Hello folks, I feel I need to ask some questions to you "experts" on the forum!
Earlier this year, we built a 1.5-story villa with an unfinished attic. Now we're tackling the upper floor, and the biggest problem I have right now is how to construct the floor structure for the bathroom. Currently, we have C24 220x45 cc60 in the floor structure with a maximum span of 4.0m. In addition to a toilet, sink, and shower, we will also have a bathtub (standard size, about 170 cm long) in the bathroom.
From what I understand, the current floor structure can handle 200kg/m2, but when you factor in ceiling gypsum + floor chipboard, water-based underfloor heating, self-leveling compound, and ceramic tiles, aren't these alone about 100 kg? Does this mean there are only 100kg/m2 left? Or am I thinking completely wrong?
Then I probably need to reinforce the floor structure with a couple more beams to get at least cc30 where the bathtub will be, right? I've read a bit about nogging, but it doesn't seem to have much impact? Especially since you still have to cut a lot of them to fit the drain pipes. It feels like, to achieve the right strength, I need to install a couple or three 4.0m supporting 220x45 in the same direction as the others to achieve cc30 under the bathtub. I really don't want any flex in the bathroom
I'll attach a drawing of the floor structure and the bathroom placement.
Earlier this year, we built a 1.5-story villa with an unfinished attic. Now we're tackling the upper floor, and the biggest problem I have right now is how to construct the floor structure for the bathroom. Currently, we have C24 220x45 cc60 in the floor structure with a maximum span of 4.0m. In addition to a toilet, sink, and shower, we will also have a bathtub (standard size, about 170 cm long) in the bathroom.
From what I understand, the current floor structure can handle 200kg/m2, but when you factor in ceiling gypsum + floor chipboard, water-based underfloor heating, self-leveling compound, and ceramic tiles, aren't these alone about 100 kg? Does this mean there are only 100kg/m2 left? Or am I thinking completely wrong?
Then I probably need to reinforce the floor structure with a couple more beams to get at least cc30 where the bathtub will be, right? I've read a bit about nogging, but it doesn't seem to have much impact? Especially since you still have to cut a lot of them to fit the drain pipes. It feels like, to achieve the right strength, I need to install a couple or three 4.0m supporting 220x45 in the same direction as the others to achieve cc30 under the bathtub. I really don't want any flex in the bathroom
I'll attach a drawing of the floor structure and the bathroom placement.
What you see in the middle of the drawing is a wind brace in the ceiling as well as double rafters on the outer edge where the stairs will be mounted in the space above the bathroom. Perhaps these will also help when we are working on the bathroom? Grateful for any possible answers
200 kg/sqm is the useful load, i.e. the combined weight of people and furniture. In addition, there is the weight of the construction itself. The biggest problem is that the span is too large in relation to the size of the beams, which creates a deflection problem. It is unpleasant and also an additional problem in a bathroom with ceramic tiles on the floor. This problem is only marginally solved by inserting floor joists of the same dimension in between the existing ones. However, you obviously increase the floor structure's capacity to carry larger loads through a smaller distance between the beams. What is the most suitable measure depends on how it looks and how far you have progressed in the work. One possibility is to insert glulam beams between the existing floor joists. If you choose the dimension 90x225 mm, these will take over the load-bearing of the floor from the existing beams because the next layer will end up 5 mm higher. This layer must consist of a sheet material that is sufficiently stiff, preferably k-plywood, 21-24 mm.
Hi, thanks for the response. We haven't done anything at all yet and are just at the starting point of launching the project. My thought was to start with the floorboard so we can move around up there. Right now there is only insulation in the beams.
But if I understand you correctly, adding some extra 220x45 to achieve cc30 wouldn't help as the span would remain the same? If we plan to add 225x90 under the entire bathroom floor, do you mean that they should support the bathroom instead? Should they be placed at cc60, or should we add more at cc30?
But if I understand you correctly, adding some extra 220x45 to achieve cc30 wouldn't help as the span would remain the same? If we plan to add 225x90 under the entire bathroom floor, do you mean that they should support the bathroom instead? Should they be placed at cc60, or should we add more at cc30?
I have read it a few times but something I don't understand is the "spännvid" table. It's some form of report. What does the table actually mean? That the dimensions listed in the table work or? Is it the maximum? I'm not really following there..N Nils82 said:
The support leg's task is to handle some of the loads on the truss, particularly snow loads, so that the dimensions of the high leg do not become too large. This results in a point load on the floor joist, which does not reduce the span. However, the sloped ceiling does affect the deflection assessment somewhat. It is simply not possible to stand in the middle of a floor joist. When I check the deflection based on these altered details, I conclude that 45x220 is still too weak. If you have several 45x220 c/c 600 where the ceiling in the floor below is attached, I believe my suggestion with glulam beams is best. The trusses are calculated for snow zone 3.5, which means somewhere along the northern coast. There is every reason to avoid underdimensioning.
The industry regulations on bathroom construction are just industry regulations, designed by companies that want to sell tiles. They are not Building codes. One problem with them is that they assume certain conventional material choices, which do not always lead to optimal choices.
The industry regulations on bathroom construction are just industry regulations, designed by companies that want to sell tiles. They are not Building codes. One problem with them is that they assume certain conventional material choices, which do not always lead to optimal choices.
Hello!
I received a response from the designer who manufactured the roof trusses and the extra beams and she replied:
"What we usually do when it's a bathroom is to place the beams at cc 300 mm and then support the loads because you halve the load width."
I guess I should be able to trust her.
I received a response from the designer who manufactured the roof trusses and the extra beams and she replied:
"What we usually do when it's a bathroom is to place the beams at cc 300 mm and then support the loads because you halve the load width."
I guess I should be able to trust her.
She has only answered half of the question. I completely agree that doubling the beams at c/c 300 mm results in a halving of the load width, which I have mentioned in my previous response. What she doesn't address is the deflection issue, which cannot be solved with more of the same beams. Placing glulam between the existing beams is a much better solution for a limited additional cost. You won't be satisfied with the other option. But, you do as you wish.
Thanks for the good response. You suggest I should add glued laminated timber 225x90 at CC60 between the existing joists in the bathroom and that it should suffice? As you say, it's only 5 mm higher in the bathroom, and it's not something one will notice since you have to level anyway.J justusandersson said:
Does it matter if I make holes in these for sewage penetrations? With reinforcement, of course.
It depends on where the penetrations are and how large they are. Ideally, you should avoid making holes for plumbing (if you're installing glulam beams, you can drill into the old ones fairly freely). Holes should be made in the center of the beams, not at their edges. Some areas must be avoided. 50 mm plumbing pipes are not as sensitive as 75 and 110 mm. My experience is that a well-planned pipe routing in a new bathroom can solve the issue.
Glulam beams 90x225 mm on c/c 600 mm solve all problems, both deflection and load.
Glulam beams 90x225 mm on c/c 600 mm solve all problems, both deflection and load.