by Chris Swanson
Water intrusion in a waterproofing system is commonly seen often due to a poor railing installation, which causes failure in the deck coating system. There are a multitude of railing systems seen in the field. As installers, and in a perfect world, these systems are installed without penetrating the actual deck, for example, they may be attached to a fascia, framed in with collars, or connected without ever touching down on actual deck via framing. Still in many instances we commonly see the type of railing system with baseplates that are bolted down on the deck. Running into this detail in the field is more common than rare, so explaining the methods in which we deal with this the best will give insight into making sure the installation of the railing system does not derail a waterproof deck coating. Essentially, the idea is to integrate the railing system into the deck coating system without water intrusion being an issue short term or long term.
There are basically three different methods you can go about the installation of this certain type of detail:
1. Bury the railing baseplate with the deck coating
When installing the bolts and plate directly over the plywood it can create a difference in the deck coating’s elevation to the plywood and will be liable for the coating to rip or tear if pedestrian traffic weight is heavy around the areas. It is highly suggested that each baseplate is furred/mounted cut into the plywood so once the bolts are installed they sit flush with the plywood giving a more even surface to waterproof. Using a liquid sealant or membrane to fill the bolts threading and to seal the bolts themselves after fastening will give the baseplate a more secure tight fastening. Once the feet are installed the waterproofing membrane and finished coating surfaces should evenly bury the baseplate as clean as you can aesthetically get each post to look. Burying the baseplate is WICR’s preferred method of installation mainly due to the fact that anytime there is waterproofing over something that is fastened you will have a better chance to ensure moisture protection.
2. Leaving the Baseplate Exposed
Leaving the baseplate exposed sometimes comes down to aesthetic or preference by the customer or general contractor. In some situations the feet are housed by a separate metal cover that sits over the baseplate. In others the feet are left to be exposed and weathered. Identical to the installation where the feet get buried, there should be a strong sealant or liquid membrane that is poured into the threads and over the bolts during installation for the strongest fastening to the deck possible. In this method of installation you are penetrating through the waterproofing coating so this is a very important, if not the most, part of the installation. The underside of the baseplate should also receive a coat of the sealant to ensure any moisture cannot find its way into the bolt penetrations. The maintenance of these individual railing feet should be cared for regularly (every 1-2 years) and recaulked from time to time to ensure that these penetrations stay waterproof.
3. Exposed baseplate with housing
As said earlier in this post, having a railing system that is fastened elsewhere from the actual deck will ultimately be the best solution for a waterproof deck coating application, to avoid any of these extra measures to be taken. It is also important to understand over a significant amount of time inevitably the movement and contraction of a baseplate mounted railing system can loosen and also open the door for moisture intrusion. Which is why taking the detailed steps of initial fastening, caulking, and prep ensures you have the tightest possible bond to the deck. Working closely with whomever is installing the railing system and coming together with a game plan to address the issue is the best way to ensure that the outcome is bulletproof. Both methods of installation explained above are very common situations seen by WICR Waterproofing & Decking in the field frequently, and with the correct steps taken, there should not be any leaks or water intrusion.