Question waterproof barrier

[Billyboy1122]

Have a barn project going up (Michigan barn build) in gallery forum. Considering synthetic felt for exterior walls before vinyl siding to really seal it up from wind and water and polystyrene sheeting inside(two layers of 2") with all edges and joints spray foamed any body do this? Happy with it? My only fear is the old adage about not trapping building materials between two water barriers any thoughts or experience would be appreciated paying as I go going to take 2-3 months to side and roof trying to avoid the tyvek shredded flapping in the wind also

 

[8man]

In the humidity here we use Tyvec or a similar product under the siding. If that is the synthetic felt you are referring to it should be ok. That allows water vapor to travel through while sealing out droplets from getting in.

 

[Voi]

... and polystyrene sheeting inside(two layers of 2") with all edges and joints spray foamed any body do this? Happy with it?

I did this in part of my garage and felt like the cost of the spray foam cans added up very quick. This was like 10 years ago and I got a great deal on the foam sheets but I remember thinking at the time I didn't save all that much money.

With that said, there is work involved but the numbers suggest it's a good way to get a good R value, assuming you're not paying somebody to do it.

I'll let others answer the vapor barrier question.

 

[mtmgtz]

I did this in part of my garage and felt like the cost of the spray foam cans added up very quick. This was like 10 years ago and I got a great deal on the foam sheets but I remember thinking at the time I didn't save all that much money.

With that said, there is work involved but the numbers suggest it's a good way to get a good R value, assuming you're not paying somebody to do it.

I'll let others answer the vapor barrier question.

I think if you wanted to do this method, I'd buy one of the semi-professional spray foam kits that has a couple tanks of foam components. I'm sure you'd burn through a lot of small cans of spray foam which would add up real quick.

 

[Voi]

I think if you wanted to do this method, I'd buy one of the semi-professional spray foam kits that has a couple tanks of foam components. I'm sure you'd burn through a lot of small cans of spray foam which would add up real quick.

I'm thinking the same thing. I think they might even make a Froth-Pak for filling gaps, like when you're doing an entire building of windows.

I have an insulation project coming up and plan to look into it more.

 

[Architorture]

You could also just get foam insulation with tongue and groove edges and skip all the spray foam...if you stagger your joints there won't be much air movement through the 2 layers.

All that said I hope you are planning some sort of sheathing over all of that insulation...if it ever caught fire you would have one hell of a fire on your hands with a barn full of 4" insulation

 

[Billyboy1122]

Inside is going to be white steel barn panels 3x14' tall and steel on ceiling I want to make it as airtight as possible these Michigan winters get brutal trying to keep all the heat in I can with radiant tube floor t5 high bay lights dont want to short myself on light or heat I also thought the foam sheets would give a nice flat surface to lay steel over .. From the YouTube videos and googling it the sheet and sealed edges run about 60 percent of the cost of going with closed cell kits

 

[Architorture]

i'd still look into getting the tongue and groove edge material...it is usually what is used when rigid foam is installed in commercial construction applications without the use of any additional sealer other than a tape over the joints.

using that method you will probably have more success stopping air movement than trying to get the foam to spray into edges butted up to one another.