Hardi Plank Siding

Installing 7 1/4" X 12' Hardi plank siding on a 20' section of the house and not sure what to used to hide the seams. Thought about using a paintable door and window sealer but have not found any that are sandable. Wondering if a cement based grout, or something simular would work best. Any suggestions, comment appreciated!! dave

 

You're not lapping/overlapping it?

 

Yes, I am overlapping the planks about 1 1/2 " just not sure the best way to hide where the 2 planks join? 1 plank extends the 12' and there's a 6' piece to complete the run, and it's where they join that I am not sure the best way to blend the 2 pieces?

 

Oh, duh! I get it now, the vertical joint where two pieces meet, not a horizontal joint.

 

The Hardie instructions address this very well. http://www.jameshardie.com/pdf/insta...plank-hz10.pdf

 

Appears it's basically a latex sealer and fairly certain the local hardware store should carry it. Thank you for the resource!

 

Looking at your first post....why would it need to be sandable? You will never completely hide the joint. This isn't like working with sheetrock.

More importantly...did you flash behind each joint as they recommend?

 

IMO, the best practice is to flash behind the joint, then just butt the pieces together with moderate contact and no caulk. The pieces can expand and contract slightly, and they lay flat. It just seems that the stuff expands and contracts just enough that if you caulk it, the caulk joint will break loose from one side or the other. The caulk can also cause the joint to bulge just slightly when the piece wants to expand. With prepainted siding, the butt ends are already painted, but if you are putting up primed hardi, be sure you paint the ends before you butt them.

I've seen pictures of houses done both ways and after a few seasons, the uncaulked joints look best when viewed from the side.

But if you absolutely want the joints caulked, I would still flash behind each joint, but then leave a minimum 3/16" gap. Be sure both butt ends are clean and have been primed with a latex primer, then paint those same ends, and give it plenty of time to dry. Then caulk with a sealant that meets ASTM c920 specs or a latex caulk that meets ASTM c834. (read the label)

 

Not sure what they recommend for flashing, but I have used window sticky tape run up under the course that will cover it, and stop it just short of the bottom of the hardi.
Some "contractor" sided a local funeral home a few years back and caulked all the joints. Can't find a smilie for "puke", but that's the feeling I get when I pass by. It just doesn't look good.

 

I've always been scared to use the window flashing tape, due to the horror stories I've heard about some butyl flashing tapes melting in the hot sun and then the goop runs out of the siding laps. I don't know that I've ever heard which brands will do that.

I've alternated between using flat metal roofing shingles and Tyvek that has been doubled over.

 

I do see the possibility of running goop, but haven't had it happen yet. I like the Tyvek approach as well. I guess anything to shed water out of the crack area to the layer below would work within reason.

 

Already laid the 1st couple lengths of hardiplank siding and did not use the flashing strips, may consider for the remainder of the project? Browsed thru the paint section of local hardware store and sales person, who said he just installed the hardiplank siding on his house, recommended " Big Strech" sealer; according to item description, it will not crack and used to seal doors, windows, and siding. The sealer comes in different flavors so I picked a color closest to the color of the exterior paint. Lesson learned, read instructions, if item does not come w/ instructions try and find them online. Appreciate everyones input, thank you!!

 

Big Stretch is an awesome elastomeric caulk/sealer. I would lay in a bead before jamming the pieces together, and try to avoid applying it after the pieces are up. It will squish out just fine.

 

Sounds great, I had not thought about applying before joining the 2 sections, imagine with a little patience may be able to minimize the seam. Appreicate the suggestion!!.

 

Instead of a butt end joint, cut them 45 degrees and have a slight overlap. The joint won't be invisible, but it will be far less noticeable. Baseboards are often joined in this manner.

 

Food for thought, there's a 1 1/2" overlap with less than 6" of hardiplank exposed. I have several pieces of scrap and should be able to get a fairly good idea whether a butt, or 45 degree cut will mininize the appearance of a joint, thank you for the suggestion!!

 

Follow the manufacturer instructions. If they don't recommend a scarf joint...there's a reason. Probably because the thin edge would be very susceptible to damage. This isn't wood trim you are dealing with.

Once again...you will not make joints invisible.

 

You can't miter hardie plank siding easily without compromising the thin area created by the miter. In addition Hardie only recognizes butt joints in their literature.

 

This project has been an ongoing learning experience and could not have done it without suggestions and input from DIY members. Thought I would update for any member who is considering using hardiplant for exterior siding? Found the suggestion of applying the sealer before butting the joints together worked best for me and used a small plastic spreader to smooth any excess compound. Decided to cut the hardiboard joints square using a 7 1/4" Hardiplank circular saw blade, they can get expensive, at least $50, depending on size, and that the cheaper $20 variety last bout as long as it takes to cook a 3 min. egg. Rather than use my 12" compound miter saw decided to purchase a used circular saw and it worked fine. Took a pic just before completing this phase of the project and pleased with outcome. Again, thanks to all for the suggestions and input!

 

I'm sure you did fine....but I have a question.

Where's the rest of the house? That looks like some sort of shed or 1/2 a modular home of some sort.

I'm sure it's just the pic....but it looks odd.

 

It's a small cabin, approx. 800 sq ft., add 150 sq ft to include a 10x15' loft, but it's not a good picture, to the left of the extension ladder the wall and roof is recessed approx. 7' then the wall and roof line continues out and upward another 12', with more light, and another angle the rest of the side of the house can be seen. The cabin was built in the mid 60's, and don't believe it came with square walls, or level floors. Apparently, back then soup can lids were an acceptable method for plugging holes in roof and floors, while newspaper was used for insolation?? Anyhow, it's definately a smaller home, thank goodness, as mentioned, the project has been a learning experience and hopefully provide a few pointer in what to look for, and not, in buying another home?

 

My Grandmothers old house in San Diego had newspaper insulation. More than was expected for a house in that climate.

Tiny 4 room + bath home. The garage was almost as big as the house....but she and Grampa raised my Dad there back in the 30's. Heck...it actually had a floor furnace....which it seems was pretty uncommon. No A/C but lots of tree cover and a great little garden in back.

 

The newspaper wasn't so much used as insulation but to stop all the drafts. I used to enjoy reading some of the old news on the walls..... haven't seen newsprint pasted on the wall in a long time.

 

Oh...in my Grannies case...it wasn't pasted or anything...just stuffed in the walls between studs. I saw it when she asked me to replace a light that quit working. Didn't open up walls or anything...just pulled the fixture off and saw what was in the cavity.

Boxes? We don't need no stinking boxes. Just screw it to the lath....

Hey...I was only 19 y/o, so I just replaced what didn't work.

Not positive but I think Grandpa (my namesake but no memory of him) may have built the place.

 

What I've seen is the newsprint applied like wallpaper but instead of hung on plaster/drywall it was hung on what ever type of wood was used as a wall covering. It wasn't uncommon to see multiple layers - the paper was prone to rip where ever 2 boards met.

Hey, maybe grandpa was ahead of his time - isn't cellulose ground up paper

 

Yes, nothing like sitting in the bath and peeping thru the cracks to check on the weather. What I found most disturbing, purchased the cabin in late 70's, just after prior owner made a couple upgrades, then later found newspapers in the walls dated from the mid 70's; I mean, newspaper for insulation in the 50' and 60's, maybe, but find it hard to believe it was acceptable in the mid 70's, cheapscapes, and yes the newspapers did make for interesting reading.

 

Don't mean to beat this thread to death but for 'Info Purposes' thought it would be of interest to any member who intends to cut hardi-board, or hardi-plank. About 1/2 way thru the project, and shopping for a 3rd hardi-board blade, decided to give a 7" Diamond Dry Cut Segmented rim blade a try, so far, it has outlasted the other 2 blades and still cutting well; most importantly, not only is the blade lasting longer but it's cheaper and makes for a cleaner cut, does not chip away at the material. Anyhow, food for thought!!!.

 

Segmented blades do cut well and last longer, but James Hardie doesn't recommend cutting with segmented rim blades due to the amount of dust they create as they grind through the cement. (See their instructions regarding cutting and warnings about silicosis.)

 

Imagine that's why the cuts are smoother, chips the material as oppose to grinding. I found the segmented blade cuts thru the material much easier and although there is some increase in cement dust I wear a mask regardless. Apprciate the info, for improved filtering probly break out my automotive painting mask?

 

stole this dust control idea from a pro who was cutting granite.

Have not used it for Hardi-plank but have successfully for many other cuts to reduce dust: fill a plastic gallon milk jug with water, punch a hole about 1" above the bottom, place it near the saw blade so when you loosen the top of the jug the water pees out, adjust location based upon pressure, etc so the water stream hits your blade, when done cutting retighten the cap for the next cut and you have a poor man's wet saw.

Not sure if it will work here or not but it is cheap thing to try is you have alot of cuts to make.

 

spiper, the only problem with that idea is that fiber cement siding is not supposed to get wet, and if it does, you need to wait until its dry before you install it. Wet cutting is not recommended by the mfg, but cutting with a carbide tipped fiber cement hardie-blade with a vacuum assist saw is.

The best bet is always to follow the mfg's directions which are quite clear.

Fiber cement blades will be trashed if you cut into any wood, even once. They are only made for cutting fiber cement, so if your blades aren't lasting very long, I'd say that you need to be careful about what's underneath the siding as you cut.