The Forestry Forum
General Forestry => Timber Framing/Log construction => Topic started by: Anjou on January 04, 2025, 09:00:04 PM
Happy new year to you'ns!
Trying to get the Mennonites to build me a 2-story, 30'x40' Pennsylvania Bank Barn (30'x40'), with a 7:12 asymmetric roof. The recurring response to my structural concerns about their design ideas is: "you should be OK." All measurements below are the true size, not nominal dimensions -- the Mennonites are recommending hemlock for the structural timbers. After wasting a year, I will be having the plans drawn up by an experienced draftsman, after consultation with a structural engineer. The main bay (20' wide x 24' deep) of the upper-level needs to simultaneously support two 9'x18' hay wagons, loaded with 50-pound small bales. The overlays are supported beneath on 12"x14" Summer beams atop 12"x12" posts. The span for the summer beams is 13-14'. The span for the overlays is 11-12'.
Issue 1: Spanning the 20' great door opening, while supporting the roof. You should be OK with an 8"x14" beam.
Issue 2: Spacing 8"x10" overlays and 2"x8" T&G flooring. You should be OK spacing them at 30" o.c. Note that the Mennonites had suggested 1.5" T&G flooring and 6"x8" overlays at 30" o.c.
Issue 3: Your grandmother should have no problem sliding open the 10'x12'x2" great doors.
What do you think? Thus far, I've been basing my opinions on a 1910 barn framing sketch (not sure how to attach that) and my very limited observational experience. I have serious reservations about their structural engineering abilities.
As I see it you have two choices.
Run the numbers yourself and verify if the timbers can support the load and span.
Or hire a timber framed experienced structural engineer to review the design.
Good luck with your project.
Jim Rogers
Quote from: Jim_Rogers on January 05, 2025, 09:24:26 AMAs I see it you have two choices.
Run the numbers yourself and verify if the timbers can support the load and span.
Or hire a timber framed experienced structural engineer to review the design.
Good luck with your project.
Jim Rogers
And of course, option #3, accept their design decisions.
Jim Rogers