5 posts / 0 new
Last post
flipfriddle
Insulating Porch

I'm finally having a contractor come in and replace the rotted jalousie windows in my porch. The porch was originally open to the elements but was closed in by the previous owners years ago. I am going to insulate the short knee walls and soffits, but I was curious how I should insulate the floor? The porch is up off the ground by about 2.5ft on piers and has empty joist bays right now. I'm thinking rigid insulation in the joist bays would work. Would I need a vapor barrier if I use rigid foam?
A second question I have is the porch currently has a double column design on each corner. The two columns are about 8 inches apart and the previous owners stuck a single pane of glass in the opening with stops on either side. I plan to get rid of the glass, add some blocking in between the columns and close the opening, insulating the gap, and using paneling on the inside to match the rest of the interior. On the outside I was going to sheath it with OSB, and then cover that with clear pine and paint it. I'm not sure what sort of weatherproofing I should add on top of the OSB. Should I just do tar paper, or house wrap and caulk all of the seams, before I put on the finish trim, or is there more I should do?
Thanks for any advice. I can supply photos if it would help.

dj1
Re: Insulating Porch

Flip
This is more than a lawn mower...
1. I would lay a vapor barrier.
2. A photo will help, but in the meantime: I would use plywood, wrap it good with Dupont wrap, apply the finish panels and moldings - and it will be ready for paint. Just make sure no water can come in at the bottoms and the tops.
Enjoy your summer projects!

canuk
Re: Insulating Porch
flipfriddle wrote:

I'm finally having a contractor come in and replace the rotted jalousie windows in my porch. The porch was originally open to the elements but was closed in by the previous owners years ago. I am going to insulate the short knee walls and soffits, but I was curious how I should insulate the floor? The porch is up off the ground by about 2.5ft on piers and has empty joist bays right now. I'm thinking rigid insulation in the joist bays would work. Would I need a vapor barrier if I use rigid foam?
A second question I have is the porch currently has a double column design on each corner. The two columns are about 8 inches apart and the previous owners stuck a single pane of glass in the opening with stops on either side. I plan to get rid of the glass, add some blocking in between the columns and close the opening, insulating the gap, and using paneling on the inside to match the rest of the interior. On the outside I was going to sheath it with OSB, and then cover that with clear pine and paint it. I'm not sure what sort of weatherproofing I should add on top of the OSB. Should I just do tar paper, or house wrap and caulk all of the seams, before I put on the finish trim, or is there more I should do?
Thanks for any advice. I can supply photos if it would help.

One question that will have some influence on the answers ---- are you planning to heat/cool this space ?

Re: Insulating Porch

No permanent heating or cooling apart from a ceiling fan in the summer (with the windows open) and a small ceramic space heater to take the chill off in late fall and early spring. We'll have to see if just opening the room to the house in the dead of winter makes it liveable or not. Currently we use the porch as a walk in freezer in January and February. :)

canuk
Re: Insulating Porch

Since there won't be any conditioning of this space ( heating/cooling ) then vapour barrier is not required.

For insulating the floor using the rigid foam within the joist bays will work.

However, you could also use regular batt insulation which may be more econmical.
Apply rigid foam to the rim joist around the entire perimeter --- Fill the entire joist bays with batt insulation then attach 2 inch rigid foam sheats to the underside of the joists. Use foam in a can to fill all voids around the perimeter and in the butt seams of the rigid foam sheets.

By completely covering the bottom side with the rigid foam will increase the insulation performance not only with the extra R value but with providing a continious thermal break to the floor.

As for using housewrap or tar paper for the siding --- since this space will not be conditioned then house wrap isn't necessary but it will work as a weather barrier --- tar paper is cheaper and will also work as a weather barrier.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.