Taping plasterboard for MVHR

[Navron]

We are currently quite far through a build - brick and block construction with stud partitions upstairs, then all plasterboarded and wet plastered. Flooring upstairs is Kaberdeck that's all been glued together with expanding foam. We have the MVHR going in in a couple of weeks and I'm wondering about taping up all the joins between plasterboards. By my rough calculations I would need thousands of pounds of tape to cover all the board upstairs and downstairs. We will be taping all the windows, but is it necessary to tape every single plasterboard join? Note we have 2.9m ceilings downstairs and vaulted ceilings upstairs that go from 2.2m to 3.2m and about 390sqm total, so it's a lot of tape we would need. Is there a cheap tape that can be plastered over or some other way of achieving adequate air tightness?

 

Note we are mostly doing MVHR for the mechanical ventilation bit and only secondarily for the heat recovery bit.

[jayc89]

Make your external walls airtight, which it sounds you are doing with wet plaster and taping the window reveals. The only PB tape you need is scrim for rigidity, to reduce the risk of cracking. 

[Navron]

Thank you. I think I have described the construction incorrectly. It is actually like this: some walls are wet plastered but the majority will have a make-up that is brick, insulation, block, plasterboard and then a skim coat. So for those walls that are plasterboard with a skim coat on top, will I need to tape up all the plasterboard joins and also tape the plasterboard to the floors and ceilings?

[j_s]

I would use an airtight paint on the block work before the plasterboard is attached. A full perimeter of board adhesive on each board as well as top to bottom and left to right in a plus shape on each board. This way the plasterboard and skim are cosmetic and a backup airtight layer. That is if your builder or plasterer plan to dot and dab. I would use an airtight expanding foam like illbruck fm330 or soudal sws airtight foam at the wall to floor junction. This is what I have done in my recent renovations.