Hardi Board Installation

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Old 02-27-16, 08:30 AM
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Hardi Board Installation

I have some rotted T1-11 siding I need to repair. I am thinking about repairing the rotted T1-11, putting house wrap then Hardi Lap Siding. I have some question.


1) Looking at the photo below you can see the bottom of the T1-11 is rotted.

02.27.2016-11.07.21 - Bobby1002's library

I could cut out the bottom 16” or so, Z Flash and install new T1-11, but I was thinking it would be better to cut out the rotted T1-11, install blocking and install Pressure Treated Plywood in the damaged area and patch the T1-11 and Plywood butt joint. My thinking being near the bottom if water splashes up or weeds grow up the Pressure treated plywood would not rot like the T1-11. So it will look like the photo below:

02.27.2016-10.56.44 - Bobby1002's library


If I go this route my question is the T1-11 is 5/8”. I am still looking to find a local place that sells 5/8” Thick PT plywood. Does this option seem the best way to go.

2) The 2 roofs intersect on both sides where I will be installing the Hardi Lap Siding as shown in the photo below. As you can see they used T1-11 with z flashing. I am thinking on the roof sloping down I would use either L or step flashing and some type of rain diverter at the end to direct the water away from where the facial would hit my new Hardi plank. I would caulk between the Hardi and the Facial, which seems like a leak potential. I circled the ares in green. I am not sure how to best side this location. Any suggestions?



02.27.2016-11.22.15 - Bobby1002's library


3) Between the Studs and the original T1-11 Siding is felt paper as a WRB. Is adding house wrap between the T1-11 and the Hardi going to be an issue?

4) Flashing around the windows and door. I am not sure how you can do a perfect leak proof flashing without removing the T1-11 and windows, which I am not going to do. I am thinking about running the house wrap right up to the window and then run Flashing tape against the window edge and over the house wrap. Then install the window 1x4 trim, top header and then Hardi.
 

Last edited by rwbil; 02-27-16 at 10:08 AM. Reason: additional info
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Old 02-27-16, 10:46 AM
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1. If you are covering in housewrap, it should never get wet, so I don't see what the point of treated plywood is, but yes you could do that. You could also use regular plywood then cap the bottom edge with z flashing, installed on top of the plywood and backward.... as a cap to shield it from splashing.

2. Yes, the shingles should have step flashing, the lowest piece should have a kickoff that directs water away from the wall. Subfascia (the framing behind the outer fascia) should have step flashing that will shed water over the lap siding. Generally the fascia should be cut back so that the siding can run behind it, rather than burying the end of the fascia in the siding.

3. Nope. But personally I would not waste time patching the rotten siding, I would tear it ALL off. Is there wood sheathing behind that felt paper? What kind of shape is it in?

4. You're right, you really can't do a perfect job, which is why the siding should probably all be torn off. The windows do not need to come out. Why are you against removing the siding? It doesnt cost anything to remove the siding... no plywood to buy...it may be a whole lot faster to tear it all off, paper the wall tape the nail fins and be ready for siding. You don't need to tear all the siding off the whole house at one time... just work on one side at a time. To properly flash the windows, the flashing tape needs to be applied to the nailing fin of the window. That's behind your current siding, so to get to the nailing fin, you just remove the sheets of siding. The housewrap does not necessarily need to go behind the nailing fins, since it will be taped with flashing tape, but if you can pull a few nails on the bottom fin and tuck a strip of wrb under the fin with a putty knife, that would be great. On top of the window, the wrb should overlap the top piece of flashing tape. (cut a flap, fold it up, tape the window directly to the original sheathing- not to the felt paper- fold flap back down, tape ends of flap.)

The bottom edge of your siding is so close to grade that you should install a pvc 1x6 frieze banding that would never rot. Drip cap (either a real pvc drip cap nose or a z-flashing on top of that) then a 1/4" space, then start lap siding above that. Generally fiber cement siding should be kept at least 6" above grade, 1 - 2" above a roof, patio or sidewalk. Each brand will have specific installation instructions you should follow regarding clearances.
 
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Old 02-27-16, 01:15 PM
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XSleeper,

I do not want to remove the T1-11 as here in Florida they are installed with ring shanked nails and I actually went to the emergency room from removing one sheet one time (my clumsiness but T1-11 nailed with ring shank nails is not a piece of cake to remove). 2nd I would then have to install either plywood or insulation board do give backing strength to the Hardi planks. The wall is currently studs, 30 # felt (WRB) attached to studs and then T1-11.

Hmmm, now that I think of it this section is an addition so it is possible they did not meet the codes and used regular nails. I will have to check. If I can remove the T1-11 would you recommend studs, rigid insulation, house wrap then Hardi.

One of the reasons I wanted to use the PT plywood was for the reason you mentioned close to the grade.

You mentioned If you cover in house wrap it should never get wet, but I read on the web some saying it does get wet behind the house wrap. Do you put any tape over the nails attaching the house wrap to stop water infiltration? My thinking is the house wrap will allow the water vapors to escape if water does get behind it and trapped.

On 2 you stated subfacial. I got rafters and facial nailed to rafters. You stated it should have step flashing to divert water away from lap siding. Do you have a picture of that? I was thinking I could remove the facial and then run felt behind it and behind the Hard Board. The felt would extend over the top of the lower Hardi plank so water could run off. I am not sure how that would work. I could cut the facial back as you mentioned, but it just seems like whatever I do when I come up to that intersecting roof there will be problem area.

The T1-11 does not cover the entire nail fin. I could cut back the T1-11 a little more then run the flashing tape against the window a little bit on the nail flange and then on top of the house wrap. On the bottom I guess I could cut the T1-11 further back 2 to try and get the house wrap under the nail flange. So it would run under the nail flange then step up to run over the T1-11. Might be better to do that with Flashing tape which is stronger. So flashing tape under flange step up and over house wrap. After all, all this will be covered up my the Hardi Board trim.
 
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Old 02-27-16, 02:22 PM
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I wondered if there wasn't any sheathing behind the siding, you confirmed that. The ring shank nails must be a Florida hurricane code... I'm not up on that, but if that's the case, each piece of siding is likely a shear panel, required for strength. So, no... you would not use 1/2" foam. 5/8" plywood, nailed per Florida code.

Cheap woven housewrap might let some water through... i would never suggest you use that. A good brand of wrb, such as Tyvek, will not get wet behind. If it does, there is either an installation problem, like you lapped it backwards, or there is a leak from up above it that is getting behind it at the top, or it might on occasion get condensation behind it (like dew), and housewrap are vapor permeable, meaning they can dry to either side as needed. No you don't tape over nails. So normally, no... it does not get wet behind the wrb. If you stucco or dryvit on top of Tyvek, it might be prone to get wet behind, because the tyvek can't breathe to the exterior. In cases like that you need to use a drainwrap like Tyvek stuccowrap.

Here is one picture i found of the kickout flashing. Go to Google images if you want to see more. http://michaeldleavitt.com/mdl/image...ickout-MDL.jpg

All you need to do is lap your siding and flashing so that one course of flashing sheds onto the next. You can't direct water behind the siding, you always want to lap it on top. So you would put siding on up to the bottom of the fascia... (that's how it is spelled)... cut back your fascia, pry it loose so you can slip a step flashing behind, then the bottom of that step flashing would cover the TOP of your piece of siding below. Then your next piece of siding could go on, and the kickout flashing would probably lay on top of it... each course flashing the next. Then the next piece of siding would probably have a slot cut in it so that it can drop down over the step flashing, covering the top edge of the flashing. Sorry if this sounds confusing, it's easier to do it than it is to describe it.
 
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