I am currently investigating a timberframe design for a new house in the Indianapolis area of Indiana, in the United States, and have decided to go with a timber frame design.

Right now, I am in the 'gather information, snap shots, ideas, and assorted data' stage - or just a little beyond: I'm laying out an actual initial floor plan. However, I have gotten to that stage where I require some actual engineering questions answered (although very simple engineering questions and very roughly).

1. In bent/bay dimentions listed on standard plans, what part of the frame are dimensions measured _from_? Beam center to center? Outer edge of beam? Inner edge of beam? We're looking at standard available frames from several companies - although we will probably have to alter the packages slightly.

2. In room layout design, how big are the beams? I assume that the space of the actual beams has to be taken out of the corners of the room's floorplan. I realize that this will vary _greatly_ with the design. Currently I am looking at the following rough design:

2 stories, 28 foot wide bents, with a 14 foot bay. 3 bays, for dimentions of 28' x 42' -- or 6, 14x14 foot squares, arranged in a 2x3 pattern. A fairly simple 2 story Yankee barn design, with one end being an open cathedral ceiling, the middle upper bay being an open loft with dormers on each side for dual office space. Ideally, but not absolutly required, would be hammer beams on the end great wall bent, and the bent framing the loft's overlooking the great room. We'd also like to use the pulin roofing system.

I also realize that the wood choice will affect beam cross-section, but we'd _very_ much like to build with planed white oak members.

I realize that for a detailed answer, I should take this to a professional designer and get a frame design done, which IS what we are planning to do; but we'd like to have a floor plan worked out before hand, designed around the way we live, as a starting point, and we're simply wondering:

a) how practical our current ideas are and
b) how much space we should allow for the beams in the floor plan layout.

Dear Josh,

I just finished designing a timber frame barn for NJ which closely matches your dimensional requirement. I can maybe cut you a deal to supply a similar barn design to match your exact size requirements.

Check out the design section of our website at http://www.clik.to/WorldofWood to see some of our standard designs.

Drop me an email if you are interested.

Regards

Ken Hume

[This message has been edited by K F Hume (edited 06-30-2001).]

Josh
I’ve been doing some research into the answers to some of your ‘basic’ questions.
First, years ago I asked an old carpenter friend of mine one of these basic questions. “When you’re given the dimensions of a house as 24’x36’, where are these measurements actually taken from?” He told me that these dimensions were of the house foundation, all sheathing was then added to the outside of these dimensions.
Now with timber framing this maybe also true. The only exception that I’ve seen is when you are enclosing with insulated panels. Sometimes there is a ledge on the outside of the foundation for the panel to set on.
Next, I checked in my book “A Timber Framer’s Workshop” by Steve Chappell and his drawing show the posts are included inside these measurements (24’x36’). Any posts in the center of a bent are measured to the center of the post. That is, if you have a 24’ wide house with a post at 12’ the center of that post is at the 12’ measurement. Regardless of the size of that post. I’m quoting a drawing on page 200 in his book.
This drawing is of a 24’x36’ Hammer beam cape, with three bays. One bay is 14’, another is 10’ and the last is 12’. With an open ceiling in between the areas of the 10’and 12’ bays.
As to how big are the beams of a house layout, from my past reading, and if I’m wrong, I’m sure someone else will correct me, you design the floor joists necessary to support the floor, based on the size of the span between supports. Then the timbers necessary to support the joists. If it is a summer beam it has to be bigger than the joists. Then the plates and posts to support the summer beam. Basically from the center of the room out, making bigger timbers each step out. And as you said the wood choice affects the size of these beams.
To answer your question “how practical are our current ideas?” I’d say ok. But don’t restrict your designer to the actual post locations, as he will need to place them where they need to be for the best support.
And “how much space should we allow for the beams in the floor plan layout?” Most drawings show (in plan view) the posts as squares or rectangles in the corners of the drawings, again inside the overall dimension of the building.
If this doesn’t answer your questions, possibly you should buy this book and review this drawing to answer more of your questions. I believe it is available at the Timber Framers online store. I’m no expert but I hope this has helped you. Good luck, Jim