On June 24th I wrote a detailed letter to the City of Berkeley’s Building Department, City Manager and City Solicitor regarding their memorandum of proposed changes to the Cities Building Codes.

They want to implement various changes related to the construction of and methods of waterproofing balconies, along with requiring inspections of decks and balconies on apartment complexes and condominiums, While their proposed changes are well intentioned, some of them are a little crazy in my opinion.

My biggest objection is having Architects, General Contractors and Pest Control Technicians inspecting decks…why do I say that?

Read my letter and leave a comment telling me what you think!

1. In lieu of plaza deck assemblies, I would instead propose that the City of Berkeley consider implementing a requirement that only pedestrian traffic coatings be used on plywood covered decks. The main reason for this is that pedestrian traffic coatings are “an all in one” solution to waterproofing these decks while providing a walkable surface at the same time. They can be easily inspected and are relatively easy to repair if damaged. Most Division Seven Pedestrian Traffic Coatings are also Class A roof rated systems (ASTM E-108) and many are also rated as One Hour assemblies (ASTM E-119), therefore meeting the Cities fire resistant requirements. Many of these systems can be finished in any number of ways with texture and pigmented sealer as well as stained/stamped etc to look like tile, stone, wood etc. There are several different system types available, leaving architects and specifiers choices among concrete based coatings, liquid applied coating, slip sheet systems and sheet goods. Concrete and many of these coatings can also be used to correct deficient slope conditions, so achieving a 1/4” slope per foot is very easy to do on flat decks that were not framed with slope in them.
2. In regards to the Berkeley Building Code changes proposed, I concur with the recommendation to require Ventilation of weather exposed enclosed assemblies under Section 1203.6. Most of our manufacturer’s already require this in their general requirements in their CSI specifications. I also concur with the inclusion of access panels on the underside for inspection of the framing.
3. In regards to adding Section 1404.13 Projections exposed to weather, after consideration, I concur with using pressure treated wood or steel for framing the deck. I do believe that properly waterproofed, conventional douglas fir framing is perfectly suitable for the framing, however, rot resistant materials will certainly perform better if exposed to water over a longer period of time.
4. Under Section 2304.11.4.2 Wood structural members, I propose that the City eliminate the use of moisture permeable floors or roofs such as concrete or masonry slabs. My reasoning is that these types of assemblies trap water in them and as they are typically part of a plaza type deck system, are not conducive to using them on balconies covered in plywood anyway.
5. Regarding adding Section 601.4 Structural Maintenance; I concur with requiring inspections. I have several changes to propose; these being requiring inspections every two years instead of the proposed five year interval. In my experience as a waterproofing contractor and consultant, five years is to long between inspections. A lot of serious damage can occur in a short time. Manufacturer’s of Pedestrian Traffic Coatings require as part of their warranty that their systems be inspected yearly. Regarding who should inspect the decks-waterproofing is a specialty trade. In my work as an educator, I usually have a room full of people where 90% or more are general contractors. General contractors are just that, generalists. I’ve found in my experience that most do not understand waterproofing in general and decks in particular. While structural pest control licensees know the signs of dry-rot, wood destroying organism infestations etc, they do not understand waterproofing either. Engineers and architects are generally familiar with waterproofing concepts and can certainly recognize inherent defects and issues with contiguous building materials and would be suitable candidates to perform inspections. I believe the best candidates to perform deck waterproofing inspections are waterproofing consultants. As a group, we are very familiar with installing and maintaining waterproofed decks and balconies. It may sound self-serving and I appreciate anyone thinking that it is, however, as an example, I’ve spent nearly 14 years as an estimator and owner and applicator of a firm specializing in waterproof deck installations. I’ve found that many of my peers were applicators and as we “age” out of being able to work on our hands and knees we seem to transition into consulting and inspecting. The Roof Consultants Institute (RCI) and Sealant Waterproofing Roofing Institute (SWRI) are two organizations that are focused on roofs, decks and waterproofing systems and are probably best qualified to do such inspections. We have familiarity with general building requirements and understand the importance of contiguous building materials needing to be weather resistant as well.
6. I would suggest that the City add the following requirements for deck waterproofing; these being that building inspectors begin inspecting the waterproofing of the decks as it’s being installed, including inspecting the flashing system and substrate prior to covering with a membrane. Most importantly, inspectors should verify that the deck is sloped or tag the deck so that it will be sloped and they can check the slope before signing off and allowing finish coats to be installed. Once the membrane is installed, but before it is decoratively finished, it be inspected again. As part of the requirements, the City should allow only ICC-ES pedestrian traffic coatings with Class A ratings minimum and One Hour where already required. The ICC-ES report should be made part of the submittal for building permit approvals.
7. Regarding substrate-the use of Oriented Strand Board (OSB) for pedestrian traffic coatings is not accepted by ICC-ES nor any manufacturer. All fire testing is performed using plywood only. OSB, in my experience, despite the claims by manufacturer’s that it’s better at water resistance, is a sponge. I’ve seen OSB expand and it doesn’t return to it’s original dimensions. Therefore, OSB should be banned for use on decks and plywood be the only acceptable substrate allowed. I would caution against requiring pressure treated plywood, mechanical fasteners used on some systems may not be compatible and liquid applied coatings may have issues as well with compatibility.
8. Regarding railings-steel/aluminum railings that mount onto the deck should be banned. In my experience I’ve found that it is impossible to guarantee a waterproof deck won’t leak when railings penetrate the waterproofing. Only metal railings that mount to the fascia should be allowed. Wood 4×4 posts penetrating through the plywood and bolted to the deck framing can be flashed and waterproofed. The key in waterproofing these wood posts is that they MUST be wrapped with bituthene/Tyvek/building paper and then either boxed in for a final finish or a post sleeve, typically made of plastic/synthetic materials is slipped over and finished on top with a decorative “hip roof” style cap to shed water.