Weatherproofing Plasterboard

Discussion in 'Painters' Talk' started by Convey766, Jun 11, 2018.

  1. Convey766

    Convey766 New Member

    I have an Edwardian Terrace house where the front door is set back about 2ft from the front facia and originally this was an open storm porch area. It looks like in the 1950s a secondary vestibule" glass door was put in to enclose the open storm porch.

    In this enclosed storm porch area, when the house was renovated a few years back, the Builder replaced the old lathe and plaster walls (breached fire Regulations for HMO) and put in 30 minute fireproof Plasterboard on one side of this enclosed small porch area. There have been no problems since.

    I now want to remove the 1950s vestibule door and bring the house back to its original open storm porch.

    I therefore need to make the plasterboard (now painted) as weatherproof as possible. Can anyone advise as to the best material to use for this? Would the use of exterior paint be sufficient? I saw that Tanking is the best possible way to waterproof plasterboard but its not clear whether tanking solution could be used over the existing painted surface.
  2. Bob Rathbone

    Bob Rathbone Well-Known Member

    Plasterboard does not respond well to damp, even the early morning dew type that your porch will be subjected to in summer months. You could try soaking the wall with a silicon based water proofer, might work but I have never tried it on plasterboard. Take particular care with the lower part of the board as this will be most affected. The old lath and lime plaster would not be affected by damp in the same way as plasterboard.
    KIAB likes this.
  3. KIAB

    KIAB Well-Known Member

    Bottom edge of plasterboard will be most at risk, will suck up any moisture, if you get driving rain,or any ground moisture coming up through floor in open storm porch.

    I would have use Knauf Aquapanel Exterior, or similar cement board product & definitely not plasterboard.
    Last edited: Jun 11, 2018
    DIY womble likes this.
  4. Josh.91

    Josh.91 Member

    But you'll be restricted if you want to then paint anything Silicone based
  5. DIY womble

    DIY womble Well-Known Member

    Was curious about this situation and tried a piece of plasterboard painted with varnish , 2 coats , lasted for weeks out in the rain without any problems. Go for cement board as kiab says but make sure you have it well insulated if it's on an internal ( heated ) wall
    KIAB likes this.
  6. Josh.91

    Josh.91 Member

    Could possibly tile it
    DIY womble likes this.
  7. KIAB

    KIAB Well-Known Member

    Cement board over painted with masonry paint.:)
    DIY womble likes this.

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