Understanding Type of Roof Truss and OBD

[kijijiseller]

Hello,

I've had some concerns with a new build and bowed floor in the second floor hallway. The hallway is wide is it's noticeable.

Looking at some measurements the second floor wall is offset roughly 2-3 ft from the first floor shown in the attachment. Basement has a steel beam running down the centre. I guess there is a second beam between the first and second floor?

From the photos in the attic, can this truss be identified as a self supporting or load bearing truss? I'm curious if the second floor wall is meant to be load bearing , and if so I'm trying to identify in the OBC what offset these walls are allowed. I'm not exactly sure the verbiage to be looking for.

 

[fatboy]

Not seeing the truss specs, (which is exactly what you need to ask for) it is difficult to say.

Not familiar with the acronym "OBD".

 

[kijijiseller]

Not seeing the truss specs, (which is exactly what you need to ask for) it is difficult to say.

Not familiar with the acronym "OBD".

Referring to Ontario Building Code

 

[Mark K]

What is the reason for concern? Is it because you have some reason to believe it is unsafe or a code violation or is it because the bowing is bothering somebody? Do not be surprised if you find out that it is not a code issue but rather a case where some unintended hard points were created thus causing the bowing of the plywood.

You are going to need an engineer to sort out the cause for the bowing.

The secret to understanding what is going on is to understand what the original construction documents show.

I cannot remember seeing a steel beam in a wood framed building unless an engineer was involved in the design. The steel beam suggests that they wanted to have an opening below the wall on the first floor which was acting as a bearing wall. I also would not assume a steel beam between the first and second floors unless you can confirm it exists.

 

[Keystone]

There’s many questions here, is the floor system cantilevered, age of house, do you have access to the original construction documents, why the photos if the engineered roof trusses, how great is the bow in the floor, the end of these walls are they exterior or interior, etc etc etc... If I we’re in your shoes, I’d contact the approving building department and then the builder if this is a newer installation. Seems likely you will require a licensed Design Professional’s assistantance.

 

[TheCommish]

Are the truss running parallel to or 90 deg. to the second floor wall? If parallel is there a truss bear on the the second floor walls? Does the truss design include a bearing point on the second floor wall, oar are the trusses clear span?

 

[bill1952]

I think you need to have someone knowledgable about this type of construction (residential?) look at it. A more complete drawing - showing where the truss is - would help.

 

[tmurray]

The trusses look like they are probably clear span, but it is difficult to say without seeing the design details from the supplier.

If the hallway wall is not considered a load bearing wall, there is no requirement for its location. If it is a loadbearing wall, then it needs to be bearing on top of the beam/wall below to create a clear load part to the foundation. Offsets are possible through an engineered design under Part 4 of the code.

 

[Inspector Gadget]

The floor is engineered system - and thus, it's subject to Part 4 calculations. The only person who can tell you what is acceptable - and what isn't - is a pEng with suitable qualifications. If this is a new build, you should be able to obtain the plans from the joist/truss manufacturer, and verify they were used as designed. (I say that, because I've seen a situation where someone cantilevered engineered joists when they weren't designed that way.)

 

[SCBO1]

There should be a load bearing information tag on the truss if it was designed for a cantilever. Most truss manufactures place information or caution tags on trusses so that the truss is placed properly over bearing points. The tag could be on the truss on the bottom cord of the truss? or the plant that maunfactured the trusses may have indicated this information on the layout plans. It is not uncommon to have a truss installed backwards or upside down if the framer was'nt competent. *See SBCA reference document or see if Canada has something simular?

 

[tmurray]

There should be a load bearing information tag on the truss if it was designed for a cantilever. Most truss manufactures place information or caution tags on trusses so that the truss is placed properly over bearing points. The tag could be on the truss on the bottom cord of the truss? or the plant that maunfactured the trusses may have indicated this information on the layout plans. It is not uncommon to have a truss installed backwards or upside down if the framer was'nt competent. *See SBCA reference document or see if Canada has something simular?

Sometimes those tags disappear during construction.

On one occasion I had a red seal certified carpenter (fully licensed here in Canada) install the trusses in his own home backwards. When I got on site he and his father were up finishing up the roof shingles. I was explaining the situation as diplomatically as possible and did not bring up the fluorescent pink tags that say "THIS IS A BEARING POINT" in big, bold letters in the middle of his open concept kitchen. The man looking up at the trusses and seeing those tags then asks, "Oh, is that what those tags mean?".

 

[Mac Moonfire]

I agree with the comments above. If it's part 4, well, you can ask the P.eng to comment, or give him/her a call.
Have you read 9.23.9.8. of NBC? the NBC illustrated part 9 guide is also worth the detour for that section.
Let us know what comes out.
Cheers

 

[Genduct]

I think Mark K had it right when he said this situation needs an Engineer's Review and the answer is not in the CODE

In general, trusses are designed for a point load where a purlin is located. Even thoughwe see them aas supporting a uniform live and dead load onplywood. The "Standard " truss was never designed for that offset load condition you describe. The least that would be seen is a vertical member to tranfer the load.

Now perhaps the wall above was never meant to be load bearing and we are talking about just the added dead load of the partition. OR perhaps the original trusses were a little"Light" in their design and there is some, unexpected load being tranfered. Point is it requires a thoughtfull Engineering review to determibne what we, here, are just guessing at

IMHO, Mike

 

[bill1952]

We have no way to know if 2nd floor wall to right is a bearing wall. If the floor "slumps", it may be 2nd floor joist problem or could be whatever supports the far right end of second floor joists is sinking. Far too little information to offer any answers with certainty. I can guess if that's a hallway, there are rooms with exterior bearing walls which support the truss in a normal fashion.