Blocking Air Conditioner Noise

Q: How can we block noise from the air conditioner that sits next to our patio? How about some sort of wooden wall lined with cork or foam?

A: First of all, you need to make a decision about how seriously you want to take this sound-reduction challenge. Some sort of wooden barrier would be effective, though I wouldn't use any foam or cork. Neither of these materials age gracefully outdoors unless they're fully protected from water. And that would be a difficult trick in a fence-type situation. If this were my home, I'd consider two approaches. The easiest is an all-wood wall made of overlapping 2-inch thick pressure treated lumber, surrounded by a 6x6 outer frame. This may sound like overkill, but the key to noise abatement in this case is mass. Thin wood just won’t cut it. Make the wall as tall and wide as seems appropriate given the aesthetics of your situation. Another option that's more trouble to install but potentially more effective is a masonry wall built using textured blocks or bricks. The blocks with rough faces look good all on their own, without any sort of surface treatment. Any masonry wall needs a substantial foundation, but it's also the most effective solution I can think of. You might also consider having your air conditioner moved further away from the patio as part of the strategy. Even a few metres can make a big difference when coupled with a good wall.