What Community Managers Should Know About Decks

Decks when properly waterproofed with the required flashings and proper maintenance will last the length of other building components.  This requires proper installation of a good quality decking or elastomeric deck coatings with flashings properly integrated and top coatings applied as the wear surface breaks down.

When making repairs to a deck, you need to make sure the fire rating for the construction is maintained.  Often this is a 1 hour fire rating for the deck.  This can be obtained with 1 1/8” thick deck sheeting and a soffit underneath comprised of5/8” fire rated gypsum.  The deck surface should have a good slope for drainage of surface water.  ¼ of an inch per every foot is recommended.  Through the use of perimeter flashings and waterproof coatings the water can be directed away from the building and safely over the deck edge flashing.

The deck framing should also be properly vented.  This will provide for drying of components should they become wet.   This is obtained through the use of continuous strip vents, in the soffit, along the front and rear of the deck.

Properly installed deck flashings include: deck edge, deck perimeter, door pan and saddles at any post penetrations and deck to building transitions.  These flashings should be recessed and securely fastened down into the deck surface to minimize ponding of water.  The building siding and weather resistant barrier (WRB) must be overlapped over the deck flashing to maintain the building claddings’ ability to drain properly.  The building cladding should be held up off the decking surface 1½”.

Deck railings should be 42” high and not have an open spaces larger than 4”.  Cedar or steel railings are good, but a powder coated aluminum or stainless steel railing is best.  These railings come in a variety of designs, picket, glass panel, or cable.  The railing must anchor into a double rim joist or blocking designed to transfer the load into the building.  The current International Building Code, requires the railing to resist a load of 50 lbs. per linear foot, applied in any direction at the top and it must transfer the load into the structure.  Railings must also be able to support 200 lbs. of force applied in any direction at any one point along the top.  The infill portion of the railing must be able to withstand 50 lbs. per one square foot.  This includes openings and space between rails.