Friend is installing new windows on an already build 3 season porch – he ash installed new windows and is interested in tightening the space up as much as he can with out pulling off the old siding.
Siding is masonite (original siding) covered by vinyl siding.
he will put insulation in the walls – his question – should he also put a vapor barrier against the siding? tks Dudley
Replies
He would be making it into a conditioned space, and the vapor barrier should be placed "as appropriate" for your climate, which I would guess would mean towards the inside in MD, not the outside.
But likely a vapor barrier isn't needed at all, since the space is inevitably going to be leakier and therefore lower humidity (in the winter) than the rest of the house. (Whether local code may require something is another issue.)
He might want to put some sort of wind barrier (eg Tyvek) against the siding, but retrofitting such a barrier can be difficult.
So Dan (I'm the one insulating the porch), are you saying that, I put in foil backed (one sided) insulation with the foil on the inside of the 2x4's? No foil back on the exterior side? And/or, if I caulk the 2x4's that sit on a (4 courses) brick base all around to keep bugs, dampness etc. should I put a sheating with tyvek on it before insulating?
Thanks,
Porchguy
A little clarification; The exterior side of the walls are sided and are going to stay as-is, right? And the interior of the walls are open 2x4 stud bays?The framed walls are sitting on brick, is the brick going to remain exposed on the interior or covered up?If the walls are sitting on 4 courses of brick, is porch floor slab-on-grade? Or framed and elevated with a crawl space underneath?
Here's the skinny. This was a screened porch which I have ripped out and put in slider windows that sit on a shelf. Below the shelf is simply 2x4 studs on top of a 4 course row bricks to get above grade. The height of the 2x4's on the brick to shelf is 1 1/2'. When the porch was built (26 years ago) they simply nailed masonite siding onto the studs. They have since been covered with vinyl siding. So, I was going to caulk the stud joints and where they meet the bricks to keep out dampness and bugs. I will not cover the brick to floor (which is concrete) on the interior. But, given that I want to insulate, I was wondering if I need to put a vinyl (vapor barrier) cover next to the interior siding before putting the insulation in to avoid mildew and moisture. This will not be heated or cooled in the winter/summer months simply a kind of Floriday room off the family room which has a sliding door from the house to the porch. The windows are to keep the snow, rain and dirt out year round now and, make it more longer seasonal room.
As for the concret floor, I was thinking about putting down a TREX floor on a 2x4 frame. What do you think?
Porchguy
Based on your description below, you probably don't NEED a vapor barrier, period. But if you install one (eg, the one that comes attached to the insulation), it should (based on the conventional wisdom) be installed towards the "warm" side.The purpose for installing Tyvek or something similar would be to prevent air from blowing through cracks it the siding and degrading the insulating value of the (I presume fiberglass) insulation in the walls. You alternatively could just caulk every crack you can find, or install the insulation backwards (from what's described above) so that the vapor barrier serves as a wind barrier (of sorts -- not very good but better than nothing). You run a very slight risk of creating conditions that could lead to condensation in the walls if you install the insulation "backwards" like this, but probably not enough of a risk to worry about.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Thanks for your insight, I'll follow your instructions and simply install it as it is supposed to be. I'll also caulk, REAL GOOD!