Building a carport

[lost in isaan]

Hello everyone,

 

I'm in the process of building a 17x5m carport that will serve as a rainwater collector and support 30x340w solar panels. However, I have some concerns about the builder's suggestions.

 

The builder proposed using ready-made concrete pillars and a 1.5mm steel roof structure, but after doing some research, I'm not convinced that this would be sturdy enough to support the weight of the roof with solar panels (~15kg/sqm). I'd appreciate any thoughts or recommendations on this matter.

 

Additionally, I'm concerned that I may be paying too much for the work. The builder quoted me 195k for the job, which includes a polished 10cm concrete floor, 10 pillars, and metal sheets for the roof. However, based on my calculations, the materials alone shouldn't cost more than 60k.

 

Do you have any tips or suggestions on how to proceed? Should I consider finding a new builder? Thank you for your help.

[DaLa]

I can't see the load being spread over 10 pillars being a concern. However your post (no pun)  lacks any detail on the roof construction. 1.5mm ( I presume wall thickness) is only 10% of the design consideration. Triangulation and load transfer is the key. As always (bored of saying this)  get 3 quotes, spend any savings on obtaining a structural design by an independent engineer. 

 

You only want to do this once so pay more now , save twice as much later.

[Kwasaki]

Without seeing plans and a list of quantities who knows. 

 

A framework that is erected  on the roof when finished will take the solar panels i would expect.

 

Edited March 20, 2023 by Kwasaki

[Yellowtail]

Just do it yourself, that way you know it will last and you do not have to let some shady contractor rip you off. 

 

You've already done the engineering and the material take-off, just have the material delivered and do it. You can usually get workers to help you for about 200 a day. 

[Elkski]

Does this shed have any walls.  10 posts?  Can't imagine a spacing that's logical for 10.  5x17m  is it going to span the 5m width?  Then that's 3m between 5 posts along the sides?   1.5mm is just steel but I would think the solar panels would bolt to the support structure?   Sounds like you need to draw up a plan. 

[Yellowtail]

3 minutes ago, Elkski said:

Does this shed have any walls.  10 posts?  Can't imagine a spacing that's logical for 10.  5x17m  is it going to span the 5m width?  Then that's 3m between 5 posts along the sides?   1.5mm is just steel but I would think the solar panels would bolt to the support structure?   Sounds like you need to draw up a plan. 

He has already done the engineering and material take-off, so he must have the drawings. 

 

OP, why not post the drawings? That will help a lot. 

[lost in isaan]

Thank you for the feedback. Lot's of good suggestions. I'll see if i can find any builder i can hire. The structure itself will look similar to this:

(Picture stolen from https://<URL Automatically Removed>/construction-in-thailand/180243-thai-style-building-carport-do-yourself.html)

 

[Yellowtail]

1 minute ago, lost in isaan said:

Thank you for the feedback. Lot's of good suggestions. I'll see if i can find any builder i can hire. The structure itself will look similar to this:

(Picture stolen from https://<URL Automatically Removed>/construction-in-thailand/180243-thai-style-building-carport-do-yourself.html)

 

Yeah, I would not pay 195K for that.

 

Does that include an underground cistern to store the rainwater? If not, what are you going to do with it? 

[lost in isaan]

6 minutes ago, Yellowtail said:

Yeah, I would not pay 195K for that.

 

Does that include an underground cistern to store the rainwater? If not, what are you going to do with it? 

The current plan only includes the construction of the carport, but I also intend to install five 2,000-liter tanks underneath it for easier maintenance compared to underground tanks. I will personally add the rainwater harvesting system at a later stage.

[EVENKEEL]

I had a 7 Mx7 M carport built, using 4x4" steel posts with footing, only 2 posts as otherside attached to house. Labor was 25,000thb and they primed all steel and total cost was 47,000thb. I bought all materials. No cement.

 

I just recently got a labor estimate for a 3x7M shade, 350 thb/sq M. No cement, again I'm using 4x4" steel posts with a footing.

 

Mine has a 7 M span both ways, the less posts you have the easier parking you'll have, 15 M span you can get by with 3 on each side. The good roofing with the inside insulation cost 150thb/M 3 yrs ago.

Edited March 20, 2023 by EVENKEEL

[PJ71]

42 minutes ago, Yellowtail said:

You can usually get workers to help you for about 200 a day

Sorry this comment does not really help the OP but there's no chance you'll get people working for 200 baht a day, not i my experience have i heard this price for many years.

[Dante99]

Might try to get contractor bids for the labor only then you buy the materials.  Good way to insure quality materials.  Really not that many things to buy.

[Yellowtail]

5 minutes ago, PJ71 said:

Sorry this comment does not really help the OP but there's no chance you'll get people working for 200 baht a day, not i my experience have i heard this price for many years.

Where do you look? 

[lost in isaan]

11 minutes ago, EVENKEEL said:

I had a 7 Mx7 M carport built, using 4x4" steel posts with footing, only 2 posts as otherside attached to house. Labor was 25,000thb and they primed all steel and total cost was 47,000thb. I bought all materials. No cement.

 

I just recently got a labor estimate for a 3x7M shade, 350 thb/sq M. No cement, again I'm using 4x4" steel posts with a footing.

 

Mine has a 7 M span both ways, the less posts you have the easier parking you'll have, 15 M span you can get by with 3 on each side. The good roofing with the inside insulation cost 150thb/M 3 yrs ago.

Thank you, this is really good.

[EVENKEEL]

2 minutes ago, Yellowtail said:

Where do you look? 

If I was paying day rate, I wouldn't think of paying less than 500thb/day. Not for someone with more than 2 braincells.

[Denim]

1 hour ago, Yellowtail said:

You can usually get workers to help you for about 200 a day. 

Good luck with that.

[PJ71]

1 hour ago, Yellowtail said:

Where do you look? 

Where i live.

 

Where do you look?

[Yellowtail]

26 minutes ago, PJ71 said:

Where i live.

 

Where do you look?

Where I live, but I got all I need so I'm not looking. 

[rwill]

Best to look at the cost per square meter.  Yours would work out to approximately 2,294 baht/SqM.

 

It's always a good idea to get more than 1 quote.

 

 

Edited March 20, 2023 by rwill

[PJ71]

2 minutes ago, Yellowtail said:

Where I live, but I got all I need so I'm not looking. 

That's nice - have a great day.

[Yellowtail]

2 minutes ago, PJ71 said:

That's nice - have a great day.

Thank you, and you do the same! 

[LukKrueng]

3 hours ago, lost in isaan said:

Hello everyone,

 

I'm in the process of building a 17x5m carport that will serve as a rainwater collector and support 30x340w solar panels. However, I have some concerns about the builder's suggestions.

 

The builder proposed using ready-made concrete pillars and a 1.5mm steel roof structure, but after doing some research, I'm not convinced that this would be sturdy enough to support the weight of the roof with solar panels (~15kg/sqm). I'd appreciate any thoughts or recommendations on this matter.

 

Additionally, I'm concerned that I may be paying too much for the work. The builder quoted me 195k for the job, which includes a polished 10cm concrete floor, 10 pillars, and metal sheets for the roof. However, based on my calculations, the materials alone shouldn't cost more than 60k.

A couple of years ago I had 2 structures built - both walled up - and if I remember correctly I paid about 180k all included (workmanship, materials including electric wiring), so seems this price for an open carport is not cheap at all

[Chongalulu]

3 hours ago, EVENKEEL said:

I had a 7 Mx7 M carport built, using 4x4" steel posts with footing, only 2 posts as otherside attached to house. Labor was 25,000thb and they primed all steel and total cost was 47,000thb. I bought all materials. No cement.

 

I just recently got a labor estimate for a 3x7M shade, 350 thb/sq M. No cement, again I'm using 4x4" steel posts with a footing.

 

Mine has a 7 M span both ways, the less posts you have the easier parking you'll have, 15 M span you can get by with 3 on each side. The good roofing with the inside insulation cost 150thb/M 3 yrs ago.

The only thing I’d say about roofing with that incorporated insulation from our experience is that the heat eventually breaks down the glue and the insulation falls messily off. Also birds pick at any breakdown to make nests. Subsequently we just used good non insulated roofing and specified WHITE to ensure heat/sun reflection.

[DUNROAMIN]

If your a farang double price. I prefer to construct myself, that way I know  that it is constructed correctly.

[unheard]

11 minutes ago, nchuckle said:

The only thing I’d say about roofing with that incorporated insulation from our experience is that the heat eventually breaks down the glue and the insulation falls messily off.

There's a much better option over the glued-on very thin silvery material.

It comes in the form of the 25mm PU insulating layer, which is also applied by the roll-forming shop during the roof sheet production.

PU insulation has different properties and applied without any additional gluing agent, therefore it doesn't fall off and has much, much better insulating qualities.

Edited March 20, 2023 by unheard

[unheard]

3 hours ago, lost in isaan said:

The current plan only includes the construction of the carport, but I also intend to install five 2,000-liter tanks underneath it

What is the usage plan for collected water?

Edited March 20, 2023 by unheard

[Yellowtail]

33 minutes ago, unheard said:

There's a much better option over the glued-on very thin silvery material.

It comes in the form of the 25mm PU insulating layer, which is also applied by the roll-forming shop during the roof sheet production.

PU insulation has different properties and applied without any additional gluing agent, therefore it doesn't fall off and has much, much better insulating qualities.

As the only function of the roof is to collect rainwater that will be stored in tanks underneath, insulating it makes little sense. 

[unheard]

7 minutes ago, Yellowtail said:

As the only function of the roof is to collect rainwater that will be stored in tanks underneath, insulating it makes little sense. 

On the contrary, it makes a lot of sense.

On a sunny day a metal roof without insulation will be re-radiating lots of infrared energy, in-directly heating up everything parked underneath.

Edited March 20, 2023 by unheard

[Encid]

Just now, unheard said:

There's a much better option over the glued-on very thin silvery material.

It comes in the form of the 25mm PU insulation layer, which is also applied at the roof sheet roll-forming shop.

PU insulation doesn't fall off and has much, much better insulating qualities.

BlueScope have a very good PU foam backed roof sheeting and I think it's available in different thicknesses too...

 

[Yellowtail]

2 minutes ago, unheard said:

On the contrary, it makes a lot of sense.

On a sunny day a metal roof without insulation will be re-radiating lots of infrared energy, greatly heating up everything parked underneath.

Are you trying to argue it is hotter standing in the shade than in the sun? There will be no walls, and nothing parked underneath but water tanks. 

 

In any event, there will be solar panels shading the roof, did you read the OP?