Fixing to walls

[Brendan]

Before first fix plumbing I bought all the bathroom furniture at my builder's request.  This included wall-hung vanity units for all three bathrooms.  The downstairs shower is also supposed to have a seat and handrail to make it suitable for elderly relatives to use should the need arise.  The bathrooms are all in the timber frame extension so essentially the walls are boarded stud walls, whether internal or external.

 

From the pre-boarding photos I have, I can't see any extra bracing/noggins/ply board that would support these things.  It is possible something was put in, but in the absence of photographic evidence I would assume it hasn't been (I have asked the builder if they can supply any evidence).

 

The bathrooms are all fully tiled now, so I have no inclination to undo all of this to find out what's there.

 

1) Is the Hardie backer type board within the shower enclosure able to support any load, or is it more or less the same as plasterboard in this respect?

 

2) If there is no evidence of any support behind the plasterboard, I assume I am right that I am going to be stupid doing anything other than buying new floorstanding furniture?

 

 

Picture of the downstairs bathroom pre-boarding, for example:

 

[Pocster]

I’d certainly be concerned wall mounting without a known fixing into a noggin . Hardie board is surprisingly strong - you could try a test hole and fixing - guessing some form of metal expanding fixing ( like for plasterboard ) .

[ProDave]

What's the other side of the wall?  Easier and less intrusive to cut a hole in the plasterboard to see and patch up afterwards.  Any sockets on the other side of the wall, if so easy to spring a socket box out for a look.

[Brendan]

1 hour ago, ProDave said:

What's the other side of the wall?  Easier and less intrusive to cut a hole in the plasterboard to see and patch up afterwards.  Any sockets on the other side of the wall, if so easy to spring a socket box out for a look.

 

The wall is insulated so it's difficult to see much - I tried poking my inspection camera in around the pipework, but all I could see was insulation.  I don't think there are any sockets on this wall on the other side - which is an as yet undecorated room (bare plaster).

[Brendan]

I’ve been sent this photo by the builder. Behind the Celotex is a layer of OSB, then the timber frame with further Celotex in between the studs. 
 

I assume these panels of OSB are fixed through the Celotex and into the next layer of OSB. 

 

I’m not convinced that’s a particularly sturdy mounting for a wall hung vanity unit. Any comments?

[markc]

Probably skew nailed or screwed to the mullions, ideally would be on noggins but the PB or backer boards will hold even if theses boards are just used as load spreaders

Edited August 3, 2023 by markc

[Big Jimbo]

I would go and give your builder a pat on the back. Most, don't even consider where you might be mounting things.

[Brendan]

It’s a shame they can’t confirm whether they’ve done any preparation for the shower seat that needs to support the weight of a person. Something that we talked about several times. 

[Big Jimbo]

If you cant see because it has already been plasterboarded or whatever. poke a hole through with a bradall, or a small dril. If it's not tiled yet, than it's easy enough to sort out now.

[Conor]

Hot does the shower seat mount? I made my own out of ply and made sure it was wide enough to screw in to a stud on each side.

[Brendan]

The shower is already tiled, so in the end I have opened the wall from the other side. They had installed a sheet of OSB (probably 18mm) with some extra noggins. 
 

I’ve taken the opportunity to add another 18mm ply securely fixed behind the OSB. The specialist disability bathroom sites I found generally recommend 36mm to fix a seat into. 
 

I could have just bought a floor standing seat, but I wanted something discreet that would fold away when not needed.