Hi guys. I need some help from the hardware experts out there. Over the weekend, I picked up a thoroughly used Rainbow Play system for my kids. If you haven't ever seen one, it's one of those cedar wood, fort style playground systems. Rainbow just happens to be the brand everyone goes ga-ga over. So when I saw one advertised at 40% of the price of a new one, I got it. The wood is in OK shape...there are couple pieces that were in mud that had to be replaced and I'm sanding the rough spots down and refinishing it as we speak. Once I'm done, the structure itself will look better than new. However, when I was breaking the structure down to move, I noticed it was put together with 9/16" lag screws. Most of the screws were pretty rusty and need replacing. My question is this, since cedar is pretty soft, would I get more structural strength doing away with the lags altogether and drilling through the piece and replacing them with carriage bolts? I THINK it would be better and stronger and do less "eating away" of the wood, but it might not matter at all...I don't know. What do you guys think?
Need Help. Lag Screw vs. Carriage Bolt
- Thread starter woodlab
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Daviddubya
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- Jan 22, 2007
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It would definitely be stronger and will require less maintenance using through bolts - carriage or machine, depending on whether you like round heads or hex heads. For outdoor applications, it is best to use stainless or galvanized hardware, both of which are expensive. Stainless is prettier. If you need a large number of bolts, nuts and washers you can buy a box of 50 or 100. The best price on stainless boxes I find is at Ace Hardware, believe it or not!!! I would use bolts, especially if the old hardware corroded and the wood is weakened, as you mentioned.
Brice Burrell
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Two things come to mind, first, a bolt will stick out the other end and be somewhat sharp, you may be able to find caps to put over the ends. Next, your kids will out grow the playset before galvanized hardware will rust out, so I see no need to go with stainless.
Thanks. I felt like through bolts would be better, but you never know...sort of like how surprised I always am at how strong "just glue" is. However, being in cedar and being taken out and put back in so many times, I think the threads are on their last bit of bite (say that 3 times 
). I'll PROBABLY go with stainless for BOTH reasons you guys pointed out...
1) it does resist corrosion better
AND
2) my kids will outgrow this set in 4-5 years. If I upgrade the structural hardware to stainless, I'll use it as a selling point when I need to sell this one and get the "super-duper-mansion model".
The good thing is that the only exposed part of the bolt will be the rounded bolt head. The nut on the other end will be recessed into the wood. I'm also a little surprised that this isn't standard construction on this type of playground system...you would think that for the $3600
o) they're charging for this thing AND that it will be used by kids, they would go all out on the hardware (I got mine for a steal at $1200 and still felt like I paid too much for a swingset...but what are you gonna do when a 4 year-old angel says "Daddy...pleeeeeeeeeeze" :). You can see from the picture below (from Rainbow's website) that the entire deck is supported by a gambrel-like "bent-leg" support system. This has to put a great deal of force on that joint. Again, this is intuitive on my part and a stress test could prove me wrong, but it seems that at that angle the joint WANTS to fail. I mean, would any of us build a dining table like that and expect it hold up over years of use? So, bolts...definintely better. Now...maybe I need to fabricate a steel truss support for that joint... 8)
Any other "no-brainer" upgrades you guys would recommend?
). I'll PROBABLY go with stainless for BOTH reasons you guys pointed out...1) it does resist corrosion better
AND
2) my kids will outgrow this set in 4-5 years. If I upgrade the structural hardware to stainless, I'll use it as a selling point when I need to sell this one and get the "super-duper-mansion model".
The good thing is that the only exposed part of the bolt will be the rounded bolt head. The nut on the other end will be recessed into the wood. I'm also a little surprised that this isn't standard construction on this type of playground system...you would think that for the $3600
o) they're charging for this thing AND that it will be used by kids, they would go all out on the hardware (I got mine for a steal at $1200 and still felt like I paid too much for a swingset...but what are you gonna do when a 4 year-old angel says "Daddy...pleeeeeeeeeeze" :). You can see from the picture below (from Rainbow's website) that the entire deck is supported by a gambrel-like "bent-leg" support system. This has to put a great deal of force on that joint. Again, this is intuitive on my part and a stress test could prove me wrong, but it seems that at that angle the joint WANTS to fail. I mean, would any of us build a dining table like that and expect it hold up over years of use? So, bolts...definintely better. Now...maybe I need to fabricate a steel truss support for that joint... 8)Any other "no-brainer" upgrades you guys would recommend?
If you decide to go with the carriage bolts, I'd suggest that you use Torque Washers as well. These nifty washers have four prongs on the back of the washer that bite into the wood to keep the washer from spinning, and a square hole in the middle that fits the underside of the carriage bolt head. They distribute the load effectively, and prevent the bolt from sinking into soft woods like pine or cedar commonly used for swing sets. They can be tough to find, but a google search for "torque washers" should help.
I'm dancing as far from the obvious as I possibly can.
I'm dancing as far from the obvious as I possibly can.
I built a similar Rainbow unit for my kids just under 5 years ago. Ours doesn't have the long swing bar. It's swing bar contains one swing and is unsupported on the end. I don't know how old yours is but I thought all Rainbow units were Redwood. At least they were back in 2002. Also, it was constructed using lag screws and bolts. The bolts were for the main assemblies and the screws were for the angle supports, legs, etc.
Anyway, one thing to constantly check is the tightness of the bolts. Those swings can put a lot of torque/twisting action on the unit if used hard. I go out every spring and throughout the summer and check all bolts and tighten any that have come loose. This was the worst throughout the first year and now things are staying pretty tight. The lag screws have remained tight. Believe it or not but that design has remained rock solid so far and that's with three kids pounding in it for nearly five years.
PaulD
Anyway, one thing to constantly check is the tightness of the bolts. Those swings can put a lot of torque/twisting action on the unit if used hard. I go out every spring and throughout the summer and check all bolts and tighten any that have come loose. This was the worst throughout the first year and now things are staying pretty tight. The lag screws have remained tight. Believe it or not but that design has remained rock solid so far and that's with three kids pounding in it for nearly five years.
PaulD
When the kids outgrow this one, I will probably end up building the replacement. After seeing the mediocre quality of hardware and construction, I'm a little underwhelmed with the famous "Rainbow quality". Man, if I could get the prices they're asking for these swingsets, I'd quit my job.
