here is the situation. I was asked to reinforce and old timber frame floor. the floor is 16′ x 20′. an 8×8 beam runs across the short distance in the center of the room and there are 4×4 joists on 4′ center going in the other direction. there is a pretty severe sag in the middle and the room is destined to become a library (lots and lots of weight). below the room is a garage with a low cieling. the homeowner wants to be able to pull the car in right in the center. my idea is to find a steel i-beam, jack up the floor to where it need to go (there isn’t much over this floor, so I don’t think I will have a big problem jacking it up and inch or two), and put the i-beam under the wood beam with jack posts on either end. I am wondering if anyone has any feed back on this, any better suggestions, and also, roughly, what size i-beam I should use.
thanks a lot
Replies
I wouldn't make a call on that .This is one of those jobs where a engineer is worth the cost.
Don't run into situations like that very often but when I do I've never been regretted the call.
Its also a good way to let the owners know that this is a major issue and if they balk at the fee its time to look for a new client with more realistic expectations,
4 foot centers on the joists? I'd look seriously at getting some lumber on closer centers, maybe even 12" centers if this room is loading up with books. 10' span for the joists isn't too bad.
I'd agree that you want an engineer to investigate the loads, especially for the posts and what they're bearing upon. You might need pretty hefty piers/footings for the posts.
Blue thumb,
didn't you see where this is a timber frame? four foot centers is very typical with thimber frames..
before you do any analizing you need to first understand the medium.. type of material the timbers are made of, where in the log the timbers were milled from, how tight the growth rings are etc..
please don't use your stick building expertese here..
First, run the problem by an engineer for the load calcs and beam requirements as well as the possibility of adding more joists.
Second, consider doing away with the 16' 8x8 wood beam. It's taken a set and would be added work and time to bend it back without lifting the ends, too. Any beam under that would compromise the already low garage ceiling you said you had.
Third, bearing in mind that as a library grows, so does the weight on the floor and you have no idea how the room will be utilized over time and where the books and shelves will be placed. Consider, if possible, adding another beam, dividing the 20" span into 3rd's. This will require reviewing the load paths and the bearing points.