Covert covered deck to three season room

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Old 07-04-15, 09:57 AM
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Covert covered deck to three season room

We have a 40 foot deck along back of house which is covered with waterproof membrane to provide a dry storage area underneath. 20 feet of the deck at one side, where door from house is, is covered with another deck on top with waterproof membrane. I would like to enclose the covered portion of the deck and make a three season room. There will be a sliding glass door leading to uncovered deck. I am trying to decide how best to build the wall where the new glass sliding door will go with appropriate flashing etc. The vinyl flooring is currently continuous on both decks and is sloped slightly away from house for drainage. I was thinking of a 2by6 caulked and screwed onto the vinyl, then framing the door from that, with the 2by6 serving as the sill, or door could go directly on existing floor. I'm worried about water getting in under the 2by6 as the floors on both sides are level.... Should I flash the 2by6's on floor, or is caulking sufficient.

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Old 07-04-15, 10:16 AM
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You mention "vinyl" as a floor covering. Certainly this isn't a linoleum type product. Is there any slope to the upper deck to rid it of water? Does it overhang the lower deck to eliminate capillary action of the water?
Building the wall can be straight forward with certain cautions. Any hole you make in the waterproof covering must be sealed prior to the fastener entering it. I would use a product like PL8X to adhere your bottom plate to the floor covering, as well as the door threshold. It also should be sealed properly against the weather. Your wall will hold things together, and once the adhesive dries, you won't move it. You will need to flash over your door frame, but if the flooring is truly waterproof, no flashing would be necessary, except flashing tape for the door.
 
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Old 07-04-15, 10:24 AM
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Duradeck vinyl sheathing.

I am concerned about rain getting under 2by6 used as base of wall, or water pooling next to the 2by6 in heavy rain. Presumably the weight of the wall may cause a slight drop in floor, so water outside could flow towards it... I am used to having an elevated cement base to start a wall on..
 
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Old 07-04-15, 10:37 AM
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I will use a strog adhesive to attached pressure treated 2by6 bottom plate (blue) to duradeck (green). The wall will be sheathed in plywood, then building wrap, and vinyl siding. Do I need to flash the bottom plate as I can imagine some water pooling against it in wet weather... and if so, how... Name:  deck2.jpg
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Old 07-04-15, 10:39 AM
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Any bottom plate will have a sill seal applied to help prevent seepage. Owens Corning Foam SealR Sill Plate Gasket 5-1/2 in. x 50 ft.-2FS - The Home Depot In addition using a good bead of sealant under all your bottom plates, you should not experience leakage. I would not entertain removing the vinyl as it will surely leak at that point.
 
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Old 07-04-15, 12:38 PM
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I'm confused now. Where do I glue it with PLX8, where does the foam sill plate gasket go, and where do I caulk. I am starting with a duradeck surface and a 2by6 pressure treated board for bottom plate
 
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Old 07-04-15, 01:05 PM
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If you use the foam sill seal, you will fasten with conventional screws through your flooring. Sealing the outside of the plate will be an absolute necessity. Flashing with galvanized metal is a plus if you are installing siding over it all. What are your plans for exterior covering? 1/2" OSB then vinyl or other? If you just want to fasten it down with an adhesive, the PL8X or equivalent will act as a sealant as well, and must be applied in solid ribbons along the length of the plate.
 
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Old 07-04-15, 01:15 PM
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I plan to use a foam sill plate and screw the 2by6 bottom plate through the foan and flooring. Caulk edges. I with then sheath in 1/2 inch OSB, house wrap, then vinyl siding. My concern is that water on the flooring surface outside will come up against the 2by6 bottom plate - even if it doesnt leak under, that board will still get damp. How would I flash with metal at bottom? I am used to started a bottom plate at an elevation from ground level and rain; not on the same level.

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Old 07-04-15, 01:32 PM
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Extend your OSB on down onto your plate as shown in blue and apply flashing as shown in red. No nails in flashing except to hold it under WRB.

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Old 07-04-15, 01:38 PM
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Thank you. What is WRB ? house wrap - weather resistent barrier?

I was thinking of flashing exactly like that, but then I have the same question as to how to seal / attach the flashing to the exterior flooring surface?
 
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Old 07-04-15, 02:02 PM
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Yes, WRB=weather resistive barrier, or Tyvek. Don't attach the flashing to the flooring. The less holes you poke in it the better flashing job it will do. Sealing the flashing to the floor may negate the air needed to keep the area behind the flashing dry. It will lay in just fine.
 
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Old 07-10-15, 04:21 AM
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Using a foam sill plate gasket, do I need to apply sealant under or on top of the foam strip before screwing the wooden subsill onto it and into deck surface.

If I didnt use foam sill gasket, I would glue/seal the subsill to deck along with screws, but with the foam would that decrease the effectiveness...
 
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Old 07-10-15, 04:45 AM
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Make your gasket continuous, taping any joints you have and once you apply pressure from the screws, I would just apply a good bead of OSI Quad or equivalent to the edge of the plate where it meets the decking to help further prevent weeping. Nothing is perfect, so we have to do a little extra sometimes. I know you want to eliminate the possibility of seepage into your new room. This, along with the WRB, flashing, etc. will make a good seal.

You won't be able to glue the plate down if you use the foam seal, as it will not have any effectiveness. I think that is what you are asking.
 
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