Non-Load Bearing Block Partition Construction

[eyecatcher]

Also wondering what thickness of block we should use. Q-CON blocks come in standard sizes of 20x60cm at 7.5 10 and 12.5cm thickness. I believe the builder is going to plaster them, about 1cm each side and he's recommended the 7.5cm thick blocks. Thoughts?

If it was me, my thought process would go like this.

**How many blocks do I need?

**Do I have a door frame; if so; how wide is my doorframe?

7.5cm blocks plus plaster is going to make life easy with the doorframe, no reveals, quirks which means untidy details.

**Do I need a wider block? will the wall be carrying tv screen, aircon, music speakers

**What is the extra cost for the wider block? is is worth it?

**Who is going to carry those blocks up 22 storey when you are refused access to use the lift.

**Will the block fall apart when i scutch out for lighting backboxes. (qcon block certainly has the advantage here)

**Does the extra block thickness have any detriment on my living space/aesthetics and room balance.

**do I need to buy a pcx when a dream will do?

hope that gives you an idea.

[IMHO]

I found these statements at AAC product websites in just 5 minutes of searching ... and also take notice of the link below in blue...

AAC Sound absorbency and sound reduction:

Sound absorbency of air borne sound for 3" & 4" walls is 38 to 40 db. Hence, it is ideal for auditoriums and theaters and for cutting off workshop sounds from offices.

Sound Absorbent: Walls constructed with eight-inch thick AAC building blocks have a Sound Transmission Class of 45 when tested in accordance with ASTM 1190-90. This acoustic barrier, combined with the product's light weight and fire resistance characteristics make it an ideal building material for party walls and partitions separating multi-tenant dwellings. Benefit: AAC is a natural material for use as a dividing wall between movie theaters, town homes, and multi-residential apartment and condominium complexes. The inherent sound transfer benefit results in a superior finished product that is completed without otherwise necessary soundproofing products.

AAC buildings are quiet due to the mass and cellular structure of AAC walls and floors. This gives it STC ratings of 44 to 50 depending on finishing materials. Furthermore, AAC is so good at blocking noise it is used for sound barrier walls along highways.

And here is an extensive one with a web link that provides in depth information about AAC and noise reduction / absorption ... My take after reading all this information is that the issue of high frequency noise reflection is a issue looking for a problem...

http://www.mhe-international.com/aac_autoclaved_aerated_concrete_material_advantages_sound_insulation.php

Sound absorbency of any material depends on frequency - higher frequencies have very short wavelengths, and very little energy, so are easily absorbed. Low frequencies have very long wavelengths, and substantially more energy and are much, much tougher to absorb.

Even according to the chart on the page you've linked, AAC block's ability to absorb 125Hz is almost 4 times less than it's ability to absorb 4000Hz (and that will change with block thickness - that chart doesn't specify). And I can guarantee you It's ability to absorb sub-bass frequencies very quickly diminishes to next-to-zero, just like any other wall type.... You'd actually need a 4.25M thick wall for it to have any chance of absorbing 20Hz, for example (1/4 wavelength @ 340M/sec) - and 4 times thicker to be really effective (full wavelength).

The good news is, all audio frequencies do get reflected by hard surfaces though, and each time they are reflected, there are losses in magnitude, simply because the sound is trying to physically move a structure that doesn't want to be moved (mass). If you can mechanically decouple the inner wall that's receiving all this energy from the outer wall, you'll achieve the best overall results - and it's effective for all frequencies too - not just higher ones.

In short, from the perspective of sound insulation:

* Double walls with a cavity, with the outer and inner walls mechanically decoupled as best you can, will always achieve a better result than any single wall design, and will be effective at attenuating all audio frequencies.

* AAC blocks might have an advantage over regular blocks at higher frequencies, but the difference IRL might only be marginal.

* Stuffing the wall cavity with damping material will improve attenuation at mid and high frequencies (but not for bass), and again the benefit IRL might only be marginal.

* Mass matters, as it results in more kinetic losses.

Edited January 8, 2015 by IMHO

[MoD1977]

You are right IMHO, the problem are the low frequencies.

Maybe its an good idea to put a line of Rubber between the slap and the inside wall from the homecinema.

And also put some rubber between the slap from the hc and the rest of the house.

Do you think this will help?

[waters]

Okay understood - on all points @eyecatcher - and thanks very much again for taking the time to reply.

One of the partitions will indeed have an air conditioner attached to it and there are two door frames. The door frames are exactly 95mm - and so a 75mm block with 1cm of plaster on each side should match up nicely. Does this makes sense? That said our existing steel frame and plaster board walls are 100mm thick, and so there is about a 5mm lip, or reveal, on the inside of the frames.

From everything I've read, AAC walls are very strong, and so I'm assuming that hanging the inside portion of a 17,000 BTU Mitsubishi Mr Slim air condition will be okay?

[IMHO]

You are right IMHO, the problem are the low frequencies.

Maybe its an good idea to put a line of Rubber between the slap and the inside wall from the homecinema.

And also put some rubber between the slap from the hc and the rest of the house.

Do you think this will help?

That would likely improve things, yes, but it's also going to have it's own problems too of course.

In a typical house, assuming double block walls using normal construction methods, the weakest links are then actually going to be the ceiling first, followed by any doors and windows. I'd say there's a lot more to gain on focussing on those areas, rather than trying to take wall isolation to extremes.

[JDGRUEN]

Okay understood - on all points @eyecatcher - and thanks very much again for taking the time to reply.

One of the partitions will indeed have an air conditioner attached to it and there are two door frames. The door frames are exactly 95mm - and so a 75mm block with 1cm of plaster on each side should match up nicely. Does this makes sense? That said our existing steel frame and plaster board walls are 100mm thick, and so there is about a 5mm lip, or reveal, on the inside of the frames.

From everything I've read, AAC walls are very strong, and so I'm assuming that hanging the inside portion of a 17,000 BTU Mitsubishi Mr Slim air condition will be okay? c

I read on another forum where a fellow hung the inside Air Con unit on the AAC walls, - and it worked out well - but stated that the outside compressor unit - being much heavier had to be hung on a standard concrete area of the wall. Which I suppose could be inserted in an AAC wall much as they often do with the concrete window frames. And / or use steel reinforcement in the AAC blocks

[waters]

Hi JDGRUEN - that's the same for us - the outside compressor is on a balcony and tied to a load-bearing concrete wall. Only the internal blower, and radiator (I'm not sure what you call the inside part!) will hung on the AAC wall.

[kamalabob2]

Waters: I live in a Buriram Province home built with 7.5 AAC block interior walls that separate each room. In my ground floor office the large Daikin Inverter a/c unit is attached to 7.5 interior wall. The compressor is on a 2nd floor balcony, but bolted to the tile floor of the outside shaded balcony and NOT onto the 12.5 thick AAC exterior wall. The 32K Mitsubishi a/c unit in the bedroom is mounted to an interior 7.5 thick aac wall. The large compressor unit is bolted to the tile floor on a balcony. The drain of the interior Mitsubishi a/c unit drains under a counter in a bathroom near a floor drain all hidden from view. All of the air conditioning cables and pipes were hidden in the 7.5 autoclaved blocks or the 12.5 autoclaved blocks. Now the Wall Profiles. These metal strips are NOT expensive. Diamond Building Products makes these in Thailand. That is the same Diamond Brand as the better quality stainless steel water tanks sold all over Thailand. The metal strips go on every 3rd block working up from the floor as I recall. You can ask the representatives from Q-Con or Super Block or Diamond Block who speak and understand English any questions about the light weight autoclaved blocks. I made it a point to ask questions to the Diamond Building products sales manager who was fluent in English at the Buriram Home Show Expo. She told me she would return in February 2015 to Buriram to spend five days at the Home Show Expo. If I was building a 2nd home in Thailand I would certain use AAC blocks for all interior and all exterior walls. It has proven a good way to keep the house cooler. My wife is a very good cook, but she likes to sing karaoke near where I watch Farang TV. The interior AAC walls and a thick glass door help with the 2nd issue.

[waters]

Hi kamalabob2 - thanks very much for the reply. Very reassuring! I'll speak to Q-Con and ask them about how to tie in the partition wall to the load-bearing walls on either end. It does sound however, that the metal strips you are referring to, might be a little different from the larger full-length Wall Profiles described by eyecatcher above.

Stay tuned...!

[waters]

I think at this point, the only thing I'm still a little unsure about, is how - with a 7.5cm thick block - plus plaster - do you enclose a regular electrical box?

I've seen examples of how a finished wall can be chased out, and what I think is a pvc pipe drawn down with electrical wires inside, but where does the electrical outlet box go if you want the faceplate to be flush with the wall?

Do you cut a hole in the wall where the electrical outlet is placed? (usually near the floor - same for telephone, or cable TV).

[billphillips]

I've just seen this post .....

Tile paste joints = forget it, use sand and cement. Thin joints are used to maximise the u value of the block. That is to say; insulation. Sand and cement mortar is not an effective insulator but it is stronger, on internal walls sand and cement mortar is better. The block manufacturer says to use thin paste joints only to give a maximum u value.

Wall plates or block bond = forget them too, a simple large screw and plug in the wall on every course will stop the new work falling over. Alternately I suspect the builder, without prompting, will drill a 9mm hole and hammer a 10mm steel rod into every course.

Air con = is not heavy, requires no special steel mods. Can be fixed to lightweight blocks as well as any surface, it's really not a big deal.

Over the door = lintel is not required. A single 10mm steel rod in the mortar will stop any cracking. Your builder will build the frame into the new wall and that will act as a form for the new work.

Building onto a concrete floor = NO NO NO. You need a full structure analyse before contemplating that move. Concrete floors in Thailand are usually created using a precast 50mm slab with a very small amount of steel rod incorporated. Torn off cement bags are stuffed into the joins and then approximately 40 to 50mm of concrete is poured over them. Sometimes incorporating 3mm steel mesh. By any standards ... It's inadequate.

Do not contemplate building a solid wall of any type onto a concrete floor. You need to consult with the original architect of the building. The result of a catastrophic failure of the floor due to a ton of building materials (deadweight) instead of the liveweight it was designed for could land you in serious trouble.

A simple test = stand in the approximate area of the proposed wall ... Jump as high, and come down as heavy as you can onto the floor. You should not feel it move and you should not hear a drumming sound. If that's the case, it may, only may be ok to build on it.

You really must get something in writing from a suitably qualified person before you start the work. All of the verbal advice from unqualified (so called) experts will disappear with them. They will be just slightly ahead of the dustcloud they are creating while making their escape.

[IMHO]

I think at this point, the only thing I'm still a little unsure about, is how - with a 7.5cm thick block - plus plaster - do you enclose a regular electrical box?

I've seen examples of how a finished wall can be chased out, and what I think is a pvc pipe drawn down with electrical wires inside, but where does the electrical outlet box go if you want the faceplate to be flush with the wall?

Do you cut a hole in the wall where the electrical outlet is placed? (usually near the floor - same for telephone, or cable TV).

Once rendered on both sides, 7.5CM AAC becomes 10cm thick overall, which is enough for flush fitting electrical boxes, and also exactly the thickness of standard door and window frames. If using double blocks with a cavity, the conduits would normally go in the cavity, not chased into the wall.

[waters]

Hi billphillips, IMHO - thanks again - more priceless info. The forum has proved valuable as an understatement.

billphillips - I've seen the precast 50mm slab floors you speak of, and I'm reasonable sure that's not the case here (although as you've suggested, we'll check). We received two separate quotations for the work, and both contractors, along with the Juristic Condominium Office where we submitted drawings - have said that an AAC wall is fine (it was the first builder that recommended Superblock) - although you're suggestion of receiving something in writing is a good one and we'll do that too.

The building was built in 2000 and its architect was a former chair of the Architect Council of Thailand (who also lived in the building after it was built). Even to my untrained eye - the quality of materials, and overall design seems to be very good. I've watched an 'Ideo Mobi' go up in less than a year, about 300 meters from us, as well as been inside, and the differences are dramatic. Even the conduit used in the ceiling for the fan/extractor from the bathroom, is a solid rectangular steel vent shaft leading to the balcony, tied to the concrete ceiling (above the drop), and not the round flexi-tube that's used elsewhere. All other conduits and junction boxes are clearly labelled and neatly tied into place.

Thanks also for clarification on the sand/cement vs. AAC 'glue'. That's a big help - and one less thing to worry about. Same for the method of tying the new wall to the existing load-bearing wall at either end, with a large screw and plug, or steel rod.

IMHO - re: finished wall thickness, and electrical boxes - thanks and understood.

Will post pictures of the work in progress if anyone here is interested... ;-)

[IMHO]

Hi billphillips, IMHO - thanks again - more priceless info. The forum has proved valuable as an understatement.

billphillips - I've seen the precast 50mm slab floors you speak of, and I'm reasonable sure that's not the case here (although as you've suggested, we'll check). We received two separate quotations for the work, and both contractors, along with the Juristic Condominium Office where we submitted drawings - have said that an AAC wall is fine (it was the first builder that recommended Superblock) - although you're suggestion of receiving something in writing is a good one and we'll do that too.

The building was built in 2000 and its architect was a former chair of the Architect Council of Thailand (who also lived in the building after it was built). Even to my untrained eye - the quality of materials, and overall design seems to be very good. I've watched an 'Ideo Mobi' go up in less than a year, about 300 meters from us, as well as been inside, and the differences are dramatic. Even the conduit used in the ceiling for the fan/extractor from the bathroom, is a solid rectangular steel vent shaft leading to the balcony, tied to the concrete ceiling (above the drop), and not the round flexi-tube that's used elsewhere. All other conduits and junction boxes are clearly labelled and neatly tied into place.

Thanks also for clarification on the sand/cement vs. AAC 'glue'. That's a big help - and one less thing to worry about. Same for the method of tying the new wall to the existing load-bearing wall at either end, with a large screw and plug, or steel rod.

IMHO - re: finished wall thickness, and electrical boxes - thanks and understood.

Will post pictures of the work in progress if anyone here is interested... ;-)

Even if the floors are 10cm think, they still might only have been engineered for a max. 200kg/sqm load. Any floor where you have 5cm prefab planks with 5cm of topping concrete will be this spec for sure, but even if it's solid concrete it still might only be designed for this type of load. Typically, the higher design spec of 500kg/sqm is only used for outdoor floors (balconies/terraces) and wet areas (bathrooms, maybe kitchens). The difference in size and layout of the rebar is quite substantial.

You need an engineer to asses, bottom line.

If the wall you're proposing isn't too far away from a supporting beam, you should be OK. If it's mid-way between beams, that's the weakest point in the floor though, so weight loading really does matter.

Edited January 9, 2015 by IMHO

[waters]

Okay thanks IMHO - we'll double check. The partitions are going to form a perfect 'T', roughly in the middle of the unit, and so the overall weight of the partitions in the middle, at the 'T' junction will certainly be higher than at the edges.

Anyone care to guess how much a 1 meter stretch of 7.5cm thick, fully rendered Q-CON AAC wall might weigh?

[waters]

Back of envelope:

Weight of single 20 cm.x 60 cm. x 7.5 cm. Q-CON AAC block = 5.58 KG

1 meter length of a 2.5 meter tall wall = 12.5 blocks heigh and 1.6 blocks wide.

Therefore - 1 meter run will use approx. 20.83 blocks (less when you subtract the mortar).

20.83 blocks x 5.58 KG = 116 KG.

How much to add for the plaster? If it was doubled that would be a little over 200KG per meter run, and more per square meter at the 'T' intersection of the two partitions.

[IMHO]

Back of envelope:

Weight of single 20 cm.x 60 cm. x 7.5 cm. Q-CON AAC block = 5.58 KG

1 meter length of a 2.5 meter tall wall = 12.5 blocks heigh and 1.6 blocks wide.

Therefore - 1 meter run will use approx. 20.83 blocks (less when you subtract the mortar).

20.83 blocks x 5.58 KG = 116 KG.

How much to add for the plaster? If it was doubled that would be a little over 200KG per meter run, and more per square meter at the 'T' intersection of the two partitions.

According to the Q-con spec docs, which are based on a total rendered thickness of 9cm (which no contractor does), 7.5cm blocks work out to 90kg/sqm when rendered. 100kg/sqm would be what you'd work on though - i.e. 250kg per meter in your scenario.

Edited January 9, 2015 by IMHO

[billphillips]

Just a small tip re the electrical boxes .... Assuming you will use round yellow pvc pipe as conduit; you can purchase brownish / red coloured back boxes, also pvc, that clip onto the end of the pvc pipe. An optional spot of glue holds them in place while the builder daubs mortar around. They save a lot of prancing around trying to obtain fixings. The finished plaster secures them with the flanged edge of the box keyed into the new work. Yes, you will need to chase out the wall but an easy task in lightweight blocks. For the air-con, remember to use 4mm cable with a direct route back to the distribution board. Best of luck with your project.

[JDGRUEN]

OP Waters... I have to differ with the recommendations to just use Sand/Cement mortar versus the Thin Set mortar. I would have to see some engineering test results on added strength before I would actually believe it.

My reasoning... if I was doing work in the USA with AAC blocks and the local mason said he could do it with sand/cement mortar because if asked to keep the mortar layers consistent and as thin and reasonably possible - but still thick enough to be effective - then I would trust that, And trust that the mortar would be mixed with consistent ratios of ingredients.

But with Thai brick/block layers every batch of mortar is likely to have a different ratio of what ever they have on hand... Different courses may well end up with too much or too little and sometimes just right cement/sand/water ratios.

Then - I have observed Thai workers in construction all over Thailand and have yet to see any consistency as to thickness of the mortar layer varying by 100% difference from one course to another. Any projections as to block height to produce wall height will be out the window as well as the over all look of the wall without plaster or stucco. I realize that the rendering covers all this up but is that what you want?

Also - I watched one crew here in Ao Nang mix mortar for a hotel with AAC walls ... The ground crew mixing the mortar were using scoops of sand hand raked into the scoop containing about 1/3 dirt and gravel and whatever from the ground it laid on. And the block laying was just the same as what you see when they use the little bricks or even the bigger bricks -- but not as bad as when they lay regular concrete blocks. The finished walls looked like the waves of the ocean 1/2 kilometer away.

With ACC Thin Set binder -- you have consistency -- each plastic tub of the same brand of Thin Set is going to have the same ingredients and is not going to be mixed with dirt or the wrong ratio of sand to cement and water. Plus the layer on 'glue' on the top of each course is likely to remain at an even thickness - iF the process is demonstrated correctly by a supervisor who has to been told how to do it... And the thin layer will be enough to more than properly hold everything together. The concept of building a virtually 'monolithic' wall is done with Thin Set.

Also - Lintels... because an opening for a window or a door with AAC requires only a steel plate bridging the opening - I see no reason to skip it as has been suggested..

And one more comment. A few of the comments on this thread cause me to think that the poster has no ideal that AAC is considerably lighter in weight than regular concrete blocks... Maybe I miss read - but - such excitability that I saw written makes me wonder.

Good Luck on the wall building ...

When I get to building my Bungalow in Sing Buri ... I will post a thread... I love the concept of AAC as can be easily seen but the infill walls of the bungalow I am planning will be done using pour in place foamed lightweight concrete. I love Thailand - out in the smaller towns... just build what you want. I shake my head at the mountain of bureaucratic forms - fees and filings back in Texas just for a septic tank or an outbuilding... Even when one owns the property free and clear... which I will never understand...

[waters]

Thanks again billphillips and JDGRUEN. Much appreciated, and noted on all points.

At this point we've cleared out nearly everything from the unit. The kitchen co., has just come in and discussed plans with the builder. With all the old material out, we have a nice list of tasks, mods, electrical requirements etc. On Monday we're going to sit down with the builder and go through everything (in a nice and friendly manner). I've also just spoken to Q-CON, and if we buy their products from one of their dealers in the area, they will send one of their technicians along to discuss materials and methods with our builder.

Fingers crossed!!! :-)

Edited January 9, 2015 by waters

[IMHO]

Thanks again billphillips and JDGRUEN. Much appreciated, and noted on all points.

At this point we've cleared out nearly everything from the unit. The kitchen co., has just come in and discussed plans with the builder. With all the old material out, we have a nice list of tasks, mods, electrical requirements etc. On Monday we're going to sit down with the build and go through everything (in a nice and friendly manner). I've also just spoken to Q-CON, and if we buy their products from one of their dealers in the area, they will send one of their technicians along to discuss materials and methods with our builder.

Fingers crossed!!! :-)

No mention of an engineer yet... fingers crossed indeed.

[Crossy]

No mention of an engineer yet... fingers crossed indeed.

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

[waters]

Here's a follow up post, with some photos, after having completed the renovation. We used Q-Con blocks from SCG. The builders put a reinforced section above the door frames, for the entire length of the wall (they called it 'En' in Thai - although I'm not sure what this translates to exactly). They also tied the ends of the wall to the existing walls with small steel studs, every other row. To my untrained eye - they seemed to do a good job, and it all worked out well. You can see the air conditioner hung on our new AAC/Q-Con partition. :-)

Thanks again for all the advice here in the forum.

I now have a question about sound proofing our windows and balcony door frame - another thread coming soon... :-)

Edited March 1, 2015 by waters

[bbradsby]

OP, hopefully we just missed the part where you got written approval of your block wall floor plans from the HOA and the structural engineer of the building? Gypsum board on metal studs would have served your purposes easily, including wall-mounted equipment, and acoustically could have done as well with proper design & construction. If gyp/stud walls were what the original builders used, thats what the structure is designed for. Likely not anything more!

[edit] I see now that its done, seemingly without the above approvals? If so, youre banking your - and your downstairs neighbors - fate on the safety margin of the engineering design [unknown] and the quality of [Thai!] construction. No one should consider the OP's path as one to follow.

Edited March 21, 2015 by bbradsby