Footings, Columns,Beams, and Floor slabs

Almost everything that needs to be said about concrete, cement, hand-mixing, uses and prices has been said on this forum. Please check out the contributions before posting new questions.

Moderators: Sometimewoodworker, MGV12, BKKBILL, pattayapope

Footings, Columns,Beams, and Floor slabs

Postby sirineou » Tue Aug 14, 2012 6:25 pm

The bare bones of Thai Construction.
I Have being looking for information on these subjects to confirm what I already know,and learn thinks I don't know, and for the most part I had to chase it all over different threads, and had to wade through numerous posts of other technical information, and friendly banter to find the information I needed.Al very informative and entertaining I might add.So My thinking is to consolidate all the information in one thread for easy access.
First Footings:
How do I know if I need piles driven in to the ground before I can pour a footing? a question whose answer might be obvious to thase of as who have experience in building but no so apparent to some one starting to build for the first time.
Once we have an answer to the above question, then we can proceed in talking about the construction of the average footing, hole size and depth steel, type of concrete, pad width and thickness,
average Columns, steel to use, Thickens of column for a particular grid spacing, grid spacing, curing times, drying etc
Beams, same as columns, steel, sizes for a particular column grid, and any questions that I forgot to ask.
I know all the this information is available in other threads and links to these thread might be a good way to back up the information.
Floor slabs, concrete pour, or pre-stressed concrete planks, Thickness of slab, steel rebar. etc
So let's start with footings,
How do I know if I need piles, I mean aside from hiring an engineer, are some areas in Thailand where piles are needed more than others? is the previous use of the land, an indicator of why piles might be necessary? etc.
I talk to my self because I am the only one who will listen
User avatar
sirineou
 
Posts: 1133
Joined: Wed Jun 03, 2009 9:30 am
Location: USA/Thailand, khon Kaen

Re: Footings, Columns,Beams, and Floor slabs

Postby fredlk » Tue Aug 14, 2012 6:51 pm

sirineou wrote:How do I know if I need piles, I mean aside from hiring an engineer, are some areas in Thailand where piles are needed more than others?

Bangkok and the surrounding areas are or were swamp and marshland and so piles are always used.
I built on the slopes of a hill and felt it safer to use piles while nobody could tell me if this was necessary. As far as I know nobody else in this area has done so.
User avatar
fredlk
 
Posts: 5879
Joined: Tue Apr 07, 2009 3:11 pm

Re: Footings, Columns,Beams, and Floor slabs

Postby Roger Ramjet » Tue Aug 14, 2012 10:01 pm

sirineou,
I used bore piles for the simple reason I had neighbours. The driven piles will damage nearby houses in some cases.
Bore piles are three times more expensive than driven piles. The Or Bor Tor and bore pile company will know the projected debth for your area.
The difference between the depth of my piles over a 30 metre by 11 metre area varied from 16 metres to nearly 30 metres, it just depends where they hit the rocky soils.
Every one of my piles were tested after they were in situ and all passed. If they had not the company would have dug them out and replaced them.
Good luck.
User avatar
Roger Ramjet
 
Posts: 5251
Joined: Tue Apr 27, 2010 12:55 pm

Re: Footings, Columns,Beams, and Floor slabs

Postby sirineou » Sat Aug 18, 2012 3:57 pm

Is a 10 cm footing pad adequate for a 4x4 meter grid ? or would 20cm be better?
how about the columns , is 20 cm adequate? for a 4x4 meter column spacing?
and for the same spacing is a 30 cm beam adequate?
I talk to my self because I am the only one who will listen
User avatar
sirineou
 
Posts: 1133
Joined: Wed Jun 03, 2009 9:30 am
Location: USA/Thailand, khon Kaen

Re: Footings, Columns,Beams, and Floor slabs

Postby fredlk » Sat Aug 18, 2012 4:09 pm

sirineou wrote:how about the columns , is 20 cm adequate? for a 4x4 meter column spacing?
and for the same spacing is a 30 cm beam adequate?

The standard on most builds seems to be 20 centimetre columns and beams of 40 centimetres. I have beams of 6 metres on 20 centimetre columns.
User avatar
fredlk
 
Posts: 5879
Joined: Tue Apr 07, 2009 3:11 pm

Re: Footings, Columns,Beams, and Floor slabs

Postby geordie » Sat Aug 18, 2012 4:18 pm

sirineou wrote:Is a 10 cm footing pad adequate for a 4x4 meter grid ? or would 20cm be better?
how about the columns , is 20 cm adequate? for a 4x4 meter column spacing?
and for the same spacing is a 30 cm beam adequate?

you really do need to put a bit more thought into this :roll: a 20cm footing pad will always be better than a 10cm ? the heavier the better but then you hit cost constraints :( is the gain worth the extra cost
if you take a look at the variety in scale on RR,s build diffent sizes all over the place ?? there is also what is going above to consider what loads are to be put on it
my comments may be wrong but never deliberately
If it aint broke, dont fix it
User avatar
geordie
 
Posts: 3867
Joined: Sun Oct 12, 2008 4:39 am

Re: Footings, Columns,Beams, and Floor slabs

Postby Roger Ramjet » Sat Aug 18, 2012 4:26 pm

sirineou,
You have to tell us what sort of land you're contemplating building on, if you have neighbours close by (hammered piles will cause you to be hated and might even crack their walls), what the structure will support (tile roof, steel roof etc), and most importantly all columns, and beams are not equal, it depends on what they support and where.
An example is if you are building an outside staircase. Thais rarely take this into account and do not use piles or footings. The end result is the staircase breaks away from the main house structure. When my wife and I looked at new 6-9 million baht homes we couldn't believe the dilapidated state they looked in with both front and back concrete stairs separated from the main building.
Also, if you have an inside concrete staircase you will need greater support with piles and also footings. You might like to look at this page (or just before, ten after) I tried to cover everything.
viewtopic.php?f=3&t=1864&start=315
Also on Max's build in Chiang Mai where he was building his observatory tower where he found that no two columns or beams were equal as each supported a different weight, so in the end he erred on the side of over engineering like I did.
The rebar you use is also important. There are different grades of rebar that I also covered with photos. An example is that say, 12mm rebar (white) will support 5 tonnes, but 12mm purple will be rated to support 9 tonnes. In each case you look at the metal disk that is attached to the lot of rebar.
User avatar
Roger Ramjet
 
Posts: 5251
Joined: Tue Apr 27, 2010 12:55 pm

Re: Footings, Columns,Beams, and Floor slabs

Postby geordie » Sat Aug 18, 2012 4:31 pm

Roger Ramjet wrote:sirineou,
You have to tell us what sort of land you're contemplating building on, if you have neighbours close by (hammered piles will cause you to be hated and might even crack their walls), what the structure will support (tile roof, steel roof etc), and most importantly all columns, and beams are not equal, it depends on what they support and where.
An example is if you are building an outside staircase. Thais rarely take this into account and do not use piles or footings. The end result is the staircase breaks away from the main house structure. When my wife and I looked at new 6-9 million baht homes we couldn't believe the dilapidated state they looked in with both front and back concrete stairs separated from the main building.
Also, if you have an inside concrete staircase you will need greater support with piles and also footings. You might like to look at this page (or just before, ten after) I tried to cover everything.
viewtopic.php?f=3&t=1864&start=315
Also on Max's build in Chiang Mai where he was building his observatory tower where he found that no two columns or beams were equal as each supported a different weight, so in the end he erred on the side of over engineering like I did.
The rebar you use is also important. There are different grades of rebar that I also covered with photos. An example is that say, 12mm rebar (white) will support 5 tonnes, but 12mm purple will be rated to support 9 tonnes. In each case you look at the metal disk that is attached to the lot of rebar.


you should read all the thred he is trying to formulate a ""menue"" for basic construction :mrgreen:
my comments may be wrong but never deliberately
If it aint broke, dont fix it
User avatar
geordie
 
Posts: 3867
Joined: Sun Oct 12, 2008 4:39 am

Re: Footings, Columns,Beams, and Floor slabs

Postby sirineou » Sat Aug 18, 2012 5:26 pm

geordie wrote:
you should read all the thred he is trying to formulate a ""menue"" for basic construction :mrgreen:


I am trying to consolidate all the basic information for easy reference thread, for those that are just starting and might have the same questions in their minds, in one thread
Then people can expand by asking questions that more specifically pertain to their particular situation.
In the particular situation I am referring to
,I have never met the person I am doing the design for, and never seen the property. I an doing it as a favor to a Thai friend and doing it over emails, and with common access to the sketch up CAD program.
you can see the location of the columns from the location of the footings
Image
and I have explained to them that everything I suggest is dependent on the soil conditions of their property.I am giving them the basics and they need to make adjustments if necessary.
Ok as you can see it is a two story structure, 14x8 m designed on a 4 m wide x 3,5 m long grid.
Now that they want the additional weight of the beams, and pre-stresed concrete planks under the roof , I am forced to re-think my 20 cm column design because of the additional weight..
So the question is , should they upgrade to a 25 cm column, or as suggested use heavier steel, or both and what size rebar do you all think should be used for the 20 cm column, of for the 25 cm column.
I am also thinking about the forms for the columns, with the 20 cm columns that I am familiar, they can use the 8 inch and 10 inch wood that is commonly sold in Thailand, How about the 25 cm column ?
I talk to my self because I am the only one who will listen
User avatar
sirineou
 
Posts: 1133
Joined: Wed Jun 03, 2009 9:30 am
Location: USA/Thailand, khon Kaen

Re: Footings, Columns,Beams, and Floor slabs

Postby geordie » Sat Aug 18, 2012 7:02 pm

the colums could realistically stay the same dimention and upsize/upgrade the steel i would be inclined to do the same with the footings upgrade them as thats where the extra few ton (15 +)ton will ultimately end up putting pressure with such wonderful balconys for burglars to use i would not worry to much about the roof why so much wasted space that could be living area
my comments may be wrong but never deliberately
If it aint broke, dont fix it
User avatar
geordie
 
Posts: 3867
Joined: Sun Oct 12, 2008 4:39 am

Re: Footings, Columns,Beams, and Floor slabs

Postby sirineou » Sat Aug 18, 2012 7:20 pm

geordie wrote:the colums could realistically stay the same dimention and upsize/upgrade the steel i would be inclined to do the same with the footings upgrade them as thats where the extra few ton (15 +)ton will ultimately end up putting pressure with such wonderful balconys for burglars to use i would not worry to much about the roof why so much wasted space that could be living area

Geordie, I told them the same thing, I told them when the burglars brake through your roof tiles and find the cement planks, they are going to get mad, they are not going to say " oh well" turn around and leave, they will probably brake a window or door and get in. and aside from the stolen items now they will also need to replace the window or door. I told them that for the expense of the false floor, they could have a wonderful burglar alarm installed, But you know Thai women, you can not reason with them. :lol:
I talk to my self because I am the only one who will listen
User avatar
sirineou
 
Posts: 1133
Joined: Wed Jun 03, 2009 9:30 am
Location: USA/Thailand, khon Kaen

Re: Footings, Columns,Beams, and Floor slabs

Postby BKKBILL » Sat Aug 18, 2012 7:24 pm

sirineou wrote:But you know Thai women, you can not reason with them. :lol:

Very true on the building end just ask RR :D :mrgreen: :D
It's not who you know, it's whom you know.
User avatar
BKKBILL
 
Posts: 2942
Joined: Tue May 26, 2009 10:05 pm
Location: Mae Taeng, Chiang Mai

Re: Footings, Columns,Beams, and Floor slabs

Postby Roger Ramjet » Sat Aug 18, 2012 7:58 pm

sirineou,
You're going to have major problems with the footings and foundations in the centre of the house because they are carrying the most loads, so you must combine piles joined to the footings. If you have a look at the page I posted you'll see the three major foundations carrying the most load were not only joined to three piles, they were then linked at the footing to carry the extra load. Your columns therefore cannot stay the same as they will be supporting more weight unless.......
Upgrading the rebar to support that weight is not really the whole answer. Rebar in itself doesn't support the structure, the concrete does, which is where the strength is rebar is there for binding purposes and to add flexibility. I personally would make the columns thicker and also add the next sized rebar for those bearing columns. It will depend on the roof and where the columns are positioned and also where the supports for the roof are, and where that weight centers on and what it is carried by.
I'm sorry if my explanation isn't the best, what I'm trying to tell you is that pilings, columns, footings all carry different weight loads in different areas of the house. You can't do a standard model for any house.
I would suggest a quick trip to the Or Bor Tor's engineering department with the design, they have the CAD program that will tell you all that and works out the variables at the touch of the "enter" button.
The engineering specs for my house ran to over 150 pages alone. It is far more complex than you think, which is the problem with sketch-ups.
BKKBILL,
Decoration bill, decoration. All you have to do is remember to say "Can't, the engineer said so"..........well that works a few times anyway. #@$%&*% wooden doors with #$%^@!# stained glass. Be warned I shall return the favour at the right time.....now I'm sweating the wallpaper.
User avatar
Roger Ramjet
 
Posts: 5251
Joined: Tue Apr 27, 2010 12:55 pm

Re: Footings, Columns,Beams, and Floor slabs

Postby sirineou » Sat Aug 18, 2012 8:33 pm

The build is in Udon Thani, so I don't think it needs piles, but I don't know that for a fact. I have told them to see what others in the area are doing, and check with the local Or Bor Tor's engineering department , for specific instructions.it is a basic 4m x3,5 m grid,
Image
in this drawing they have all the information scenery to build this structure. all we need to settle is on the size of the footings and if the beams are adequate. I am relatively good at doing force vector analysis and I don't see how in this instance the center beams and footings will be carrying a greater load, other than the fact that the center beams carry the load of two sides of the beams where the outside carry the load of only one side .
Is that why you think the center footings should be stronger?
I talk to my self because I am the only one who will listen
User avatar
sirineou
 
Posts: 1133
Joined: Wed Jun 03, 2009 9:30 am
Location: USA/Thailand, khon Kaen

Re: Footings, Columns,Beams, and Floor slabs

Postby Roger Ramjet » Sat Aug 18, 2012 8:55 pm

sirineou,
What are the stairs made of? If it's a normal Thai house they'll be concrete. Other columns carry burden from the roof structure, the slab floors and the beams and don't forget the bathrooms, walls and with open areas such as verandas you're looking at opposing forces, both lift and carry weight. I used to have Mini Cad + 4, which to be honest was a pain. Nowadays the CAD programs they use work quietly work in the background and instantly give a solution.
As I said before, don't forget to cover the outside stairs as well or they'll break away from the house structure. They need to be part of the beams and also have either piles and footings, or both. Personally I would eliminate those two columns interfering in the space downstairs (it's only 4 metres wide) and I'd increase the load carrying capacity of the columns and beams.
User avatar
Roger Ramjet
 
Posts: 5251
Joined: Tue Apr 27, 2010 12:55 pm

Next

Return to cement, concrete and mortar

Who is online

Users browsing this forum: No registered users and 1 guest

cron