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Earthquake Safe Construction for Half-Height Sleep Loft?  XML
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Ken Kanagawa

Joined: 07/09/2017 06:33 PM EDT
Messages: 6

My apologies if this is not an appropriate question for this forum, you guys are clearly the experts so here I am.

I'm about to build a sleep loft platform 4" off the ground of my two girls bedroom which will divide the space into equal upper and lower bunks - think tour bus or capsule hotel. The front fascia/outside edge will be a bookshelf floor to ceiling that's independently constructed and supported, creating partial privacy in the respective spaces.

I want to make this as safe as possible. Los Angeles being earthquake prone as it is I'm wondering:

A) what fasteners you'd recommend for my anchoring the upstairs loft platform's ledger boards into the studs (big lag screws?)

B) how many studs they should fasten into (some? all?)

C) whether it's ok to go over top of the drywall versus removing for direct connection to the studs.

I'm attaching a rough drawing of the sleep loft, it's framed on three sides by structural wall studs - the existing three walls of the room. The platform will be 11 feet wide, 44" deep and the ceiling is 8"2'. I'm thinking 2x4 framing spaced at 18 with 5/8 birch plywood over top. So the platform itself is as light as possible.

Thank you for any suggestions!

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Mike Casey

Joined: 06/28/2014 07:21 PM EDT
Messages: 1245
Location: San Diego CA


I'm not an engineer, so I can't confirm earthquake safety. I would use lag screws long enough to penetrate the drywall and into each stud at least 1.5 inches for the ledger. No need to remove drywall. However, I believe 2x4 studs are too small. I'd use at least 2x6 and 2x8 is probably most appropriate. It might be easier to just purchase bunk beds and fasten them to the wall.

Mike Casey
Director of Education
Home Inspection University
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Ken Kanagawa

Joined: 07/09/2017 06:33 PM EDT
Messages: 6

Thanks for this info Mike. The lag screws sound like a good way to go. True 2x4" might be too flimsy I was mostly thinking how to keep the weight as low as possible given the platform will be suspended over another bed. I'll take another look at what's commercially available but I like taking a DIY approach as long as I can make it safe. Gracias!

Dom D'Agostino

Joined: 12/08/2014 01:25 PM EST
Messages: 161
Location: Orlando, FL

Your proposed platform will be a lot heavier than you think.

Got the lumber yard and stack a dozen 2x4's on top of a 2 sheets of 5/8 plywood. Then try to lift it.

You can certainly build it, but better to overbuild this platform (actually a floor structure).


Joined: 12/05/2017 06:36 AM EST
Messages: 1
Location: United Kingdom

Thanks for such a value able information about earthquake safe construction really help a lot.

This message was edited 1 time. Last update was at 12/07/2017 06:15 AM EST

The Rock

Joined: 06/18/2014 10:46 PM EDT
Messages: 881
Location: Dallas, Texas

Hello, Ken.
Don't know where you are at this point. Earthquake forces induce stresses through lateral acceleration. Your rigid platform attached on three sides appears to provide for a sufficiently lateral-resistant structure. But that's all "theory." In real-life, the weak point in your structure will be at the connections, (ie how skillfully they are done.) The front girder (ledger) appears supported only at the ends, so will have to be stiff enough to resist defection/bending.
-Philo (Cal-Berkeley, School of Engrg... lol!)

PHILO RAMOS, BS Civil Engineering
PRECISE Home Inspections, TREC#4319
Texas Professional Real Estate Inspector Association (TPREIA) #418
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