From my perspective as custom home designer, draftsman, and builder, a master carpenter has the toughest job of any tradesman on a site, being the one not only to lead in forming up a structure from two dimensions of lines to three dimensions of substance, but also to provide for, adapt to, or compensate for all the other trades at work from start to finish.Before The Architect
INTRODUCTION
This article is the first of two about the fundamental materials and methods of house frame work in building a home.
GENERAL
Dimensioned framing members shall not be less than 2 linear inches nominal thickness
A span table reference shall be amended as follows
For a clearspan
Considering qualification otherwise for all relevant criteria, e.g., specie, loads, elasticity, etc., the stated maximum length of a framing member
Shall be decreased by not less than 15% for application
If the foreshortened length is too short for the application, then the member shall be modified in the following, descending order of preference
The member length shall be shortened as by a girder or beam or
The member depth shall be increased by one standard measure, e.g., as from 2 linear inches x 8 linear inches to 2 linear inches x 10 linear inches
The member shall be doubled or
A Pressel-Ballard Brace may be applied (see below) or
Spacing shall be reduced to 12 linear inches on center where elasticity is within tolerance (note: spacing shall not be greater than 16 linear inches on center) and solid, full-depth block shall be at thirds, on center
Engineered lumber shall be applied
As an alternative given responsible clearances, consider to
Halve the clearspan with girders
Doubled members
Each not less in dimension than an attached joist
Fasten to each joist with a fully-nailed, fully engaged joist hanger (no shorties, no wiggle-room)
Shim girder tight to joists as needed
Post girder as needed in interim and termini
Comment:This house designer is not so much in favor of engineered lumber as he is in disfavor of down-grading hand-framed structural members in its lieu.
Strongbacks
Shall not be less than 2 linear inches x 6 linear inches
Shall set at mid-span
Shall be tight to a web members and bottom chords
Unless web members are not in-line
Whereat right-angle scabs shall be applied
Fastened with not less than 3-10d common galvanized nails at each meeting face of Strongback
To web member and
Bottom chord
Framing members shall be spaced not greater than 16 linear inches on center
Comment:Not ever.How serious is this custom house designer about this bad boy spacing?Serious enough he is to have turned down a commission recently, solely because of this spacing limit.The author heaved himself into his own hole with a passing reference to the client-proposed 24 linear inches on-center spacing as a fine start to a new residential building genre – the disposable house.(He was rebuilding on Maryland beachfront.)The prospective client was not amused.Neither was the author.
Wood members shall not come into direct, permanent contact with concrete or other masonry, and this includes engineered lumber
Preservative-treated sills shall be of either –
Southern Yellow Pine or
Douglas Fir
Comment: As between ‘em, performance properties seem closely similar.Differences: availability and price– site-specific criteria for framing; Douglas fir’s been heralded as more stable and holds coatings better – more a compliment to finishing material than rough. Southern Yellow Pine's dust is sort of oily and not so fly-away and fine as Douglas Fir's.
Wood members proximate to concrete pockets or walls or other concrete structures
Shall be given air space to breathe, especially at butts
Reinforced from roll-over and other moisture-driven distortions over time
Firestops
Shall be at not less than the following sites
At each concealed space or cavity not less than 10 linear feet in length in any direction
At openings around vents, pipes, ducts, chimneys, fireplaces, electrical conductors, and other openings at ceiling-to-roof and floor-to-wall
At openings between attic spaces and chases for factory-built chimneys
At furred spaces
At the ceiling and floor levels of combustible construction
At 10 linear feet on center wall intervals on the vertical or the horizontal
Except at 8 linear feet on center when backing wall panels and
Except at 8 linear feet on center for lateral wall bracing
At sites involving metal plate-connected, open-web wood floor trusses
To more or less evenly isolate not greater than 750 square feet at a time
At penetrations to fire-stops from any direction
At each interconnection between concealed horizontal and vertical spaces, e.g., at
Soffits
Drop ceilings
Cove ceilings
The concealed segments of barrel, channel, or box, and other vaulted ceilings, etc.
At stairs
Head
Foot
Outside faces of stair stringers
Between studs along and in-line with each run of stairs for unfinished walls below stairs
At the joint of Type-X wallboard to gas curb
Shall be of not less than the following materials
Nominal 2 linear inches x lumber
1 ½ linear inches x 1 linear inch wood blocks
Tightly packed, unbacked fiberglass insulation
2 layers of ¾ linear inch plywood
Sheet metal not less than 24-gauge
Not less than ½ linear inches drywall (gypsum) board,
Other materials approved by the building authority having jurisdiction
Notwithstanding in all cases, fire-stopping materials themselves for other than through-penetration fire-stopping in conformance with not less than most recent ASTM E136 to qualify as “noncombustible" (a/k/a American Society for Testing and Materials, "Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 degrees C")
Notwithstanding in all cases, through-penetration fire-stopping materials conforming to not less than most recent ASTM E814 (a/k/a American Society for Testing and Materials, “Standard Test Method for Fire Tests of Through-Penetration Fire Stops")
Shall be fitted exceedingly tight overall in the stopped space
For regular spaces, by meticulous cutting and fitting
For irregular space, by intumescent sealant
For other than the spiral staircase
Sheathe underneath from outer stringer to outer stringer including header cleat with 1 layer, 5/8 linear inch Type-X gypsum wallboard
Where walls run below or immediately next to outside stringers
Frame walls with lightweight, or cold-formed, steel and
Sheathe exterior with 1 layer-5/8 linear inch Type-X gypsum board
If continuous Type-X envelope cannot be applied on the vertical below a staircase, then
Frame with lightweight, or cold-formed, steel and
Sheathe the interior with 2 layers-5/8 linear inch Type-X gypsum wallboard and
Where applicable on the exterior of the wall sheathe with 1 layer-5/8 linear inch Type-X gypsum wallboard
Where stairwell wall extends above a stringer or below a stringer as, for example, a mid-landing
Frame the wall in lightweight, or cold-formed, steel and
Sheathe the interior with 2 layers-5/8 linear inch Type-X gypsum wallboard and
Where applicable on the exterior of the wall sheathe with 1 layer-5/8 linear inch Type-X gypsum wallboard
Wallboard seams shall be taped and seams and nail or screw pocks shall be taped and all shall be deeply mudded
Protrusions shall be sealed with firestopping materials conforming to not less than most recent ASTM E84 and E814 and shall not exclude tumescent sealant
Comment:Huh?Steel frame?Double Type-X?
Think about it.
House on fire.Say you went to all the trouble of lining your stairwell with Type-X.Flames get to the wood studs and in short order the Type-X is without support, it collapses…onto the stairway.
Admittedly, there’s little chance that most stairwells can be completely clad with Type-X on the outside of the stairwell frame, though this custom house designer insists that you give it your best.So, the steel’s there to break down more slowly when engaged, to wrack and sag but not to cinders and ash; the extra layer of Type-X on the inside is there to better hold its form and hold flames from you on your way down the steps.
Disclaimer: All information on this site is provided for informational purposes only! By no means is any
information presented herein intended to substitute for the advice provided to you by any health care or other professional
or organization.
