Overbath shower screen onto thin clinker(?) block

[Naoto]

Hi this is first time I post in this forum, although I have been reading many topics and got lots of useful information before, so please tell me if I am posting the question in wrong place.

I'm in the process of bathroom refitting and so far I managed to fit bathtub and vanity unit, tiled the wall and put the floor and now going to fit shower screen over the bath. My house was about 60-70 years old and the bathroom is enclosed by two external cavity walls, one single skin brickwork internal loadbearing wall and one non loadbearing wall on which the shower screen need to be installed.

My concern is if this non loadbearing wall have sufficient strength to support heavy shower screen (860x140x6mm glass). I am not sure how to call but think the wall is called clinker block? Anyway, it is made of coarse, black, crumbly material and when I chased it for hot and cold water supply pipes for shower, I could easily make grooves with cold chisel and hammer within an hour. The wall is only about 50mm thickness and 2260mm long x 2450mm high within which there is a 770mm door opening at one end, sitting on floorboard and there is no restraint at the top. Apparently, the wall was built after ceiling plasterboards had been fixed to the ceiling joists, which is parallel to the wall, and considering that, I dont think there is any decent restraints on both vertical end (to external cavity wall and internal loadbearing wall) either.

I am planning to increase the number of rawlplug fixing points to cope with crumbling problem. I fixed timber battens to the wall with rawlplug to support bathtub, which are quite rigid, so I think I can secure the bathscreen to the wall tightly as well. What I am worried about is the wall might overturn because of the heavy screen, or at least some movement might occur, which in turn make the plaster & adhesive on the surface loose and the wall tile rather unstable.

I dont think it would squash me to death even if whole the wall fall onto me as the block is so thin and light, but I dont want one small piece of tile to fall onto my small children.

I would very appreciate if someone with structural engineering knowledge or similar experience advise me if it is safe or not (I am hoping someone tell me "Thats no problem. Ive done million of times, go ahead!") Because of my terrible writing, it may not clear so please tell me if you need more information to answer the question.

Thanks for your help!

 

[SALL2009]

Hi this is first time I post in this forum, although I have been reading many topics and got lots of useful information before, so please tell me if I am posting the question in wrong place.

I'm in the process of bathroom refitting and so far I managed to fit bathtub and vanity unit, tiled the wall and put the floor and now going to fit shower screen over the bath. My house was about 60-70 years old and the bathroom is enclosed by two external cavity walls, one single skin brickwork internal loadbearing wall and one non loadbearing wall on which the shower screen need to be installed.

My concern is if this non loadbearing wall have sufficient strength to support heavy shower screen (860x140x6mm glass). I am not sure how to call but think the wall is called clinker block? Anyway, it is made of coarse, black, crumbly material and when I chased it for hot and cold water supply pipes for shower, I could easily make grooves with cold chisel and hammer within an hour. The wall is only about 50mm thickness and 2260mm long x 2450mm high within which there is a 770mm door opening at one end, sitting on floorboard and there is no restraint at the top. Apparently, the wall was built after ceiling plasterboards had been fixed to the ceiling joists, which is parallel to the wall, and considering that, I dont think there is any decent restraints on both vertical end (to external cavity wall and internal loadbearing wall) either.

I am planning to increase the number of rawlplug fixing points to cope with crumbling problem. I fixed timber battens to the wall with rawlplug to support bathtub, which are quite rigid, so I think I can secure the bathscreen to the wall tightly as well. What I am worried about is the wall might overturn because of the heavy screen, or at least some movement might occur, which in turn make the plaster & adhesive on the surface loose and the wall tile rather unstable.

I dont think it would squash me to death even if whole the wall fall onto me as the block is so thin and light, but I dont want one small piece of tile to fall onto my small children.

I would very appreciate if someone with structural engineering knowledge or similar experience advise me if it is safe or not (I am hoping someone tell me "Thats no problem. Ive done million of times, go ahead!") Because of my terrible writing, it may not clear so please tell me if you need more information to answer the question.

Thanks for your help!

Firstly I’m not a structural engineer or a builder. So what I'm going to say is my opinion and might be wrong. Some experts might give you more advice.

I had one of these clinker block walls in my house and I had to remove it and replace it with stud for a structural issue (not affecting that wall). But the blocks are quite weak and came down very easy. If you tap the wall, you will feel the vibration across the wall. So you will get movement for sure. Adding extra raw plugs to it would probably just make it weaker at those points. I personally wouldn't install a shower screen on such a wall. The fixings for these screens need to hold quite lot of weight and the block could crumble at the fixing point over time and the screen could fall. I wouldn't think the whole wall would drop though.

 

[joe-90]

Nearly all the weight is straight down - it won't fall down with a little flippin shower screen.

 

[Robert9999]

I am not a builder, but I'm treating this as an applied mathematics problem which I do know something about.
The weight is of course downward but this does produce a turning effect tending to pull the top fixing from the wall (and trying to press the bottom one into the wall which matters a lot less). And a large 6mm glass panel has an appreciable weight. This will be much more pronounced when the screen is opened a little way and so not leaning on the edge of the bath.

Hope this helps.

 

[Steve]

I wouldnt. Thermalite blocks are ****e.

One of my parents neighbours has had a thermalite block wall replaced with stud wall, because it was built onto floorboards in between two joists - no wall below, and it was distorting the ceiling.

But stud is a lot better for fixing to. Double bonus.

 

[joe-90]

If you take the top fixing out the outward force would be minimal. A child could easily hold it flush.

 

[RonnyRaygun]

If you take the top fixing out the outward force would be minimal. A child could easily hold it flush.

About 5kg...same in opposite direction for bottom fixing...with fixings top and bottom that is...

That's until you slip in the shower and grab the screen

You can decide for yourself if the wall will take the load...

 

[Robert9999]

If you take the top fixing out the outward force would be minimal. A child could easily hold it flush.

Yes, and if you remove all the fixings there won't be any force pulling the wall.

If you remove the top fixing you just add extra force pulling out the next one down.

 

[joe-90]

It's not going to fall down mate. Sorry but it just won't.

 

[RonnyRaygun]

Yes, and if you remove all the fixings there won't be any force pulling the wall.

If you remove the top fixing you just add extra force pulling out the next one down.

Do the calc...two fixings you've got around 5kg force each fixing in opposite directions...that's the force a person (or child) would have to apply at the top if only the bottom fixing was in place...thought applied maths was your thing

 

[Naoto]

Thank you all for advices. The shower screen weigh about 20kg and the top fixing point situated at 1300mm from the bottom, so pulling force at top fixing would be around 6.6kg. The screen has three fixing point, one at the top, another at the bottom and one in between. As I stated at the o/p I am planning to add two more fixing points at 100mm above and below original top fixing point, just to be sure. There is no information about how much weight rawlplug can take when fixed into clinker block, but as an guide, blown rawlplug can take 17kg force when fixed with 6mm screw into 2.8N/mm2 blockwork. I guess this data was for modern aerated blockwork such as thermalite or celcon and not for old clinker block but combining it with my feeling when I tried to pull the timber batten for bathtub attached to the wall, I think it would not pull off. I am more worried about the stability of the wall itself as the wall is only 50mm thick and there seems to be little restraint, almost freestanding!

I guess I need to incorporate some sort of restraint at the back of the wall to prevent overturning.

 

[joe-90]

Fasten a batten to it and pull for all you're worth and I bet it doesn't move. I've knocked those walls down and they take some hammer.

 

[Naoto]

Fasten a batten to it and pull for all you're worth and I bet it doesn't move. I've knocked those walls down and they take some hammer.

Having heard the sound when I knock the wall, I think I could knock it down with my punch or elbow, much easier than this.

http://www.youtube.com/watch?v=AF--c_X-7rM&feature=related

 

[RonnyRaygun]

I guess I need to incorporate some sort of restraint at the back of the wall to prevent overturning.

That's probably the best solution if you are worried and it won't get in the way. Would need to be secured into the floor and a ceiling joist...or a noggin if it lands between two joists. Then fixings at 450mm centres into the wall.

Personally I don't think it's going to pull the wall over by itself, but as I said it would be easy to slip and apply a lot more force to the fixings.

I honestly have no idea how you would go about calculating the overturning resistance from the load applied by a single fixing at the top of a wall...any flexure calculation in masonry is a poor approximation of what happens in reality anyway...