Hello,
I am going to make a 4-meter joist for an extension.
Is 45x195 k24 cc30 sufficient, or do I need to go up to 45x220?
Regards,
Janne
I am going to make a 4-meter joist for an extension.
Is 45x195 k24 cc30 sufficient, or do I need to go up to 45x220?
Regards,
Janne
You mean that you have a four-meter span on the floor joists in the floor structure?
I haven't seen any table that considers the walls' load, but if we entertain the idea of not worrying about the walls, the infamous span table says that 45x195 is sufficient up to 3.5 meters. 45x220 is not included, instead, it goes up to 70x195 to reach four meters with c/c 30. Now, it's important to consider that the table is developed for deck flooring structures. It would be interesting to see how to calculate floor joists for a regular building.
I haven't seen any table that considers the walls' load, but if we entertain the idea of not worrying about the walls, the infamous span table says that 45x195 is sufficient up to 3.5 meters. 45x220 is not included, instead, it goes up to 70x195 to reach four meters with c/c 30. Now, it's important to consider that the table is developed for deck flooring structures. It would be interesting to see how to calculate floor joists for a regular building.
Checked now on traguiden.se which has dimensioning examples. They seem to indicate that 45x220 is sufficient for a four-meter span if you have glued particleboard as the subfloor. Here they talk about a c/c of 60 so you might manage with 195.
http://www.traguiden.se/TGtemplates/popup1spalt.aspx?id=679&contextPage=1465
http://www.traguiden.se/TGtemplates/popup1spalt.aspx?id=679&contextPage=1465
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It is more than enough with a joist of 45*195 with c/c 300 if you are not going to have abnormally large weights in the extension like a 2-ton billiard table, etc.
But in any case, if you're going to use tiles on the floor, use glued floor gypsum!
But in any case, if you're going to use tiles on the floor, use glued floor gypsum!
Self-builder
· Stockholm
· 8 599 posts
In my summer cottage, the floor joists are 4.8 m with dimensions 45x195, spaced at 60 cm (I should add that I added a central support so the actual span is 2.4 m - this was optional if you wanted to make it more stable according to the supplier).
In the loft, it's the bottom chords of the roof trusses that form the "floor joists," with dimensions 45x220, spaced at 120 cm.
It feels stable enough - but it's the supplier who calculated it, not me
/K
In the loft, it's the bottom chords of the roof trusses that form the "floor joists," with dimensions 45x220, spaced at 120 cm.
It feels stable enough - but it's the supplier who calculated it, not me
/K
I have a 3.9m span and 45x220 cc600 with noggins in the middle and screwed and glued floor chipboard, it is designed by a structural engineer, he said that the dimension can handle about a 4.2m span. There doesn't seem to be any flex in the floor anyway. It becomes cheaper with fewer joists and less work than 45 x 195 cc300.