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DCRestimator
12-11-2006, 01:57 PM
When I figure gable end framing at 16" on center i've always taken my total square footage and multiplied .75 to get Lineal footage at 16" o.c. I then add 10-15 percent as a waste factor. Just recently I read in a published estimating manual that 1 sq.ft. of gable area = 1.88 LF of material.
If this is the case then which example is right.
Mine:
28' gable with a 12/12 pitch= 196 sq.ft. (X) .75=147lf (1.10)waste=162LF

Theirs:
196 sq.ft. (X) 1.88 = 368LF. Even without a waste factor theirs is more than twice my amount. These calculations are based on half the width because only one gable is being figured.
Which way is right?

Bob Kovacs
12-11-2006, 06:17 PM
Well, I think the "right" answer is actually closer to the 1.88. Even when estimating standard walls, 0.75 only gets you the studs at 16" o.c, with no extras for jacks, kings, corners, etc. I always figure walls at 1.00, which covers those items- if the lumberyard is notorious for sending crap lumber, you may have to go to 1.1 or 1.2 to allow for culls.

Now, regarding the 1.88, I'm wondering if they were including material for plates as well. If so, I can see that number possibly making sense. If you had a 20' long gable on a 12/12 pitch, you'd have 100 SF of wall (which would be 100 LF of lumber just for the studs, per my formula), 20' of bottom plate, and around 56' of double top plates. That's a total of 176 lf, while not really allowing for the cutoffs/waste you'd get by not being able to perfectly optimize your lumber with all of the gable stud cuts.

Bob

David Meiland
12-11-2006, 06:22 PM
Bob... just curious... how long would it take you to read plans and list the structural lumber for a semi-complex 2000SF house? Joists, wall framing, some beams, rafters, sheathing.

Bob Kovacs
12-11-2006, 07:30 PM
Probably around 15 minutes. Did you need some help? lol

Seriously, I haven't done heavy piece-by-piece takeoffs for a while, but if I was doing it regularly, I'd set up a decent spreadsheet like what Bill Lacey posted a while back. While there'd be the initial investment of time to prepare that spreadsheet, I'd saw a full-blown lumber takeoff could be done for a house of that size in 1-1 1/2 hours once it was set up (maybe less).

Bob

Bill Lacey
12-12-2006, 07:15 AM
The standard framing part of a take off goes pretty quickly. The structural part could take a long time, depending on how accurate the details on the plans are. I could generally complete a full take-off including lumber, engineered lumber, shingles, windows, doors, siding, interior doors & trim, and some other crap in about a day (8 hours). Most of those items were done using my spreadsheet and that helped speed up the process. Like Bob said, the lumber portion could be done in about an hour, depending on complexity.

Bill Lacey
12-12-2006, 08:28 AM
Getting to the gable area/framing quantity thing.

Here are the variables I used:

Gable Span = 24'
Roof Pitch = 6/12
Rafter Height = 9-1/4" (2x10)
Seat Cut = 3-1/2"
Heel Height = 8-19/32"
Tallest Stud = 5'-7 1/2"
Area of Gable = 89.18363 sqf
Area of Framing = 68.54253 sqf

Figuring 2x4 wall construction, here is what I came up with for a list of materials for both sides of the gable:

2 - 2x4-12' Bottom Plates
2 - 2x4-14' Top Plates (assumes single top plate)
4 - 2x4-12' Gable End Studs (8/6')
Total LF of Material = 100 LF

89.18363 x 1.121282 = 100 (based on gable area including rafter depth)
89.18363 x 1.233410 = 110 (includes 10% waste factor)

68.54253 x 1.458949 = 100 (based on gable wall framing area only)
68.54253 x 1.604843 = 110 (includes 10% waste factor)

If you use the total gable area SQF (including the heel height/rafter depth) then 1.88 seems a bit excessive for material quantity. However, if you use the area of the gable end framing only, 1.88 would be like adding a 25% waste factor.