I'm working on making a sleeping loft in the attic of an old log house from the 1800s. There were timber beams with a spacing of about 70 cm. The beams are 120-150 mm high and maybe between 80-150 mm wide and 440 cm long. Some type of rough boarding is nailed under the beams (the ceiling under the attic). The insulation consists of sawdust, chips, stone, and "other". At first, I planned to just lay a 27 mm pine floor directly on the old joists, but the floor was very shaky when you bounced a little.
So... Now I've dug up the insulation and laid down a 45x145 C24 beam with joist hangers between all the original joists to get a spacing of about 35 cm. Then I've placed 1 bridging piece per gap between all the joists. But it made no difference. Will it get better when I lay the floor? Could it be due to the heavy insulation?
Yes, so 145mm is what fits. Or sure, I could lay down 220mm as well, but then I lose 75mm in ceiling height. And with 145mm, the highest ceiling height becomes 160cm. So I guess it’s a trade-off between a wobbly floor and ceiling height. I chose 145mm since the original beams were around that thickness.
I found a craftsman knowledgeable about old houses, and he said it was probably because it was heavy "insulation." I was considering replacing it with a lighter material, but he said you should try to keep the original insulation since it has good heat/cold storage properties and soundproofs well.
So I've decided to let it be wobbly; the space will be a sleeping loft in an old summer house, so it’s not like there will be a dance party up there, haha. Plus, a wobbly floor is period-appropriate for an 1800s house
You can't fit a low steel profile as support bearing transversely at a suitable place? For example, an HEB 100 or equivalent? Such a one would relieve well.
Can't you fit in a low steel profile as lateral support at a suitable place? For example, a HEB 100 or similar? Such would provide good support.
Bullebupp said:
Unfortunately, there's a masonry chimney in the middle. Tomorrow I will remove some of the insulation to see if it improves things.
I made a calculation on the website I linked to, if you could place the beam offset so that it lies 1800 mm from one edge then the floor joist could manage with 45*145 mm without becoming too flimsy. But of course, introducing an extra beam as support involves a lot of work, so you might not be keen on that solution in a space where people mostly sleep.
I did a calculation on the page I linked to, if you could place the beam offset so it's 1800 mm from one edge, the floor could manage with 45*145 mm without being too unsteady. But of course, adding an extra beam for support involves quite a bit of work, so you might not be so keen on that solution in a space where people mostly sleep.
It wasn't particularly easy to find one of those steel profiles here haha. Now I have removed probably 700kg of stone and sand from one part of the attic where it was most unsteady, and it made a significant difference actually. I think this will be fine. It would be quite a bit of extra work to insert such a beam, for sure. Now it feels okay actually, and this will have to do.
It wasn't particularly easy to find such a steel profile here hehe. Now I've removed probably 700kg of stone and sand from one part of the attic where it was the most shaky, and it made a real difference actually. I think this will work fine. Installing such a beam would definitely mean a lot of extra work. Now it feels okay actually, and this will just have to do.
thanks for all the help and tips anyway
I understand it's not your idea but something that was done a long time ago, but why on earth would anyone "insulate" with sand and stone? Seems insanely stupid. If it insulates, then it's only against sound.
throw away all the old insulation. it's probably sawdust, etc. weighs a "ton". buy 2nd-grade RHS steel profile, e.g., 40x60x2, 40x70x2. weld together on height, and you'll get 40x120 or 40x140 mm. then weld cross-braces underneath on cc. 600mm for screwing from below. drill several holes laterally alternately in the upper and lower profile and screw sideways. you'll get 3 load-bearing walls in the steel, ensuring a rigid floor. wood can never replace a floor in tight spaces like steel. then box between the joist rows with wood. completely fine. use beam screws. long drill bit.
I understand that it's not your invention but something that was done a long time ago, but why on earth would one "insulate" with sand and stone? It seems extremely dumb. If it insulates, then it's only against sound.
Yes, sand and stone would likely insulate very poorly. But so does timber. However, it has good heat-retaining properties. I found many old bottles, even a tooth and bone from an elk. Then there's a substantial hook in the ceiling. And a hatch up to the attic from the kitchen. So it could have been used as some sort of pantry or something.
When I've arrived here in the winter, the house is very cold. It takes a day to get the frame up to temperature. But then the house stays warm for a long time. So it works at least
I wonder if it would work to screw-glue a steel strap, about 2-3mm thick, under the floor joists to absorb some of the forces. It's on the underside where the stretch is longest, and therefore the forces are highest.
