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Published July 02, 2010, 12:00 AM

Eco-friendly, efficient deck options plentiful

Dear Jim: I want to build a deck off my family room sliding glass door. I want it to be as environmentally friendly and energy efficient as possible. What design and material suggestions can you give me?

By: James Dulley, INFORUM

Dear Jim: I want to build a deck off my family room sliding glass door. I want it to be as environmentally friendly and energy efficient as possible. What design and material suggestions can you give me? – Robert C.

Dear Robert: A deck can actually be energy efficient in several ways. If having a deck allows you to spend more time outdoors, then you should be able to set your central air condition thermostat higher during the times you are primarily outdoors. Setting it higher even for just a few extra hours per day can significantly reduce your electric bills.

A properly designed deck with a pergola or some type of tall side wall can also provide shading for your house. This is particularly helpful if it can shade the glass patio door. A tremendous amount of heat transfers in through a large glass door when it is exposed to the direct afternoon sun.

In addition to saving energy, you can make environmentally friendly choices for the decking materials. For the deck framing, engineered lumber can be used instead of standard solid 2x lumber. Engineered lumber is stronger and often made from smaller wood pieces so less prime wood is required overall.

The choice of decking is most important. Pressure-treated wood is abundant and the least expensive material to use. The only environmental drawbacks to wood are its limited life and the harsh cleaning and sealing chemicals that must be applied every year or two to extend its life.

Trex just developed a new decking material, Transcend, which is the most environmentally friendly material available. It is made from 95 percent recycled materials, primarily from plastic bags and sawdust. I just replaced my 10-year-old deteriorated wood decking with it.

Transcend is different from other composite decking in that it has a thin polymer top cap. This makes it easy to clean without harsh chemicals, and it does not stain or support mildew growth as many composite materials do. It is more expensive than wood, but considering its very long life and minimal maintenance, it is a good long-term investment.

Building a vertical wall on the southwest side of the deck is most effective for shading. This also provides privacy. The simplest design uses just standard posts covered by lattice. The openings in the lattice allow some breezes to pass through. Planting climbing vines along the lattice also enhances the cooling by natural transpiration from the plants.

Another option for the shading wall is to install horizontal slats. By tilting them at the proper angle, the direct afternoon sun can be blocked while providing ample area for breezes. The best angle for the slats depends upon your area’s latitude and the deck’s orientation to the sun. Make some cardboard slats to test for the best angle.

To block the sun from a more overhead direction, build a pergola over the deck. This is attractive, and by allowing plants to grow up and over it, it can provide additional shading.

The following companies offer alternative decking materials: Azek, (877) 275-2935, >www.azek.com; Rhino Deck, (800) 535-4838, www.rhinodeck.com; Timbertech, (800) 307-7780, www.timbertech.com; and Trex, (800) 289-8739, www.trex.com.


Dear Jim: My central air conditioner outdoor condenser unit is mounted on a concrete slab. It was level when it was installed several years ago, but now it looks tilted. Will this reduce the efficiency of the unit? – Doris M.

Dear Doris: The outdoor condenser unit for a central air conditioner can have a slight tilt and still work fine. Check with your heating and cooling contractor for manufacturer’s recommendations for the maximum tilt.

Since these concrete slabs are seldom installed on footers, they all will settle and tilt a little. The fact that you noticed it means it might be extreme. Contact a contractor who specializes in leveling slabs and patios.


Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com.

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