"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"

Moisture Management

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

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 sealing

Building 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 cost

Building 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.

We are also using DOW SIS Structural Insulated Sheathing on this project. This product replaces OSB or plywood sheathing and is wall sheathing, foam insulation, and weather barrier in one product.

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.

More at http://www.gregfitzpatrickgc.com/

Energy Efficient House Framing

Maine 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 Cottage

We 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 Thoughts

Green Home Thoughts is an ongoing discussion regarding energy efficient and sustainable new home construction.

More at www.gregfitzpatrickgc.com