Tilmac Construction Standards |
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Tilmac
State-of-the-art knowledge of construction, home electronics, and systems engineering.
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The following construction standards are in addition to the latest Talbot County, Maryland Standards and apply to all Tilmac Construction homes. SITE Avoid problem locations. Orient the building to minimize mechanical HVAC needs and maximize storm water drainage and daylighting. UNIVERSAL DESIGN Where sufficient space exist, interior doors shall be rough framed for three foot openings then reduced to the desired size. In bathrooms, 2x6 supports for hold bars shall be installed behind WC, tub, and shower walls. In homes with the living area and/or master bedroom on the second level, a 5ft. x 5ft. shaft shall be rough framed for a future elevator if possible (the area may be used for closet storage before it is needed). FOUNDATION The finished crawl space elevation shall be 6 inches above the exterior finish grade existing prior to excavation. Compacted run bank gravel shall replace the topsoil removed. A capillary break shall be installed in the foundation wall and in all piers and #4 steel rebar dowels installed every 3 feet shall be used to tie the block together. The crawl space floor shall be covered with 4-6mil polyethylene overlapped. A 1-2 inch "rat slab" shall be poured on top of the poly. A 1/4 in bead of latex sealer shall be placed on the inside edge of all perimeter block and on the outside edge of all pier block. A coated aluminum termite shield shall be placed on top of the bead and a 8 in seal sealer shall be placed on top of the aluminum under the sill plate. The foundation wall shall contain no vents and be air sealed to 1.25 square inches equivalent leakage area per 100 square feet of exposed wall. A passive Radon mitigation system leading to a sealed sump pit shall be installed. Rigid insulation shall be installed on all exterior foundation walls. No mechanical equipment shall be installed in the crawl space. NOTE: These standards may not be applicable to homes constructed in flood zones. FRAMING Only advantech (or equal) shall be used for subflooring. All exterior framing shall be 2x6 construction with half inch OSB sheathing. All exterior door and window headers shall have a top and bottom plate and the inside cavity shall be filled with a rigid foam thermal break. Use sealant caulk liberally so the completed wall is air sealed to 1.25 square inches equivalent leakage area per 100 square feet of exposed wall. This is particularly important:
GARAGE The garage floor shall slope toward the driveway at a slope of 1/100 pitch. On attached garages, all doors between the garage and house must be exterior type with weatherstripping. The finished garage floor height must be at least 4 inches below the house floor. The adjoining wall must be air tight from the footer all the way up the roof (this includes the foundation wall, building wall and the attic). WINDOW & WINDOW INSTALLATION All window and door openings shall be flashed using roofing felt or Tyvek flashing (not tyvek house wrap). Windows shall be installed with a sealant under the nailing flange on the top and both sides. The bottom flange shall not be sealed. Window selection is critical and windows must have a U value less than or equal to 0.32 and have a SHGC of less than or equal to 0.34. Only high performance casement or fixed pane units are recommended on water front or exposed locations. CLADING The water plane on top of the sheathing shall be Tyvek house wrap. The tyvek shall be continuous and shall be lapped in a roofing fashion. All seams shall be overlapped at least 12 inches and shall be taped. Tyvek over a window shall be installed on top of the nailing flange. If fiberous cement siding is used, two layers of 15 lb roofing felt shall be used in lieu of Tyvek. PLUMBING To the maximum extent possible, supply water lines shall not be installed in outside walls. The drains in a double sink shall have separate traps. A radon vent pipe shall be run from the sump pit through the roof via a heated wall. INSULATION AND AIR SEALING All penetrations (wire, pipe, etc.) in all walls, floors and top plates shall be plugged with foam sealant. All exterior wall spaces behind tubs, soffits etc shall be insulated, drywalled and taped prior to the installation of the fixture or soffit. The ceiling dry wall shall be sealed to all top plates. Ceiling penetrations shall be minimized. Blown in cellulose shall be used where possible; fiberglass must be kept outside the building envelope. ELECTRICAL All electrical branch circuit wire shall be 12 gauge copper or larger. All electrical boxes in exterior walls and ceilings shall be airtight types. All duplex outlet connections shall use the screw terminals, not the push on connectors. Only airtight IC rated fixtures shall be used for recessed lights. A duplex outlet shall be located within 24 inches of the sump pit and a location near the radon vent pipe. For circuits whose loads are more than 100 wire feet away from the main panel, a separate subpanel shall be utilized. A separate sub panel shall be installed for the HVAC system and for the home's emergency circuits. (well, refrigerator, freezer, microwave, ceiling fans, and limited lighting). Panels shall be sized to reserve 25% capacity and circuit positions for future expansion. A light and duplex outlet shall be installed near all entrances to the attic and crawl spaces. ELECTRONIC All electronic wiring (tel., TV, etc.) shall be home run back to a central panel. At least two spare CAT5e and RG6Q runs shall be provided in the attic and crawl space for future use. If a security alarm system is not installed as part of construction, all exterior entry/exit doors (not sliding glass or patio doors) shall have security entry sensors installed and the wires run into the crawl space for future use. HVAC HVAC Systems shall be sized based upon a "ACCA Manual D & J" based calculations. The airconditioning portion shall be slightly undersized so as to keep relative humidity below 50 percent throughout the year. Supply and return ducts should be rigid galvanized sheet metal sealed with mastic and mesh and shall have a leakage of less than 10 percent. Building cavity returns shall not be utilized. All HVAC equipment and ducts shall be within the building envelope. All combustion appliances, including fireplaces, shall be sealed and shall use external air for combustion. All thermostat wire shall provide at least 4 spare conductors. As BHC Homes are built extremely tight, all homes must have appropriately sized Energy Recovery Ventilator installed with necessary controls. Air intakes shall be at least 10 feet away from exhaust outlets, driveways, plants, and sources of heat or moisture. FINISH MATERIALS Composite materials that contain ureaformaldehyde resins (phenolformaldehtde or diisocyanate glues are acceptable) should be avoided. Where unavoidable, it is recommended that the surface be sealed with laminates or water based polyurethane. Hard floor surfaces are preferred however carpet may be used if it meets the Carpet Rug Institute IAQ standards. Do not use vinyl wallpapers PAINTING Only very low VOC paints and water based polyurethane varnishes shall be used within the interior spaces. Avoid paints with ethylene glycol (propylene glycol are ok) and acid cured polyurethane finishes. FINAL GRADING A minimum 6 inch drop within the first 10 feet shall be provided. All downspouts shall extend three feet from the house and shall have 2 ft. splash plates installed. |