My wife is an engineer and safety is her #1 priority for our mobile sauna build. Before putting the siding on our mobile sauna I decided to research how to make it a bit safer.
I used carriage bolts to secure my pressure treated deck for my sauna to my trailer and I’m confident the floor deck isn’t going anywhere but what’s to stop the walls from blowing off the deck? This helpful video on tiny house structural strength suggests a new type of screw that replaces conventional lag bolts: Exterior Structural Wood Screws.
I got box of 40 6″ screws and installed one down through the floor plate and into the 2×8 joist below; 10 on each long side and 4 on each short side for a total of 28. They go down through the 1.5″ wall stud, through the 3/4″ floor and then 3.5″ into my 2×8 floor joists (actual 7.25). Total cost for the box of 50 was $42.
Then I used 50 feet of 16-Gauge Galvanized Strap for $81 and installed on my corners as suggested in the video to prevent the building from twisting.
Finally, I bought a 12-pack of 4.5″ structural screws for $15 and installed two of these in each corner where the top plate meets the wall below.