Glue nailing on existing beams or distribute on cc30 instead? Which gives the best result?
In terms of strength, it doesn't matter whether an extra joist is placed straight against a joist or between the joists. With sufficiently thick floorboards, cc 60 is fine. However, cc 30 allows for thinner floorboards to be used without sagging.
For the 70x170 that have extreme wanes, with only 20-30 mm width at the top and bottom, it might be a good idea to place a new joist next to them, as such a joist is estimated to have less than half the load-bearing capacity of a proper (rectangular) 70x170 joist.
Personally, I would place new joists between the old ones, i.e., cc 30 cm, and an extra joist straight against the old joists that have extreme wanes (half-clefts).
Gluing joists together doesn't add anything significant strength-wise unless the quality of the joists is poor. (Compare to glulam)
In conclusion, it's worth mentioning that from my experience, old timber is infinitely better and stronger than modern balsa wood from the lumberyard. Not because the wood is old, but because they carefully selected building timber in the past. Today's fast-growing trees probably wouldn't even be suitable for interior moldings.
For the 70x170 that have extreme wanes, with only 20-30 mm width at the top and bottom, it might be a good idea to place a new joist next to them, as such a joist is estimated to have less than half the load-bearing capacity of a proper (rectangular) 70x170 joist.
Personally, I would place new joists between the old ones, i.e., cc 30 cm, and an extra joist straight against the old joists that have extreme wanes (half-clefts).
Gluing joists together doesn't add anything significant strength-wise unless the quality of the joists is poor. (Compare to glulam)
In conclusion, it's worth mentioning that from my experience, old timber is infinitely better and stronger than modern balsa wood from the lumberyard. Not because the wood is old, but because they carefully selected building timber in the past. Today's fast-growing trees probably wouldn't even be suitable for interior moldings.
Exactly as I thought, and since there are 28x120mm floorboards here, the thickness should be enough for it to be stable even with cc60. But then huggan wrote that it would be much better with cc30, meaning the stiffness of the floor improves with cc30, which made me naturally curious about why that is. However, we will find out in six monthsOldboy said:
Sounds like a very good idea.
Shouldn't there be a bit more stability and less movement between the beams if I also put some glue between them? I'll go with glue; it can't hurt, right? It would be impossible to separate them later, but that's not something I planned on anyway
All the old wood in the house, 3" plank walls, and beams, etc., is very hard and stable. Many are not smooth and nice on the surface and edges like today's planed beams, but when you cut into them, you notice how hard and fine the wood is. In terms of hardness, it feels like really hard pine or even birch or something like that. What lowers the "quality" is the "halvklovorna" in (some) beams.
You can do that. I can imagine it would be quite expensive as it's about some beams. It should probably be around 4-5mm thick for it to be really good. But sure, it would stiffen up enormously. If the beam structure consisted of 120x120, I probably wouldn't have had any choice but to reinforce with HEA beams or similar.
Considered possibly screwing mounting bands onto the underside or on the sides at the bottom of each frame, but the question is if I have the energy. It has to be tight as well, so I think I'll stick to just wood. Possibly I'll glue-nail 45x45 on the lower edge on each side of every 45x170 beam to stiffen up a bit. Such an upside-down T should be equivalent to 2 whole beams, I guess, as it's the tensile loads that spruce beams are weak on. Or I'll put one in the middle of the room where it flexes the most.
If you're really paranoid, you can glue-screw oak on top to get more resistance to compression too There are so many methods, and one is crazier than the other.
Thought of another method, which is probably much cheaper than a whole metal sheet. To screw a profile angle at the top and one at the bottom of each 45x170. Then you have both tensile strength and compression resistance. It should be really stiff.
A HEB 160 in each space would be nice haha... too bad I'm not a millionaire
Considered possibly screwing mounting bands onto the underside or on the sides at the bottom of each frame, but the question is if I have the energy. It has to be tight as well, so I think I'll stick to just wood. Possibly I'll glue-nail 45x45 on the lower edge on each side of every 45x170 beam to stiffen up a bit. Such an upside-down T should be equivalent to 2 whole beams, I guess, as it's the tensile loads that spruce beams are weak on. Or I'll put one in the middle of the room where it flexes the most.
If you're really paranoid, you can glue-screw oak on top to get more resistance to compression too
There are so many methods, and one is crazier than the other.Thought of another method, which is probably much cheaper than a whole metal sheet. To screw a profile angle at the top and one at the bottom of each 45x170. Then you have both tensile strength and compression resistance. It should be really stiff.
A HEB 160 in each space would be nice haha... too bad I'm not a millionaire
Well, but the ones I mean are not as thick as a steel beam as you might imagine them, but 1-3mm in thickness.
But no idea what they cost.
They are used, for example, as roof beams in light halls, isover had some construction description of such as floor joists (300mm high).
But no idea what they cost.
They are used, for example, as roof beams in light halls, isover had some construction description of such as floor joists (300mm high).
Hm, 1-3 mm? If it's only 1 mm, for example, it feels like either the screw/nail has to be set all the way on the upper part near the top, or it will compress itself and give way by bending. At the bottom, there are no issues as there's only tensile force.
If you place a 1mm sheet between two wooden beams, it's a different matter, as the wooden beams hold the sheet together at the top so it can't bend and thus compress.
However, if it's a C-profile as you've also mentioned, that's a different case because it can't bend in the same way at the top but will still likely resist the pressure quite well, I presume.
There are many solutions. I've also considered strapping each beam with steel banding, tightening it properly with the bander, and then placing a couple of screws at each end. That should stiffen it up significantly. The question is whether the steel banding might fatigue over time and then lose its tensile strength. In that case, it might rather just rattle against the wood when walking on the floor.
In the following pdf, from pages 8 to 26, there are several interesting examples of different solutions. It involves steel banding and extra beams at the bottom, etc. Then they've calculated what gives the best results and is most economically justifiable. Quite an interesting read actually:
Svikt i träbjälklag (Skanska Teknik AB)
If you place a 1mm sheet between two wooden beams, it's a different matter, as the wooden beams hold the sheet together at the top so it can't bend and thus compress.
However, if it's a C-profile as you've also mentioned, that's a different case because it can't bend in the same way at the top but will still likely resist the pressure quite well, I presume.
There are many solutions. I've also considered strapping each beam with steel banding, tightening it properly with the bander, and then placing a couple of screws at each end. That should stiffen it up significantly. The question is whether the steel banding might fatigue over time and then lose its tensile strength. In that case, it might rather just rattle against the wood when walking on the floor.
In the following pdf, from pages 8 to 26, there are several interesting examples of different solutions. It involves steel banding and extra beams at the bottom, etc. Then they've calculated what gives the best results and is most economically justifiable. Quite an interesting read actually:
Svikt i träbjälklag (Skanska Teknik AB)
Come up with another method that is incredibly simple. Just band around the bottom part! It's super fast and probably cheap too (if you have access to a bander and steel band, of course).
It takes about 30 seconds per stud, but even with all the handling around it, it probably doesn't take more than a minute, at most two minutes per stud. No need to screw or anything. Just band around it.
You can even use double or triple bands for safety.
It should become really stable, as you apply a lot of compression at the bottom of the stud, depending on how tightly you band.
It takes about 30 seconds per stud, but even with all the handling around it, it probably doesn't take more than a minute, at most two minutes per stud. No need to screw or anything. Just band around it.
You can even use double or triple bands for safety.
It should become really stable, as you apply a lot of compression at the bottom of the stud, depending on how tightly you band.
Hmm, maybe it has to do with the spaces. It strangely enough works for me. I'm using Firefox if that matters.JOW said:
If you try the following and go through Google then?
https://www.google.se/#q=SBUF+11235+Slutrapport_Svikt+i+tr%C3%A4bj%C3%A4lklag.pdf
If that doesn't work either, you can always search for the following on Google, and it will appear directly:
SBUF 11235 Slutrapport_Svikt i träbjälklag.pdf
SBUF 11235 Slutrapport_Svikt i träbjälklag.pdf