Building second-storey poured concrete floor

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Re: Building second-storey poured concrete floor

Postby thaifly » Sun Feb 01, 2009 11:41 am

RY12 wrote:..which was from memory about 240 BAHT a slab...
gidday ry12....its the thai fly frommae rim...well master thaifly havent heard of that name since i went to kindergarden.... re the price of a slab... ....well i was stretching my memory over 12 months on this one...have drank plenty of heinkens in between..so my memory maybe a little shattered...suggest you take a trip to your local hardware where you will be able to get a more accurate and up todate price than mine...and the service to go with it....one thing for sure the slabs are not expensive...be very nice to tell the forum on how much they are...ITS ANOTHER WIN...AND A CLEAN SHEET...FOR MAN/UNTD...MGV12..GIDDAY TO ALL...its the thaifly frommae rim
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Re: Building second-storey poured concrete floor

Postby Rick B » Sun Feb 01, 2009 12:17 pm

When I last bought concrete floor slabs (back in Aug-Sep 2008), they cost between 180 - 210 baht per sq. m. Each slab was 35 cm wide and 5 cm thick. The actual length determined the unit price, with slabs < 1.8 m at 180 baht/sq. m, <3.4 m at 190 baht/sq. m, < 4.1 m at 200 baht/sq. m and > 4.0 m at 210 bath/sq. m. The delivery truck had a hoist built onto the flat bed of the truck and it was used to unload and raise the slabs into place. I believe I paid 500 baht extra for the use of the small crane/hoist. In my case, my laborers worked with the driver and his helper to unload the slabs. I remember they lifted six slabs at a time, all of the same length. From my experience, it is better to limit the length of the slabs to 4 meters. But, longer slabs can be obtained (say up to 5 meters) with extra/stronger wire mesh inside the concrete slab. After the floor slabs were laid in place, wire mesh (20cm x 20 cm grid) was laid and a 5 cm thick layer of concrete poured on top, the same as mentioned above by Thaifly. Pictures of my floor slabs used during the house construction can be seen in my picture gallery. I used them on both the first and second floors of my house.
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Re: Building second-storey poured concrete floor

Postby thaifly » Sun Feb 01, 2009 12:30 pm

gidday to the VERY ASTUTE RICK B...its the thaifly frommae rim...many thanks for the info....i shall correct myself that i should have said 240 PER SQ METER..not a slab..saves a trip ry12 trip to the hardware shop...actually my price is very comparable to yours rick..as i had labour in thrown in...its a too much heinkens gidday to allITS THE THAIFLY FROMMAE RIM
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Re: Building second-storey poured concrete floor

Postby RY12 » Sun Feb 01, 2009 11:19 pm

Rick B wrote: From my experience, it is better to limit the length of the slabs to 4 meters. But, longer slabs can be obtained (say up to 5 meters) with extra/stronger wire mesh inside the concrete slab. . Pictures of my floor slabs used during the house construction can be seen in my picture gallery. I used them on both the first and second floors of my house.


Wow, that is still pretty cheap for those slabs. Why do you say it's better to limit them to 4 meters? Is it structurally more safe or just hard to install if they get longer than that? Reason I ask is I notice the 'crossy' official thai government house plans all limit the space between posts to about 4 meters... so I was wondering if that was for the slabs. I was hoping to get a house a little wider than that... but not if it will be unsafe or prone to bending.

Here's the link to Rick's photos:

http://www.coolthaihouse.com/cthpics/di ... =55&pos=21

I've actually seen those slabs before on all over thailand, i've always wondered what they were, now i know! is that rebar arch towards the end of the slab for that other preceding slab's half-meter or so rebar extension to fit into?

Rick B wrote:After the floor slabs were laid in place, wire mesh (20cm x 20 cm grid) was laid and a 5 cm thick layer of concrete poured on top, the same as mentioned above by Thaifly

5 cm seems pretty thin... but i guess it's true that if it cracks it's not that big of a deal if there's wood or tile on top of it.

Were you worried about the second-floor slabs Rick (assuming the first floor was slabbed too like you said), i.e. the posts and ring beams on the ground floor being strong enough to hold it up? I guess with that much weight, I'd get a little paranoid about whether the posts are perfectly plum, made of the right concrete, etc... but maybe it's not that big of a deal if thais do it that often. Anyway thaifly, i was just watching an american colonial movie and they were calling eachother 'master', do the australians use it to refer to children?
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Re: Building second-storey poured concrete floor

Postby Rick B » Mon Feb 02, 2009 12:00 am

Why limit the slabs to 4 meters? I think this is a carryover from a while back when floor slabs weren't strong enough to span more than 4 meters. I think today, though, that they have improved the design and floor slabs can now be used on spans greater than 4 meters. You may, however, have to special order these slabs as they are probably not standard. Of course, if there is a concern about a significant width to span with floor slabs, you can easily install a supplemental beam between the two main beams and then cut the span distance in half. The rebar arch I think you are talking about is used for lifting the slab from the truck to the house beam. It is also used to install a short piece of cut rebar to help two floor slabs stay together better. This rebar is tack welded in place to the floor slabs exposed rebar. The poured floor on top of the floor slabs is typically 5 cm. If you didn't use floor slabs, the typical floor thickness would be 10 cm of poured concrete (4 inches). Since the floor slabs are 5 cm thick, a 5 cm poured floor on top of the slab results in a floor the same 10 cm thickness (or 2 inches plus 2 inches). This is not too thin, provided you use a good standard concrete mix. If you're putting in floor tiles, you'll probably add another 1-2 cm of concrete and tile on top of the 10 cm slab and poured concrete floor. I was not at all worried about the weight of the floor slabs on the second floor. As I said above, a 10 cm thick floor or all poured concrete or floor slab and poured concrete on top, is going to weigh about the same. Also, I have full faith and trust in my Architect/Engineer as well as the builder. The latter did excellent work and was always concerned about the plumbness of all of the columns, etc. It doesn't hurt to be concerned and to check their work throughout the build.

I hope this responds to your questions.
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Re: Building second-storey poured concrete floor

Postby RY12 » Mon Feb 02, 2009 1:34 pm

Rick B wrote:Why limit the slabs to 4 meters? I think this is a carryover from a while back when floor slabs weren't strong enough to span more than 4 meters. I think today, though, that they have improved the design and floor slabs can now be used on spans greater than 4 meters. You may, however, have to special order these slabs as they are probably not standard. Of course, if there is a concern about a significant width to span with floor slabs, you can easily install a supplemental beam between the two main beams and then cut the span distance in half.

Thanks for the info rick. I'll just have to go see if the local supplier has 4+ meter slabs... we're trying to make this little house as cheap as possible, so we don't want to pay for all the extra labor forming up supplemental midway beams to cut the span distance in half (you'd need more posts to hold up those midway beams wouldn't u? seems like it'd put a lot of stress on the other main beams)... however 4 meters wide makes for pretty small rooms, as one can see in the drawing below i made, so maybe we'll spend that extra money.
Image
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Re: Building second-storey poured concrete floor

Postby jazzman » Mon Feb 02, 2009 3:58 pm

A 3.5 x 3.5 m or 4 x 4 m grid sizes for ground beams and ring beams are pretty much the standard in Thailand. Thus 12.25 m2 or 16 m2 are the standard sizes for, for example, a bedroom or a kitchen etc, in a 'non-designer' house,which compares fairly well with a typical, English home.
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Re: Building second-storey poured concrete floor

Postby geordie » Mon Feb 02, 2009 5:18 pm

Not being a structural engineer i am assuming that if you exeed the standard 4x4 mtr grid you will probably have to beef up the ring beams I:E more steel or heavier steel
The standard grid is so commonly used this expense (engineer) is almost surplus and you would expect him to rattle of the steel requrements at 4x4 without consulting calculations
Given you want to enlarge the rooms another option is to actually keep the 4x4 grid and tack the extra space on the side
This means you still have useful space downstairs although you have legs a metre apart at the side of the house when you do build underneath you could if you wished leave the outside pillars and infill the inside ones giving an overhang shading the walls
my comments may be wrong but never deliberately
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Re: Building second-storey poured concrete floor

Postby jazzman » Mon Feb 02, 2009 8:12 pm

Good reasoning Geordy, but probably the best thing for RY12 to do is simply download the full set of plans for the Crossy house and just use the bit on the left and let a competent builder or consultant do the necessary modifications, and trust their local knowledge of materials and methods. These things are built by the million in Thailand.

Probably a more useful approach would be to obtain accurate quotations based on the part of the Crossy design to be used, either for materials, and labour, or a turn-key solution; but being sure not to get ripped-off. Either way, it's not going to be an expensive project and it could easily be done by a local team without the expense of paying a contractor's profit.
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Re: Building second-storey poured concrete floor

Postby Rick B » Tue Feb 03, 2009 8:49 pm

RY12, my main bedroom is 4.5m x 5.5m and is plenty big. For this room, we used floor slabs 4.5m long. Remember, the floor slabs only have to be as long and the short side of the room. So the room can be as big as you like, by extending the long side of the room. In fact the 4.5m long slab was the longest ones we used. We also had several mid-span beams included in our beam design. These additional beams did not always tie in where there was a column. Some were tied in to another beam perpendicular. Of course, the entire beam design must consider the loads each beam will carry. You can't simply add in another beam without any technical consideration of what you are doing to the entire beam design. I hope this doesn't confuse you. Bottom line, I would expect there to be floor slabs available now at the length you need, since floor slabs are quickly becoming the normal way to pour floors.
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Re: Building second-storey poured concrete floor

Postby geordie » Wed Feb 04, 2009 10:10 am

geordie wrote:Not being a structural engineer i am assuming that if you exeed the standard 4x4 mtr grid you will probably have to beef up the ring beams I:E more steel or heavier steel

jazzman wrote:Good reasoning Geordy, but probably the best thing for RY12 to do is simply download the full set of plans for the Crossy house and just use the bit on the left and let a competent builder or consultant do the necessary modifications, and trust their local knowledge of materials and methods. These things are built by the million in Thailand.


Rick B wrote:RY12, You can't simply add in another beam without any technical consideration of what you are doing to the entire beam design. .


I think we agree it can be done wthout too many problems but care and desighn have to be taken with the ring beam before adding an extra with no columbs
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Re: Building second-storey poured concrete floor

Postby xerostar » Sat Jul 04, 2009 8:34 am

I am planning an 18M x 18M two storey house.
(next to my first 18M x 18M single storey house - see earlier post).

I need to know what standard sizes are available. i.e. for precast concrete floor-slabs.
Then I can design the concrete ring beams and columns to match.

We will be using 60cm x 20cm x 12cm SuperBlocks for the walls.
I found some excellent tables from the SuperBlock website showing the
recommended heights for walls between beams against lengths of walls between columns.
http://www.superblockthailand.com

Also has anyone got a detailed drawing of the cross-section through an upper floor ring-beam/floor-slab joint?

My basic design so far includes a ventilated crawl space between the ground floor ceiling and the second storey floor.
The idea being:
a) to give the building more height.
We have a great panorama that's not quite visible from ground level.
b) to give easy access for plumbing/electrical installation/maintenance
c) sound and heat insulation between the 2 floor levels. i.e. allow air to "cool" the upper floor
and keep the ground floor cooler.
e) as a handy storage area for stuff.

In designing our present one storey house, I made the mistake of making the bedrooms too small.
3M x 3M x 2.5M ceilings basically.
I was recently staying in a hotel room that I thought to be the ideal minimum size for a bedroom.
I measured it and found it to be 4M x 4M x 3M ceilings.
The ceiling was vaulted (not sure of the term) and they had used a nice dark timber cornice.
So I will be using those sorts of dimensions for the bedrooms this time.

Any feedback welcome
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Re: Building second-storey poured concrete floor

Postby dozer » Sat Jul 04, 2009 9:37 am

I need to know what standard sizes are available. i.e. for precast concrete floor-slabs.
As far as the hollow core sizes, it is available at any building supply (eg. Homemart, Global House, etc....) check there they will have the standard sizes.

My basic design so far includes a ventilated crawl space
I like the idea although normally just a drop ceiling is used. Do you mean to have two separate levels of concrete floor slabs (hollow core) or how will the lower level of the crawl space by made?

I measured it and found it to be 4M x 4M x 3M ceilings.
Have found the same thing with room size, normally Thai based designs call for many very small bedrooms + bathrooms, 4 x 4 is a reasonable size.
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Re: Building second-storey poured concrete floor

Postby xerostar » Sat Jul 04, 2009 12:06 pm

Thanks Dozer

Perhaps I should have asked:
"I need to know what standard sizes should be available. i.e. for precast concrete floor-slabs."

I'm used to looking at what's in stock at Homex or at the hardware store.
Then I ask: "can I get other sizes besides these?"
The answer is usually "no have!"
Then I say: "do you mean you do not have other sizes in stock or do you mean there are no other sizes available?"
The answer is something like: "yes, no have!" - which leaves me none the wiser of course.

I have on occasion purchased what I saw in Homex and later found another hardware store that stocks 3 different sorts, all better than the one I got from Homex because I thought that the particular item was not available in Thailand.
Not being a Thai speaker and expecting my wife to interpret is a problem because she doesn't know much
about hardware or building and nor do the shop assistants! Very frustrating!

I had envisaged a solid floor for the crawl space - I'm afraid to use wood because the white ants here
are shocking. They will build tunnels up anything to get to a meal. They are fast too.
Also they find there way through a wall, even though you thought everything was air tight and impenetrable.
I'm worried about my book collection and how to store them. I am leaning towards tubular steel framed shelves with sheet steel backing and sides. That way hopefully I will see the tunnel before they get into the books.

I recently lost a valuable wooden African mask. (similar to the one in the movie of that name ;-)
It was stored in a thick leather bag, in a cardboard carton on a tiled floor.
The white ants drilled holes through the thick leather to get to the mask.

Everywhere at our place the workers have used wooden pegs to mark concrete levels during pouring. Now we have little square holes in the concrete - neatly removed by the ants. As you can imagine the ants are happy because there is no need to tunnel through concrete, a perfect invitation to tile level, from where all sorts of goodies are within easy reach. Sorry for the rant - a bit off topic.

If I can't use wood for the floor of the crawl space, I feel concrete may be the only way to go.
Expense may be the deciding factor though. Can you suggest something else?

I hate "crawl spaces" or "horizontal wriggling spaces" so I plan to make the space 150cm to 180cm high.
Maybe even 2M! No what the hell, - 2.5M!
The staircase would have a middle landing with a door leading into the space.
That would make it a "crawl space for gentlemen". (No need to get on ones hands and knees!).
In fact it may be just an excuse for an extra storey with bedrooms, bathrooms etc. Very handy when you have
an ever expanding family and friends coming to visit (and stay).
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Re: Building second-storey poured concrete floor

Postby dozer » Tue Jul 07, 2009 7:50 pm

Sounds like an interesting design, although if the crawlspace was really 2m I think you would need to call it a floor.... I would think that for a crawl space you would normally just use a drop ceiling but that eliminates the storage concept. If you did want to go with wood aged teak would be neat and look really cool as a ceiling material, the termites/ants or anything else won't eat it, but it wouldn't pencil out as concrete would be cheaper.
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