Hello,
I'm working on an extension angled out from the existing building, and the initial plan was that when we were to open up between the new and the old, we would place a visible beam in the ceiling between two studs on either side. I got a construction drawing for this from an engineer.
However, now the builder I've hired has suggested instead placing a beam between the roof trusses up in the attic. The advantage is, of course, that you avoid having a visible beam and can thus open up all the way to the ceiling. My builder has, on his own initiative, put a joist (2"x9") between the collar beam and the sloping part of the truss. However, when my quality manager was there, he thought it seemed a bit under-dimensioned and suggested I talk to an engineer.
Here comes the problem: I can't get hold of my engineer; he doesn't answer the phone, and I suspect he's on vacation or something similar.
What do you think in this forum: has anyone done a similar adjustment before? For me, it involves two trusses that need to be adjusted. Should I let the builder wait until I've contacted an engineer, or am I worried unnecessarily?
I'm working on an extension angled out from the existing building, and the initial plan was that when we were to open up between the new and the old, we would place a visible beam in the ceiling between two studs on either side. I got a construction drawing for this from an engineer.
However, now the builder I've hired has suggested instead placing a beam between the roof trusses up in the attic. The advantage is, of course, that you avoid having a visible beam and can thus open up all the way to the ceiling. My builder has, on his own initiative, put a joist (2"x9") between the collar beam and the sloping part of the truss. However, when my quality manager was there, he thought it seemed a bit under-dimensioned and suggested I talk to an engineer.
Here comes the problem: I can't get hold of my engineer; he doesn't answer the phone, and I suspect he's on vacation or something similar.
What do you think in this forum: has anyone done a similar adjustment before? For me, it involves two trusses that need to be adjusted. Should I let the builder wait until I've contacted an engineer, or am I worried unnecessarily?
What dimensions has the designer suggested for the beam underneath then?
How wide are the roof trusses?
Are there any other load-bearing walls that relieve the roof trusses?
How far is it from the outer wall (where I suppose the original lintel was planned) to the place where the new lintel is located?
How large was the original beam? In the same material as the one now installed?
Very generally and simply, one could say that since the beam has been moved closer to the center of the house, it must be larger to achieve the same effect. If the beam now sits halfway between the outer end and the center of the roof truss, it must be able to carry 1.5* the load (e.g., by being 1.5* as wide).
So, if the original beam is smaller than 2*9", it COULD be okay, otherwise, it probably isn't. It would be a good idea to ask a constructor.
Also note that a change in the measurement "in height" has a much greater effect than a change "in width." In other words, perhaps a 2*9" is okay if originally it was supposed to be 2*7".
However, I don't remember if the height has a square or cubic effect. Anyone?
/ Fredrik
Are there any other load-bearing walls that relieve the roof trusses?
How far is it from the outer wall (where I suppose the original lintel was planned) to the place where the new lintel is located?
How large was the original beam? In the same material as the one now installed?
Very generally and simply, one could say that since the beam has been moved closer to the center of the house, it must be larger to achieve the same effect. If the beam now sits halfway between the outer end and the center of the roof truss, it must be able to carry 1.5* the load (e.g., by being 1.5* as wide).
So, if the original beam is smaller than 2*9", it COULD be okay, otherwise, it probably isn't. It would be a good idea to ask a constructor.
Also note that a change in the measurement "in height" has a much greater effect than a change "in width." In other words, perhaps a 2*9" is okay if originally it was supposed to be 2*7".
However, I don't remember if the height has a square or cubic effect. Anyone?
/ Fredrik
I think your builder is completely off, a common rule and especially one of the weak dimension in this context is way too vague, you will experience a significant deflection.
I am facing the same problem and have found this online. Download the dimensioning table via the following link.
http://www.svensktlimtra.se/page.asp?id=36
Good luck
//Joachim
I am facing the same problem and have found this online. Download the dimensioning table via the following link.
http://www.svensktlimtra.se/page.asp?id=36
Good luck
//Joachim