Bathroom balls up - actual bonding strength of OB1 sealant / other construction adhesives?

[Participant]

Hi all

I made a booboo in my current bathroom project. I need to hang a double sink wall-hung vanity unit on the wall and although I did put wooden battens behind the wall to mount it onto, I miscalculated and the wood is too low for the required bracket height, meaning I only have tiles + plugs to mount into. This is insufficient as the weight of the unit + sink is already pulling the unit away from the wall slightly.

This is a major **** up but my options to fix it appear to be:

1. Remove tile(s) and install wood at the correct location. Highly undesirable as everything has been grouted.
2. Use plugs in the tiles and liberally apply OB1 / other construction adhesive to the brackets, vanity, and sink, and hope this is enough to bond it to the tiles.

WWYD?

 

[Participant]

Toggle fixings
Sticks like **** adhesive liberally applied
Adhesive in the toggles as well
CT1 around the perimeter to seal
Hope and pray

You can get little legs as well if needed

Thanks for this. Do you mean floor-standing legs?

 

[Participant]

Surely the unit is >600mm and you can find some studs to get a fixing into.

Yes it's 1200mm wide but the location of the studs doesn't match up with the location of the unit's fixing brackets, which are right at the edge of each side. Maybe I could put screws through the centre into the stud but this section isn't structural / designed to be mounted through.

Put proper support in now while you have the chance. No worrying then.

Very sensible but the wall is finished and this would involve destroying the wall, retiling, and regrouting. For a perfect finish, probably a day's work.

What I want to know is - just how good are these modern construction adhesives? If they're that good, rawl plugs in the tiles combined with lots of glue should cause me no issues right?

 

[Participant]

Got a link to the Vanity unit?

Can't find the original retailer link any longer but it's this one:

https://amzn.eu/d/0WN3qDA

Sounds like consensus is that I can't chance my arm with adhesives and I should go through the bedroom behind and make a proper fixing.

Very sensible, goddamnit. What a stupid ******* mistake with all the measuring and planning.

 

[Participant]

I've had a think (early morning active brain) and reckon I have an acceptable solution that doesn't involve going into any walls.

As I mentioned, there is wood between the studs for mounting, but it's lower than the position of the factory brackets.

What I'm thinking - and I think people alluded to this above - is that I could add brackets at the correct height and screw them into the vanity lower down, something like:

Combined with lots of OB1 on the sink and vanity, I'd have thought this would be fine?

Just to be clear I understand it - if you use OB1 or some other adhesive you'd then be asking the tile adhesive to do the work right? i.e. the vanity is held onto the tiles and you're hoping the tiles don't come off the wall?

That is correct, the tile adhesive would be taking the load in this situation. I believe the tile adhesive has been very thoroughly applied and could bear the weight though, especially since it would be spread across several tiles.

 

[Participant]

Hi all

To hopefully tie this one off, I used the following extra L brackets on each side directly below the factory brackets.

All four of the yellow screws on both sides are into the wooden noggins I placed between studs in the wall for mounting, so hopefully that is easily now strong enough. Not sure why I panicked about opening up walls etc., just didn't think of this.

Thanks for all the help anyway.

 

[Participant]

Might be worth just driving a screw through that back bit of wood too?

Yes that might be a good shout actually. I can hit studs easily through that bit.

 

[Participant]

[
... just saying this is a moment force situation , it is the rear top edge fixture that carries the larger/tension pulling away from wall force, as the unit tries to pivot on the bottom compressed fixing,
so if you have a 50kg sink + 20kg foot in the basin centre of gravity 30cm from wall you have 200Newtons.

but ok this guy has 600N on one plasterboard fixing.

]

Thanks - are you saying you have concerns that what I've done is still insufficient? 8 screws into noggins?

 

[Participant]

It wasn't clear to me at what level of the unit those angle brackets are - near the top, or greater that half way up ? which is where the pull force is;
the white nylon connector is presumably just providing internal structure for the wooden carcass.

I suppose the misalignment of the noggins wasn't large - so near the top then ? ... and the ceramic/comp basin where the intended connections are is also supported by the wooden structure where you added the angles

The white nylon is the factory bracket that's basically at the very top; the brackets I've added are only ~50mm below them, so also very near the top.

Yes the basin is supported by the wooden vanity carcass and is glued to the vanity with OB1.