modify attic truss 2

Please hire a local structural engineer to assess and design. This is not trivial. Most anything is possible with enough money.

Just so every can see, the OP is swapping a 2 x 4 bottom chord for a 2 x 8.

I suspect you will need to reinforce the roof rafter.

This should be easy to solve though. What is your role here? Owner? If that's the case your post won't last long....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Hire a local engineer. That being said, using the interior walls for support can make these quite easy.

Thanks LittleInch...i am contractor here...this plan was given to me by an architect but some reason i am not conviced the truss are beefed enough...good point on rafter reinformcenet too.

any pointers how and where online i can run some load analysis ?

Patel456 said:

any pointers how and where online i can run some load analysis ?

Click to expand...

Here's a link: Link

Is this, somehow, a design-build project?

If not, do you think the architect is acting outside of his expertise?

If not, why do you doubt the plan?

Have you tried talking to the architect about this? You can hire a structural engineer and get his opinion, but 1) you'll be on the hook for the engineer's fee and 2) having an engineer review this doesn't make them the engineer of record - you'll just have set yourself up for a very contentious relationship with the architect.

Please note that is a "v" (as in Violin) not a "y".

First of all, if you have doubts about the structural modifications given to you by an architect, I would suggest first expressing those concerns to the architect. As an engineer, I would often have contractors asking questions about my designs. I always took the time to look into their concerns, ESPECIALLY if they thought my solution was underdesigned. Any good architect would do the same.

Secondly, if this project would have any consequences for the structure being improperly designed (which I think we can say is obviously the case), don't attempt to run any sort of analysis yourself. Even if you can find some program online to run this (which I think you won't), suppose you use that program incorrectly and it tells you everything is good. Now, you proceed to construct it. Later on, there's an issue and although unlikely, it could end up in court. What will you tell them?

I think it's beside the point here, but if this were my project to design as an engineer, I would want to use the interior walls below for structural support (as XR250 mentioned). I would likely sister the existing truss bottom chord with dimensional lumber or LVLs and possibly also sister the top chords with similar material. I would have no clue if your modifications shown above will work, without knowing local loading conditions and existing truss geometry and material.

These raise a lot of issues.
Are the walls below continuous? Are they supported well enough? (is there a basement below)
And then the reinforcement where you are cutting the access for the stairs.
Sit down with the Arch and ask him to walk through this with you.
He may have done a lot of work (or outsourced it) and just not bothered to tell you.

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