Over the past two weekends I’ve been engaged in some rather heavy physical labour: I’ve been building a new fence in my backyard, mainly for aesthetic reasons but also so that the wife and I can let our cat outside without it being menaced by the neighbour’s giant dog.
I hadn’t done any real carpentry since high school shop class so I went into the project with some pretty basic thinking – the process of building a fence can’t have changed that much in the history of building fences, right? Dig your holes, stick some posts in them, nail together some cross-beams and attach the boards. It seems relatively straightforward.
That was the case for the most part, but we were surprised to learn that some modern technology has actually entered the equation. While stocking up on the requisite supplies, we inevitably came to the question of how to secure our posts in the ground. Since time immemorial, the answer to that has been concrete. But lo, there’s a new option in town: foam.
The Home Depot guy suggested something called Sika Post Fix as an alternative. As per the website, it’s “a two-part, pre-proportioned polyurethane resin which when mixed produces an expanding foam” that fills the hole and then solidifies into a base that’s as solid as concrete. Naturally, this appealed to the nerd in me so we picked up seven pouches, one for each post.
The process couldn’t be more straightforward. The mix comes in two attached-but-separate pouches; you simply squeeze one into the other, then mix up the whole pouch for about 20 seconds. Then, you cut a small hole and pour the liquid into the hole. That’s when the magic happens.
The liquid instantly congeals into a bluish foam that then expands quickly upward, taking about two minutes to fill the hole. It’s pretty much exactly like those baking-soda-volcano science projects we used to do in grade school. About two hours later, it’s rock solid, except with any excess material on the surface, which is relatively brittle and can be easily carved away with a knife.
I’ve never used concrete so I can’t really compare it to the Sika foam, but the wife and I were both deterred by the notion of having to mix and pour it, then cleaning up afterward and waiting a full day for it to dry. The foam is made for people like us: painfully easy-to-use, no mess and fast-acting.
We’re also not positive how the foam is going to stand up to our horrific winters, so we’re putting a good amount of faith in Home Depot’s decision to sell the stuff in Canada in light of that fact. That notwithstanding, I couldn’t recommend the foam more – it made a relatively difficult project a tad bit easier.
It’s not cheap, though. Each pouch costs around $15, with its manufacturer suggesting that each one can fill a three-foot hole. With concrete, you’d need about two $6 bags each, meaning that the foam is slightly more expensive in theory.
In practice, though, we ended up needing about two pouches per hole, which was considerably more costly than concrete. But after the back-breaking work of digging holes and the rock-and-root excavations that inevitably followed, it was money well spent.
Here’s a video showing how it works: