Need a 800 sqm roof - Advice needed

[inventorinthailand]

Hi,

 

We need to build a large 800 sqm (20x40m and 8 meters high) roof and want to do it at as low cost as possible. I'm a mechanical designer but I have never designed a house or roof before.

Should I use steel or concrete pillars, prefab or made at site? 

What kind of roof trusses?

Sheet-metal or ceramic roof panels? 

 

We might make a concrete slab as well if not too expensive.

 

Location, Sattahip Chonburi

 

Please advice me :-)

Edited March 18, 2017 by inventorinthailand

[canuckamuck]

If this is simply a roof, than the lighter you build the cheaper it will be. It is hard to beat sheet metal for accomplishing that goal. As a roofing material it is nearly weightless.

Your next problem is  strength. A roof that big catches a lot of wind. You'll need to study up on roof shapes to reduce the amount of lift. Also you will need to design a truss system that takes the load of that wind and disperses it. As far as pillars go, 8 meters is way up there. You can go with concrete with re-bar or steel, but I like steel. You can do more with it. You can add to it, and drill holes through it. Concrete is no where near as friendly. You will need to find a good welder or two.  Last roof I put up, that was just a roof, I used steel for pillars and it came out cheaper than concrete, But I was only  4 meters high.

[inventorinthailand]

3 minutes ago, canuckamuck said:

If this is simply a roof, than the lighter you build the cheaper it will be. It is hard to beat sheet metal for accomplishing that goal. As a roofing material it is nearly weightless.

Your next problem is  strength. A roof that big catches a lot of wind. You'll need to study up on roof shapes to reduce the amount of lift. Also you will need to design a truss system that takes the load of that wind and disperses it. As far as pillars go, 8 meters is way up there. You can go with concrete with re-bar or steel, but I like steel. You can do more with it. You can add to it, and drill holes through it. Concrete is no where near as friendly. You will need to find a good welder or two.  Last roof I put up, that was just a roof, I used steel for pillars and it came out cheaper than concrete, But I was only  4 meters high.

Thanks for the information. How big was the roof and what did it cost to build?

[Crossy]

As noted above that's a big roof, what's its purpose in life?

 

Are you hoping for a 20 x 40 x 8 m space with no columns, edge support only? Will it have walls, doors?

 

To be honest, I suggest it's outside the scope of a DIY design, it will weigh many tons and generate an equally large amount of lift in a blow.

 

I suggest you look around your area for something similar and ask who built it for them. At least then if it decides to emulate an A380 you have someone to blame.

 

[canuckamuck]

The pillar base was 13 meters by 6. The roof goes about 1.5m past the edges. I can't remember the costs at the moment, got a head cold, but I am sure it was around 35 - 40k. No pad. The labor was free as it was for the church by the church.

[Crossy]

@canuckamuck That ties up with our biggest roof (only 6m x 6m) which was about 33k all in including labour food and after work beer for the boys.

 

The structure our OP is looking at (@ 800m²) is going to be a lot more than 22 x the price of 36m².

[canuckamuck]

Yep, it's going to be a lot more. And he'll need a crane.

[Crossy]

3 minutes ago, canuckamuck said:

Yep, it's going to be a lot more. And he'll need a crane.

 

Just one?

[harrry]

I thought one of the ways they built large roofs like that now was to use high pillers and have the roof structure suspended from them..sort of like a suspension bridge.

[Crossy]

There's loads of useful information here http://www.steelconstruction.info/Single_storey_industrial_buildings#Design_concept

 

But I still don't think it's a DIY job :)

[Anthony Loh]

Steel structure will be a bit fast as compared with the concrete structure as CS needs a lot of columns to support the loading. As that you maybe safe some money but it all depends on the concept of the roof and for a 800 sqm and high 8 meter, I'm more worried on the loading and movement as this are the safety features and it involved with engineering design.


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[Kwasaki]

15 hours ago, inventorinthailand said:

We need to build a large 800 sqm (20x40m and 8 meters high) roof

15 hours ago, inventorinthailand said:

Should I use steel or concrete pillars, prefab or made at site? 

What kind of roof trusses?

Sheet-metal or ceramic roof panels? 

 

Need more info 8m to eave l take it. ?

Columns within floor space or not. ?

As said not DIY and not gonna be cheap whatever way.

[Anthony Loh]

This is the project that I completed last year in Singapore as a construction manager


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[Anthony Loh]

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[Kwasaki]

8 hours ago, Crossy said:

There's loads of useful information here http://www.steelconstruction.info/Single_storey_industrial_buildings#Design_concept

 

But I still don't think it's a DIY job :)

Yeah more the type info he needs and steel structure for sure, less intermediate columns makes it a little cheaper.

[inventorinthailand]

Hi, I do not intend to build it my self. I just wanted some input on what material so I can make a rough cost estimation. I have never build a house before and will probably never do.

 

I did played around little with my CAD-tools for a few hours, my first rood design ever :-) and this steel construction weights 18,5 metric tons made by 120x80 i-beams and the columns are 400x155mm. To that comes roof panels. Heavy indeed.

 

Picture-1

Picture-2

Picture-3

 

Edited March 19, 2017 by inventorinthailand

[inventorinthailand]

I will probably make a 4 meters brick wall as well and the transparent plastic sheet panels on the upper wall and some on the roof... 

 

[inventorinthailand]

6000 bricks later and more steel beams.... Need to work on the details and then run some load simulations and hopefully reduce the roof weight significantly. 

 

Picture-4

Edited March 19, 2017 by inventorinthailand

[inventorinthailand]

What about precasted columns and roof beams in concrete? More costly?

[silverado]

180 thb / 1 meter square for  sound/heat insulation panels. (90 thb /1 meter w/o insulation)

metal frame very simple/basic (no need ingeneer) as the weight is very low

 

Edited March 19, 2017 by silverado

[Anthony Loh]

7 hours ago, inventorinthailand said:

What about precasted columns and roof beams in concrete? More costly?

It is more difficult to set up the precast column because of the height ( 8 m above ground and also the base foundation complex with the steel column as it involved a lot of frame work to hold and support it. Same to the roof beams as the load weight. 

 

It were be batter if you can provide us the layout plan so that we can share our advice to you. Regards

[Kwasaki]

10 hours ago, inventorinthailand said:

What about precasted columns and roof beams in concrete? More costly?

Your building a factory man, precast concrete columns would be OK or steel but what you have already posted images of has to be a steel roof structure because of the span.

As for roof weigh reduction go aluminum roof sheeting.

As for prices on steel versus concrete columns you will have to send specification to companies for quotes.

[Kwasaki]

2 hours ago, Anthony Loh said:

It is more difficult to set up the precast column because of the height ( 8 m above ground and also the base foundation complex

Sorry mush that's nonsense 8m is not that high.

OP is talking factory construction not small housing projects.

[Kwasaki]

Most of your research can be done google-ling .

This may help.

https://www.google.co.th/#q=industrial+Steel+roof+truss+fabrication+companies+in+Thailand&*

[inventorinthailand]

5 hours ago, Anthony Loh said:

It is more difficult to set up the precast column because of the height ( 8 m above ground and also the base foundation complex with the steel column as it involved a lot of frame work to hold and support it. Same to the roof beams as the load weight. 

 

It were be batter if you can provide us the layout plan so that we can share our advice to you. Regards

Look at post 16 and 18. click on the ling for pictures. I cant add pictures of some reson

[Anthony Loh]

My advice is, half using concrete column by casting on site till the top of brick wall level, after that install the I-beam from the concrete column till the height that you need. This matter will safe you some money.

By the way, I be coming down to sattahip chonburi next month with my family for holiday and will be staying for a week in Pattaya. If you need more advice, maybe we can meet up for a coffee as a friend. Just PM me if you interested.


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[Anthony Loh]

Maybe this can help you. Cheers


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[Anthony Loh]

Sorry mush that's nonsense 8m is not that high.
OP is talking factory construction not small housing projects.

Thank you very much! Just for info, i have been working in construction and building for the pass 20 years as a manager. Completed 76 story condominium in Singapore with 1111 units and many other high rises project.


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[inventorinthailand]

We have been looking around for a warehouse to rent but it would cost us 1-1,5 million baht (100-150 baht/sqm) per year. If we can build this for just above 1 million, we would probably rent a piece of land and go for it....

 

Budget so far.... I have looked around and Thais are building roofs with much less material. Need to put some effort on the roof design and also add a few supports in between.

How much for concrete workers, welders and crane rent?

 

Amount Price Total Notes Concrete (m3) 170 1 600 272 000  - 20cm thick, Also Incl a 200 m3 water reservoir Bricks (pcs) 6 000 13 78 000   Colums (meters) 112 890 99 680   Insulated Roof Panels (m2) 1 140 180 205 200  - or 102 000 ininsolated Steel roof ? ? ?  - Any ide about price per ton? Doors, inner office walls ? ? ?   - We might build a platform 10x20m on 4 meters level for office and some storage. Work force ? ? ?  - 500 baht per day and head I have read, plausible or not? Machine/Crane rent ? ? ?  - What can a crane cost per day?           Total     654 880

[inventorinthailand]

34 minutes ago, Anthony Loh said:

My advice is, half using concrete column by casting on site till the top of brick wall level, after that install the I-beam from the concrete column till the height that you need. This matter will safe you some money.

By the way, I be coming down to sattahip chonburi next month with my family for holiday and will be staying for a week in Pattaya. If you need more advice, maybe we can meet up for a coffee as a friend. Just PM me if you interested.


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Yes, If designing concrete columns correctly, We might even be able in the future to mount a small crane/lifting device just under the roof if we want.