Done Right: Roof Decks Built to Last
- July 24, 2013
- Jeff King & Co
- No Comments
Practical Benefits of San Francisco Green Building
In San Francisco, green building is more than bamboo floors and low VOC paint. We believe that building right is the process of understanding how an entire system works together, and carefully selecting the materials and construction practices that bring longevity to a home.
Our current project on Lombard Street is the perfect example. If living space is a premium in San Francisco, it’s even more so on Telegraph Hill. Between three decks and a top story solarium these homeowners have over 1,400 square feet of living space to capture the outdoors. In fact the majority of the home’s prime entertaining space is exposed to the elements and built atop living space. Our job is to make sure it’s built to last.
A Quick Guide to San Francisco Roof Decks
Topping off living space with decks is a great way for homeowners to get some private sunshine in the city. However, when improperly built and maintained, these decks can pose serious – and expensive – problems for the living area below.
We’ll use this San Francisco green building project as an example of the right way to construct decks over living space with a special eye for water drainage and waterproofing. Done right, a roof deck can bring 30 years of enjoyment and peace of mind. There is great value in that longevity from the standpoint of both environmental impact and homeowner convenience.
What We Found: Water Damage and Rot
Unfortunately this home’s existing decks were not built to last. After just seven years, the materials had worn through and caused extensive leaks directly over the home’s kitchen, living room and master bedroom. Opening up the floors and ceilings exposed water damage that had penetrated the home’s infrastructure to leave rotted plywood and deteriorated framing. It was the classic example of using the wrong material for the wrong application – with big consequences.
BEFORE: Holes in original waterproofing material
First and foremost, we found that the roof plane did not have an adequate slope for water drainage. The decking had been sitting directly on a tar-based roofing product, causing friction to wear through the material and break its waterproof seal.
BEFORE: Water damage from deck leaks
When rot is caught and corrected early on, it’s relatively easy (though not cheap) to replace finishes and plywood. If the water damage reaches structural framing, homeowners are looking at extremely expensive repairs. It can take less than three months for a severe leak to cause tens of thousands of dollars in repairs. That’s why we take great care to build a roof deck right the first time. The value is seen not just in saved dollars on repairs, but in the confidence that one’s infrastructure is dry as a bone and strong enough to carry the weight of your home.
The Right Way to Build a Deck Over Living Space
If I could give San Francisco homeowners one piece of advice about roof decks, it’s this. Use the right material for the right application.
What really affects the lifetime of your deck is the part you don’t see: the waterproof membrane underneath. At Lombard Street, we are using a liquid applied membrane that is flexible enough to move with San Francisco’s heat differentials throughout the day. This is a great material for its flexibility, strength and easy maintenance. Applying a new layer of coating every five years will keep the deck fully sealed and waterproof.
AFTER: New liquid membrane traffic decking
On top of the sealant are pallets of ipe wood. There are many benefits of an ipe wood deck from its beautiful red color to its long lifetime. Lasting up to 100 years, FSC ipe hardwood is one of our favorite exterior materials for San Francisco green building.
Clever Deck Design for Low Maintenance & High Durability
The beauty of this deck is easy access to the liquid applied membrane underneath. Most decks require a level of demolition to reseal the base layer, which is costly in both dollars and environmental resources. We have constructed this deck in a way that all materials float on top of each other, making it extremely simple to lift and move the wood. Maintenance becomes simple and cost-effective, and with new sealant required every five years, those savings add up.
For quick water drainage, the roof plane is built at a slope. These plastic pedestals are installed at different heights to create a level surface for the wood palettes to rest on.
Next step: installing ipe wood palettes over the waterproof membrane and pedestals
Saving Money on Roof Deck Maintenance
The greenest house is one that lasts, and this deck will last for decades with the proper care. The combination of durable materials and smart construction makes for a deck that is easy and cost-effective to maintain through the years. But most of all, the homeowners can live with the peace of mind that their deck won’t be falling into their kitchen anytime soon.
Wood pallets over plastic pedestals to allow for quick drainage
This deck construction is a prime example of how to take advantage of San Francisco green building practices for durability and comfort. If you have a roof deck or other deck above living space, do a favor for your peace of mind: build it right and build it to last.
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To learn more about best practices for constructing decks over living space, check out Professional Deck Builder’s article “Building Waterproof Roof Decks.“