Lap Siding: How (Not) To Install Hardiplank And The Like

In a comment on my first "how (not) to" hub--How (not) to install a low-flow toilet--I was told, "you are so not 'Canada's worst handyman!'" This might seem self-evident, given that I live in Atlanta, but I chose to take it as a compliment to my skills anyway. (And I suppose that I should explain, for those not versed in Canadian lore, that "Canada's Worst Handyman" is a popular 'reality' show.)

However, I do find that I have a tendency to discover at least a few of the pitfalls in any given project the hard way. The bright side of that is that I can then share those pitfalls with you, dear reader, and save you the hassle. So, since you are reading this, perhaps you need to do some siding? OK, then, let's start.

As you can see, we have a shed that was seriously in need of siding; how our neighbors put up with this for such an embarrassingly extended time I don't know!

The first thing is to estimate the materials needed. At the store, the salesman told me that he needed to know the square footage of wall to be covered. Time for some math. . . The shed is ten by twelve, with eight-foot high walls, and with two doors. So multiply the height times the width for each wall, and subtract the area of the doors.

The triangular area of the gable ends might seem intimidating at first, but the geometry works out such that you can just multiply the height of the gable by the width of the wall. ("Height of the gable" means the distance from the peak of the gable down to the line where the eaves meet the top of the wall.) Adding it all up, I found I needed a little less than five hundred square feet of board. Since I wanted extra board for another small project, I rounded up to five hundred; that worked out to be 70 12-foot boards.

But what sort of boards, exactly? There are a number of options. However, this Hub isn't about the virtues of each. We chose Hardiplank, a popular and durable choice today. It was pretty affordable, as well, since our building supply store sells a couple of types of Hardiplank basically as a loss leader (less than $5 per 12-foot length, as of this writing.) You can read more about the environmental virtues of Hardiplank at this Hub:

The photo above shows the Hardiplank on a pallet--and brings us to the first "how not to." Hardiplank is durable--but not if you handle it incorrectly. How did those boards in the center get broken?

I discovered a few ways to do it:

--You can lift the board with your hands too close together, putting too much stress on the center of the board;

--You can handle too many planks at once, and the weight of the upper boards will tend to snap the lower board. When they give way, the upper board will "flop" and break too;

--You can move too abruptly, especially when lifting one end of the board, as when placing it on your work table.

So, when handling Hardiplank, keep your hands well apart to spread the pressure, move deliberately, and move boards no more than two at a time.  If you stick to one at a time, you can follow the Hardie company recommendation by carrying them on edge.

And if you're like me, remember that swearing at broken board doesn't mend it, and can be quite embarrassing if those long-suffering neighbors happen by.

Applying the siding starts at the corners. That's where you put the trim pieces, which serve to cover the ends of the siding boards. There are different sizes of Harditrim available, but 1' x 4' is pretty standard, and that's what I chose. I also followed a time-honored practice by covering the corners first with tar paper. The concept is to keep out any water that may come through the potentially vulnerable corners. I'm not sure it's really necessary, but it's also cheap and pretty easy, so why not?

There is a small "how not to" here, though--if you're siding over foam board, as I was, don't try stapling the tar paper. It just won't hold. I ended up using duct tape to hold the tar paper until the boards went up, thereby securing the paper in place permanently.

Speaking of securing the board, you have choices of fastener, too.  There are siding nails intended for the purpose; but roofing nails and coated sinker nails have their adherents as well.  The roofing nails have a tendency to bend and damage the siding, in my experience at least.  And the sinker nails, though they work well, don't meet the corrosion resistance recommendations of the Hardie company.

If you are cheap, er, I mean "frugal," you can piece corner pieces to reduce waste, as shown in the photo above. I chose the corner which will not often be seen close up to piece together. Use 45-degree angle cuts, sloping downward to avoid any tendency for water to seep into the joint.

The saving for the poorer appearance and slight extra work was about $9. Was it worth it? You make the call!

By the way, when nailing Harditrim you should plan on drilling pilot holes for the nails. It's tough to force a nail through the material without one, and if you succeed--most likely two or three nails later--you'll tear up the board quite a bit.

(Yes, I discovered that the hard way, too.)

While some Hardiplank is pre-finished, the board I chose is not. It must be primed and painted. I chose to cut pieces to length first, then prime them using a roller before installing them. The finish coats were then applied using brushes. I chose water-based Kilz for primer, and a semi-gloss latex exterior paint for the finish coats.

The advantage of this work flow is that it's a compromise between having to work far ahead with your boards on the one hand, and brushing all coats onto installed siding on the other. I don't like to cut too far ahead of where I'm installing the siding boards, as no matter how careful you are, there will be variations in the length needed as you ascend the wall. But if you apply all the coats first, you'll be waiting a long time for paint to dry. Besides, you need at least one coat on top of the caulk and nail heads, anyway.

On the other hand, primer can be applied to a pre-cut length very quickly with a roller--probably in just a couple of minutes. And it will usually be dry enough to handle in half an hour, or even less in full sun, during which time you can be cutting and installing siding. So I'd cut and paint three or four pieces at a time, and put them in the sun to dry, supporting them on a couple of Styrofoam blocks I hadn't yet recycled.

By the way, it's best not to leave your Hardiplank exposed to the elements--especially rain.  It seems to infiltrate the board some, and make it even more prone to breakage.  And it definitely can result in soiling and staining.

Of course, you must start at the bottom of the wall, overlapping boards as you go--most Hardiplank is intended to overlap by an inch and a quarter. Use a level to mark where the top edge of the board will be--I marked directly onto the trim piece, which worked well since that nice white primer made for an easy-to-see mark.

It was convenient to mark four boards or so ahead. Recheck level frequently as you install the boards!

Also, keep in mind that you want to maintain the same spacing on each surface. If you don't, the appearance at corners--or on opposite sides of doors--will suffer badly. (The board on each side of my front door could line up better, if you look closely--but I'm not giving you a close up!)

Long pieces require you to pre-place a support--sometimes called a "buck"--at one end. The buck should be set carefully, so that it supports the board within a half-inch or so of the correct level. Place the board on the buck while you nail the other end in place, then go back and fasten the "bucked" end, correcting the level as you do.

You can buy special brackets for this, too. But if you don't do a lot of siding, it may make more sense to use various improvised props, as I did.

Speaking of cutting the board, my main tools for this are shown above. It's all very normal: a tape to measure length, a carpenter's square to keep angles "right," a circular saw (supplemented by a jig saw as needed), and a small surform plane to clean up the ends a bit once you've cut them.

A regular crosscut blade works fine, but does dull quite a bit cutting Hardiplank. It would probably have been better to use a masonry blade, but I didn't think of this until my blade was already dull. If you try the masonry blade, let me know how that works!

I'd recommend a dust mask when cutting Hardiplank. I know Hardiplank is supposed to be friendly to the environment and all, but is it really a good idea to inhale cement dust?

The James Hardie Company suggests not, too--see their website for more detailed instructions. They are particularly concerned about your safety if, unlike me, you do your cutting indoors rather than out.) Their Hardieplank page can be found at the link below.

As the picture above shows, sometimes it's not enough just to cut a plank to length; you will probably also have to trim out bits for doors, windows, or light fixtures.

Start by measuring carefully and repeatedly. The old adage is to "measure twice and cut once," but twice isn't always enough for me! Allow a little extra--say, an eighth inch on each side of a opening. (Think carefully about which way the allowance needs to go--it's surprisingly easy to apply it backwards.)

This door opening was done by making the long cut first as a "plunge cut." Keeping the ends attached ensures that the board doesn't break. (A plunge cut is made by holding the blade of the circular saw above the material, keeping the front edge of the saw's base plate firmly in contact. Start the saw, then carefully pivot the blade down onto the cut line you have marked.) The short cuts can be made easily with supports on each side of the cut.

As the second photo shows, I propped the work piece up above the work table, setting the saw blade to a shallower depth above the work table surface. (See picture three for a closeup of the blade being set to depth.)  The corners were finished with the jigsaw, as shown in the bottom picture.

It's jumping ahead a bit, but there's another trim that you may need to make:  the trim to fit a roof gable.  I know I had trouble doing this, until I learned this method from Ian Denham, of The Mountain retreat, near Highlands, North Carolina.

As shown above, begin by marking a level line horizontally from the point where the roofline meets the edge of the wall. I call that my "baseline." Use a square to find the point where your baseline's distance from the roofline is equal to the width of your board. Finally, measure the distance from this point back the point where you began the baseline. I call this the "run."

When you are ready to cut your first gable board, you simply measure the distance of the "run" from the top corner of your siding board, mark it, and use a straightedge to draw a line back to the bottom corner of the board. This will be the correct angle to cut.

(Of course, most times it won't work out that the cut line needs to be exactly at the corner of the siding board. Then you have to adjust the line upwards, either by cutting the line directly on the board, then trimming the excess, or by making a template using a waste piece.)

That was the situation with my project, and the resulting cuts are illustrated in the photos below. For the smaller cut, it was easy enough to make the cut beyond the end of the work table; for the larger, the work piece was raised above the table using small blocks.

A few miscellaneous points remain. One is that you need solid wood behind the siding to nail into. For the most part, that is not a problem; studs--the vertical 2 x 4 pieces within a wall--are spaced 16 inches apart, which means that there is likely to be a stud close to where you need to nail.

But there are exceptions. One exception can happen at corners, as illustrated in the photos below. The width of the stud in the corner is less than the width of the trim piece on the outside of the wall. That meant that there was no overlap between the two. So it was necessary to provide a nailer to secure the ends of the siding boards.

Fortunately, this isn't very hard; cut a 2 x 4 to the correct length, tap it into place as shown, and secure it with nails driven at an angle through the corner of the 2 x 4. (This is called "toe-nailing.") Voila! A place to drive your nail.

Another issue is the tolerance between the trim board and the siding itself.  As shown below, it's standard to leave a small space between the two, which will be filled with caulking.  This space makes installation easier, and makes it less likely that siding will bow out later.  I used a standard latex caulk for this, applying it according to the manufacturer's instructions.

If, like me, you choose an unfinished siding, you are going to need to paint once the caulking is complete. I like a semi-gloss finish for most exterior projects, but that is up to you; many folks like satin or even eggshell.

(For those uninitiated in painting lingo, these terms refer to how "shiny" the finish will be. The shiniest finish is "gloss;" the flattest is called "matte." In addition to affecting the preferred appearance, finishes affect the ability to clean a surface as well; shinier surfaces are generally a bit easier to clean--though they may also sometimes show dirt more clearly.)

Although a roller is just the thing to prime the board quickly, it is not so useful for painting a lap-sided wall--the wall is not flat enough!  So, unless you have a spray rig, you will be using brushes.  The larger the brush, the faster you can cover an open area, so if you are like me you may be tempted just to charge ahead with the biggest brush you've got.  (The larger one in the photo is a 4-inch brush.)

Resist this temptation.  The results will be better, and you will actually save time, if you use a trim brush to paint edges and corners before attacking the wide-open spaces.  The pictures below illustrate the "better results" part.

Here's an illustration of the two-brush process. Here, the edges and corners have just been done with the trim brush. (Painters call this "cutting in.") Not only is it neater to do with the smaller brush, it is much faster. Finishing the open areas with the big brush is very, very quick once you have completed the "cutting in."

Normally, you are going to need two finish coats. If you're lucky, or very meticulous with your first coat, you may be able to get away with just the big brush for the second coat.

Mostly.

So, how did it work out, you ask?

I'm pleased. The job isn't perfect, but looks decent. (Finally!)

Doing it myself certainly held the cost down greatly. It took about 45-50 hours to complete the project from start to finish. (Your results, as they say, may vary--you may be more or less efficient and/or energetic than I am.)

Just be careful how you use the ladder--but that's a subject for another Hub!