Urgent: Q-con vs red brick double walls

[cooked]

So what you are trying to say is that using foam insulation the cavity is better? Maybe, it is also more expensive and in my view unnecessary in Thailand.

Whether the air is moving or not, its value remains the same. Heat from radiation goes into the wall and warms it. This heat is then transferred to the inside wall by radiation. This wall then again stores heat before radiating it into the interior. Insulation is about reducing temperature variations and slowing down heat transfer. I know that some engineers in my class had difficulty with this concept, The calculation of the insulating value of a particular construction element does not take into account of whether the air is moving or not. Ventilation will, if anything, reduce heat build up in the cavity.

[ignis]

Why not use 2 x 7 cm Q-con with a cavity between ?

Anything with a cavity is an open invitation to unwelcome guests Termite and rats just to name a few Q-Con is extremely good however if you are hanging kitchen units you need to ensure you use the proper plugs/screws otherwise they would fall away Most Thai houses are rendered so why not use the very large grey breeze block In the western world if you were building in Breeze block you could build up to 5/6 courses per day as the mortar need time to dry with Q block there is no limit as you have to use a special adhesive however I have seen Thais putting mortar in between which is incorrect. Q block is new in Thailand even in the Western world a lot of builders shy away from it because they are to set in there ways !!!!!!!!

Q block is new in Thailand................ how long before it is not new to Thailand ?

10 years ago this month, I wanted a kitchen built on the back of our new build house, Kitchen 3m x 10 m, asking builders appears they had no idea and gave every reason why it should be red brick.. = no one had the job, I built it myself, simple to use [is not the 1st time as had used a few times over past 20 years before]

Glue, and used the rendering designed for these blocks.. simple and fast if you build 100% true, straight and take care on cutting.......... now a day see many houses and projects the Q-block is used far more then red brick......... if you don't have an electric saw a normal wood saw will cut them easy, just take a bit of time to cut 100% or time is lost filling all the errors and chips.

looking at some builders they still have no idea how to render these block... it is easy, mix rendering add washing up liquid and wet the blocks simple and fast, washing up liquid make it slide easier and not dry as quick in hot weather, always did this in Portugal, also works well here.

So 10 years on there has not been a single crack in any wall.

[ignis]

As a PS......... No edit button ?

If built with those tiny Thai red brick, chances are drilling the wall to fit something you will drill into mortar and not the red brick anyway. Q-block with the correct fittings are much stronger then fixing to mortar between red brick.

[trogers]

Hello Resa -

It's your dollar at the end of the day, so all parties involved would have to follow your wishes, if you really have your heart set on the Q-con.

I went with a cavity wall in red brick, without anyone's recommendations, after weighing up the qualities of the Qcon, and a couple of variations of them.

I'm not so sure about what they're telling you about the thermal properties of red brick vs Qcon - as far as I know, the insulating properties of Qcon are supposed to be very good.

From my own experience with them, you can't use normal render with Qcon, and are limited to a very thin coat of boon gow, which is a ready mixed concrete, which may cause problems later, in terms of overall strength / drilling into them - not sure how they'd stand up to a shoulder test..

Having said that, you can buy everything bespoke to use with those particular blocks, for fixings, lintels, etc, but strength wise, I'm not so sure.

The builders might favour red brick, as they are a bit more forgiving in terms of rendering after - don't need any special tools or training - you don't need to be so precise with your shuttering and pours, or the laying of them - you can always get everything more or less square after with a good layer of render, using basic brickwork and lintel pours.

There are a couple of alternatives available - one is called clc block, if I remember correctly - very lightweight, and you can use normal render and concrete with them - they claim to get stronger over time, once plastered. The only drawback with these blocks is you must render within a certain amount of time after laying them, otherwise they become compromised with the elements.

In short, I chose red brick, because that's what I trusted to be strong, without any shadow of a doubt, after looking at, and getting a sample of all the alternatives - you know the saying 'built like a brick shit house' - well, it's true. I've just had all my walls rendered, and they are now around 10 inches thick - and extremely strong. I want to be hanging furniture, water tanks, TV's, etc, and I want to be able to drill into my walls without having to worry about using special fittings, or weight issues.

The cavity should mitigate any heat issues, but remember this is only one line of defence amongst quite a few others that your architects should be employing to keep your house cool and energy efficient (Raised up off the ground, shading, insulated and breathable roof, UV reflective windows etc). The cavity should also insulate against sound. My house is surrounded by trees, but certain parts of the house do receive direct sunlight at certain times of the day - my walls are cold to the touch inside.

If you go for red brick - order them from Ayudhaya - best in the Country. Also, make sure the builders put breather pipes in all of your lintels to mitigate the heat upwards, otherwise there's no point, and all your rendering will crack over time.

If there's anything you want to know - please ask.

Good luck.

The ground under a house sat on the ground is cooler than the air blowing under a raised house although concrete paths around the house and joined to it would transmit that heat.

House on ground have problems with moisture, insects and dust - esp in rural areas where the surroundings are not paved or landscaped.

Built-in furnishing should be fixed on timber runners, and not directly onto walls, be they red brick or Q-con. These runners will spread the load.

Not when you actually put a plastic membrane under the concrete as I did and treat the ground with termite spray under that also vibrated the concrete added waterproofer and then compacted it all with a powerfloat

Sure, when you are constructing in a large city with professional builders and tradesmen.

Now try it with hand mixed concrete, no vibrators or power float. Even the 'plastic membrane' will probably be something left over from wrapping furniture. This is the common form of construction you can find in the rural areas.

And a ground floor 15 cm higher than the soil outside the main door is sure way to invite sand/soil into your home.

[kannot]

My houses are in the country not in a city the workmen were locals and dint mind doing it as I wanted, BUT yes they will try and do it their way when they can. I stopped all of that from day one, all muck stays on the path around the house and around the soil is another meter of stones chippings so when it rains none splashes on the path or up the walls.

Cpac with slump test is only a call away no hand mixed used even for the pathway.

The local builder had all the tools mentioned above which is why i chose him many dont .

I bought the plastic it wasnt cling film.

And I did seal my cavity shock horror hahahah no damp no mould no insects, no need to vent them, anyone thinks different can read our resident nuclear physicists comments (Naam) on the link I posted a s cooked said "simple physics" and also his other comments on slabs on the ground being cooler than raised houses, just saying like.

I think there was someone who did the r rating s for walls and the best was double concrete block with fibreglass in a s opposed to single 20 cm thick block might have been CTH website??

[kannot]

Ill just clarify slightly, RENDERED walls do not need weep holes even more so if a waterproofer is added into the mix, brick walls unrendered YES, my walls are double block rendered and sika waterproofer added into the render .

BBA in the Uk states this on their website.

[thomas2969]

Fact is:

For heat Protect, Q Con is the best. But also more expensive than the red bricks. Problem in Thailand also is, there is not much builders who really know how to to build with q con.

[passingas]

Building with AAC block is no different than filling in with red brick. Both are just fill...a sill beam joins the course where a window will set (from column to column), and a header or lintil will be formed and poured where the top of the window/door will be (column to column) after the rest of the wall is built up. AAC uses a special glue type mortor, while the red brick will use regular, cement mortor. The structural integrety of the dwelling, comes from the concrete piers, beams and columns, which should all be wrapped in plastic after being poured and the forms taken off. This will allow the moisture given off from the exothermic reaction of very hot concrete (primary cure process), to naturally baste itself and greatly aids in the proper curing of the concrete. Concrete loves to stay wet for at least 28 days for a proper cure to begin...it still cures many decades after the fact if done properlly from the beginning. Thais look at concrete as pourable brick...as soon as it can stand on its own, the form it ripped off and it just sits there and dries out completely. This leaves you with very brittle concrete that will never ever come close to curing. If using AAC block near bathrooms, run a couple of courses using regular masonry block on the floor...AAC block is very pourus and will allow water seepage and you don't want that. pg

[canopy]

If using AAC block near bathrooms, run a couple of courses using regular masonry block on the floor

Don't do that. Just like a typical Thai builder, you made something up instead of following the directions of the AAC manufacturer. It has been said many times in this thread it is worth saying again: a big problem with AAC is not many builders know how to build with them. AAC manufacturers offer wonderful fact sheets for design & installation, but most builders would never stop to read those.

[Khun Jean]

And with AAC blocks also read the instructions on the bags of 'glue'.

I was just in time to take out 2cm thick layers of it, sigh...

Reading the instructions has to be done by you because for most 'builders' everything is just cement that has to be mixed with lots of water.

[passingas]

Khun Jean is so correct....all I can say is...."shame on you if you don't take a lead in the process and be there 24/7 to make sure it all gets done correctly"...or at least to your specifications. Construction here is as different as their culture is to yours. Learn what bird-dogging means if you want things done right...or more realistically...not done wrong. pg

[cloudhopper]

I use AAC block on the exterior walls and inner course of red brick. The gap has conduits, pipes and 3" foil wrapped fiberglass insulation. All the inner walls are double red brick. The red brick has much more thermal mass. Hot room air is vented at the insulated ceiling into the (otherwise) sealed attic space which has an extraction fan at the top.

[Beardog]

I personally would never use red brick except to make a double wall. The red brick is what they use in wood fired Pizza ovens. Unless you enjoy an extra 6-10 degrees in your house use Superblock or some aerated block & only use the red brick to make a double wall. Best yet if you have the small amount of extra go fully western & double it with the same Superblock or Q con or the like. Our 1st house sucked so bad I got a cat & knocked it down & built(with a good contractor( not brain dead like the 1st idiot) & built a real house that stays very cool & has only one superficial rendering crack after 2 rainy seasons. Red brick is awesome for making a pizza oven.....Just saying...... In the 2000's era everyone is using the aerated brick due to it's ease of construction & in general excellent r- values for insulating. You get what you pay for. If you are tapped out use the low end stuff but if your not poor get the real deal. You will be much happier for it. The only red brick I ever want to see is to fill a small gap. Otherwise it is like fixing a dent on a fender by filling it with newspaper & paper mache instead of metal finishing with a minor skim coat of bondo. I f the builder even suggests red brick once I do not need to talk any further. To me it is truly the agony of defeat!

Edit: To make it worse the red brick does not hold the weight of cabinets worth a crap. Been there done that. The only joy I had was demoing the 1st build with the excavator I rented That & I would never ever build directly on the ground ever again. Very Bad Idea!

Edited October 19, 2013 by Beardog

[passingas]

Refractory brick, not that red brick you see all over here, is used in pizza ovens. Refractory brick is the only kind that will take that kind of heat and not crack, explode, crumble or a number of issues due to not being heat resistant. pg

[Toy77]

So talk about ventilated spaces - they are NOT insulated spaces. Duh.

Cavity walls consist of two 'skins' separated by a hollow space (cavity). The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material, and therefore will slowly draw rainwater or even humidity into the wall. The cavity serves as a way to drain this water back out through weep holes at the base of the wall system or above windows.

The science of cavity insulation

The reason cavity insulation keeps heat in is that the polymer and air in the cavity are good insulators. This is because the distance between the particles in the air is greater than in a solid. Other benefits of cavity walls are their resistance to moisture from the outer side to the inner wall and the increase of sound proofing.

http://en.wikipedia.org/wiki/Cavity_wall

Myself being electrical engineer, cannot claim to be expert on this ... But so being civil engineer does not give expertise in this are also ... You need to be thermal engineer to claim expertise in insulation area.

Moisture/sound barrier seems like the most probable explanation for cavity wall (moisture being probably the real one in my opinion ... And sound properties being positive side effect ... And therefore validating the need to drain it as specified in many civil works standards that I came across in my field of work)

I have to agree though that cavity itself is a poor heat insulator ... Air is good insulator if it does not move (it conducts heat poorly by itself) ... BUT when air is moving there is another type of heat transfer that comes to play - convection ... When convection happens - cavity becomes poor insulator

Thermal engineer are expert in fluid mechanics so they can correct me if I am wrong ... Natural convection can happen given enough spaces between walls (friction?). Most spaces in cavity walls are large enough ... So they alone are poor insulators

Notice how closely glass are spaced in double glazing (3 to 5mm) ... If you want to improve insulation property of window you use tripple glazing ... You do not increase air space between double glazing - convection

So for cavity wall, you use insulation to increase thermal performance ... Note that its not fibers that increase insulation - it's air between fibers that does it ... The purpose of fiber is to impede air movement and as result impede convection (same as fur for animals)

If air was such a good insulator by itself, we would not put insulation in attic or dropped ceiling ... There is plenty of air there ... But we do and it is not cause air is poor insulator - it's to stop convection

Just my thought ...

[moench]

How about this one?

Why some Thai company not start to produce this type of brick.

Have air in the carvity wall and form insulation

[Toy77]

The cavity in those blocks look too large to be effective insulator ... Cavities in those blocks are likely there to reduce block weight .... And the form is not that great insulator ... Plus, I can imagine all sort of difficulties in installation process (running utilities through those forms ... Placing the blocks themselves - probably have to separate form from blocks and install each separately ... If that's true, would it be better to put a better insulator there instead of foam).

I am researching this topic myself to decide masonry unit for my future house ... And it seems AAC blocks are the way to go ... Their solid wall construction have lowest U-value per thickness. (See http://www.samsung-heatpumps.co.uk/documents/U-Values_from_Domestic_Heating_Design_Guide_v1.0.pdf).

I don't want any cavities if possible, as I agree with the comment here regarding vermin (the biggest problem with vermin in cavities - you don't even know about them as you can't see them).

Also, lowering U-value of wall too much might not improve thermal loads if you have large windows ... There is REASONABLE limit where you can go with thermal design in tropical countries (thermally broken aluminium for windows? ... Tripple glazing?) .. Thailand does not have as large temperature gradients between outside and comfortable zone compare to UK ... Therefore what they use in UK might be overkill in Thailand

Also, I partially disagree that brands and pricing for AAC blocks don't matter. You usually get what you pay for. More expensive ones might have better quality control - meaning you will get on average more blocks from them that fit their claimed specifications. Of course, there are rare exceptions where you get superb products at unbelivable prices. But again, if its too good to be true - it probably is.

[rijb]

Doesn't a thermos bottle use air as an insulator?

We found it almost impossible to seal to a double wall with cement.

The ants use the space as a freeway to get around the house. They'll use electrical outlets, nails holes, etc. as portals.

[Toy77]

I think thermos use vacuum ...

And yeah, ants are pain in Asia ... But what worries me are termites ... So I am not considering cavity walls insulated or not

[reflectionx]

Go with the red brick. It's very simple - don't expect them to install something properly that they are not familiar with. They cannot even install properly things that they are familiar with, let alone other stuff. Make sure that you babysit them all the way. Sometimes even an hour is enough for them to make a mess that needs days of cleaning.

The worse part is that we ALWAYS tell them not to touch anything in the next 1 hour before we come back, but they still do it, <deleted> !!!!