Optimium-Value Engineering (OVE)

This may be a good time to mention the subject of Optimum-Value Engineering (OVE) as it offers a method of framing that meets the structural needs of the building while reducing the amount of lumber used. Joseph Lstiburek's article The Future of Framing Is Here in the October / November 2005 issue of Fine Homebuilding magazine provides a good overview of this technique. Additional interesting OVE links are provided on the side panel under INTERESTING RESOURCES.

OVE is a good option to employ as the super insulated exterior walls are created by using two spaced stud walls. The framing techniques use common building practices with some modifications that would need some retraining of traditional framing crews. Not all the practices need to be Incorporated into the framing, i.e. a hybrid system can also be used. Courses need to be developed and offered at our provincial community colleges to train existing and future carpenters. Before materials are ordered and framing commences, the contractor and crews need to develop a plan of action so that everyone on the job site knows what is expected. Local building officials also need to contacted and buy into the OVE techniques to be used prior to framing so no surprises occur once work begins. As with all framing, unique conditions may require some specialized engineering. The designs I am offering attempt to make the framing as simple and straight forward as possible, however, beams, joists and lintels need to be verified by sound engineering.

Maison Cocagne House employs various OVE framing techniques in : two stud corners (see CONSTRUCTION DETAIL link Q. Corner Framing), properly sized window and door headers, stacked framing, single top plates, floating corners, etc. Windows are sized to fit within the 16" o.c. stud spacing. Allowances need to be provided for the 1/2 inch plywood boxes that surround the window opening plus rough opening clearance. The 16" o.c. spacing of the Maison Cocagne House super insulated stud walls accommodates 29-inch wide windows (30 1/2 inches between every second stud minus 1/2" each side for plywood box minus 1/4" play each side equals 29 inches). Spacing the super insulated stud walls at 24" o.c. would accommodate 21-inch wide windows (22 1/2 inches between studs minus 1/2" each side for plywood box minus 1/4" play each side equals 21 inches).

MAISON COCAGNE HOUSE - Roof @ Attics Details

Roof trusses at attic (north) wall are parallel chord trusses to allow for 18 inches of glass fiber batt insulation (R60). The roof trusses are installed at 16 inches on center in line with wall studs below. 6-mil vapor barrier is attached to the bottom chord of the truss. Gypsum wallboard or other desired finish is attached to the truss chords on 1x4 furring strips at 16 inch on center perpendicular to the trusses.

The benefits of installing radiant barriers are still in question. If used, I would recommend attaching the radiant barrier taping all joints to the bottom chord of the trusses after installing the vapor barrier, but prior to installation of the furring strips.

Roofing material is TRACC Moderne Slate roof shingles over ice shield underlayment. This is a 50-year roofing material made locally from recycled materials capable of withstanding a 175 mph wind driven rain. This is a very important feature on the Northumberland Strait where northeasters are not uncommon. The roofing sheds snow easily so consideration must be given to sliding snow in our climate. The roofing also works well for a rainwater collection system (guttering not shown).

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Red dashed line shows location of the 6-mil vapor barrier in the wall system. Red dots show locations where barrier is sealed with acoustical caulking. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. The design allows for the walls to be framed and insulated on the floors and lifted in place using wall jacks. A perimeter truss with 2x4 vertical blocking in line with the 2x4 wall studs above and below is required to carry the loads to the foundation. Details for optional balloon framing and openings are provided in the links and will be discussed later.

MAISON COCAGNE HOUSE - Roof @ Bedroom Details

Roof trusses at bedroom (south) walls are raised heel trusses to allow for 18 inches of glass fiber batt or blown insulation (R60). The roof trusses are installed at 16 inches on center in line with wall studs below. 6-mil vapor barrier is attached to the bottom chord of the truss. Gypsum wallboard or other desired finish is attached to the truss chords on 1x4 furring strips at 16 inch on center perpendicular to the trusses.

The benefits of installing radiant barriers are still in question. If used, I would recommend attaching the radiant barrier taping all joints to the bottom chord of the trusses after installing the vapor barrier, but prior to installation of the furring strips.

Roofing material is TRACC Moderne Slate roof shingles over ice shield underlayment. This is a 50-year roofing material made locally from recycled materials capable of withstanding a 175 mph wind driven rain. This is a very important feature on the Northumberland Strait where northeasters are not uncommon. The roofing sheds snow easily so consideration must be given to sliding snow in our climate. The roofing also works well for a rainwater collection system (guttering not shown).

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Red dashed line shows location of the 6-mil vapor barrier in the wall system. Red dots show locations where barrier is sealed with acoustical caulking. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. The design allows for the walls to be framed and insulated on the floors and lifted in place using wall jacks. Details for optional balloon framing and openings are provided in the links and will be discussed later.

MAISON COCAGNE HOUSE - Second Floor Details

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Red dashed line shows location of the 6-mil vapor barrier in the wall system. Red dots show locations where barrier is sealed with acoustical caulking. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. The design allows for the walls to be framed and insulated on the floors and lifted in place using wall jacks. A perimeter truss with 2x4 vertical blocking in line with the 2x4 wall studs above and below is required to carry the loads to the foundation. Details for optional balloon framing and openings are provided in the links and will be discussed later.

MAISON COCAGNE HOUSE - Basement / First Floor Details

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Red dashed line shows location of the 6-mil vapor barrier in the wall system. Red dots show locations where barrier is sealed with acoustical caulking.Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. The design allows for the walls to be framed and insulated on the floors and lifted in place using wall jacks. A perimeter truss with 2x4 vertical blocking in line with the 2x4 wall studs above is required to carry the loads to the foundation. Details for optional balloon framing and openings are provided in the links and will be discussed later.

The foundation is formed using LOGIX insulated concrete forms. While not a fan of rigid insulation, insulated concrete forms do have their place in the design of a foundation. The two layers of insulation used in the ICF system provides R20 insulation for the basement plus facilitates installation of finishes both inside and outside as well as easing reinforcing placement. The concrete foundation walls also create an effective vapor barrier. Care should be taken in laying out the exterior dimensions of the building and height of basement walls to match the dimension of standard ICF components (standard LOGIX block is 16" high x 48" long x depth desired). The 12" x 24" footings are the standard architectural overkill. Adjustments are feasible based upon engineering for local soils and conditions.

As mentioned in an earlier posting, crawl space and slab-on-grade foundations are also feasible, but space must be made on upper floors for mechanical equipment. See links to construction details for additional details and foundation systems.

MAISON COCAGNE HOUSE - Second Floor

SECOND FLOOR

Bedroom 1 14' x 15'

Bedroom 2 14' x 15'

Full Bathroom 8' x 7'

Stair/Hall 8' x 17'8

Attics (2) 14' x 8' ea

745 sf (outside dimension)

650 sf (inside heated space)

The Second Floor of the Maison Cocagne House is designed to be the private area of the house. The main components are two bedroom areas separated by a bathroom/stair core. Adjacent to the bedrooms are attic spaces with sloped roofs. The core walls are framed as double stud walls to accommodate the heat recovery ductwork that will be discussed later. These spaces make up the thermal envelope of the main house. The bathroom is designed as a full bath located in a dormer. Cost reduction could be achieved by constructing the house with a full bathroom on the main floor and a compact 1/2 bath at the second floor (negates need for dormer). Finishes and final furnishing arrangement of areas are up to the occupant.

Windows would be high efficiency, triple glazed casements.

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. Tongue & groove sheathing can also be used at outside stud walls to facilitate insulation installation. Details for air-tightness and openings are provided in the links and will be discussed later.

MAISON COCAGNE HOUSE - First Floor

FIRST FLOOR

Living/Dining 14' x 22'

Kitchen 14' x 15'

Laundry/Pantry 14' x 7'

3/4 Bathroom 8' x 7

Stair/Hall 8' x 17'8

Enclosed Porches (2) 14' x 8

990 sf (outside dimension)

860 sf (inside heated space)

The First Floor of the Maison Cocagne House is designed to be the public area of the house. The main components are a living/dining area and a kitchen/laundry/pantry area separated by a bathroom/stair core. The core walls are framed as double stud walls to accommodate the heat recovery ductwork that will be discussed later. These spaces make up the thermal envelope of the main house. The bathroom is designed as a 3/4 bath, but could also be a 1/2 bath. Finishes and final furnishing arrangement of areas are up to the occupant.

The house is accessed through a central open porch and two enclosed porches that would act as thermal collectors during cold months and as expanded living area during warm months. These porches could also be designed as open porches if the occupant so desired. There is also a secondary rear entrance from the laundry/pantry.

Windows of the main house would be high efficiency, triple glazed casements, double glazed casement and fixed windows at the porches. Doors would also be selected for high efficiency.

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. Tongue & groove sheathing can also be used at outside stud walls to facilitate insulation installation. Details for air-tightness and openings are provided in the links and will be discussed later.