Exterior Siding

Exterior Siding, How to Choose It

John P. Bridge

I’ve written about exterior siding in the past, particularly about “cardboard siding,” otherwise known as “masonite” or hardboard siding. Masonite siding has become the mainstay of tract home builders throughout the country simply because it is cheaper than wood siding. And like wood siding, unless it is conscientiously (and continuously) maintained, it will eventually have to be replaced.

Where I live (in the Houston area), it is common to see “brick” houses with brick veneer on their fronts and masonite siding on their sides and backs. In many cases, the masonite is made to look like colonial or traditional clapboard siding. In other instances, the siding will be in 4 by 8 sheets with vertical scoring intended to imitate board and batten (or reverse board and batten) siding. Hardboard siding will hold up as long as the homeowner knows how to maintain it, which, I’m afraid, is seldom the case. It is also extremely important that the siding be installed correctly before the homeowner inherits it, which, I’m afraid, is almost never the case.

If I may digress (I never seem to have any trouble doing that.), there are parameters that govern the installation of exterior sidings in general. In the first place, exterior walls have to “breathe.” This means the siding material cannot be absolutely air-tight. Otherwise, moisture can accumulate behind it. In the old days, when most sidings consisted of wood boards lapped over one another, there was no problem with air flow, as the cracks between the boards provided plenty of ventilation.

When moisture accumulates behind the siding, various problems are caused, including mold, mildew and rotting. Keep in mind, then, that exterior siding usually doesn’t rot from the outside but rather from the inside.

Masonite siding is delivered with its face primed with some sort of paint, but the reverse side (which faces the inside of the wall, where all of the aforementioned problems occur) is left bare. It is a good idea to “prime” the reverse side of the siding before it is installed. Oil-base primer will work. Two coats of primer should be applied to the reverse sides of the boards nearest the ground. In the case of 4 by 8 sheets, the bottom two feet should receive the extra coat. When repainting masonite siding, pay particular attention to the bottom edge. Make sure you reach under and thoroughly coat it.

Priming or otherwise sealing the reverse side of any composite or wood siding will help preserve it, but this is almost never done. It takes time, and in the construction business, time is money. If, however, you are building your own house, or adding onto it, you should take the time to perform this simple act.

You should also do it if you’re using plywood siding. But if you value my advice (my wife and a few others do), you won’t use plywood siding at all. Plywood siding usually comes in 4 foot by 8 foot sheets. It is composed of several layers of wood veneer (plys) sandwiched together with exterior glue. Three things can happen to plywood siding when it accumulates moisture: it can delaminate (the plys come unglued), it can swell and therefore warp, and it can rot.

While it’s true that diligent maintenance can preclude the above calamities, I don’t see a lot of sense in inviting trouble when affordable alternatives are available.

Both masonite and plywood sidings normally incorporate a tongue and groove arrangement where the boards are joined. Do not attempt to pack the boards tightly together. Leave a little play in the joints to accommodate swelling that might occur. Once again, priming the boards thoroughly, back and front, will minimize swelling.

There are vinyl sidings that, when properly installed, will last a long time. The drawbacks are that vinyl tends to fade, and expansion and contraction due to temperature change can cause it to buckle, although the buckling is usually slight. Additionally, vinyl siding is not painted (a plus), so you cannot change the color of your house as the years go by (a minus, if you happen to get sick looking at it).

There is also aluminum siding, whose characteristics closely follow those of vinyl siding. The aluminum is generally anodized, making its color permanent for all practical purposes. Aluminum siding is easily crushed when something or someone hits (or leans on) the side of the house.
Both vinyl and aluminum have one other common drawback: they don’t “breathe” well, and if not properly installed will cause an excess of moisture to build behind the siding. We’ve already been there.

Wood sidings are still used. They include cedar, redwood (if you can find it), and boards of other soft woods, chiefly fir and pine. Wood board sidings are essential if a “period” motif is to be achieved. Nothing quite replicates the enduring allure of real wood. Installed and maintained correctly, wood lasts a long time, but not forever.

And that brings me to what I consider the best siding of all: fiber-cement siding. This is the stuff made from modified (and reinforced) portland cement. There are several brands available, the leading products being from the James Hardie company. As siding goes, the cement products are bullet-proof.

Fiber-cement siding is available in a number of surface textures, and there are panels of various sizes. When properly installed, cement siding will last indefinitely. It will not swell and warp, and it is highly rot resistant, although cement materials will eventually rot if continuously subjected to moisture. The rotting process, however, takes virtually forever and can be prevented altogether by applying paints formulated especially for cement siding. These paints are purported to last 15 to 20 years. Not bad at all.

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