Sloped concrete roof construction

[Silencer]

I'm looking for information (proper design, cost vs other options, primarily) for building sloped concrete roof slabs (not concrete roof tiles) for a couple roof sections of a planned house build. If you have sources, or personal experience, in using this type of roofing system please let me know. I'm considering other roofing options but want to be informed before speaking with the builders. 

[Kwasaki]

Concrete section ready made slabs can be used to construct a roof making sure joining edges are sealed. 

Top coating then can be done by various methods. 

Slight sloping is carried out for a construction of a flat roof. 

Making a sloping roof could be done but with all different types of roofing covering available most designers will not see the point of it unless you have a specific reason. 

 

[Silencer]

16 minutes ago, Kwasaki said:

Concrete section ready made slabs can be used to construct a roof making sure joining edges are sealed. 

Top coating then can be done by various methods. 

Slight sloping is carried out for a construction of a flat roof. 

Making a sloping roof could be done but with all different types of roofing covering available most designers will not see the point of it unless you have a specific reason. 

 

Thank you. Yes, I understand the sloping would be minimal compared to another roof style, as long as it meets proper roof drainage requirements, that is fine. I was unaware of the pre-fabricated slabs, I will look into availability of such in my area.

[Excel]

16 minutes ago, Silencer said:

Thank you. Yes, I understand the sloping would be minimal compared to another roof style, as long as it meets proper roof drainage requirements, that is fine. I was unaware of the pre-fabricated slabs, I will look into availability of such in my area.

Unless specifically requested during fabrication the pre-cast concrete slabs are not made with waterproofed cement to my knowledge. However, in all case the slabs are covered with a concrete screed so I would suggest a 50 mm screed, with reinforcement giving a 25/25 re-bar cover the concrete having mixed in, the water inhibiter. I am actually doing that on my next build next year but will be also including a waterproof membrane as a section of the roof will be a tiled party area the tiles will be affixed with an epoxy adhesive, as per swimming pool tile  norms.

Edited April 21, 2022 by Excel

[KhunLA]

BlueScope rolled steel, why would you use anything else ?

[Kwasaki]

1 hour ago, Silencer said:

Thank you. Yes, I understand the sloping would be minimal compared to another roof style, as long as it meets proper roof drainage requirements, that is fine. I was unaware of the pre-fabricated slabs, I will look into availability of such in my area.

They come in different width and lengths they reasonable priced. 

 

They can be made to look good on underside as a ceiling finish with some finishing work and then get painted.

[Excel]

1 hour ago, KhunLA said:

BlueScope rolled steel, why would you use anything else ?

He is asking about a concrete roof specifically

[Excel]

5 minutes ago, Kwasaki said:

They come in different width and lengths they reasonable priced. 

 

They can be made to look good on underside as a ceiling finish with some finishing work and then get painted.

I shall be using the hollow SCG ones to give additional thermal insulation 

[KhunLA]

7 minutes ago, Excel said:

He is asking about a concrete roof specifically

Understand, but he may not know the availability, and advantages of a steel roof.  Simply better all the way around; cheaper, lighter, cheaper because lighter, less steel to support, last longer, can pick out different thickness of insulation, blocks the heat, instead of radiating it.

 

It really is no brainer.

[Kwasaki]

1 hour ago, Excel said:

Unless specifically requested during fabrication the pre-cast concrete slabs are not made with waterproofed cement to my knowledge. However, in all case the slabs are covered with a concrete screed so I would suggest a 50 mm screed, with reinforcement giving a 25/25 re-bar cover the concrete having mixed in, the water inhibiter. I am actually doing that on my next build next year but will be also including a waterproof membrane as a section of the roof will be a tiled party area the tiles will be affixed with an epoxy adhesive, as per swimming pool tile  norms.

Any waterproofing can be done after. 

[Kwasaki]

4 minutes ago, KhunLA said:

Understand, but he may not know the availability, and advantages of a steel roof.  Simply better all the way around; cheaper, lighter, cheaper because lighter, less steel to support, last longer, can pick out different thickness of insulation, blocks the heat, instead of radiating it.

 

It really is no brainer.

Not if you want a second floor later or your want roof top sitting area. 

[Excel]

2 minutes ago, Kwasaki said:

Any waterproofing can be done after. 

Not as effective and usually not permanent. Sure it is a cheap charlie solution if you want a bodge but a professional, durable and log lasting method is to do it properly in the first place..

[Kwasaki]

Just now, Excel said:

Not as effective and usually not permanent. Sure it is a cheap charlie solution if you want a bodge but a professional, durable and log lasting method is to do it properly in the first place..

Well waterproofing a flat roof after planking the area can be done in several ways, what the OP wants I don't know.

He wants to know about a concrete roof he an have one. 

[sometimewoodworker]

2 hours ago, Silencer said:

Thank you. Yes, I understand the sloping would be minimal compared to another roof style, as long as it meets proper roof drainage requirements, that is fine. I was unaware of the pre-fabricated slabs, I will look into availability of such in my area.

The precast planks are available in every area they are available in a verity of lengths, very reasonably priced, are always used under a screed that is reinforced usually with a pre made mesh but you can always use a thicker rebar if you like, you can use a waterproof concrete for the screed but concrete cracks so you need to account for that in some way, this is usually with flexible joints often with a flexible membrane or paint.

The only possible downside is they need to be craned into place, that isn’t a problem if you design it into the build and virtually every supplier has a crane truck specifically for the job.

[Excel]

11 minutes ago, sometimewoodworker said:

The precast planks are available in every area they are available in a verity of lengths, very reasonably priced, are always used under a screed that is reinforced usually with a pre made mesh but you can always use a thicker rebar if you like, you can use a waterproof concrete for the screed but concrete cracks so you need to account for that in some way, this is usually with flexible joints often with a flexible membrane or paint.

The only possible downside is they need to be craned into place, that isn’t a problem if you design it into the build and virtually every supplier has a crane truck specifically for the job.

Correct as you have just reiterated what I posted earlier. However I will add one addition to that, although we have no idea what the OP is wanting nor his spans, the crane truck you mentioned by the supplier holds good for run of the mill conc planks but in my case I will be hiring a mobile crane as my spans are 10 mtr. and a chunky piece of structure

[sometimewoodworker]

31 minutes ago, Excel said:

I will be hiring a mobile crane as my spans are 10 mtr. and a chunky piece of structure

We did the same as we had a verity of items 2 of them being 18 metre trusses  and the posts were much faster using one

 

 

 

[kiteman9]

I have built a sloping flat roof with concrete planks. On top of the planks a 3 to 5 inch thick sloped poured steel reinforced concrete layer. Covered with a coat of epoxy resin thinned down with lacquere thinner. Withen an hour or so before fully cured, then lay down a fiber cloth material that is impregnated with an elastomeric paint. To a specific mill thickness. https://www.jorakay.co.th/en/repairing/waterproofing/crocodile-roof-shield

[unheard]

16 hours ago, Excel said:

Not as effective and usually not permanent. Sure it is a cheap charlie solution if you want a bodge but a professional, durable and log lasting method is to do it properly in the first place..

Are you building a bomb shelter?

Bluescope (insulated) rolled metal roofs are the most cost and thermally efficient roof option on the market.

Calling it a cheap charlie solution is misleading.

[Excel]

4 minutes ago, unheard said:

Are you building a bomb shelter?

Bluescope (insulated) rolled metal roofs are the most cost and thermally efficient roof option on the market.

Calling it a cheap charlie solution is misleading.

Perhaps you should read what the topic is about ! Its regarding a concrete roof -nothing else.  And in the context of that specific post upon which I commented and the suggested solution to make something waterproof, anybody with a modicum of experience will understand it is a cheap charlie approach. Clearly you do not have that experience nor is it anything to to do with bluescope or any other metal roof covering .

Edited April 22, 2022 by Excel

[unheard]

16 hours ago, KhunLA said:

Understand, but he may not know the availability, and advantages of a steel roof.  Simply better all the way around

Agreed.

[unheard]

8 minutes ago, Excel said:

Perhaps you should read what the topic is about ! Its regarding a concrete roof -nothing else.  Clearly you do not have that experience nor is it anything to to do with bluescope or any other metal roof covering .

Perhaps you shouldn't be so aggressive in responding to others opinions.

KhunLA has stated his opinion and informed the OP of other available options.

Edited April 22, 2022 by unheard

[Excel]

1 minute ago, unheard said:

Perhaps you shouldn't be so aggressive in responding to others opinions.

 

 

Perhaps you should simply keep on topic, now that would be an achievement especially for the benefit of the OP.

[Rampant Rabbit]

18 hours ago, Excel said:

Unless specifically requested during fabrication the pre-cast concrete slabs are not made with waterproofed cement to my knowledge. However, in all case the slabs are covered with a concrete screed so I would suggest a 50 mm screed, with reinforcement giving a 25/25 re-bar cover the concrete having mixed in, the water inhibiter. I am actually doing that on my next build next year but will be also including a waterproof membrane as a section of the roof will be a tiled party area the tiles will be affixed with an epoxy adhesive, as per swimming pool tile  norms.

I  would  add a  thick durable  plastic  membrane, concrete alwasy cracks

[Excel]

1 minute ago, Rampant Rabbit said:

I  would  add a  thick durable  plastic  membrane, concrete alwasy cracks

That's already been stated both by myself and @sometimewoodworker  .  It goes without saying it's a necessity for a professional build.

[bbko]

Here's some roofing material I'm looking at for a DIY extension of my parking/patio area that currently has orange terracotta cement tiles.  Just showing the OP of other possible options.

Ceramic steel roof CMR, the new innovation of ceramic coated steel roof. The first and only one in Thailand Helps reflect sunlight and UV & IR rays well, reducing heat inside the building make the house cool Eliminate heat problems And the noise of the roof during heavy rain is better than the general metal sheet roof. The curls are beautiful. Beautiful, fresh roof color, durable for 30 years, safe for health. and environmentally friendly

 

• Made from Aluzinc steel sheet Coated with ceramic beads and high quality water-based polymer resin paint.
• The material is strong and durable. Resistant to all weather conditions Safe from rainstorms, strong winds and hail.
• The steel roof has a textured surface. Helps distribute the impact force of rainwater reduce the noise of the roof while it rains well
• Helps reflect sunlight, heat and UV & IR rays, reducing heat inside the building to cool.
• Beautiful color, durable for 30 years, has a long service life.
• Easy to install, convenient, work completed quickly, saving overall costs.

https://www.thaiwatsadu.com/th/product/หลังคาเหล็กเซรามิก-CMR-รุ่น-มาตรฐาน-ขนาด-76-x-120-ซม-สีอิฐ-Terracotta-60352004

 

 

 

[KhunLA]

19 minutes ago, unheard said:

Perhaps you shouldn't be so aggressive in responding to others opinions.

KhunLA has stated his opinion and informed the OP of other available options.

Get use to it, as there appears to be a major reading comprehension issue on the forum.

OP asks for other option ... apparently missed by some.

 

Even after previously pointed out, and still missed... again ... vs other options

[sometimewoodworker]

FWIW blue scope makes a deck material that is designed to be concreted over, you can use that as a substitute for the precast planks

[Silencer]

Thank you all for your suggestions, especially details on concrete roof construction using the pre-cast panels. I have since looked into SCG and VCON hollow concrete roof panels, which look like viable options. Spans would be 5m, 7m, in combination with sloped tiled or shingled roof.  For other ideas, thank you also for mentioning the ceramic coated steel and bluescope/concrete new products. As background, my current roof quotes are about 1.1M baht for three hip style shingled roofs and this is why I am looking at other options. I'm aware of Bluescope and tiling options, I primarily wanted to get smarter on concrete options. Cheers.

[Thomas I Glover]

A slate roof will likely last a lifetime. The only maintenance is to seal the roof with a 15 year sealant (minimal) and it should last forever. I am a roofer and have seen a lot of shingle roofs fail yet never seen a slate roof fail. If there is a leak then it is most likely poor workmanship or poor design by the architect or builder. There are some contractors and architects that don't know what they are doing and a slate roof is not in their scope so to speak. So if you have properly designed and installed slate roof then it will last.

[Kwasaki]

13 minutes ago, Thomas I Glover said:

A slate roof will likely last a lifetime. The only maintenance is to seal the roof with a 15 year sealant (minimal) and it should last forever. I am a roofer and have seen a lot of shingle roofs fail yet never seen a slate roof fail. If there is a leak then it is most likely poor workmanship or poor design by the architect or builder. There are some contractors and architects that don't know what they are doing and a slate roof is not in their scope so to speak. So if you have properly designed and installed slate roof then it will last.

Agree synthetic slates will outlast many other roof materials.