I have a metal shed (specifically this one) that I intend to turn into a small workshop. Insualtion is a must as it turns into an oven in the summer and a fridge in the winter, but I am aware that metal sheds are prone to condensation even uninsulated. Current plan is to build a freestanding frame inside it, and insulate using PIR insulation boards - I'm ruling out spray-foam insulation because it is cost-prohibitive in the UK (a single Froth-pak 180 is ~£300, professional spraying is rare so quotes start at well above £1k regardless of job size) and not wanting the hassle of dealing with isocynate safety.I know that to prevent condensation and mould within the insulation that at least one vapour barrier will be needed, but there's a lot of conflicting information on where that barrier should be installed and whether there should or should not be ventilation (and what parts should be ventilated to where), mainly because most advice is based on insulating large structures where the insulation is applied to the outside of the frame and then metal cladding added.The shed is a continuous metal envelope (including the floor) punctured only by the doors and two small side ventilation grills. My assumption would be to:Add a vapour barrier (bonded to the outer wall and roof?)Build the freestanding frame, with the frame just barely touching the outer wall (and at this point add some sort of conduit to later run power from an internal sub consumer-unit and a couple of data runs)Adhere the insulation panels to the inside of the vapour barrier in between the framing of the walls and roofCover the frame and insulation with plasterboard (sheetrock)For the two ventilation grills a 'hole' would be left in the framing (to add a floorstanding AC unit or an MVHR unit at a later date), though I am unsure of how to secure the vapour barrier around these. For the door I can only think of adhering the insulation boards directly to the inside of the door skin (with some chunks removed from the backside of the insulation to accommodate the multipoint locking mechanism). The floor is a metal skin sitting on rubber pads on top of the concrete base, with an OSB floor on top of the metal skin with an ~ 1cm air gap between metal and OSB (and this will be covered in rubber tiles for grip), so I'll likely leave this without additional insulation.So, questions:1) Do I need an additional vapour barrier on the inside of the insulation (between the inside of the frame and the plasterboard), and/or move the vapour barrier from between the shed wall and insulation to between the insulation and plasterboard?2) Does there need to be a ventilation gap between the shed wall and the vapour barrier, and if so should that gap be ventilated to the inside or outside of the shed?3) Does the insulation itself need to be ventilated to the inside/outside of the shed? via /r/DIY https://ift.tt/2LdXH7W
