I have built a custom construction for a washbasin in our new bathroom. It consists of a simple marble slab with white wooden borders underneath. When it comes to mounting it on the wall, it is intended to be done with French wood screws through three irons in the rear border. However, I am a little worried about whether this will hold properly or not, which is why I would gladly appreciate some advice from you!
According to the calculations below, I have figured out that the three mounting points must each support at least 70kg - would this be possible?
The wall is said to be "extra reinforced" according to the contractor, though I'm not sure what that means...
The width of the construction is 55cm
3 irons with 2-3 French wood screws each will be spread over the 55cm
The depth of the construction is 37cm
Total weight of the construction is 30kg
Additional weight to consider would be if someone leaned with 20kg on the edge of the construction
Given this, I have tried to calculate the force on the wall using moments and concluded that it needs to support a total of 200kg
Given 3 different mounting points spread over the 55cm width of the border (each with 2-3 French wood screws), this means about 70kg per mounting point
It all depends on how the wall is constructed. If there are noggins in the right place (where the screws need to go in), then there are no problems at all. The screw will not be the weak point in that case.
However, if it is just plasterboard with tiles on it, the whole thing will come crashing down onto the floor!
If it is fiberboard (preferably at least 15mm plywood), it will also hold, although a French wood screw might not be the first choice in that case!
Do not use franska wood screws. They are of poor quality, coarsely threaded, and generally ugly in a visible construction.
Use Jetting screw instead. They have better quality, better threads, and you usually do not need to pre-drill.
Thank you very much for your responses! I have now figured out how the wall is constructed (the craftsman's description below): Crossbeam approx. 200x45, plywood board 15mm, wet-area board, waterproofing layer, and tiles on the outside
I also attach two pictures of the construction showing how I envision it (a total of 30 kg).
It sounds reasonable to change the screw - is "Jettingskruv" the best or are there other alternatives?
When you hear how the wall is built and see the pictures - are you still convinced that it will hold?
Again - thank you very much for your help - it is invaluable (at least worth a new bathroom wall =))!
If that's all your craftsman wrote on the wall behind there, that thing is not coming down anytime soon. If something happens, it will be the wooden frame that gives way, it won't come off the wall.
Jettingskruv is very good, it also works well with large plumbing screws. Drill through the tile and the waterproof layer and then screw through the rest. Put silicone in the hole after you've drilled, before you've screwed in the screw!
I also wonder how well-stocked a hardware store needs to be to have Jettingskruv - because I assume they aren't available at Claes Ohlson? I live in central Stockholm and would like to buy them somewhere in the center.
There seem to be many different variants of Jettingskruv, is there a specific model I should go for? For example, any of these here:
[link]
I also wonder how well-stocked a hardware store needs to be to have Jettingskruv - because I assume they don't have it at Claes Ohlson? I live in central Stockholm and would love to buy them somewhere in the center,
Thanks again!
Use this screw, and it will work great. It also matches well with stainless steel in a bathroom!
