[QUOTE=Worth1;650739]Thanks.
If a person used 4 inches worth of high density foam board it would be R20.
Every inch has an R factor of 5 with this stuff and it doesn't break down.
Another thing to do is put that silver stuff pointing towards the outside.
The stuff is around 40 dollars for a 4X8X2 sheet.

Worth[/QUOTE]


I have been thinking of ideas for insulating the greenhouse I have now, as well as building another one that is insulated. The most realistic idea I have is to make the north and end walls out of 1/4" OSB with 1/2" foil-faced foam panel inside that.

[url]https://www.menards.com/main/building-materials/insulation/insulation-panels/johns-manville-foil-faced-polyiso-foam-insulation-1-2-x-4-x-8-r-2-7/p-1444438920894-c-5779.htm?tid=3416852253727271463&ipos=2[/url]

The panel is R2.7. I think R3 would be a realistic guess for the osb/panel combo.

The question that requires more creativity is, what if I wanted something retractable? Like a curtain or tarp that would roll up and down over the clear south wall, or possibly even insulated shutters that open and close. I can think off all sorts of crazy ideas, but I don't know the best one to pick.

This stuff is about the same price and has an r-value of 3.2 :
[url]https://www.menards.com/main/building-materials/insulation/multipurpose-insulation/reflectix-4-x-100-single-reflective-white-double-bubble-insulation/p-1444452048012-c-5778.htm?tid=-4924375193444481117&ipos=16[/url]

[url]https://www.amazon.com/Industrial-Grade-Insulated-Polyethylene-12x20Ft/dp/B004ZRMLYM/ref=pd_sbs_60_4?_encoding=UTF8&pd_rd_i=B004ZRMLYM&pd_rd_r=RX93PNY81YT25D3DXD7N&pd_rd_w=LN8Y7&pd_rd_wg=15G5P&psc=1&refRID=RX93PNY81YT25D3DXD7N[/url]

I like the insulated tarp idea. But I am wondering if I could make my own, to make a thicker version.

[QUOTE=Cole_Robbie;650814][url]https://www.amazon.com/Industrial-Grade-Insulated-Polyethylene-12x20Ft/dp/B004ZRMLYM/ref=pd_sbs_60_4?_encoding=UTF8&pd_rd_i=B004ZRMLYM&pd_rd_r=RX93PNY81YT25D3DXD7N&pd_rd_w=LN8Y7&pd_rd_wg=15G5P&psc=1&refRID=RX93PNY81YT25D3DXD7N[/url]

I like the insulated tarp idea. But I am wondering if I could make my own, to make a thicker version.[/QUOTE]

I don't see why not.
Worth