Questions for Sealing the new Tyvek and Vinyl Siding

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Old 08-31-11, 08:23 AM
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Questions for Sealing the new Tyvek and Vinyl Siding

I finally have started the project to replace hail damaged vinyl siding and do some air sealing while it is open. I am starting at the most protected, least noticeable and most easily accessible area till I get the hang of it. There is no house wrap and if the gaps around this door are any indication, it's no wonder I have breezes inside just about everywhere. I assume there is similar work around the rest of the house.

My plan is to caulk every seam/joint between osb panels, around windows/doors and especially under the threshold plate of the double door where water routinely comes in, and then cover with Tyvek.

What can I do to protect the bottom edges of the sheathing where it meets the patio? I had thought to install some kind of flashing all along the bottom and caulk it thoroughly (and I do mean thoroughly) to the concrete and the Tyvek to prevent the standing water that always is present during any significant rain from reaching the wall. Is there another approach I should consider?

Do I need to loosen the deck ledger to tuck the Tyvek under or is flashing the top of the ledger sufficient?

Finally, (at least for today; this is a pretty big project) what do I do with the Tyvek around the door trim?

Siding Project pictures by Yukon_Youngun - Photobucket
 
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Old 08-31-11, 11:38 AM
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Over the deck, you would want to flash the ledger itself. Usually this is done before the deck boards go down, so that the flashing can completely cover the top of the ledger- a downward lip on front prevents water from blowing back under the flashing. With vinyl siding, it's important that the dripcaps be against the sheathing, taped to the sheathing with window flashing tape, if possible, and then the tyvek laps over the top of that. The Tyvek does not need to go behind the ledger. But you may want to remove floor boards so that you can directly flash the ledger, not just the floor boards since that won't do much good.

Under the deck, you would also need a drip cap under the deck ledger, so that water does not get behind the siding. Caulking the top of the j-channel to the ledger will also work, but metal flashings are always better since caulk can fail.

Your OSB should not be that close to the cement, it is just asking for trouble. I would make sure it is cut up at least 3/4" from the cement to prevent wicking. You should flash the wall to the cement, caulk underneath the flashing (against the cement) with a cement sealant, vulkum or OSI Quad, then push the flashing into the sealant. Again, you'd tape the top of the flashing directly to the sheathing with window flashing tape, and lap the tyvek over the top of that.

Caulking the front of a door threshold rarely does any good because those thresholds are hollow underneath, and have hollow end caps. So if you caulk it, you will need to do the ends of the sill where it meets the jambs, and then pay special attention to sealing the end caps, in addition to just the front of the sill.

You should have a drip cap over the top of your brickmould on the top of the door. This would also be taped directly to the sheathing as mentioned above.

If you are planning on replacing the door trim, I'd take it off, run the tyvek to the rough opening, then install the new trim on top of the tyvek. If you want added protection, add more window flashing tape, folding it out slightly onto the sides of the brickmould.

Another problem might be the way the siding starts in a j-channel against the cement. j-channels catch a lot of water as rain runs down the house. ALL this water then dumps out the ends of the j-channel or overflows out the front... not exactly what you want to have happen so close to your door. It's often best if you do use a j-channel in a spot like that to drill large weep holes in the bottom of the j-channel every 16" or so, and then keep it up off the cement 3/4" or so so that it can drain. That way the water is dispersed instead of being dumped out in one or two locations. Not sure why that siding wasn't started in a starter strip (instead of j-channel), but it's too late for that now.

If you want your tyvek to be a true air barrier, you will need to tape every edge and seam with tyvek tape or window and door flashing tape. Very few contractors will do this because it's too time consuming, and the benefits are pretty hard to measure.
 
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Old 09-01-11, 07:38 AM
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Thanks for your advice. You have cleared up several of my concerns that I would have wasted days thinking about.

I had not thought about drip edge below the ledger, but it makes sense so adding lower drip edge to the plan.

I won't be able to cut back the lower edge of the sheathing, but will have to depend on a really good flashing and sealing job. Besides this area, if we continue around to the right from the photos where we go off patio, the grade is similarly too close to the top of the slab. I suspect that similar flashing & sealing would help here too to keep splashing and standing water away, as well as insects. I would just be sealing flat metal to the vertical edge of the slab instead of horizontal. (We do have tentative plans for a gravel bed there, and perhaps a french drain for the same reasons.)

Since I am doing new siding, I can easily replace the bottom j-channel with a regular starter strip. I have always seen the channel used this way and thought it pretty stupid to funnel water right into the wall like that. Now, I see it's likely one of those contractor short cuts and not necessarily a system design flaw. Still, the flashing seems to be key here, and I'm guessing that doesn't get done all the time either.

Now, for air sealing I tape the Tyvek to the flashing. Do I just lap the Tyvek slightly over to leave vertical surface to tape to, or will the tape hold on the horizontal surface of the flashing where it will be flooded on occasion? The drip edge and flashing material I am looking at has less than 2" to work with.
 
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Old 09-01-11, 12:24 PM
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When you nail the drip cap directly to the sheathing, what I was suggesting was using window and door flashing tape (sticky butyl rubber like pella tape or protecto-wrap) to tape that upper leg of the drip cap (that you say is about 2" high) to the sheathing. What this would do is give you a lot more area to lap the Tyvek over. That way you could keep the Tyvek 2-3" higher than the bottom edge of the drip cap and your tape would not be subject to as much weathering.

Something else you could do along grade (or over the cement) is install a PVC 1x8 (like Azek or Versatrim) in order to keep your siding up out of the dirt and reduce that dirty splash back when it rains. You'd cap the top of the 1x8 with a drip cap, and then start your siding up above it in a starter strip. You could also caulk the snot out of the bottom edge to seal it to the cement and keep water out. Kind of like what you plan to do under your flashing. Just an idea you could think about.
 
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Old 09-02-11, 01:12 PM
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Of course, it would be 100 again today and rain expected tomorrow evening...

Oh, yes, I just lost my head for a moment about the tape on the flashing. Plenty of room to tape the Tyvek down over the first layer of window/flashing tape. Question now is, use Tyvek tape next or more window tape? I'll assume window tape, suspecting that the Tyvek tape is designed to stick to the wrap and not whatever rubber material the other tape if made from.
 
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Old 09-02-11, 04:19 PM
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I think the tyvek tape will be fine to seal your lap joints (you usually overlap 6" minimum) and it should also stick to the surface of the flashing tape.
 
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