Floor structure in barn loft help?

[justusandersson]

It's important to secure them against tipping. Angle brackets are probably best for that. If you have the correct dimensions on the cross beams, no other measures are needed.

 

[Novisfixaren]

It's important to secure them against tipping. Angle plates are probably best regarding that. If you have the right dimensions on the cross beams, no other measures are needed.

Ok, what do you mean by right dimensions? You mean in relation to the span?

Blocking stiffens up the construction further and is a fairly simple/cheap measure, right?

 

[justusandersson]

Ok, what do you mean by the right dimensions? You mean in relation to the span?

Yes.
Bridging has no effect against deflection from an evenly distributed load. They can marginally reduce the impact of a point load. It's not something that should be planned when you can build a floor structure from scratch. Screw-glued particleboard on top of the beams, however, does have an effect, and can allow you to reduce the dimensions of the beams.

 

[Novisfixaren]

Yes.
Blocking has no effect on deflection from a uniformly distributed load. They can marginally reduce the impact of a point load. It's not something you should plan on when you can build a floor structure from scratch. Screwed and glued chipboard on top of the beams, however, has an effect, and can allow you to reduce the dimension of the beams.

Ok I have now supported the floor structure with beams from below. The span between beams is about 4.5 meters.

The question is how I should approach the existing floor structure which currently consists of:

45x220 cc 120cm this is insulated and finished.

Questions:

1. Can I supplement with e.g., 45x95 cc60 transversely on top of the current floor structure, or does the current floor structure need to be supplemented with 45x220 between each 120cc bay (which means removing insulation) so it becomes cc 60?

2. The current floor structure 45x220 is not quite level. How do you straighten this easily? Nail on e.g., 45x95 on the side of the 45x220 that are not level?

It's good that there is 20cm of insulation in the floor structure as it is uncertain whether both the loft and the ground floor will always be heated in winter.

Tearing down the floor structure is not an option as the ceiling on the ground floor is plastered and finished.

 

[justusandersson]

The best would be if you could reduce the distance between the support beams to about 3.6 meters. With screw-bonded chipboard on top, you can then manage with c/c 1200 between the joists.

If you are going to have screw-bonded chipboard on top of the joists, you must align them with glued-on wedges so that you get full interaction between the joists and chipboard.

 

[Novisfixaren]

The best option would be if you could reduce the distance between the support beams to about 3.6 meters. With screwed and glued particle board on top, you can then manage with c/c 1200 between the joists.

If you are going to have screwed and glued particle board on top of the joists, you must align them with glued-on wedges so that you get full interaction between the joists and the particle board.

Reducing the distance to 3.6m means installing an additional support beam in the middle of the ground floor, which limits the use of the ground floor significantly.

The alternative then remains to let the 45x220s that are on cc120 stay but install completely new 45x220 cc 60 everywhere? Each beam needs to be leveled and individually supported against the support beam?

 

[justusandersson]

Then the option remains to leave the 45x220 that are on cc120 in place but install entirely new 45x220 cc 60 everywhere? Each beam should be leveled and supported under each one individually?

Yes. That way you'll manage to keep the deflection under L/300. It will be a bit wobblier than desirable, but you'll have to put up with it.