Sealing around the edges of a shub

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neb

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#318869 28-Feb-2025 01:54

The Casa de Cowboy came with a shub, which has the problem shown in the photo below. What happens after a few days of non-use is that the sealing strip around the edges separates out from the wall, leaving a gap that water can get into.

With constant shower use this isn't the case, so I assume water is getting in and causing the formica to swell up slightly, closing the gap. For reference the edge of the shub looks like this.

This gap opens up pretty much every time the shower isn't used for a few days, for example if we're away. Is this something to worry about, and if so how would I seal it? I've thought of white electrical tape over the join which would move with the sealing strip, but that's a bit of a bodge.

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Smpl Mnmlst
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#3348574 28-Feb-2025 02:38

What material are the horizontal beadings - PVC?

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neb

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#3348575 28-Feb-2025 02:42

eracode: What material are the horizontal beadings - PVC?

Yes, or some similar plastic.

It's not clear what's attached it to the formica elsewhere, presumably some sort of adhesive. It's holding up everywhere else, just this one section about 40cm long opens up when it's had a few days of non-use.

mentalinc

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#3348581 28-Feb-2025 06:59

This gap opens up pretty much every time the shower isn't used for a few days

This sounds like the timber below is drying and therefore shrinking leaving the gap. Which might indicate the wood behind is very wet (and maybe mouldy).

I'd consider removing the wall panel to check before sealing all the moisture into the wall.

Are you able to see the otherwise of that wall in another room?

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#3348588 28-Feb-2025 07:23

Definitely agree with @mentalinc - you really need to know what's going on around the shub. Would not be a good idea to just, say, run some silicon sealant around the beadings without that knowledge.

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eracode

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#3348590 28-Feb-2025 07:32

neb:

eracode: What material are the horizontal beadings - PVC?

Yes, or some similar plastic.

It's not clear what's attached it to the formica elsewhere, presumably some sort of adhesive. It's holding up everywhere else, just this one section about 40cm long opens up when it's had a few days of non-use.

Not that it really matters but that wall-lining is most likely Seratone - a 5mm hardboard product with a 'glazed' surface finish on one side. It's designed for wet areas and will stand up quite well to moisture/wet. Unlikely to be formica.

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neb

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#3348791 28-Feb-2025 21:47

mentalinc: I'd consider removing the wall panel to check before sealing all the moisture into the wall.

Are you able to see the otherwise of that wall in another room?

The builders had a look when they did the rebuild, signs of old water stains but no rot anywhere. With the current baking heat and low humidity it'd be the perfect time to seal it, just not sure what the best approach is. How are the strips normally attached?

And @eracode thanks for the info, good to know.

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#3349769 3-Mar-2025 23:19

Check the Seratone installation manual. That pvc flashing has a channel to receive the Seratone sheet that should have a bead of silicone at the bottom. Ref Fig 18. Note now this is now only for baths although in about 2001 i did a shower over bath and I'm sure it was the preferred method. Now shower over bath has to be Fig 17 or Fig 17a where Seratone has a drip edge.

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neb

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#3349775 4-Mar-2025 00:34

Thanks, didn't know about that one. Looking at the manual Fig 17 seems to be what's been done here, with a caveat that the house was built in the mid-70s and it's not clear when or if the bathroom wall was redone, parts aren't original any more but I don't know if the shower area is. So it depends on whether they had silicone sealant when it was installed, and so how well it was installed and has held up.

Next time it's had a chance to dry out a bit I'll try and slide a spudger into the gap to see if it meets any resistance.

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#3349776 4-Mar-2025 00:43

Fig 18. Fig 17 does not have the plastic moulding.

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#3349777 4-Mar-2025 00:45

We may be looking at different docs, I'm looking at the Seratone Classic one which I assumed would be the closest to what's been used here.

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#3349795 4-Mar-2025 01:14

Yes your 17 is current 18. Your 16 in latest installation instructions loses the visible sealant at bottom. It would soon be mouldy.

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#3349796 4-Mar-2025 01:50

I've been trying to find any install instructions older than the 2020s, so far without success. I did find a BRANZ document about 1940s-1960s building standards which mentions that Seratone became available in the 1960s so it could well be the original mid-70s install. I'll email Laminex on the off chance they have any info. The real question would appear to be what sort of sealant was used in the 1970s or perhaps 1990s, and whether it could have broken down or developed cracks since then. It seems like acrylic latex was the go-to in the 1970s, which wouldn't be used today.

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#3349798 4-Mar-2025 06:04

Have a look at the surface of the Seratone. If it is mid 70's it will have had 50 years of being cleaned and probably end of life.

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#3351513 8-Mar-2025 17:30

After waiting a week for Laminex to reply it looks like they're not going to... here's a photo of the situation at the other end of the bathtub where the internals are visible. It's significantly magnified so looks a lot worse than it is at actual size. The filler feels rubbery so possibly silicone, the colouring looks like general dirt and muck so no indication of what it actually is. The hole that's visible goes back as far as I can get a piece of 0.8mm wire in so presumably they ran a bead of silicone along it, pressed the moulding into place, and the filler then slumped a bit as it cured. So it looks like it's pretty well sealed, but also that some water can get trapped in the gap.

Question now is, is this normal for these sorts of installs, or something to get looked at? A google search has turned up a pile of places that will repair obvious water damage, but this seems more like a preventive maintenance sort of thing, if that.

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#3352778 11-Mar-2025 20:02

Managed to lift it up a bit and get a camera lens in close enough to get a shot of what's behind the moulding.

Absolutely nothing, the cowboys who owned this place snotted the end up with a bit of silicone and that's it. The rest of the length has the Seratone, a gap, and then the top of the shub.

Can anyone recommend someone on the North Shore who'll redo this sort of stuff? Either that or someone who does this sort of stuff who can point out if there's more required than just remove, clean, run silicone along it, and press on new moulding?

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