Load capacity for 12 x 12 inch timber?

[Plupp 55101]

Hello!

I'm working on a design for a timber post foundation to place a house on. Someone will calculate the specifics for the building permit later, but I'm currently checking if my plan is even feasible.

Floor Joists:
I'm thinking of laying 3 rows of 12 X 12 inch beams horizontally (as seen on a drawing) with a post spacing of about 3.9m center-to-center.

Like this:

X-----X-----X-----X
4.3m center-to-center between here
X-----X-----X-----X
4.3m center-to-center between here
X-----X-----X-----X

Each row X-----X-----X-----X is 15.6m and consists of 3 12x12 inch beams in a row. So a total of 4 posts per row. 12 posts for all 3 rows.

Floor Beams:
Then 16 pieces of 6 X 8 inch beams vertically over these, where the posts will be approximately 4.3m center-to-center.

Will this even be possible, do you think? How durable is timber compared to glulam? Glulam is extremely hard, so you'd need crazy dimensions to compare.

Then there will be ordinary construction wood between these floor beams, so it will be 60cm center-to-center. Also a few noggins horizontally.

I know that 45*220 can handle 3.6m, so reasonably the floor joists of 12*12 inches should handle 3.9m? And the floor beams of 6*8 inches should handle 4.3m?

 

[klaskarlsson]

Hello!

I am drawing a timber foundation to place a house on. I will have someone calculate it for the building permit later, but right now I'm checking if my plan is even feasible.

Floor Joists:
I'm thinking of first laying 3 rows of 12 X 12 inch horizontally (if you look at a drawing) with a distance of about 3.9m center to center.

Like this:

X-----X-----X-----X
4.3m center to center here
X-----X-----X-----X
4.3m center to center here
X-----X-----X-----X

Each row X-----X-----X-----X is 15.6m and consists of 3 12x12 inches in a row. So a total of 4 posts per row. 12 posts for all 3 rows.

Floor Beams:
Then 16 pieces of 6 X 8 inch placed vertically across these where the posts would be about 4.3m center to center.

Is this even possible, do you think? How durable is timber compared to laminated wood? Laminated wood is really hard, so you probably need crazy dimensions to be comparable.

Then there will be regular construction wood between these floor beams making it 60 centers. Also some shorter beams horizontally.

I know 45*220 should handle 3.6m, so reasonably the 12*12 inch floor joists should handle 3.9m? And the floor beams on 6*8inch handle 4.3m?

Is it for practical dimensioning or for a building permit?
In practice, 300x300 mm should hold very well, even though almost 4m between the posts seems a bit too long to avoid any sway. When it comes to the floor beams, wouldn't the center be much smaller? 16 on 15.6m gives about the recommended center of 120?

For the building permit, you will probably need to calculate the deflection, etc. - and that would likely include having some quality measure of the wood as well.

https://www.traguiden.se/konstrukti...uktionsvirke-i-ett-fack/?previousState=101000
https://www.traguiden.se/konstrukti...dbalkar-till-1-planshus/?previousState=101000

 

[Plupp 55101]

Is it for sizing in practice or for a building permit? In practice, 300x300 mm should hold up very well even though nearly 4m between the plinths sounds a bit too far to not get some sway. Regarding the floor joists, the spacing would be much less, right? 16 on 15.6m give about the recommended 120 cc?

For the building permit, you probably need to calculate deflection etc. - and then you should probably also have some quality measure of the timber.

[link]
[link]

Hi and thanks for the response!

I don't quite understand the question - both, I assume? I want to get the building permit approved + avoid any sway. I don't want a lot of plinths for aesthetics, so I'm trying to keep the number as low as possible.

Here it says a maximum of 4.5m https://www.traguiden.se/konstrukti...grundlaggning/grundlaggning/oppen-plintgrund/ and it only has double 45x220 around and then single 45x220 in between? 12*12 inches should hold better, I thought?

Regarding the floor joists, the 120 cc is correct between these and also 60 cc where I will insulate. But I meant between the plinths simply. Same measure where it shows 4.5m here https://www.traguiden.se/konstrukti...grundlaggning/grundlaggning/oppen-plintgrund/

EDIT: now I saw the link you sent https://www.traguiden.se/konstrukti...dbalkar-till-1-planshus/?previousState=101000 that the A-measure and B-measure are different compared to the one showing 4.5m. Looks like I will have to add more plinths then. :/

 

[Finndjävel]

Hello!

I'm drawing the design for a timber post foundation to place a house on. I'll have someone calculate it later for the building permit, but I'm checking if my plan is even possible.

Floor Joists:
I plan to first lay 3 rows of 12 X 12 inches laid horizontally (if you look at a drawing) with a post spacing of about 3.9m center to center.

Like this:

X-----X-----X-----X
4.3m center to center here
X-----X-----X-----X
4.3m center to center here
X-----X-----X-----X

Each row X-----X-----X-----X measures 15.6m and consists of 3 pieces of 12x12 inches in a row. So a total of 4 posts per row. 12 posts for all 3 rows.

Floor Beams:
Then there are 16 pieces of 6 X 8 inches placed vertically across these where the posts then end up approximately 4.3m center to center.

Do you think this is even possible? How durable is timber compared to laminated wood? Laminated wood is really hard, so you probably need crazy dimensions to be comparable.

Then there will be regular construction timber between these floor beams, making it 60 center to center. Also some noggins horizontally.

I know 45*220 should manage 3.6m so then reasonably the floor joists of 12*12 inches should handle 3.9m? and the floor beams of 6*8 inches handle 4.3m?

Four posts on 15.6 meters make it 5.2m between posts, not 3.9m.

 

[Plupp 55101]

Four plinths at 15.6 meters would be 5.2m between the plinths, not 3.9m.

Right, thanks, meant 5 with 3.9. I have more sketches in front of me and at 2:03 AM the sharpness wasn't 100. It's 4 beams in a row and 5 plinths - that's how it should be, of course.

 

[Plupp 55101]

No one knows this? Does anyone know the span you can have with double glulam beams 90mm*315mm according to the tables? Can't find anything about it.. That is, between A and B here: https://www.traguiden.se/konstrukti...dbalkar-till-1-planshus/?previousState=101000