View Full Version : heavy timbers
10-28-2002, 09:58 AM
I plan to remodel my house and add a second story using heavy timbers with Structural Insulated Panels. The beams I plan to use will be about 4"x8" by 16'-0" (not quit sure until a structural engineer checks my drawings). I like to paint the beams and do not want too much "character". I been thinking of buying the beams at a local sawmill and have them air dry for a year or more before I'll use them. (I think it should dry well in desert-Idaho) How much warping should I expect in wood of this size? Someone advised me to stack them and wrap with metal bands to prevent warping...? Or should I just look for kiln dried and re-sawn beams when I get ready to use them?
Thanks for your help,
10-28-2002, 10:17 AM
About 10 years ago. I had looked into a similar type of construction. The home was in the form of a kit using pre-cut timbers and 'stress skin' panels. The company warned against buying the kit too far ahead of construction. While they dry-fit the goods togther at the factory, if you wait too long they could warp and twist to the point that they won't fit together anymore.
The benefit to getting the frame built quickly, so they said, was that once the wood dried, it would lock itself in tighter than the mechanical fasteners used for the timbers could ever hope to.
Since you seem to be in the planning stages, check out the people I had shopped with . . . they may have some floor plans you may want to take some 'inspiration' from. They'll send you a free kit with plans as well.
When it comes to
woodworking and buying
tools, I always think back to
my grandfathers advice on
golf . . . "it's not the arrows,
it's the indian.''
I've built timber frame structures. We bought the timbers from the mill dressed; they have the planers to deal with large stock.
As DW2 stated, the timbers are cut green. As they dry, they shrink and lock onto any fastener that is used. The oak pins that are used in traditional style joinery are well seasoned.
As the frame is assembled "green", you have to allow for shrinkage as the frame dries.
I've also built a false timber frame where the structure was a conventional stick building and I added non-loadbearing timbers inside for the look.
Points to Ponder
10-29-2002, 09:42 AM
Sorry I can't help with your timber question, but I see you're from Idaho(desert) (read:southern?)
Where abouts? I live in Buhl and my shop is in Twin.
10-30-2002, 10:19 AM
Thanks for your help. I have considered using a manufacurer to build the trusses for me, but I would really like to build them myself. I have easy access to a structural engineer and would like them to be my handywork. The website has some nice information though, the craftsman house trusses are very close to what I had in mind.
If I understand you right Tim, it would be best to build the trusses while the wood is still green so the timber pegs hold best. I hadn't quite decided whether I wanted to go with oak pegs or use (hidden)steel conectors. If I would use the steel conectors I would still have the issue of how to airdry the beams or have them resawn. Tim, is there a book or web page you would recommend for details on timber peg connections?
srpoly, I am in Boise, not woodworking for a living (yet) but keeping plenty bussy with my own house remodel and playing in my garage/shop.
Thanks again for your input,
10-30-2002, 09:14 PM
>I plan to remodel my house and add a second story using
>heavy timbers with Structural Insulated Panels. The beams I
>plan to use will be about 4"x8" by 16'-0" (not quit sure
>until a structural engineer checks my drawings). I like to
I can't answer on the rest but the first thing I suggest would be what you appear to be heading to do; have a licensed structural engineer at the very least check the drawings.
Not having any info/photos on your house makes it tough, but from what I have seen, a one story house was usually designed to have a foundation, studs and other structural members for the weight as well as consider this; wind loads on a ONE story house.
One can run into some serious problems if either the foundation or soil under it or the walls are not designed for (or have some decay, terminte damage, warping/bowing/settling) the additional dead weight of the wall members, sheet rock, exterior sheathing, windows, doors, floor, furniture and other loading (there is already a roof so that is not added to the load just moved up)
There would also the be additional loading of the bathroom fixtures and if a tub is used, the water capacity of the tub is another very heavy concentrated load.
Another pair of issues that are easy to forget about;
Newer houses use a lot of particle board and are just blammed together with nail guns, and then essentially sealed up like saran wrap or metal siding or vinyl which if it's done shoddy can start unseen rot in the walls real fast!
I've seen floor "joists" in home improvement places that are nothing more than 1/2" particle board strips glued into dados on a pair of something like 1x2's, geez, gimme a break! I sure wouldn't move a piano into a house with floors like like that!
Old houses were built more sturdy but age, leaks, rot, termites etc can take its toll.
The other issue is wind loading, by adding a second story you are doubling the surface area, I don't know if there is a special formula to calculate it but assume a given wall and given wind against i t produces "X" pounds of lateral force, and that the lateral force would be proportional to the surface area, but then you have other factors like leverage at play.
It sounds like you are planning to add a considerable amount of "heavy timber" and without a photo, there's no way for us to tell what you are adding this on to so I can only assume an older frame house with standard 2x4 studs unless I missed something.
DO have a licensed guy go over every detail and check out the existing house not just look over drawings in his office!
10-31-2002, 08:47 AM
Yeah, I am aware of the structural issues. I work for an architecture/engineering firm and a good structural engineer has been helping me with the design. It's the practicality of building the timber trusses I need some advise on.
11-02-2002, 12:12 PM
>Yeah, I am aware of the structural issues. I work for an
>architecture/engineering firm and a good structural engineer
>has been helping me with the design. It's the practicality
>of building the timber trusses I need some advise on.
Good good :)
Oddly enough in the news about the quake in Italy, it seems the school that colapsed had a second story added onto it later, of course a quake can be a formidable force for any building to withstand, this was the only one around there that had a second story ADDED later and from what I gather was the only one to collapse around there like this. Of course "adding" cement which doesn't have a lot of bending strength...
to a building in an attempt to "reinforce" it probably did little more than add dead weight on the foundation and walls designed for a one story building;
The investigation reflected the question among many in Italy about why the 50-year-old yellow complex, which housed a nursery, elementary and middle school, collapsed.
The ANSA news agency reported that a second story had been added to the original structure in recent years and that renovations were carried out two years ago in which heavy cement was applied to the structure to try to reinforce it.