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Are there any schematics available on how to horizontally brace a 7/12 pitch roof?
We are finding it difficult to design permanent diagonal bracing for scissors trusses. The truss is often only a few feet in depth, which does not provide adequate room for diagonal bracing. Has SBCA come up with recommendations for permanent bracing of scissors trusses?
The truss industry maintains that the design of truss roof and floor system permanent bracing is the responsibility of the building designer. System permanent bracing covers the entire structure and all bracing element interactions.
How do I, as a truss manufacturer, adequately advise my customer against the dangers of 60 ft. and over truss span installations?
I almost always see wood trusses erected with no stability bracing at points of support. It seems to me that common sense and section 3.3.3.4 of The American Wood Council’s National Design Specification for Wood Construction (NDS) require that lateral support be provided at points of bearing. Plywood decking doesn't provide any more restraint for a wood truss than it does for a roof joist. I doubt if it was a concern with short span trusses having 4 in.
Manufactured gable ends are actually frames even though they are often referred to as trusses. The webs are “studs” oriented vertically and usually spaced at 12, 16 or 24 in. O.C. The gable end frame is designed to transfer vertical loads from the roof to the continuous bearing wall below. Another way gable end frames are different from trusses placed in the interior of the structure is that frames experience perpendicular wind loads. The sheathed frame transfers the wind loads to the roof and ceiling diaphragms and vice versa.
We are having a house built and on a recent visit we brought along a friend who builds houses for a living. He noticed that the trusses were wet and a bit moldy. The wood seemed warped, brown, and had white splotches on it. We are worried that it would later make the roof uneven. How could we tell how long the trusses have been exposed to the elements? What options do we have from here? Do we request new trusses, or can these be repaired?
I would like to know the proper storage and shipping of wood trusses.
I am looking for strongback bracing requirements for a 12 in. deep residential floor system with trusses in lengths up to 19 ft. Can the strongback bracing end at a truss without tying into an end wall? For instance, can three trusses of a type be tied together by strongbacks, then the next series of different trusses be tied together without having to be tied back to the previous type of trusses?
As a forensic engineer who has investigated numerous collapses of wood truss systems, I find your web site an excellent resource on the proper erection of wood trusses. What are your opinions on steel trusses, particularly with regards to installation and bracing? Do you feel that the installation and bracing techniques utilized for wood trusses are applicable to steel trusses? Do you know if that is the general industry standard or are there specific requirements and guidelines for steel trusses? Is there a particular guideline/commentary available for metal trusses?
Is it common practice for the supplier/distributor of a truss to provide a publication regarding temporary bracing with the delivery of the material?
How important is continuous lateral bracing in roof trusses? Is it detrimental to the roof integrity if it is missing?
We have a customer that bought trusses in June. The trusses were shipped [ and one month later are] being set. The chords have weathered and bowed. What is the industry standard for dealing with this problem? What is our liability in this situation? We were not aware of any delays on the customer’s part and shipped as requested. Note: These trusses are 62 ft. scissor trusses.
I am currently undertaking a project dealing with techniques and methods of joining structural timber members. Do you have any available information on timber connections like split rings and design software?
Is finger-jointed material allowed in the manufacturing of trusses?
The grading rules usually permit some percentage of visually graded lumber to be below grade – I believe it is 5%. ANSI/TPI 1 requires that all lumber used in trusses be of the grade specified by the truss design. A strict interpretation of ANSI/TPI 1 would require that the fabricator cull the 5% that is off grade. What are your thoughts on this?
Can one use pressure-treated lumber in metal plate connected truss construction? If so, are special plates or coatings required?
When webs are cut is it alright that sometimes the grade mark is removed? From a liability standpoint, what is the rule with grade marks and web members?
What is fatigue in lumber and how does long-term fatigue affect lumber? Does long-term fatigue cause cracks in lumber? What is the difference between long-term fatigue and decay? How do you determine whether lumber has been subject to long-term fatigue or decay?
In truss manufacturing, can hemlock, fir and spruce be used instead of Douglas Fir/Larch? What grades can be used: Structural Light Framing (Select Structural through #3) only, or Light Framing (Construction through Utility) as well?
I have been told that the high temperatures and low humidity present in attics can cause deterioration of wood, leading to truss failure. Is this true? If so, what length of time are we looking at and can we see the deterioration in the wood by visual inspection?
How long does it take the moisture content to stabilize in a wood truss? I live in southern California. Also, how much deflection should be expected in a scissors truss over a partition wall?
Some questions have been raised regarding the levels of mold in the lumber used in one of our truss projects. The issue of indoor air quality is up and coming. Do you have any information regarding standard allowable values? And how can we test for these contaminants?
Where can I find a copy of the criteria used to visually grade lumber?
What type of wood is usually used for wood trusses? I live in Louisiana and I would guess pine, but I want to make sure.
I keep reading about “green” building materials. Is SBCA working on a program for fabricators to get green?
What are the health hazards of black fungus on Douglas-Fir lumber?
I would like to know if there is an age restriction on wood trusses. How long after production are they safe to use? The trusses in question are at least three to four months old. Are they still safe to use? They have not been covered the entire time and are showing signs of age.
I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values? I have a client who wants to use “all dry” lumber for his construction but I do not know if this is really necessary.