Hi there everyone, I've been following this forum for a while, awesome forum by the way everyone seems real friendly and helpful! Completely new to all this myself and am especially intrigued by these EWI systems. Have a basic understanding of how they work but have never heard of a thincoat system on a board. Any chance someone could explain the basics? Like what kind of board is this? Is this board mounted to the insulation? Is there a primer between the board and thin coat, and does it still use a mesh?
Sorry a lot of questions I know! I'm a student studying product design engineering and have just done a project on exterior facades (with a focus on EWI and rainscreen), really enjoyed the module and just want to keep myself updated. Cheers!
I just wrote you a full explanation but then ersed it with my browser by mistake. sorry pal you will have to wait til tomoz i cant be ar5ed doing it again now
basically the thin coat render that goes onto either insulation boards (slab of insulation in a handy size) or render carrier boards (typically 9/12mm thick and 8x4 external sheathing sheet) is like adhesive not sand and cement mortar so the board and render are designed for each other. It goes on only say 4mm with a 1-2 mm finish coat "hence thin coat system"
cheers jse, really appreciate the help. Nothing more frustrating than losing something you've typed out! Just read that document you linked, just to make sure, this cement board is always used in ventilated systems then? Is the thin coat render ok to use, as I'm assuming with it being a thinner coat there is less room for error? Seems like an interesting system though! Is it popular?
you need the cavity on framed buildings under NHBC and TRADA regs not really because your using a cement particle render board, or insulation, the cavity vented or not protects the sub-fram from rotting as it will have and air flow and remain dry. cases in north America where timber framed buildings where fitted with render board or insulation directly against the subframe had allowed water to track back against the frame via any details such as vent holes / window sills etc where not 100% sealed off for instance the constant damp state of the frame meant they suffer so measures were taken to prevent that
Thin coat polymer renders are used on render board and the board work needs to be tidy yes but boards are flat and rigid so I have never known it be a problem - twists in the timber framed buildings can mirror through sometimes.
cement board does not always need to be used in a vented cavity system either - the frame will be directly sheathed with chipboard osb typically and then a breather membrane such as tyvec then the cavity but then the facade can be a number of materials such as cladding or insulation boards fixed via holding rails etc