The Forestry Forum

General Forestry => Timber Framing/Log construction => Topic started by: Wedgebanger on February 24, 2019, 08:05:25 AM

Title: Green poplar and design thoughts
Post by: Wedgebanger on February 24, 2019, 08:05:25 AM
Hello all, I'm new to timber construction and would appreciate some help with a few questions I have. For starters, I have a mill and a healthy amount of poplar on the ground. I'd like to build a home utilizing timber construction with steel sandwich plates at my joints. Rough dimensions 25x52. What are your thoughts on:
A) 48" cylindrical concrete "piers" for the primary foundation to support the main posts
B) poplar as a main material, and framing it green
C) optimal truss design and spacing for posts/trusses
Also, I'm not wed to the size, just an idea of my ballpark. Foundation will be augmented by a rubble trench and 4-5" slab poured to the grade of the piers. Thanks all in advance, love the community and wealth of knowledge this forum offers.
Title: Re: Green poplar and design thoughts
Post by: Don P on February 24, 2019, 11:22:01 AM
If the piers are as wide as tall, on the rubble trench and constrained by the slab most of my concerns about differential settlement and overturning go away. Do be aware that poplar tends to check rather spectacularly. Keeping spans in the 12' or under neighborhood is good practice.


(https://forestryforum.com/gallery/albums/userpics/10017/poplarchk.jpg?easyrotate_cache=1192055717)


I'm sawing some for 2x framing and 1x sheathing now, which is where I think it shines. I've thought about building up timbers of multiple plies of 2x poplar nailed together with the joinery incorporated in the build up. Then it could be dried easily first and would be check free.

A friend dropped off several logs that had been down since last summer, I got into them and can't use them for structural, they go fast.
Title: Re: Green poplar and design thoughts
Post by: Wedgebanger on February 24, 2019, 12:41:24 PM
Thanks for the input, I'll monitor closely for checking and plan on 8' spans but will poplar make the truss spans without issue or will a central support post be necessary?
Title: Re: Green poplar and design thoughts
Post by: Don P on February 24, 2019, 02:44:34 PM
Sized correctly and on 8' centers just supporting a roof I don't believe it would be a problem.
Title: Re: Green poplar and design thoughts
Post by: Wedgebanger on February 24, 2019, 03:16:17 PM
Thoughts on a 'king strut' style truss for the 25' span? Keeping with 8"x8" poplar for the construction. How would it handle a 3' snow load?
Title: Re: Green poplar and design thoughts
Post by: Don P on February 24, 2019, 06:28:18 PM
That gets into a bunch of questions.

What is the roof pitch going to be?

Are there horizontal purlins running from truss to truss supporting the roof deck or are the trusses supporting a ridge beam that in turn supports common rafters that run from ridge to wall?

Actually need the snow load in psf rather than feet, or where are you? There is a snow load map in chapter 3 here;
https://codes.iccsafe.org/content/VRC2012/toc (https://codes.iccsafe.org/content/VRC2012/toc)

And the usual caveat, you don't know who you are talking to on the internet, you should have an engineer prepare the final plans.