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  1. #1
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    Roof design merits

    Hi all, I am a long time lurker, first time poster.

    I am planning to start a build in about 2 years time. Currently looking for some land and thinking of various house designs. I am thinking of doing a modest 2 floor build with the ground floor elevated a bit and left open, the upper floor would be enclosed. I am doing my best to find land suitable for development of a north facing home on roughly one rai of land. I think I am 2 years off starting construction as I am fairly sure we will need to fill the land and wait for it to settle.

    I want to keep the build as cool as possible because I don't really like air conditioning. We will install aircon but I hope to use it very minimally. I would love to use wood construction but will likely end up going with Q-con.

    One of the things I am considering (and would appreciate feedback on) is a straight steel roof, modestly sloped with the north edge a meter or so higher than the south edge. It would have long overhangs and would have soffit venting along the full length of both the north and south edges of the roof, (maybe east and west too now that I think of it). Significant insulation above the ceiling and likely some sort of sound deadening material on the underside of the steel. I am also looking into reflective coatings but have no idea what is available in Thailand at this point.

    One of the things that has me nervous about this roof design is that I rarely it in Thailand. Is there some fundamental flaw that I am overlooking or is it just that most people find this style of roof ucking fugly?

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    A thought on the elevated ground floor. It is a sound construction with wooden floor, but I do wonder if a tiled concrete floor poured directly on the ground would not be cooler, unless you need the elevation for flood protection. And even then you could fill it up a meter or so and compact it. The underground never gets hot. Anybody knows if that design helps keep the house cool or has any significant disadvantages?

  3. #3
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    interior air space , the more the merrier .

    Hot Air Rises so give it somewhere to go

  4. #4
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    Yeah I was thinking I want the ground floor elevated slightly (maybe only 1/2 a meter) and was planing to do a slab on compacted ground.

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    if you are going to elevate the house, why not elevate it enough so that you can have a nice big party space under the house? it would be a good place for hammocks too, nice and cool

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    Quote Originally Posted by Moolek
    One of the things I am considering (and would appreciate feedback on) is a straight steel roof, modestly sloped with the north edge a meter or so higher than the south edge. It would have long overhangs and would have soffit venting along the full length of both the north and south edges of the roof, (maybe east and west too now that I think of it). Significant insulation above the ceiling and likely some sort of sound deadening material on the underside of the steel. I am also looking into reflective coatings but have no idea what is available in Thailand at this point.
    you can buy metal roofing panels with reflective coating already on the underside, which also deadens the sound

  7. #7
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    Quote Originally Posted by DrAndy
    if you are going to elevate the house, why not elevate it enough so that you can have a nice big party space under the house? it would be a good place for hammocks too, nice and cool
    That is the plan, the ground floor will be minimally elevated and will be open "Thai style", the upper floor will be the enclosed portion, I want to have about about a 3 meter ceiling height under the upper floor, possibly lower where services need to be run.

    I appreciate the comments to date, I am very curious about peoples opinions on the roof design. I am worried there is an obvious downside to this type of design that I am missing.

  8. #8
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    ^ this might have a nice effect, but is the expensive route when you consider floorspace per baht.

    Quote Originally Posted by Takeovers
    A thought on the elevated ground floor. It is a sound construction with wooden floor, but I do wonder if a tiled concrete floor poured directly on the ground would not be cooler
    I agree with this comment.

    When I started thinking about building a house, I wanted to raise the house and have a large open useable space underneath. The FiL, local builders and architect all said that a raised concrete floor (1 metre or so) is a better and cheaper option; building out instead of up is a much cheaper option, so if you have plenty of space then you will get more floor space for your money.

    Plenty of roof overhangs with outdoor space/terraces, either raised up 1 metre or lower; both is nice and gives a split level effect - need to consider flooding/water though, so depends on the area you buy.
    Cycling should be banned!!!

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    Here are a couple of simple roofing ideas suggested by my architect:








  10. #10
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    Quote Originally Posted by Moolek
    I am very curious about peoples opinions on the roof design. I am worried there is an obvious downside to this type of design that I am missing.
    post a drawing so we can see exactly what you are considering

    I may be wrong but you describe a big single plane roof, without much drop (1 metre over?)

    large overhangs are good, as long as the structure is strong enough to resist any gales that may occur

    maybe that type of roof is not seen much in Thailand as steel structure is not traditional and most houses with steel roofs have been, until recently, fairly mundane
    I have reported your post

  11. #11
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    Are you worried about appearance? I have two ideas I am kicking around.
    Build a cheap agricultural-type barn and put the house underneath.
    Use shophouse technology which every builder knows and have a flat grass covered patio roof.

  12. #12
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    Ok here is my 2 minute drawing. I hope you like the realistic sun feature.



    This is the profile view. Notice the nice blue cool air entering the soffits on the south side that exits all red and hot on the north side. Only the yellow filled area is enclosed, the rest of the house will be open to the elements creating a large area under the house for the in-laws/out-laws and a nice sitting area in front of the house on upper floor.

    There is a second awning style roof section at the back to help shade the lower area. Total roof area to be something like 16*16 meters (256 m2) including 2m overhangs but not including the extra lower roof section(say 2*12m). Total floor space for both floors is 12m*12m but the enclosed area on the upper floor is only 8m*12m.

    I hope you enjoy my artistic masterpiece.

    *edit: crap just noticed my fancy wind arrows did't come in for some reason.

  13. #13
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    I don't see any problem with the concept. Make sure you give ample space above the ceiling plenum for air circulation and insulation.

  14. #14
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    looks good

    start building

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    Moolek... your first post answered your question in that I am of the opinion that Thai's think that a steel roof is ugly. They have this fascination with steep pitched rooves and 4m x 4m concrete posts as their standard and it is really hard to get them to think of anything else as acceptable. When we built our shed the pitch on the roof was (by Thai standards) very low at about 20 degrees. My missus reckoned everyone in the village had an opinion that it was too low but it works fine. The reason I wanted a low pitch was so that when the roof extended out past the walls, and I extended in 4m+ out, there was till enough height to drive under the roof alongside the shed. I believe their high pitched rooves are a result of the grass thatch they used to use before tiles so that the rain ran off quickly before it could soak through.

    If you have ever read the thread I posted some time ago about my missus building her house you would see early in the thread that I actually wanted to built a house with a steel / colourbond roof but she reckoned it would be ugly.
    The reason I wanted to use steel on the roof was that it lighter and therefore you could go for much larger spans, which in turn allows you to build a very large open space without ending up with a dancing pole in the middle.

    Another urban myth, at least in my opinion, is their belief that you need to build up the land and wait for it to settle. We built the land up about a metre but when we put the footing in we made sure that they dug down through the fill and into the original solidly compacted dirt under the fill.

    As Bettyboo suggested I believe it would be better to extend the whole footprint and have a single floor. Have an enclosed area around which you have large overhanging verandahs. If you have ever looked at an old timber "queenslander" style house (very popular in the Aussie tropics) you will know what I mean. They are very effective at using natural air flow to keep a house as cool as possible.

    Good luck to you whenever you decide to take the gaint leap and make sure you post us some pictures to look at.

  16. #16
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    Where are thinking of building?

  17. #17
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    Is this the metal roof you are thinking about? The overhang is 2 meters which offers plenty of shade and the back patio is also roofed with one-piece lengths of steel.



    Here is the south facing wall which shows the maximum sun exposure with the 2 meter overhang. I am not sure what kind of overhang you can have with a tile roof, but I do not think it is 2 meters. The tiles are too heavy which also requires closer support pillar placement.

    The cost of a steel roof is also much less than a tile one. I would have hated to pay for all the tiles to cover my house, patio and carport.

    The only down side will be the noise factor when it rains, but as Dr. A pointed out, you can buy steel sheets that are already fitted with noise insulation. I did not go this route and you can see more on my house build thread, if you are so inclined.


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    I think these hip roofs are very popular here. My build won't be too different from Rick's except it'll be on 1 floor only and have a hip roof.



    This large outside area with the wooden beam/stancions looks nice, imo; I might go for something like this, but scaled down...

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    Quote Originally Posted by ootai
    Another urban myth, at least in my opinion, is their belief that you need to build up the land and wait for it to settle. We built the land up about a metre but when we put the footing in we made sure that they dug down through the fill and into the original solidly compacted dirt under the fill.
    That does not help if you want to pour a solid concrete slab. For that the soil needs to be compacted.

    There is also a minimum advisable tilt of the roof. If too flat it provides lift in a storm and the roof will fly away. I don't know though what that minimum would be.

  20. #20
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    ^^
    Smart move BB. By the way, my build is only 1 story even though it looks like 2. I think these types of roofs are picking up steam here in Thailand.

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    ^ sorry Rick; I'm gonna have a good read through your thread in a while.

    (you look like you have a bloody high ceiling!)

  22. #22
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    Quote Originally Posted by Takeovers View Post
    Quote Originally Posted by ootai
    Another urban myth, at least in my opinion, is their belief that you need to build up the land and wait for it to settle. We built the land up about a metre but when we put the footing in we made sure that they dug down through the fill and into the original solidly compacted dirt under the fill.
    That does not help if you want to pour a solid concrete slab. For that the soil needs to be compacted.

    There is also a minimum advisable tilt of the roof. If too flat it provides lift in a storm and the roof will fly away. I don't know though what that minimum would be.
    I would be interested in what the minimum is since I see all kinds of slopes here in Thailand. My house slope in about 20 degrees while the patio is somewhere around 16 degrees.

    I would also think the possibility of having a roof "take off" on you would depend on how well it is anchored.

  23. #23
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    IDEAS;

    I think a metal roof will hot and transfer heat and you will definately need insulation. Most likely even with insulation you will still be able to hear the rain when it hits the roof.

    As others have stated, make sure you have enough space between the ceiling and the roof on the south side for air flow.

    You could consider sloping the roof down on the north side exterior wall, to add more shade and help prevent the wind from getting under the roof. I know this is the north side, but we are in the tropics and the sun is not that far south at certain times of the year.

    Many builders raise the first floors with a 2" pre-stressed floor panel and then pour 2" floor on top of this (same as second floor construction). They normally do this, if they have any concern about moisture, compaction or the ground settling. It is normally cheaper to just add fill dirt and pour on top of it. So this is what they do!

    You could also consider adding a crawl space and/or a partial basement under the ground floor, for extra storage and/or access to plumbing or other utilities.

    With two years you have plenty of time to plan. You may want to use this time to get familiar with the standard building materials and lengths, so you can design your house to reduce cost and waste.

    Good Luck and keep us posted.

  24. #24
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    Quote Originally Posted by rickschoppers
    I would be interested in what the minimum is since I see all kinds of slopes here in Thailand. My house slope in about 20 degrees while the patio is somewhere around 16 degrees.
    the minimum is a flat roof!

    the slope can also depend on the type of tile you use; the manufacturers often specify a minimum slope for a particular tile. Less than that can lead to water ingress

  25. #25
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    ^^^^
    It is a high ceiling and the posts are 4 meters high from ground level (except in the front bathroom and Thai kitchen). The 4 meter height was needed to accomodate the teak panels and I like high ceilings in general.

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