THE TROUBLE WITH BALCONIES AND DECKS

No other building component gives as many problems as walking decks. 

I have known architects who swear they will never design another one. 

Why are they so problematic? 

First, they have to discharge water out of the wall above the deck.  Second the deck has to be water tight and durable.  Thirdly the deck has to discharge water from the deck surface or the membrane under a concrete or tile top safely outside of the system. When you do a deck, you own the wall above and the wall below. 

1. The edges need a through the wall metal flashing, at least 4″ up the wall and no more than 4″ on top of the deck.  If a stucco wall above, a weep screed is placed per Code over the flashing with the building paper intact and on top.  Per Code the weep should be 1″ above the deck, but in fact it performs adequately a little bit above the deck.  I like to put a ‘peel & stick’ tape on top of the weep screed to protect again corrosion.  These areas are wet and condensation can rust out the metal. 

2. To make the membrane durable, workers must integrate the membrane with the metal flashing at the top of the deck and the outside drainage over the wall below.  I have been doing decks for over 40 years, and vast improvements have been developed.  We no longer use hot asphalt and paper which deteriorates after around 12 years.  Neoprene top coatings which revert after 10 years are gone now.  If the deck is clad with tile or concrete it is required to put a drainage mat (which also protects the membrane from damages).   The coatings are now urethane elastomeric, or rubberized asphalt.  We have had no failures in these products for 30 years.  

We typically use an epoxy base coat, a rubberized middle coat and a finish top coat.  These can be applied in day or two. 

But the applicator must check the base plywood to see if it is compatible with the membrane.  This means no OSB or particle board.  The plywood is best used is AC grade.  All joints should be taped with a rubberized trowel coat.   Also deformed ring shank, or spiral nails should be used.  Regular nails will back out over time, and rip the membrane. 

All these materials must be compatible with each other.  Otherwise, they disengage and fail. 

3. The outside edges of the deck must be flashed over the wall below, or into a gutter and downspout system.   Typically of galvanized sheet metal, it should be ‘pickled’ to ensure the membrane on top of it will adhere.  You don’t want to drain the deck into the wall below.  Wood and stucco walls are not designed to be a base for a water fall.  The drained water should go into a gutter, or drip free of the wall. 

All galvanized metal must be coated in the systems, or it will rust out in short order.   

The best treatment of joints is to rivet and solder them.  These are skills that are disappearing. 

But if followed, you will share our experience of more than 30 years of service life. 

Last year the state of California passed SB 721, which mandates regular inspections and maintenance of decks and balconies (among others) more than 6 feet above grade for all properties with more than 3 units. If you own an apartment building or a condo, this likely applies to you. Schedule an SB 721 inspection with Karl Kardel Company on our website today and rest easy that you will not be subject to the high fines the law brings (up to $500/day starting January 1st 2025).