Another aac blocks question

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Another aac blocks question

Postby cooked » Mon Mar 23, 2015 11:46 am

As I have mentioned before I built two houses with aac blocks in Switzerland. The blocks were 35 cm in breadth.
So I casually assumed that I could easily build a 10cm wall, non load bearing. Now the guy that sells them tells me that I have to put in metal straps every three layers, on Youtube they recommended every two layers. So what's the deal, do I really have to do this? I will be building a reinforced concrete shelf at a height of 80cm for the windows and plants so I am guessing that I don't need these straps up to this height and to be honest I don't want the hassle. Above this sill, every three layers?
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Re: Another aac blocks question

Postby Sometimewoodworker » Mon Mar 23, 2015 4:42 pm

cooked wrote:As I have mentioned before I built two houses with aac blocks in Switzerland. The blocks were 35 cm in breadth.
So I casually assumed that I could easily build a 10cm wall, non load bearing. Now the guy that sells them tells me that I have to put in metal straps every three layers, on Youtube they recommended every two layers. So what's the deal, do I really have to do this? I will be building a reinforced concrete shelf at a height of 80cm for the windows and plants so I am guessing that I don't need these straps up to this height and to be honest I don't want the hassle. Above this sill, every three layers?

Yes you do need them to tie the walls to the columns otherwise a good kick, or bump can break the wall out. They will also reduce the cracking you will probably get at the wall/column junction.

Of course you don't have to bother, just rebuild when they break or invest in a lot of mastic sealer for when they crack. :lol:
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Re: Another aac blocks question

Postby Roger Ramjet » Mon Mar 23, 2015 5:07 pm

cooked wrote: I will be building a reinforced concrete shelf at a height of 80cm for the windows and plants so I am guessing that I don't need these straps up to this height and to be honest I don't want the hassle. Above this sill, every three layers?

I used a lot of metal straps that are secured by concrete nails. I think I'm the only one who actually did. They are absolutely no hassle at all and take all of 10 seconds to bend and nail in place.
Even houses that aren't using AAC blocks will have tie ins between bricks and tiers and tie ins to walls and lintels. It adds stability, especially where there is a free standing wall like on my veranda on the second floor.
Sometimewoodworker wrote:Yes you do need them to tie the walls to the columns otherwise a good kick, or bump can break the wall out.

I will defy anyone to kick or bump any of my walls and break them and they are only 7.5 blocks.
Max and Bee in Chiang Mai tested his 7.5 AAC block walls with shoulder charges and told us all he couldn't budge them, yet he broke the red brick ones with the heal of his hand.
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Re: Another aac blocks question

Postby Sometimewoodworker » Tue Mar 24, 2015 1:30 pm

Roger Ramjet wrote:I used a lot of metal straps that are secured by concrete nails. I think I'm the only one who actually did. They are absolutely no hassle at all and take all of 10 seconds to bend and nail in place.
Even houses that aren't using AAC blocks will have tie ins between bricks and tiers and tie ins to walls and lintels. It adds stability, especially where there is a free standing wall like on my veranda on the second floor.
Sometimewoodworker wrote:Yes you do need them to tie the walls to the columns otherwise a good kick, or bump can break the wall out.

I will defy anyone to kick or bump any of my walls and break them and they are only 7.5 blocks.
Max and Bee in Chiang Mai tested his 7.5 AAC block walls with shoulder charges and told us all he couldn't budge them, yet he broke the red brick ones with the heal of his hand.

Of course they can't because you have tied them to the concrete posts etc. :roll:

Didn't you bother to read the post you quoted?

No ties = easy to break.
Ties = monolithic construction = very difficult to break.
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Re: Another aac blocks question

Postby Roger Ramjet » Tue Mar 24, 2015 3:46 pm

Sometimewoodworker wrote:Of course they can't because you have tied them to the concrete posts etc.

Didn't you bother to read the post you quoted?

No ties = easy to break.
Ties = monolithic construction = very difficult to break.

As I said I think I am the only person who used the metal tie-in straps, or the only person I recall over the last 5 years.
Max and Bee in Chiang Mai didn't use them, he used shoulder charges to test whether the Q-Con (AAC) wall (7.5) would withstand his weight against them without the tie-in straps, which they did. In fact up until that stage I was going to use the 20 (load bearing, Q-Con blocks for my build, but Max convinced me that double 7.5 AAC with an air gap (to allow for plumbing and electrical) was the way to go to hide the unsightly mess.
I used the straps because I knew about them, having worked with two Master Builders at one stage. Having also seen what Cyclone Tracy was capable of and knowing what the weather could be like in Thailand at times, I decided shoulder charges by Max just weren't enough, even though him being an ex Victorian Policeman he was a "big boy".
The original poster who built two houses in Switzerland with 35 cm blocks asked the question if he really needed to use the tie-in straps. I was pointing out that Max and Bee didn't use them, but I did. As far as I know Max's house is still standing despite the shoulder charges, which I think are better than "good kicks or bumps". What I failed to find on either of our builds (one using the tie-ins, one not) were the cracks at the column or wall junction, nor have I found either of us being forced to use mastic sealer, but that's probably because we were at both of our builds every day and supervised the work.
The original poster thought it might be a hassle, I just pointed out it wasn't really, but as they say in Thailand "up to you", both seem to work fine if done properly and no kicks or bumps will made any difference. But, I like peace of mind, so I usec the tie-in straps.
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Re: Another aac blocks question

Postby cooked » Tue Mar 24, 2015 6:12 pm

Thanks for the answers. As I said, a concrete shelf at a height of 80cm is happening soon, so on hindsight I suppose that the straps weren't necessary up to now, but they didn't do any harm. This morning I followed one useful piece of advice and used masonry nails to attach the straps to four blocks in advance. That worked much better than I had thought. So the special AAC tampons plus screws proved unnecessary, luckily I only bought one small packet, they will doubtless be of use later. I found out that you have to drill the holes in the columns before you reduce the space to less than that required by a drill!
I had the brilliant idea of putting two 45 ° corners at one point I wouldn't do that again, no way can I get a minimum of 10cm staggering in the blocks on the corners. I now 'worry' (ha ha) more about that than the straps.
Anyway as far as solidity is concerned, around 10 minutes after placing the blocks, there is no way you can correct any mistakes, they are there to stay. I'll let you know ifit falls down.
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Re: Another aac blocks question

Postby Cheeryble » Sun Jun 28, 2015 1:11 am

cooked wrote: As I said, a concrete shelf at a height of 80cm is happening soon



What's a good way to provide support off the AAC wall for a concrete shelf......it would have a fair old weight?
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Re: Another aac blocks question

Postby cooked » Sun Jun 28, 2015 7:26 am

A picture is worth a thousand words, so here's my solution. I botched the pillars a bit but it looks ok now.
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window sill.JPG
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Re: Another aac blocks question

Postby Roger Ramjet » Sun Jun 28, 2015 7:48 am

Cheeryble wrote:What's a good way to provide support off the AAC wall for a concrete shelf......it would have a fair old weight?

There is no way.
The only way you can do it with a completed AAC wall is to cut out a horizontal section of AAC block all the way to the columns, drill holes in the columns for the rebar and then put in a concrete support beam that sits on the AAC blocks. The shelf would have to be incorporated into the beam with rebar protruding and the whole thing would have to be supported on both side of the current wall. Don't forget that if you have a concrete "protrusion" (the shelf) then it needs to be balanced either side. It's rather like a balcony that sits out 1 metre, it needs double the support on the inside. One metre out means two metres in and you would need rebar through the whole thing.
I wouldn't do it, but I'd have to see a photo to actually know what you intend doing.
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