swaying block work

Hi guys

Im intending to start building work (finally) for my garden garage which will be single skinned aircrete blocks with a sand and cement render

However I need to clarify some things first.

I have been practicing my block laying skills for a few days now and have a few concerns.

Firstly when I lay my blocks once the mortar has dried I can make the wall sway back and forth, secondly im using a mortar mix of 4 to 1 with plasticiser however the mortar doesnt seem strong enough maybe its something im doing wrong?, I mix the sand and cement in a wheelbarrow well, then I add the plasticiser to a bucket of water give it a mix then add it accordingly to the barrow and mix it the correct consistency.

I have built a block wall 3 courses high and 3 blocks wide and am slightly worried if i build a garage single skin even with piers ill be able to knock it down quite easily.

I think to my self that maybe the roof will support the walls better as well as interlocking the walls but am slightly concerned.


I must add that my practise blockwall was built on top of a concreted area in the garden with a thick bed of mortar below it, is it because I have no courses below the ground that its swaying and also do I infill the gap around the blockwork with a weak concrete mix?


As im reading back what ive written it seems obvious to me that if i were to have a few courses below the ground it should solve the problem as well as the interlocking walls however I am in need of proffesional advice as this is not my area of expertise and would be guessing.

If someone could possibly explain how walls and buildings of this sort actually acheive their sturdyness in terms of standing up and not moving when pushed or hit I would appreciate it.

thank you for your time

i would suspect that the bed of muck you lay has a belly/hump in it.
when you spread the muck, it must make an even spread along the length of the block. i see diyers laying a hump of muck in the middle and bashing the block that they lay on top to achieve a level, they hope that the block will squash/level the mortar. it does not work!
the muck spews out and water is forced from the mixture and it will not stick.

in theory you should not need to bash/tap the block, you should rub it into place. reality is that this is hard to do with blocks.

a slightly wet block might help you to get them to stick.

a wall has no strength/ resistance to sideways pressure whether you build it or me. it has compressive strength and thats all. shytalk or woody can explain this better than i can but thats how it is in simple terms.

i think at 4:1 is a strong mix, i use 6:1 but i seem to remember being taught that 8:1 was the correct mix for aircrete blocks tho ive never seen anyone use that ratio.

i did say before to you to use single skin 150 blocks, they are more stable for anyone and especially a diy'er (i appreciate that you might not have been able to use them) the wobble is the reason why i suggested them.

is your floor clean! muck might not stick if its dusty.

i hope this helps a little.
remember, a wall is like a sail, it ill topple if you dont support it in someway.

you are doing nothing wrong and the symptoms are not unusual.

dry, high suction blocks will need wet muck and vice-versa. machine mixed muck is infinitely more workable than hand paddled rubbish.

an unrestrained, flat slab of blockwork will sway. it will stiffen over time, but will still wobble.
these problems are alleviated once the uppermost part of a structure is completed, i.e adding lintels wall plates joists etc.

cheers for that guys

I guess when the roof and lintels etc go in that should make it alright.


and btw atoz ur rite about the blocks its just i just wanted to practise technique and speed for laying thats why i bought the cheapest blocks which were 100mm but for the actual project am using 140 or 150 for sure.

cheers