Thai Structure Basics

[MoonRiverOasis]

Can anyone help out with some of the basic rules/guidelines of "standard" Thai structures?

i.e. The standard post size used in residential construction is ~200mm^2 - what is the maximum span between these for both single storey and two storey construction? I have been told in the past that the max. span is 5M, however I've recently seen quite a few Thai house plans with 6M spans even on the lower level of a two storey structure..

Also, what is the maximum recommended floor overhang when using a regular Thai beam (400mm[h] x 200mm[w]?) - if you're not sure what I mean here, think about an L shaped staircase landing, or an unsupported (other than beams) overhanging upstairs balcony.

Cheers!

[Rimmer]

Four meters is normal, five meters is unusual and six! Well I believe you will need RSJs. Having said that I have asked the same question of engineers, architects and city hall, but no one seems to have one answer.

Nice picture of an 'overhang' that quit hanging from a private house construction site close to Pattaya,

The same construction had six meter spans across the garage with standard 40 x 20 cast beams. After a few weeks the beams started to sag in the middle.

[trogers]

I have asked the same question of engineers, architects and city hall, but no one seems to have one answer.

Because there is no fixed single answer or rule book.

All support structures have to be calculated to suit dead load, superimposed dead load, and live load.

A cantilever beam can support a pig sitting at its end, but not an elephant.

So you need to specify type of floor or staircase materials (timber or reinforced concrete), type of wall, thickness and height, etc.

Edited March 29, 2009 by trogers

[MoonRiverOasis]

Four meters is normal, five meters is unusual and six! Well I believe you will need RSJs. Having said that I have asked the same question of engineers, architects and city hall, but no one seems to have one answer.

The architect I used for my first few houses couldn't tell me much either, so we settled on <= 4M spans everywhere. However the architect I used for my last house contruction had the answers - in that case I wanted an 8M span and we needed 300mm posts with 300x600mm beams. He worked for the project developer however and obviously had commercial building experience. I don't have his contact details though.. (It worked just fine BTW )

Nice picture of an 'overhang' that quit hanging from a private house construction site close to Pattaya,

The same construction had six meter spans across the garage with standard 40 x 20 cast beams. After a few weeks the beams started to sag in the middle.

OMG, a 6M x 2.5-3M unsupported overhang? - &lt;deleted&gt;! Anyone with an IQ above room temparature should've know that wasn't going to work

I was thinking of an overhang more along the lines of 1M (out) and 3M wide at most, with contiguous beams. Still, that image alone is enough to make me re-think the idea anyway, thanks! Looks like I'll just end up with some storage cupboards in the carport to hide the additional posts.. I can make that work

[mdechgan]

Normal spans are 4 meters which is pretty much already at max load at 40 x 20cm.

There are many variables like loads and the gauge of the steel rebars.

Spans higher than 4 meters are more difficult to calculate and require more expensive construction. Usually spans like 5 meters and above are used for factories and commercial buildings.

[MoonRiverOasis]

Normal spans are 4 meters which is pretty much already at max load at 40 x 20cm.

3.5-4M spans are common, yes, but if you look at pretty much any reasonably sized Thai house 5M spans are also incredibly common - a good example being the ubiquitous two-car carport, which in more cases than not has a floor above it of course.

In any case, we're digressing a bit.. All I was really after was the basic guidelines for larger spans, which do exist, I just wish I had paid more attention last time I went through this with the architects! But alas it was only one of 70+ points of discussion when finalizing the last set of building plans, and was the easiest issue to solve

If anyone can help with the specifics on a 6M span that would be helpful. All I'm really trying to determine is how much impact the extra meter or so in a few places will make to the bottom line before I sit down with an architect with my mud-maps and start banging it out.

[Crossy]

Our design has a 6.8m span using a 250 x 850 mm beam, like this:-

There are eight 25mm re-bars in there

The span is supported by 250mm square columns (although these will be circular in our final construction). We end up with a 10m x 7m space uncluttered by columns. Hmmm, space for a snooker table

Full plans are here :- http://crossy.co.uk/Thai_House_Plans/House30.zip

Edited April 1, 2009 by Crossy

[MoonRiverOasis]

Our design has a 6.8m span using a 250 x 850 mm beam, like this:-

There are eight 25mm re-bars in there

The span is supported by 250mm square columns (although these will be circular in our final construction). We end up with a 10m x 7m space uncluttered by columns. Hmmm, space for a snooker table

Thanks for sharing!

That's really covered a lot for me in one go - essentially it means do it where it counts, and not where it doesn't so as to keep complexity and costs in check. Especially with those 1 inch re-bars

Nice design too Crossy - this time around I'm heading for a more contemporary Thai resort-style, but I've often pondered going for a more classic design like this too. I'm sure you'll love it!

[Crossy]

Nice design too Crossy - this time around I'm heading for a more contemporary Thai resort-style, but I've often pondered going for a more classic design like this too. I'm sure you'll love it!

Yup we like it

It's actually one of the free designs that were produced by the Thai government under Taxin. There were about 30 designs available for free. Architect approved, signed off and ready to construct complete with BOQs and cost estimates.

The original site has gone (or moved where I can't find it) but I made a mirror here:- http://crossy.co.uk/Thai_House_Plans/ all are welcome to download and build

[MJo]

Normal spans are 4 meters which is pretty much already at max load at 40 x 20cm.

There are many variables like loads and the gauge of the steel rebars.

Spans higher than 4 meters are more difficult to calculate and require more expensive construction. Usually spans like 5 meters and above are used for factories and commercial buildings.

It's case by case. to calculate 5m or 6m span beam is no different from calculating 4m span. You calculate your loads for the beam and optimize your beam size and rebars based on load and span.

Same goes with costs. Some cases longer span (bigger colums and beams) might actually be more cost effective as you tend to have less columns that way. Also you might save on foundations etc. Labour costs are pretty much the same per column or beam regardless of size. It takes as much effort to do formworks etc for 200 x 200 column as for 300 x 300.

It's all about optimizing your material qty's. Less expensive steel but more cheaper concrete is usually better than other way around.

Most likely reason for Thais to use standard 4m span and 400 x 200 beams propably comes from the fact that when also using "standard" rebar config you pretty much don't have to do any calculations at all as it will take the loads you have in normal house. Kind of rule of thumb approach to structural design.

[MoonRiverOasis]

Nice design too Crossy - this time around I'm heading for a more contemporary Thai resort-style, but I've often pondered going for a more classic design like this too. I'm sure you'll love it!

Yup we like it

It's actually one of the free designs that were produced by the Thai government under Taxin. There were about 30 designs available for free. Architect approved, signed off and ready to construct complete with BOQs and cost estimates.

Wow, great stuff Crossy! DOn't suppose you still have the cost estimates?

[Crossy]

Nice design too Crossy - this time around I'm heading for a more contemporary Thai resort-style, but I've often pondered going for a more classic design like this too. I'm sure you'll love it!

Yup we like it

It's actually one of the free designs that were produced by the Thai government under Taxin. There were about 30 designs available for free. Architect approved, signed off and ready to construct complete with BOQs and cost estimates.

Wow, great stuff Crossy! DOn't suppose you still have the cost estimates?

I certainly have the Excel files that make up the BOQs (just have to find them). IIRC they have costs in but they will be well out of date now. Any particular design you're interested in?

[MoonRiverOasis]

I certainly have the Excel files that make up the BOQs (just have to find them). IIRC they have costs in but they will be well out of date now. Any particular design you're interested in?

Understood they will be out of date, but if itemised it shouldn't be too hard to get them close to a current actual I suppose - given the sometimes huge variances in material a labour costs around the country you'd need to massage it all in any case.

Out of the designs there, I'd be most interested in mash-up between #27 and #30.

How is yours progressing? (or not? )

[Crossy]

I certainly have the Excel files that make up the BOQs (just have to find them). IIRC they have costs in but they will be well out of date now. Any particular design you're interested in?

Understood they will be out of date, but if itemised it shouldn't be too hard to get them close to a current actual I suppose - given the sometimes huge variances in material a labour costs around the country you'd need to massage it all in any case.

Out of the designs there, I'd be most interested in mash-up between #27 and #30.

How is yours progressing? (or not? )

I'll have a rummage when I get home tonight (actually back to the hotel in Bangalore), pretty sure I have the BOQs for those two as we're doing pretty much the same. Got approval for a No30 but we're changing the roof to be more Ayutthaya style (Wifey is from Ban Pachi) and making minor internal layout changes, structure shouldn't change apart from 'Er Indoors wanting some of the columns circular, "to look more like trees".

27 and 30 are almost identical structurally so a combi-job should be easy.

BOQs are of course in Thai

Progress is limited, we've just finished jacking up our swamp (best part of 20 Grand US went on fill and a retaining wall to keep it in), have a look here :- http://crossy.co.uk/HouseBuilding/House%20building.html

Need to earn the cash for the next stage

EDIT If you've not already found it http://www.coolthaihouse.com/ is an excellent resource for those building in Thailand

Edited April 1, 2009 by Crossy

[Crossy]

Here we go

BOQ_27.xls

BOQ_30.xls

Pretty sure these are the right ones, I must add them to the site when I get a moment.

Edited April 2, 2009 by Crossy

[Crossy]

Missed the edit window

Anyway, I've found the Thai site (wish they wouldn't keep moving it) http://www.dpt.go.th/download/PW/house_model/framehome.html

Costings are behind the 3rd link from the left "สรุปราคาก่อสร้างโดยสังเขป / บัญชีแสดงประมาณงานและวัสดุก่อสร้าง" no idea how old they are, reckon 3 years at least

EDIT Try it with Google translator http://translate.google.com/translate?prev...sl=th&tl=en

Edited April 2, 2009 by Crossy

[MoonRiverOasis]

Missed the edit window

Anyway, I've found the Thai site (wish they wouldn't keep moving it) http://www.dpt.go.th/download/PW/house_model/framehome.html

Costings are behind the 3rd link from the left "สรุปราคาก่อสร้างโดยสังเขป / บัญชีแสดงประมาณงานและวัสดุก่อสร้าง" no idea how old they are, reckon 3 years at least

Thanks a bunch Crossy, the costings are actually 6 years old, but there's enough detail there to adjust the prices to current.

I can read Thai fluently, so no problems in understanding it all

Cheers!

[splitlid]

http://instruct1.cit.cornell.edu/Courses/a...tors/index.html

some useful calculators here