I hope with my first post here on the forum to get an answer to a question I have...
A complete renovation of the upper floor in our 1920s villa is ongoing, and with this, new PEX pipes will be run from a centrally located shaft (by the chimney) "across the joists" out to the radiators at each gable.
I thus need to drill four 30mm holes in all the beams on one side to reach the gable, and two 30mm holes in all the beams in the other direction to reach the other gable.
The beams are 3"x8" on cc25" which corresponds to approximately 7x20cm on cc63cm.
The span of the beams between the outer wall and heart wall is about 4m.
The question is whether I need to be worried and contact a structural engineer to calculate, or if I should happily drill away?
Thankful for help
A complete renovation of the upper floor in our 1920s villa is ongoing, and with this, new PEX pipes will be run from a centrally located shaft (by the chimney) "across the joists" out to the radiators at each gable.
I thus need to drill four 30mm holes in all the beams on one side to reach the gable, and two 30mm holes in all the beams in the other direction to reach the other gable.
The beams are 3"x8" on cc25" which corresponds to approximately 7x20cm on cc63cm.
The span of the beams between the outer wall and heart wall is about 4m.
- On the side where 4 pipes will be run, and thus 4 holes per beam are necessary, the holes will be drilled roughly in the middle between the support against the outer wall and the heart wall.
- On the side where 2 pipes will be run, and thus 2 holes per beam are necessary, the holes will be drilled about 1 meter from the support against the heart wall.
The question is whether I need to be worried and contact a structural engineer to calculate, or if I should happily drill away?
Thankful for help
Do they have any section on the house where you can mark the intended holes? Check this page for some guidance https://www.traguiden.se/konstruktion/konstruktiv-utformning/stomme/bjalklag/barformaga--bjalklag/
Construction veteran
· Åland
· 2 077 posts
You drill in the middle of the joist's height and as close to the middle of the span as possible, and there won't be any problems.B BMannen said:I hope with my first post here on the forum to get an answer to a question I have...
Total renovation of the upper floor is ongoing in our 1920s villa and with this, new PEX pipes will be drawn from a centrally located shaft (by the chimney) "across the joist" out to the radiators at each gable.
I thus need to drill 4 30mm holes in all beams on one side to reach the gable, and 2 30mm holes in all beams the other way to reach the other gable.
The beams are 3"x8" on cc25" which corresponds to approximately 7x20cm on cc63cm.
The span of the beams between the outer wall and the heart wall is about 4m.
I assume I'm drilling in the middle of the beams' height?
- On the side where 4 pipes are to be drawn and thus 4 holes per beam are necessary, the holes will be drilled approximately halfway between the support against the outer wall and the heart wall.
- On the side where 2 pipes are to be drawn and thus 2 holes per beam are necessary, the holes will be drilled about 1 meter from the support against the heart wall.
The question is whether I need to be worried and contact a constructor to calculate, or if I can happily drill away?
Thankful for help
No, you should probably avoid the middle of the span, as that's where the bending forces are greatest.
Feel free to drill the holes a bit closer to one of the supports.
If you're unsure, start by screw-gluing a piece of 12 or 18mm construction plywood on each side, say 1-2 meters long and as high as the beam (was it 20cm). Then drill the holes in the middle, this way the construction is still stronger than it was before.
Feel free to drill the holes a bit closer to one of the supports.
If you're unsure, start by screw-gluing a piece of 12 or 18mm construction plywood on each side, say 1-2 meters long and as high as the beam (was it 20cm). Then drill the holes in the middle, this way the construction is still stronger than it was before.
Holes should be made where the shear forces are smallest, i.e., far from the supports, so closer to the middle of the span.
Otherwise, use plyfa as mentioned if you are unsure.
Otherwise, use plyfa as mentioned if you are unsure.
I had a similar question some time ago. Got a good answer in post #3 in this thread: https://www.byggahus.se/forum/threads/roer-foer-el-i-mellanbjaelklag.300284/
Not close to the middle of the span according to this page.B bossespecial said:
https://www.traguiden.se/konstruktion/konstruktiv-utformning/stomme/bjalklag/barformaga--bjalklag/
Construction veteran
· Åland
· 2 077 posts
Mikael_L said:
Construction veteran
· Åland
· 2 077 posts
WRONG, completely wrong!
Imagine a long deck of cards, bend it and see where the cards shift the most!
Imagine a long deck of cards, bend it and see where the cards shift the most!
Midway up the beam's height, "best".
Mid-span between support points doesn't need to be the worst. The moment is managed with a couple of forces above and below the hole, the shear force is a bit "trickier" to handle, so it's advisable to avoid holes too close to the supports where the shear force is at its greatest.
What does the support of the roof look like? In my 1920s villa, the roof "rests" on the joist, which results in a somewhat different shear force distribution than for a standard beam.
Mid-span between support points doesn't need to be the worst. The moment is managed with a couple of forces above and below the hole, the shear force is a bit "trickier" to handle, so it's advisable to avoid holes too close to the supports where the shear force is at its greatest.
What does the support of the roof look like? In my 1920s villa, the roof "rests" on the joist, which results in a somewhat different shear force distribution than for a standard beam.
The wood guide and I do not agree with the senior consultant.
I tried to find a bit more information on the subject.
It seems that the bending moment is worst in the middle of the span, while the shear forces in the beam are best in the middle of the span.
It's just a choice between the plague and cholera ...
https://www.byggahus.se/forum/threads/haltagning-i-traebjaelklag.146287/#post-1087883
I tried to find a bit more information on the subject.
It seems that the bending moment is worst in the middle of the span, while the shear forces in the beam are best in the middle of the span.
It's just a choice between the plague and cholera ...
https://www.byggahus.se/forum/threads/haltagning-i-traebjaelklag.146287/#post-1087883
I would think that the wood guide is written for a slightly broader audience, which is why it's not that in-depth. Senior consultant shows an understanding of both power play and strength and I agree with him
But it's as you write, plague or cholera, although one is easier to cure than the other
But it's as you write, plague or cholera, although one is easier to cure than the other
Wow grateful for strong and quick response!
Have read a bit on the wood guide but since the exact calculation of what I need to do seems to require half a science, I'm thinking about the old carpenter's best tricks in tricky situations?
Over-dimensioning with 18mm k-plywood on each side of respective beam at 20x100cm and drilling centrally in height, in the middle of the span?
Would have wished it was just drilling, but the reinforcement is still feasible with minimal interventions in the floor... what do you think about that?
Have read a bit on the wood guide but since the exact calculation of what I need to do seems to require half a science, I'm thinking about the old carpenter's best tricks in tricky situations?
Over-dimensioning with 18mm k-plywood on each side of respective beam at 20x100cm and drilling centrally in height, in the middle of the span?
Would have wished it was just drilling, but the reinforcement is still feasible with minimal interventions in the floor... what do you think about that?
Construction veteran
· Åland
· 2 077 posts
Here we are talking about small holes and they should be placed in the 0-layer, i.e., midway through the beam height where the shear forces are minimal.