fixing into thermalite blocks

[Matt@]

I know there are alot of knowledgable people here so hopefully can get some info re. fixing into thermalite blocks.

I am looking to DIY install a bath and am a stickler for doing things properly rather a cross fingers job!

The bath is retained at the wall edges by way of 4 separate metal plates which are fixed to the wall and then the bath edge drops down onto the lip of the plates. The wall around the bath is plasterboard dot and dabbed onto thermalite blocks and I am making up some thick plywood pads which I am insetting into the plasterboard flush with the outer surface then fixed to the blocks then the plates screwed onto the ply pads.

I'm considering using M6 Rigifix or resin anchors to fix the ply pads to the blocks. has anyone got a better idea?!

With regard to resin fixings, the only ones I've ever used are those with the glass tube which you stick in a pre drilled hole in the wall then drive in the thread which breaks the glass and spreads the resin. Are there better resin fixings available than these?

Any thoughts about fixing to the dreaded thermalites much appreciated!!

 

[Beau]

Worked on a couple of places were these did the job https://www.youtube.com/watch?v=qA2tWqtde5Y

 

[Matt@]

great thanks Beau, thats one to look out for....

 

[Paul200]

'If in doubt, use chemical grout' has always been my advice - but I would use the injection method; a two part resin cartridge that you put in a normal skeleton gun - cheaper than capsules and does the same job.

I've not seen the DrylinePro fixings before but they look good. The only worry I'd have would be the gap between the block and the board causing the board to crack when the fixing is tightened. One way to prevent this is to squirt some filler foam into the fixing hole and letting it go off hard first.

 

[Dee J]

Fixing into thermalite.... best simple route that I find works is. 1) drive the hole rather than drill it use a pointed drift or an old crosspoint screwdriver so that the material is compressed around the hole... make sure the hole is tight for the plastic rawlplug, and deep enough that the plug can be 20mm below the block surface. 2) drive the plug in deep so that the expanding plug doesn't burst the block surface. 3) use a long screw that penetrates the full depth of the plug - so at least 50mm plus the thickness of the plaster and the item you're fixing. That routine is simple, and hasn't failed me yet for towel rails, shelf brackets, wall lights etc and will certainly be good enough for those brackets at the edge of baths.

 

[Lons]

I've installed hundreds of bathrooms and never trusted the metal fixings. I always fix a batten, usually 2 x 1 full length of the bath and both ends if possible to give full support on 3 sides. Then screw clamping metal plates to hold the bath tight against the wall. Never had a single failure in 18 years. Battens allow you to put in plenty of fixings and spread the load, you can even add some liquid nails if really OTT.

It is of course vital to get the batten accurate though can be shimmed a little with plastic packers as long as they are siliconed in place so can't fall out.

 

[Matt@]

I've installed hundreds of bathrooms and never trusted the metal fixings. I always fix a batten, usually 2 x 1 full length of the bath and both ends if possible to give full support on 3 sides. Then screw clamping metal plates to hold the bath tight against the wall. Never had a single failure in 18 years. Battens allow you to put in plenty of fixings and spread the load, you can even add some liquid nails if really OTT.

It is of course vital to get the batten accurate though can be shimmed a little with plastic packers as long as they are siliconed in place so can't fall out.

thanks for the info! are you saying fix the wooden batten to the wall then screw the metal plates that you use, to the wooden batten?

 

[kostello]

5mm single thread screws will go straight into thermalight blocks without a pilot hole....



Sent from my E2303 using Tapatalk

 

[Lons]

I've installed hundreds of bathrooms and never trusted the metal fixings. I always fix a batten, usually 2 x 1 full length of the bath and both ends if possible to give full support on 3 sides. Then screw clamping metal plates to hold the bath tight against the wall. Never had a single failure in 18 years. Battens allow you to put in plenty of fixings and spread the load, you can even add some liquid nails if really OTT.

It is of course vital to get the batten accurate though can be shimmed a little with plastic packers as long as they are siliconed in place so can't fall out.

thanks for the info! are you saying fix the wooden batten to the wall then screw the metal plates that you use, to the wooden batten?

Yep though sometimes you need to bend or pack the plates as they aren't used in the same way as if they are fixed to the wall, i.e. the edge of the bath sits directly on top of the batten and the metal plates screwed to the front of that to nip the edge of the bath close to the wall and stop it pulling away. Easier to do than explain.

 

[Matt@]

I've installed hundreds of bathrooms and never trusted the metal fixings. I always fix a batten, usually 2 x 1 full length of the bath and both ends if possible to give full support on 3 sides. Then screw clamping metal plates to hold the bath tight against the wall. Never had a single failure in 18 years. Battens allow you to put in plenty of fixings and spread the load, you can even add some liquid nails if really OTT.

It is of course vital to get the batten accurate though can be shimmed a little with plastic packers as long as they are siliconed in place so can't fall out.

thanks for the info! are you saying fix the wooden batten to the wall then screw the metal plates that you use, to the wooden batten?

Yep though sometimes you need to bend or pack the plates as they aren't used in the same way as if they are fixed to the wall, i.e. the edge of the bath sits directly on top of the batten and the metal plates screwed to the front of that to nip the edge of the bath close to the wall and stop it pulling away. Easier to do than explain.

ah ok, I think I'm effectively doing the same thing then. Theres no way I'd screw the metal plates direct to the wall whatever the fixing so I'm screwing them to the flush face of 20mm odd thick plywood pads that are approx 10" x 4" and I'll fix these pads to the walls with the fixings. Also the pads are cut into the plasterboard so any weight downwards is offset by the plasterboard edge.

 

[Lons]

ah ok, I think I'm effectively doing the same thing then. Theres no way I'd screw the metal plates direct to the wall whatever the fixing so I'm screwing them to the flush face of 20mm odd thick plywood pads that are approx 10" x 4" and I'll fix these pads to the walls with the fixings. Also the pads are cut into the plasterboard so any weight downwards is offset by the plasterboard edge.

The difference Matt is that you're still Hanging the bath edge on to the metal brackets where I'm fixing the batten to the surface of the plasterboard and "hanging" the bath edge, full length along the top of the batten. Screwing metal plates to the front of the batten is just to trap the bath edge tight against the wall.
Just my method, not saying you should use it.

Bob

 

[Matt@]

The difference Matt is that you're still Hanging the bath edge on to the metal brackets where I'm fixing the batten to the surface of the plasterboard and "hanging" the bath edge, full length along the top of the batten. Screwing metal plates to the front of the batten is just to trap the bath edge tight against the wall.
Just my method, not saying you should use it.

Bob[/quote]

yeh I take your point hmmm, maybe I could change to your way of doing it, I'll have a think. One thing is, the bath is a carronite so very rigid. I've ordered some Rigifix also the drylined things mentioned earlier and will have a play. The one thing I do know is thermalite fixings are a nightmare so i want to get this spot on right..

PS how do you fit your plates to the rear edge of the bath as it seems they go on after the bath is sat on the batten?

 

[Lons]

PS how do you fit your plates to the rear edge of the bath as it seems they go on after the bath is sat on the batten?

only need one towards each end of the long side against the wall Matt so have to crawl under but easy enough to do. I'm no lightweight and don't have a problem.

With my method, if any doubt then belt and braces (read OTT :lol: ) is to fix additional vertical batten from floor to underside of horizontal battens as supports and they will never move in a million years.

The more rigid the bath the better BTW.

 

[Matt@]

ok gotcha, thanks so much for the info. I'm thinking to myself what happens with my method if the wall that the long side of the bath sits to is not dead flat ie perhaps a slight lump in the middle which means bath rocks against the wall slightly (it only needs to be a couple of mm out) - if this happens the bath edge wont drop into my brackets especially as its a rigid bath with little flex. With your method you can secure as best you can then fill the gaps.

Got the dryline fittings today - rip off springs to mind as they are basically 8 rawlplugs with screws for £10.00

 

[Racers]

I put battens all round my bath and supports at the open side of the bath and its rock solid.

Pete

 

[Fatboy]

I put battens all round my bath and supports at the open side of the bath and its rock solid.

Pete

x 1

 

[Lons]

I put battens all round my bath and supports at the open side of the bath and its rock solid.

Pete

Basically what I said Pete but you express it so much better :lol:

 

[Gerry]

I put battens all round my bath and supports at the open side of the bath and its rock solid.

Pete

x 1

Me too, a 2x2 baton along the walls where the bath sits with vertical supports at the ends and one in the middle of the long side. I then screw up through the baton in to the wood block set in to the bath rim to secure it. Even just a couple of screws will provide a positive, permanent fixing. I never use the metal fixings provided.

Gerry

 

[Racers]

I put battens all round my bath and supports at the open side of the bath and its rock solid.

Pete

Basically what I said Pete but you express it so much better :lol:

Just agreeing with you

Pete

 

[Matt@]

some great advice on this thread so much so that i will now use batten.... thanks all!