Numenor Posted April 10, 2017 Report Share Posted April 10, 2017 We will be ordering a pre fab Reeds Ferry Shed in the next few months which will serve as a workshop (wife wants all explosive-y stuff out of the basement). I will be doing the wiring, insulation trim etc etc to the interior. I am in Massachusetts and the shed will be approx 12x18. Do I need a proper vapor barrier in addition to the vapor retarder included in the paper faced insulation, and will 3 Louvered vents provide enough air movement or should I upgrade to the ridge line and soffit venting? To start I will have a window AC in the summer and a small ceramic heater in the winter. Eventually I want to put in a mini split (unless the AC/space heater perform better than I think they will. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Ronn W Posted April 10, 2017 Report Share Posted April 10, 2017 If you are heating a building you definitely want a vapor barrier (like 4 or 6 mil poly) on the warm side of the insulation) to keep the water vapor in the shop from freezing in the insulation. If you are using paper faced insulation I am not so sure. Poly is relatively cheap and unfaced insulation is cheaper that paper faced so if you decide on poly you don't need the paper. Regarding venting. I assume that you are installing a ceiling and insulation. If so, soffit vents and 1 louvered vent on each gable end should do it. Actually, for a space that small just the gable end louvered vents could be enough. Put poly on the ceiling, too. Quote Link to comment Share on other sites More sharing options...
BonPacific Posted April 10, 2017 Report Share Posted April 10, 2017 Seconding Ronn. As far as I know,.you want to avoid any sort of double-barrier, as water can become trapped betaken them. From conversations with roofers you'll get better performance out of a ridge vent than gables, but it probably isn't worth it in your case. 2 Quote Link to comment Share on other sites More sharing options...
Tpt life Posted April 10, 2017 Report Share Posted April 10, 2017 Kraft facing is waxed (or something like it) to retard moisture movement. It does not need separate lining. Most go unfaced and poly when they can get bulk of each for cheaper than Kraft faced. For a shed, you might consider polyiso sheets cut to fit and caulked. You will get far superior numbers for what are likely shallow bays. 1 Quote Link to comment Share on other sites More sharing options...
Numenor Posted April 10, 2017 Author Report Share Posted April 10, 2017 Great consensus, guys. Thank you. I will plan on open faced with poly. The shed we will be getting has a cathedral ceiling and I have been going back and forth on putting in some horizontal stretches and making a mini "attic space" which would include the vents. Is there an advantage to adding this or just keep the cathedral shape? Quote Link to comment Share on other sites More sharing options...
Ronn W Posted April 12, 2017 Report Share Posted April 12, 2017 So long as the roof is made of trusses you can make the ceiling any shape you want (assuming it s a option from the manufacturer) and then vent whatever attic space is left. Since it is a prefab I assume there are trusses. If, howver, the roof is just 2x rafters, that a different ball game and you must have "horizontal stretchers" (collar ties or roof joists) to keep the rafters from pushing the side wall outward. Quote Link to comment Share on other sites More sharing options...
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