The International building code requires that a guardrail withstands a minimum of 200 lb, applied tangentially to the top rail. This means that a person or a few persons leaning against the rail could possibly apply a tangential force equal to 200 lb and the railing should be able to resist. There are several factors involved on this. However, the only factor that actually does not count is the type of railing, because, for the most parts railroads are build following common practices, and they are usually just OK. The main factor for code compliance is the quality of the installation. If one does not attach the railing properly, even if the railing is made of thick solid steel, it will not pass the 200 lb test. It does not make sense to build an iron railing that will probably need a force equal to 1000 lb just to slightly bend it and then leave it lose against the wall! But this is what happens most of the cases when a railing has failed.
TYPE OF WALLS AND THE PROPER ANCHORS FOR EACH OF THEM
There are several type of "walls" where railings are usually attached to. EXTERIOR BRICK WALL normally this type of wall has regular wood framing behind, and the brick is just attached against it. If you want to be over cautious, you may drill through the brick with a masonry bit, up until you reach the wood behind, and then pre-drilled the wood to drive a long enough 3/8 inch lag bolt into it. However by experience it is possible to use expansion bolts, 3/8 by 1 7/8 and install them into the brick and still have a strong enough grip. If the brick is lose or cracked, you may have problems. Also if you open the hole too much, the expansion might be lose or loosen up with time.Another possibility is to use concrete tap cons, which is a blue screw that is very strong. I would prefer the expansion sleeve anchors over tap cons. However, properly installed, tap cons are just fine on brick. Just be careful not to overdo while driving in the tap con, just go easy. If the brick is not enough enough, tap cons might not work. So just make sure you have a healthy solid brick to work with. If you will not en up going back to plan A. Do not use any type of anchors that would require impact, for it may break the brick, causing a greater problem.
Outside wood framing always has a 1/2 inch OSB plywood behind the siding. However you do not want to attach your railroads to the plywood only, but to the real wood framing behind. You might get away installing the rails to the plywood only, but for sure, if the railroads are high traffic, they will fail. If the building inspector catches that, you will fail inspection. But not all the time, sometimes you could leave, in good conciseness, the rail with a weak joint (not lose) on the top, if you there is a post near the wall and its four floor anchors are well attached. Actually a good post attachment would waive the necessity of an upper anchor, your railing could be left free standing, and still pass the load test. As an installer you have the right to request that the proper wood backing is installed on the walls. Inside framing, on the other hand, is covered with drywall. A drywall anchor will not take the load, even less than the OSB. So, do not install your railroads on drywall. However there is two exceptions to this rule: the first is the one we already mentioned, and the second is that if the railing is a wall mounted railing only, and let say you have 4 brackets, and one is on drywall, it is going to be probably OK if the bracket is not at one of the ends.
CONCRETE WALLS AND FLOORS
The recommended anchor for this cases is always a sleeve anchor, 3/8 x 1 7/8. Some times it may require a 3/8 x 1, or even more it is a long standard railing. Tap cons are also OK in short runs. When there is greater danger and appearance is secondary, the best way to go is to core drill the concrete and then embed the legs with hydraulic cement. Of course if you could have the railroads ready before you cast the concrete and cast them together, that would be the ideal situation. Railings joinery sometimes the railings need to be split and then joined at installation. The best joint is the welded one. You bring your welder, grind the spot, welded up and then touch up paint. However, if you paid for an expensive powder coating finish, you do not really want to weld on it, unless it is completely necessary.
Bolting is a second option, which requires a nut on the other side. It is good but too conspicuous. Particularly if one does not grind off the excess tread and leaves the bolts unpainted. If this is your case make sure the nut is tight enough and then seal it around with clear silicone to avoid moisture penetration. Self tapping screws with a neoprene washer is the best option. Screws are not so visible and provide a very strong joint, which is also waterproof. Way to go!
When installing the self tapping screws go slow with the drill, making sure it is NOT in hammer mode. If you go too fast it might kick you back and cause an injury. So be careful. Remember that at slow speed the drill has more torque, so you are not doing much more by speeding up too much. One thing to remember is that it is better if you clamp the two pieces together before drilling, and that this is the last step. Make sure everything is lined up and attached, and then install the joint screws.
INSTALLING ON CERAMIC TILE OR SLATE
Here the problem is that ceramic tile or slate break easily, especially if there is a hollow spot. First of all, make sure you tell the owner of the house or your wife that this might happen, it will keep you out of trouble. Then, always try with a thin 1/4 inch bit and then go with the 3/8 or 1/2 inch one, and make sure you use long enough screws to reach the wood or the concrete underneath.
GLUING DOWN YOUR RAILING
Sometimes there are worries about damaging the waterproofing of the deck, if that is the case and face mounting is not possible, for short spans, when there is a solid attachment of the top railing, it is possible to glue down the intermediate legs and even the posts. Use 1099 glue by 3M, which is much better than regular contact cement.
FACE MOUNTING YOUR RAILINGS
If for any reason you decide to face mount your railings, just remember that there is a lot of momentum on this type of mount, therefore the minimum spacing between bolts vertically should be 3 inches. Both screws need to be firmly attached, with a minimum of 2 1/2 inches of real wood penetration, therefore there should be 2 boards on the mounting face. Therefore use 3/8 by 3 wood lags. If you do not have 2 boards, you need to have 4 screws per leg. The best way and safer way, would be pass through bolts with washers, if you have access to the back of the face. Use 3/8 of an inch bolts. If you are face mounting on concrete you need a 3 bolts with a separation of 3 inches in between, and you need to use 3/8 x 3 sleeve anchors. If the slab is not thick enough, then do not face mount, unless you are allowed to have kickers every 6 ft minimum. I think I have covered all the possible scenarios; so, the only thing left is to say:
Happy railroads installation!
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