both healthy for the occupants as well as for the structure.
We have specified Panasonic's "Whisper Comfort ERV (energy recovery ventilator)" for this project. In place of a typical bath fan, each unit will provide a continuous air exchange for up to 500 sq ft and is 66% efficient at capturing the heat from the stale air being expelled from the structure.
The near silent continuous operation (manual operation is also an option) consumes only 20 watts of electricity (less than most compact fluorescent light bulbs).
While construction techniques that produce sustainable, energy efficient structures that are healthy to live in may cost a little more than the construction practices which have been prevalent for several decades, we believe they are well worth the difference.
Would you be willing to pay more for a new home that is built to higher standards?
I look forward to hearing from you.
Insulation that balances performance and cost
Unpredictable energy costs have made concerned Maine home builders seek better performing insulation alternatives to the traditional fiberglass batt insulation which had been prevalent for many years.We feel an option that balances cost and performance very well is the "OPTIMA" blown in blanket system.Manufactured by CertainTeed and installed locally by R.L. Garside Insulation Contractor, "OPTIMA" is a specially manufactured fiberglass designed for closed cavity installation.The crew from Garside arrived at our site Wednesday morning and proceeded to install a speciality fabric enclosing all wall stud and roof rafter bays.By mid day this was completed and installation of the fiberglass material started.Bundles of "OPTIMA" insulation are placed into a machine on their truck that separates the compressed material and sends it on demand through a hose to the installer in the house who is directing the flow of materials into each wall cavity filling it completely.An advantage of this system is that it fills wall cavities, regardless of shape, completely with no gaps or voids which is almost impossible to achieve with batt insulation.The installed material has a greater density as well. Subsequently, R values are higher with "OPTIMA"( R-23 for 2x6 walls as compared to R-19 for fiberglass batts).One crew from Garside returned the following morning to complete the installation. By noon the job was completed, everything was clean, and they were on their way to another job.Together with the DOW "SIS" insulated sheathing, Winkumpaugh Cottage has walls which are R-28.5.The roof system at Winkumpaugh Cottage includes "OPTIMA" filled 2x10 rafter cavities (R-40) and 1/2" DOW TUFF R rigid insulation with a 3/4" sealed airspace between the foil faced rigid insulation and the drywall ceiling (R-6.1) for a total R value of R-46.
Here is a review of our strategy to achieve excellent energy efficiency while at the same time controlling construction costs:
- OVE (optimum value engineered) framing techniques utilized to reduce framing material therefore creating space for additional insulation.
- Insulated sheathing utilized to create a continuous thermal break between wall framing and unconditioned space.
- Extensive wall sealing techniques employed to minimize air infiltration into the building envelope.
- Superior insulation utilized and installed following Energy Star thermal bypass guidelines to ensure insulation is in full contact with all (6) sides of each wall cavity.
Our next topic to be discussed will review moisture management and indoor air quality.
More at: http://www.gregfitzpatrickgc.com/
Wall sealingBuilding science case studies have shown Maine home builders the importance of sealing wall systems to prevent air infiltration into the building envelope.
Reducing air infiltration is as important as adding additional insulation as a strategy for improving energy performance.Additionally, leaky wall assemblies can be prone to condensation and water damage (mildew, mold, dry rot) as the air exchange creates cold spots for moisture laden air from within the building to condensate.We have previously discussed measures we have taken to reduce thermal transfer and maximize space for insulation.At this point framing is complete, roofing installed, windows and doors installed and we are tight to weather.Soon the insulation and then drywall will be installed closing in the wall cavities. Prior to that occurring we have full access to the inside of the wall cavities and an opportunity to seal any areas that could potentially allow unconditioned air from outside the house to enter into the conditioned space of the building envelope.Areas of concern are: the sill plate to concrete floor connection (even though we utilized sill seal foam during construction), all sheathing panel edges and perimeter openings for windows and doors(even though we taped all seams from the exterior with DOW Weathermate tape), and wall plate seams and penetrations.DOW professional expanding foam sealant is utilized extensively in these areas and will dramatically improve how much (or how little) air infiltration can occur.We also seal any penetrations left behind from our platform staging and penetrations from plumbing and electrical rough ins.These efforts also keep any air trapped within the wall assembly (once they are closed in) from circulating and causing convection which can create drafty conditions inside the house.To conclude, there are many areas that can potentially leak air into the building envelope if left unsealed. Each area sealed collectively helps to "tighten" the house helping to improve energy efficiency, sustainability, and comfort for its occupants.
The wall system: balancing efficiency and costBuilding science case studies have shown Maine home builders the importance of building structures which limit air infiltration and properly manage moisture.This entails sealing the building envelope to prevent unconditioned air and moisture from entering the wall system from the exterior, while at the same time limiting moisture from the interior from entering the wall structure while allowing any moisture that is in the wall system to dry to the interior.There are a number of options to achieve these goals, however, we believe the following method is a very good choice to achieve excellent performance while at the same time controlling costs.Behind exterior siding we will install Greenguard "Raindrop" house wrap. Raindrop is a unique woven house wrap with vertical drainage channels which creates an effective air barrier and drainage plane. Any wind or solar driven moisture that finds its way behind the siding will be channeled to the bottom of the wall assembly where it can drain to the outside.This drainage plane allows air circulation behind the siding so that it will dry and not be prone to moisture related problems.DOW recommends taping all sheathing seams or installing house wrap. We think that it is a good idea to do both.The Raindrop house wrap we are using will provide a drainage plane as previously discussed, and for a couple hundred dollars of DOW "Weathermate" tape (which is very good tape!) and a little time, it makes no sense to not tape all sheathing seams as well to further reduce the possibility of air infiltration.We will also caulk extensively to further seal against air infiltration from the inside of the wall system (more on this in an upcoming entry).These measures will help to ensure that air infiltration is kept to a minimum. A blower door test will be performed to reveal any air leaks that should be sealed prior to closing in the wall cavities.We will be using Certainteed "OPTIMA" blown in blanket insulation for this project (which I will discuss in greater detail in a future entry). This blown in product effectively fills all voids and gaps and maintains full contact with all (6) sides of the wall cavity reducing the possibility of convection as recommended by the Energy Star thermal bypass guidelines(in other words, the house will not be drafty).Our walls will achieve R values of R-28.5 (Optima = R-23 + SIS = R-5.5).That is a respectable R value, however, perhaps more important than wall R value is the reduction of thermal bridging accomplished through the advanced framing techniques employed (discussed in a previous entry) and the continuous thermal break achieved with the DOW SIS insulated sheathing.In our heating climate, it is important that moisture (as vapor) inside the building envelope dry to the inside rather than pass through the wall cavity and condense on the cold surfaces within the wall assembly (typically the sheathing) wetting the wall assembly causing damage and creating an environment for mildew and mold growth.The SIS insulated sheathing makes that scenario much less likely as the temperature within the wall cavity will not be as cold as if non insulated sheathing were used, however, we will utilize a latex primer on the drywall surfaces which will act as an effective vapor retarder (not barrier) to limit moisture vapor from entering the wall system, while at the same time allowing any moisture in the wall system to ultimately dry to the interior.In our next entry, we will discuss in detail sealing the building envelope to minimize heat loss and air infiltration.
Energy Efficient House FramingMaine home builders utilizing Optimum Value Engineered (OVE) framing practices achieve several goals.We help to control costs and benefit the environment by reducing the amount of lumber required to build the structure.Our current project "Winkumpaugh Cottage" is modestly sized at 20'x24', however ,we estimate that we are saving over 600 lineal feet of 2"x6" dimensional lumber as compared to conventional framing techniques.This reduction of required framing materials also serves to control thermal bridging or the transfer of heat from conditioned space to the exterior of the home through the framing. Whenever we reduce the framing lumber required in the wall system, it creates space for additional insulation instead.We have also elected to utilize "balloon" framing techniques rather than traditional platform framing, as well as a single sill/bottom plate, single top plate, (3) stud corner assemblies to allow a full cavity for insulation, right sized insulated header assemblies, and a "let in" rim joist for the second floor system, again to allow space for insulation and to reduce thermal bridging.Windows are located so as to coincide with wall layout to eliminate additional framing material.We have also specified DOW SIS Structural Insulated Sheathing to add R value and further reduce thermal transfer through the framing.The 1" SIS panels are rated R-5.5.The net result for the homeowner will be a well insulated home that is comfortable to live in and inexpensive to heat.More at www.gregfitzpatrickgc.com
Winkumpaugh CottageWe are Maine home builders currently building a guest house on a rural site while architectural plans are being completed for the future primary residence.Our challenge and our goal is to utilize energy efficient materials and construction methods which best balance performance and budget.This "cottage" will employ many of the same energy efficient construction practices as the main residence.The foundation selected for the cottage is an insulated slab on grade.After excavation of the site and construction of a screened gravel pad, we prepared a form for the 20'x24' concrete slab, roughed in plumbing utilities, and installed 2" rigid Styrofoam insulation and steel rebar reinforcement.All Styrofoam seams were sealed to establish a continuous barrier to moisture and soil gasses.More at www.gregfitzpatrickgc.com
Welcome to Green Home ThoughtsGreen Home Thoughts is an ongoing discussion regarding energy efficient and sustainable new home construction.
More at www.gregfitzpatrickgc.com