Is the Permagard failing?

RLPD

New Member
Hi,

Started a bathroom renovation a few weeks back and noticed some tiles on one of the external walls was bowing so decided to investigate as the tiles needed to come off anyway.

The old Newton lath circa 1970s (Which I was told on here) has perished but didn't seem to be any damp coming through anywhere.

I've taken off the undercoat and plaster on the external walls and replaced with permagard/dab/skim.

1st question...

How long does it usually take for dabs and skim to dry out on permagard. As it was nearly a week and there were still patches and especially around the toilet waste which was as dark as the day after I skimmed them.

2nd question...

There was a few bricks and joints not in great condition around the toilet waste, I used expanding foam to fill and the cut the parmagard around it and then used the role of joint tape they provide to patch in the gaps. Could the foam hold damp and cause a severe bridge? As now 9 days later it still looks like this.
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I have taken 400mm off the dabbed boards on the two external walls and have noticed these droplets.

If I chase out the floor along the line of the permagard and sand cement around the toilet waste properly. Would tanking the walls and floor solve this problem?

36305
 

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beader

Private Member
Looks like a condensation problem .Is the external wall solid or is there a cavity . what is on the other side of the wall ? Also looks like you might have bridged the board wit the floor in places .you should of left a decent gap between the floor and the bottom of the board.
 

RLPD

New Member
I think it’s cavity but can’t get access to behind the wall yet. I’ll be investigating today.
 

RLPD

New Member
They may be a stone wall backed onto one of the external walls.

The other side of the door lining in the picture still has the old Newton lath with a grey undercoat and skimmed. There are no problems on this wall.
 

beader

Private Member
May need to use a thermal board as it looks like warm air is getting trapped between the membrane and the plaster board and when it condensates has now where to go .
 

RLPD

New Member
May need to use a thermal board as it looks like warm air is getting trapped between the membrane and the plaster board and when it condensates has now where to go .
So the wall and floor has completely dried out after cutting away the bottom 400mm of the wall
 

martinemj

Well-Known Member
Its not easy to see from the pic but you need to vent the bottom of the plastic too so air can flow up between membrane and plastic

So what I mean is plastic should not meet floor unless you have a cavity drain installed (in which case it would go down into screed)

If you just have a mild damp and not a runing water situation you don't need a cavity drain and sump

Again when you refix board don't take to floor...


I will find a couple of drawings and post in morning
 

RLPD

New Member
Its not easy to see from the pic but you need to vent the bottom of the plastic too so air can flow up between membrane and plastic

So what I mean is plastic should not meet floor unless you have a cavity drain installed (in which case it would go down into screed)

If you just have a mild damp and not a runing water situation you don't need a cavity drain and sump

Again when you refix board don't take to floor...


I will find a couple of drawings and post in morning

Thankyou buddy, that would be a great help to me
 

RLPD

New Member
Its not easy to see from the pic but you need to vent the bottom of the plastic too so air can flow up between membrane and plastic

So what I mean is plastic should not meet floor unless you have a cavity drain installed (in which case it would go down into screed)

If you just have a mild damp and not a runing water situation you don't need a cavity drain and sump

Again when you refix board don't take to floor...


I will find a couple of drawings and post in morning

And no there is not drainage channel. I’ve also used the fleece strips to keep the bottom of the permagard tight to the wall to prevent movement for the dabs. I take it this should be removed for airflow as well?
 

RLPD

New Member
Yes I would ...

So when the permagard is installed it’s pinned to the wall with the plastic plugs with the seals to prevent damp coming though right?

What’s to stop damp coming though the gap at the bottom where the permagard meets the floor?

I’m not questioning you, I’m just trying to understand the system

Will tear away the tape and re-dab with a batten
 

martinemj

Well-Known Member
Going back to basics here are the instructions for your situation...
Drawing to follow


INSTALLATION OF SLIMLINE MESH & BASELINE MESH TO THE WALLS
mesh membranes are used in both new build and retro fit basements where
space is at a premium and or the choice of finish can be render, plaster, or dot and dab
plaster board.
It is also used to remediate damp walls and offer insulated finishes on cold external
walls above ground.
4.1 PREPERATION
Please refer to the instructions as set out in 1.1
4.2 FIXINGS
Mesh membranes should be fixed to the walls using Plaster Plugs. An 8mm
drill bit is needed and drill to a depth greater than the length of the plug. In below ground
environments plug fixings should be sealed around the collar using preformed
waterproof seals or Rope subject to how wet the substrate is.
Above ground and on non soil retaining walls Plug fixings do not necessarily need to be
sealed.
Fix in a square at 350mm centres, and then fix a plug in the centre of four fixings so it
looks like a 5 on a dice. All fixings will then be a maximum of 250mm from each other.
It is essential fixings are no farther apart than this specification to avoid rippling of the
membrane and subsequent cracking of the applied finish.
Where a Dot and Dab finish is being applied centres may be reduced to 350mm
centres.
4.3 SEALING
Flange to Dimple – Use Twistfix Tape
Dimple to Dimple – Use Twistfix Rope
Butt to Butt Joint – Use Twistfix Fibre Tape

4.4 DRY LINING
In the remediation of a damp wall mesh membrane can be installed in a dry lining finish.
To assist with the drying down of the wall it is recommended to introduce air movement
behind the membrane.
On the dry side of the membrane the use of a vapour check plaster board product is
recommended to guard against the effects of interstitial condensation.
4.5 FINISHES
mesh membrane products can be finished by rendering, plastering or applying
dot and dab adhesive grout and plaster board.
Baseline Mesh can be finished in accordance with normal plastering techniques (BS
5492:1990) using proprietary lightweight plasters e.g. Tilcon „ Whitewall‟ , Thistle
„ Carlite
Bonding‟ , or a 1:1:6 cement:lime:sand render.
NB Manufacturers recommended drying times may vary according to
atmospheric conditions.
 

martinemj

Well-Known Member
If you only have a damp wall then the above will sort it....
If you have water runing down wall ...as in basement then you would need a cavity drain and pump..

There is a need to vent the membrane at floor level say 20mm ...to allow air flow and this will help stop condensation
Fit skirting with a grab adhesive ...

I think taping the bottom has caused the issue ...
Hope that helps...
If you need to . give me a call...my website should be in signature ?

I'm not a damp expert or claim to have all the answers but have done a fair amount of this work.....although the main of my work is with lime
 
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RLPD

New Member
Thank you for this, I haven't had much experience with Damp and it quite daunting when you're renovating a flat and the client asks why the bathroom is lagging.

I'll get back in Monday and tear away the tape. Put a roofing batten down and re-dab on top of that.

Couldn't thank you enough!
 

daveJL

New Member
Hi guys - have a very similar problem to this and would appreciate any input you might have given you seem to have solved it


Thanks

Dave
 

earthy

New Member
Not intending to put a dampener (no pun intended!) on the above but, you have just moved the condensation to behind the tanking membrane, and while your plasterboard/finish may have a improved, interstitial condensation is occurring behind your work.

So what? Well, they may eventually see a damp problem at the wall/floor interface and the risk of that door case rotting has consequentially got higher (if it’s been retained?).

I know these systems are designed/marketed as ventilating - research shows there to be negligible air movement in such spaces...
 
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