Perfect picket fence

Setting Posts

When it comes to outdoor building projects, there are some mistakes you can fix afterwards, and some you can’t. And a botched fence post installation fits into the second category. It’s obvious that fence posts must be straight up and down (plumb) and solid. That’s why people intuitively set them into concrete-filled holes. But that, in itself, doesn’t guarantee long life. The key is preventing soil movement from raising your posts and ruining your fence. The water in soil expands on freezing, and this can lift posts bit by bit each year. Even if posts extend below the frost line, expanding soil can still grip the outside and cause trouble. As soil trickles in under a frost-raised post, it keeps it from re-settling. This incremental movement’two steps up, one step down’can lift a fence many inches over the years. The good news is that this sinister process can be beaten with a good post-setting strategy. Notice how the sides of the post hole are plumb, not flared near the top (which is the usual tendency when digging them). A flared hole creates a concrete plug that’s bigger at the top than the bottom’perfect for frost to grab and push. Another feature is the screenings or gravel on top of the concrete, holding the post plumb for the two days it takes concrete to set solid. This eliminates the need for wooden bracing and hides unsightly concrete.

— Lawrence Winterburn

Fence Finishing

1. Deglaze all wood surfaces

New lumber doesn’t absorb finish very well because its surface has been burnished and partially sealed by the planer at the mill. Nothing, particularly a film-forming finish, can properly grip glazed, new wood. That’s why peeling and premature finish failure is common. Experiments by Akzo-Noble, the world’s largest finishes company, demonstrated that the best way to remove mill glaze is with a 60- to 80-grit abrasive. Water-based coatings are also inhibited by acid buildup on new wood. Neutralize this with a wood treatment designed to raise its pH. Bio-Wash (www.biowash.com, 800-858-5011) is a company that makes such a product.

2. Choose a finishing product that’s UV-proof

The sun deteriorates many materials, and causes many outdoor wood coatings to fail. Even some so-called UV-resistant finishes can’t stand direct sunshine. Two excellent products are Sikkens Cetol 1 (a coloured, translucent coating) and Cabot Decking Stain (a coloured, paint-like product). The Weather Bos line is also recommended.

3. Apply the finish under proper conditions

Proper conditions are the key to a long-lasting finish. Each finish comes with instructions that recommend the best conditions for application, but it’s not always obvious when conditions are inappropriate. On a cool, sunny day, for instance, the air temperature might be within manufacturer’s specs, but the wood could be too warm if the sun is shining directly on it. Too-warm conditions will evaporate solvents prematurely and lower durability. The best day to coat outdoor wood is cloudy with no chance of rain. Coating in the shade is okay, but don’t do anything after 4 p.m. Evening dew can ruin a half-dry finish. You’ll also notice that few finish companies recommend spray application. Brushing drives the finish deeper into the pores of the wood, boosting film adhesion. To get the application speed of spraying, with the adhesion of brushing, spray the finish on the surface and brush it out immediately. It’s faster than brush alone because you’re not spending all your time dipping the brush in the can. A plywood dipping trough lined with vapour barrier plastic is another speed-finishing option. Dip your fence parts in, let them drip-dry propped up away from blowing leaves and dust, then install.

— Steve Maxwell