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RE: Banging bolts

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Bob,

It does occur with wood but this is caused by a combination of settlement in the soil (considering compaction is never 100% and there is some rebound on new construction especially if a building was removed prior to grading and compaction). Given the time it takes to get the loaded materials in place from compaction to finished framing, some rebounding of the soil is inevitable. Also there is changes in the lumber due to climate (additional drying in the desert if KD lumber is not used exclusively).

After building my own home, the first month or so living it was at times frightening. I wondered if I have made any mistakes since I could hear a sudden snap occur (not cracking exactly, but like something snapped into place). There is some twisting of the heavy timbers – especially where I used exposed 6x headers above openings in our southwest style home. I could have avoided some of this if I had experience enough to use a 2x header on the exterior face of wall and a 4x header on the interior face of wall. The gap between the two would have allowed the exterior 2x to twist to some degree without causing changes to the interior wall finishes. This is unique where you expose wood similar to what is found in a Traitional Southern Arizona home or a Santa Fe’ style home with lots of exposed wood.

So I don’t think it would have been called “bolt-banging” but I learned while chewing through my finger nails that it is a normal settlement of materials in wood framed structures.

While we are on the subject, I had a client ask me if he could not use light gauge steel stud walls on the interior of the home. Of course he can, but the truth is that there is a difference in sound of a metal stud wall and a wood wall. You have to experience it to understand, but the metal stud while solid, sounds more hollow when a door closes. There is a psychological factor in custom homes and this is why we look so closely at deflection, bounce, creaking floors (as nails pull out while joists shink) etc. If someone is going to spend on average $400,000.00 for a small home in Calfornia, they want it to sound solid. I had a client who once walked me through every square foot of her second floor to check for squeeks. I knew she was going to be a pain so I took pains to design the floor using TJI’s and set a performance level then glued and screwed the floors in place. I made sure that I had sufficient stiffness in the floor to eliminate bounce and squeek. She still found a couple, but we had the floor open and it was easy to find where the screws backed off the plywood a bit rather than tightening the sheathing down securely. Here we simply shimmed the floor and got rid of the problem before applying the Gypsum Ceiling below.

 

Interesting Question – Banging Bolts, Huh?

 

Dennis

 

From: Bob Freeman [mailto:robert.freeman(--nospam--at)idsse.com]
Sent: Tuesday, July 03, 2007 10:48 AM
To: seaint(--nospam--at)seaint.org
Subject: Banging bolts

 

Hi Bill:

 

Does this also occur in wood construction?

 

Had a project, with exterior masonry walls, wood floor and roof joists in Mesa, Arizona,  that had a loud bang toward the end of construction.  Could this be the reason?

 

Respectfully,

Bob Freeman

Architect

Structural Designer

Integrated Design Services, Inc.

(949) 387-8500

 

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