Thread: Is It Wood Or Cement?

I sometimes have a difficult time distinguishing between hardboard and cement siding. Are there any specific things to look for or other ways to differentiate between the two?

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Originally Posted by Stephen G Sheldon

I sometimes have a difficult time distinguishing between hardboard and cement siding. Are there any specific things to look for or other ways to differentiate between the two?

"Is It Wood Or Cement?

Neither of those two choices are "wood".

Ok. But is there a way to tell the difference?

Use a nail or knife to probe the surface.
Hard board is softer than cement board.

engineered or manufactured sidings/shingles/panels materials can include

Fiber cement siding (most generally utilize cellulose fibers (wood)
cement asbestos siding, engineered fiber sidings including asbestos,
engineered wood siding, composite wood, includes hardboard, plywood, T-1, etc.

Some harboards utilize polymers, waxes, resins, fillers, and/or cement.

Not all contain cementous ingrediants.

Knock test, visualizing edges, examining with more than just the naked eye. Surface temperature variations.

Without specific knowledge or invasive and/or destructive examination /removal/ sample testing it can be difficult to definitively determine the precise componants and product identification of engineered siding materials already installed and coated and without any exposed portion, backside, etc. stamped or otherwise labeled, taged, or identified.

In general, regular HI is not invasive or destructive, and doesn't include the movement or removal of building elements or damaging surfaces, including the building envelope, its paints or coatings upon sidings, etc. Doing same is not without liability.

Disturbance or damaging/probing of encapsulated asbestos containing materials or those which may be resonably suspected or expected of same, or for that matter surfaces, coatings, etc. which may contain lead, mercury, and other environmental and health hazards, by an HI is not advised.

Originally Posted by Stephen G Sheldon

Ok. But is there a way to tell the difference?

Originally Posted by Rick Cantrell

Use a nail or knife to probe the surface.
Hard board is softer than cement board.

I wouldn't want to disturb the protective coating (paint) on hardboard, nor would I want to disturb the protective surface of the hardboard.

Look for cut ends, damaged areas, nailing points, it shouldn't take too long to be able to determine if it is hardboard or not. Any swelling typically indicates hardboard. This is probably one of those times when the best way to learn the difference it to go to local building supply houses/stores and check the two different materials out. If the material is covered with multiple coats of paint, that will hide many of the differences you are looking for, but that also is an indication of something which has been installed a long time (many years, thus many coats of paint), in which case it may well be hardboard.

I try to find areas that have missed being painted, is peeling, or where caulk has pulled away. Hardboard will usually be dark brown (sometimes blond), while cement fiber is gray. Because hardboard is made of wood fiber, sometimes the end cuts are rough. The hardness of hardboard will depend on how it was made, so it may not always be softer than cement fiber. Older hardboard is likely to show signs of moisture problems or peeling paint.

The main binder of hardboard is the natural lignin found in wood, though it may have resins or other stuff added in small amounts to change its working characteristics.

Newer installations using cement fiber HardiePlank will often be coupled with HardieTrim, a product that looks a lot like plastic.

It really is not all that difficult to tell the difference. With an MDF product you can use your fingernail and make a dent in it. Better yet look at the bottom edge, with MDF it will be thicker and it will usually have a curve to it, with fiber cementitious board it is almost always squared off and has a sharper edge.

I wear a wedding ring, I have found that if I tap the siding with the ring on my finger that it has a sharp sound with fiber cement board and a dull thud with MDF.

MDF is different from hardboard, though, isn't it? Inferior, softer, even more liable to have moisture issues. Hardboard is the stuff pegboard is made of, and my fingernails, anyway, don't make a dent in that. I'd be surprised if MDF is even installed as siding these days. It's popular for dollhouses, though!

Originally Posted by Kristi Silber

MDF is different from hardboard, though, isn't it? Inferior, softer, even more liable to have moisture issues. Hardboard is the stuff pegboard is made of, and my fingernails, anyway, don't make a dent in that. I'd be surprised if MDF is even installed as siding these days. It's popular for dollhouses, though!

I believe that the pegboard you are writing about is a different product.

LP, GP, Celotex, Weyerhaeuser, Masonite all made siding products at one time. When I toured one of the LP plants they called it MDF. Most had class action lawsuits back in the 1990's early 2000 on their poop performance.

Originally Posted by Kristi Silber

Hardboard is the stuff pegboard is made of

Originally Posted by Scott Patterson

I believe that the pegboard you are writing about is a different product.

Both have what I have seen advertised as a 'tempered' finished surface in that the finished surface is somehow treated or compressed such that it becomes water resistant. Pegboard does not have the same degree of 'tempering' as it is not intended to get wet and therefore does not need to resist water to the same degree as hardboard siding needs to.

I'm not sure it is still available, but you used to be able to get the harder, glossier, surface of the hardboard siding available on solid (non-perforated) hardboard sheets which were 4'x8' in size. They even used to (maybe still do) use that and apply a layer of melamine (plastic) to the surface of it, and that melamine surface could be continuous or was available with a surface with indentations which make the board look like 'tile' (albeit really cheap tile) and it was called 'tileboard'.

MDF is, as I recall, a different product.

The bottom edge and tapping is how I identify cement fiber. They have a sharp edge and ruff cut look on the bottom.

They use allot of Miratec around here now and I am already finding swollen and rotting trim boards from not painting the cut edges and placing to close to surfaces. It's the new trim to hate because installer's don't prep it properly. MiraTEC Treated Exterior Composite Trim Product Line

The hardboard used today for siding is a better product than that used a few decades ago. It was invented in 1924, and has gone through changes since then. The older stuff is softer and soaks up moisture more easily.

I didn't mean to suggest that pegboard was the same kind of hardboard used in siding, but it's still hardboard.

Here's page about defects in installation of hardboard siding.

Go to Home Depot and get a good look.
Amazing what you can learn about materials by strolling the aisles.

Yea, push on it real hard. If it flexes, it's wood composite or hardboard. If it breaks, it's fiber cement. ROFLMAO!

Sorry, I couldn't resist that! No, don't push on it - unless of course you want to pay for it.

Like Scott said, tap on it with a metal object. (He's gonna be out of luck if he ever gets divorced.) With just a little experience telling the two apart, you can usually just tap it with a knuckle or a fingernail, and tell the difference.

Originally Posted by Scott Patterson

LP, GP, Celotex, Weyerhaeuser, Masonite all made siding products at one time. When I toured one of the LP plants they called it MDF. Most had class action lawsuits back in the 1990's early 2000 on their poop performance.

.
Yep,

Lot of Crappie Siding out there.
* usually swollen, degraded and in contact with the roof.
.

This is a good page about how different types of hardboard are made. It also mentions MDF (emphasis not mine):

"A recent development in the board field eliminates humidification by delivering a board from the hot press at 4 - 6% moisture. This product, medium density fiberboard (MDF) utilizes the dry process and synthetic resin to hold the board together because press temperatures are not high enough to reactivate the lignin. MDF is most economical in the production of thick boards, 1/2” and up, but thicknesses and densities overlap the hardboards.

MEDIUM DENSITY FIBERBOARD (MDF) may be considered the same as hardboard, even though it does not conform to the technical definition. For many uses they are equally suitable."

Originally Posted by Kristi Silber

This is a good page about how different types of hardboard are made. It also mentions MDF (emphasis not mine):

"A recent development in the board field eliminates humidification by delivering a board from the hot press at 4 - 6% moisture. This product, medium density fiberboard (MDF) utilizes the dry process and synthetic resin to hold the board together because press temperatures are not high enough to reactivate the lignin. MDF is most economical in the production of thick boards, 1/2” and up, but thicknesses and densities overlap the hardboards.

MEDIUM DENSITY FIBERBOARD (MDF) may be considered the same as hardboard, even though it does not conform to the technical definition. For many uses they are equally suitable."

Kristi,

In reading the material from that link, your post makes that last part seem as though it was intentionally "out of context" with the other information in that link, although I know that was not your intent. Reading what you posted and what the entire article says, one would likely get a completely different opinion of what that last part says - it is more than just a "technical definition" difference between "hardboard" and MDF".

Well, it's true it was out of context, but my intention wasn't to make it so. There wasn't much context for it in the article, it was was more of an aside. What I was trying to communicate through the quote was that although MDF may show some characteristics of hardboard, it's technically a different thing. Sorry if the quote provided was misleading.

Originally Posted by Kristi Silber

What I was trying to communicate through the quote was that although MDF may show some characteristics of hardboard, it's technically a different thing.

That's a good way to say it, except that I would place less emphasis on the "technically" word part.

Originally Posted by Jerry Peck

That's a good way to say it, except that I would place less emphasis on the "technically" word part.

I can't really place less emphasis on it unless I omit the word altogether...perhaps I should have, but didn't think it necessary. I've been saying since post #9 that MDF and hardboard are different products.

Originally Posted by Kristi Silber

I can't really place less emphasis on it unless I omit the word altogether...

Yep.

I've been saying since post #9 that MDF and hardboard are different products.

Yep, but that one post kinda muddied the water some on it.

Yes, I suppose that's right. I was coming at it from a very literal perspective, and focusing on the "technically," because that's what I was interested in. They are technically not the same. I can see how others might interpret it to mean, they're so close, we might as well call MDF a type of hardboard - but only if they don't read the quote carefully. Anyways, it was s'pose to be a little tidbit to lure people to look at the link, 'cuz it's quite informative about hardboard.

Originally Posted by Scott Patterson

I wear a wedding ring, I have found that if I tap the siding with the ring on my finger that it has a sharp sound with fiber cement board and a dull thud with MDF.

I knew there was a reason for getting married

Seems most listings that are incorrect here is for OSB siding. It has wood grain finish and looks just like Masonite (hardboard) or cement fiber. That siding is also crap.