Insulating roof and walls

[5thgen]

I have a 20x34 pole barn that has reflective foam insulation clamped in between the purlins and the metal exterior wall. The very top of the gable roof does have a ridge vent, and there is one eave on the long side of the building (is not vented). I am looking to maybe adding more insulation than just the reflective foam (maybe .25-.5" thick), but am wondering on how to properly keep moisture away. I am going to try and keep the trusses open as I store some things up there.

I plan to drywall the walls after the insulation is complete....the ceiling, however, will not have drywall if possible.

If anyone has any suggestions / ideas I'm all ears. Thanks for any help.



I think I have to get to something like this?

[Shocker]

Ok, so a couple more questions for ya. How wide is the space between the rafters/trusses?

How thick is the current foil backed insulation and what is it's R value?

One thing you would lose by topping the foam is the reflective quality of the foil. You could get some high density polystyrene foam panels, cut them to fit and glue them directly to the foil faced foam.

Then maybe go over the top of that with a foil backed bubble insulation. No vapor barrier needed as the foam boards are impervious to moisture.

[5thgen]

Trusses are 8' oc. Rafters look about 1.5-2 feet apart. Existing reflective foam is about a quarter inch thick. Will the area around the outer steel wall need to breathe at all? I'll do whatever I need to do to avoid condensation

I don't know the R value of the reflective foam....I don't think it is much though.

[5thgen]

here are a couple of pics of what I'm dealing with. I was going to frame the walls in and fill the space with insulation rolls.

[Shocker]

Well, how is the foil backed foam attached to the wall?

You could just go over it with polystrene boards and cover it all with poly sheeting.

[5thgen]

The foil foam is sandwiched in between the metal roof/walls and the wood. Kind of like a "steel building" with the plastic covered insulation. I may rigid foam the top and fiberglass the walls. I don't know what to do with the ridge vent though....

[VC-Racing]

Mine building is similar except mine has the "Double bubble " insulation , I too was going to add more, but after this summer I realized I had enough to keep from baking inside. Now that winter is here, I think I have enough to keep the interior reasonable warm with the help of a small propane heater I have. My ridge vent is open for the entire length of my building and I'm going to fab a hinged door , similar to a damper in a fireplace, to close or open the vent as needed.

[5thgen]

I think I'm going to just try and build a ceiling. Right now all I have are the trusses going across at 8' oc. I don't know if it will hold the weight of 3/8 or 1/2 inch drywall under.....guess I'll have to call someone to check it out.

I'm thinking a 16" oc 2x4s that would "connect" truss to truss.

[Dragster Racer]

Originally Posted by 5thgen

I think I'm going to just try and build a ceiling. Right now all I have are the trusses going across at 8' oc. I don't know if it will hold the weight of 3/8 or 1/2 inch drywall under.....guess I'll have to call someone to check it out.

I'm thinking a 16" oc 2x4s that would "connect" truss to truss.

I did that with 1/2" osb, and it worked fine. Easy to blow in insulation on top if it. I put a vb on before the osb, and my attic is vented. I think you would have to vent the attic for sure.

[5thgen]

It has a ridge vent running the length of the roof. I will add soffit vents to help bring in fresh air.