Hardiboard siding is NOT a replacement for cedar wood siding.
Hardiboard siding is an ALTERNATIVE siding to cedar wood siding as are vinyl and aluminum sidings.
Everyone hates or at least should hate the cheap ugly look of vinyl siding so hardiboard siding is a much better option.
Although homes you have seen with hardiboard siding may look like cedar wood siding there is a difference.
Despite hardiboard being an alternative, it is promoted as a replacement to wood. When comparing a house sided with cedar wood siding and hardi there will be a noticeable difference. This is also why the James Hardie manufacturer does not recommend replacing a damaged cedar clapboard with this product. It just won’t match.
Hardiboard Siding is Too Thin
One reason it won’t match is that it is too thin.
Wood cedar siding (clapboard and shingle) is tapered and has a thickness of 7/16” at the base.
Hardiboard is just a straight flat board with a thickness of 5/16”.
That is 1/8 of an inch, almost a third narrower.
This may sound minimal but it does make a difference.
That means that there is less of a shadowline. Shadowlines are extremely important on all architecture for they play with the light and create the character and interest that makes old buildings interesting.
A question I have is if hardiboard was created to replace wood siding then why is it a different thickness and shape? Well the shape may have something to do with how it is manufactured and I don’t think that makes a great difference but I would expect hardi to have the same thickness.
Hardiboard Has a Fake Texture
Do you fall for that fake wood grain?
Real wood clapboard is smooth and does not have this texture.
Only vinyl siding has it.
Hardiboard SHOULD BE replicating real wood siding not vinyl siding!
Well the good news is that hardiboard also comes with a smooth finish. Smooth is what you should ALWAYS use.
If using hardiboard one must be aware of the mistakes that can be made. Some contractors are so accustomed to installing vinyl siding that they do not understand that wood siding and hardiboards are installed differently than vinyl. What I mean is that when using wood siding, the window casing which is about 1” thick is first installed. The wood siding then butts up against that casing.
When vinyl siding is installed, the siding is first installed and then a thin vinyl casing is installed around the window ON TOP OF the vinyl siding. This is so wrong and many times hardiboard is being installed the same way. This just means that you the homeowner need to be the educated consumer. The example above was done to specifications of an architect!
Hardiboard siding can affect the design of your home. When using wood siding the outside corners can be left with an edge. With hardiboard the outside corners need trim.
Painting Hardiboard and Wood Siding
Hardieboard siding is not bad but just understand that if you want to either be authentic or have the best curb appeal, cedar wood siding is your answer. From the street however, you will not notice the difference.
There are many benefits to using hardiboard but websites sometimes provide false information to promote hardiboard siding. One big mistake they make is saying that paint will last 15 years on hardiboard siding and only 3-5 years on cedar wood siding. This is dead wrong. If there is a huge paint build up your paint will peel. However if you remove all the paint from your original wood siding you will get that 15 plus years too. Click here for an article on Why Paint Peels. Some painters have a paint shaver that removes the old paint and will not hurt the wood. I had this done to my house to get more of a life out of a paint job.
I get many emails from homeowners saying they plan to remove their vinyl siding. I think that’s great. Then they go on to say they will install hardieboard siding. Why in the world would you throw money away when you already have wood siding on your house! If your siding is old then it’s from old growth wood and that wood is like iron. Don’t waste it!
Some Other Points
Some other points to keep in mind when considering a siding is that wood is a natural insulator. Hardiboard which is a cement product will hold the cold like a freezer. Hardi is promoted as being durable due to its cement content and is therefore resistant to termites and other pests. But so is cedar. That said it is more likely that termites would infest the wood behind the hardiplank or cedar where the wood can remain damp. A big plus however is that the fiber cement will not ignite when exposed to direct flame or extreme heat. It has been rated for fire resistance rated construction.
Again, hardiboard siding is a good product and should be thought of as a second option to cedar wood siding. If your building is historic then you should stick with cedar wood siding. Manufacturers and contractors aggressively promote hardiboard and sometimes may neglect to mention some of the things covered in this article.