Engr. Osaz' Enobakhare
Nigeria

‘Perfection’ is the word. ‘Smoothness’ is the feeling. ‘Mortar’ is the item. The wall is the receiver and we are the admirers. Everybody wants a perfectly smooth wall for their interiors but we sometimes get more than what we bargained for. Rough, uneven and not properly detailed wall plastering or rendering are some end results that stares us in the face because we somehow engaged the wrong hands. But that’s not the end of the road.

Rendering (or plastering) action on wall usually precede painting. It is the process of applying mortar made from a mix of cement, fine aggregates (or smooth sand) or Plaster of Paris and water to cover the surfaces of block, brick or concrete walls. This process if not properly handled can lead to a bad output. For instance there is often the problem of unevenness in the texture of the finish, flaking-off, breaking edges, cracking, etc. which hitherto affect overall aesthetics and durability. But not all cracks on walls are as a result of poor mortar or rendering work; sometimes it is a consequence of structural defects in the building. Sometimes when this happens, there is a temptation to simply cover it with paints or other finishing material; but that really doesn’t work. The effect of a bad plastering will still resurface with time.

Talking about getting the job done properly; it is important that the mason team understands the mix ratio for mortar in order to get the right output. They must also know how to use the trowel (or application device) and smoothing devices well. A cement-sand mix ratio of 1:6 -12mm thick is generally acceptable for walls; corresponding to about 3 wheelbarrows of smooth sand to 1 bag of cement. 12mm specified here represents the thickness of the layer on the wall after application.

The nature of sand is also important. The suitable grade of smooth sand for wall rendering is one that contains a good proportion of clay which gives it a tacky or gummy feel. This does not imply the use of pure laterite. The use of sharp sand for rendering should be avoided because overtime pores are generated within the layer that affects the surface texture of the wall. The moisture content in your mortar should be adequate; just enough to make the mix workable. There are special cements used to achieve quality rendering; they were produced with the required functional requirements good mortar/plaster in mind. It is good to make use of them rather than the general purpose cement so as to obtain great results. It is wrong to use mortar made for setting blocks or bricks to also render your walls. Naturally if you make a bad mortar, you can only expect a bad rendering.

Once there is a noticeable defect on a rendered wall, even if it has been painted; it is better to simply chip-off, prepare the surface and reapply properly so that it cures without cracks. Although it may cost more to chip-off old rendering layers before re-applying mortar or P.O.P, the durability potential often override the cost burden, hence making it a cost-effective approach to the alternatives. The use of filling materials to close-up voids in walls to create even texture without chipping off in walls is a welcome development but it is not often the best option; especially if the defect is on a large scale. If you must use filling materials some Experts advice that you drill tiny holes into sections of the wall (using a simple drilling device) to allow for a good grip to the wall; the hole is such as extends beyond the plastering layer well into the wall fabric. Special gums are sometimes used to fill the hole to enhance firmer grip; thereby improving stability.

Source: https://engineerosaz..com/2017/07/bad-rendering-or-plastering-of-your.html

Please take off this picture. The picture is a property of Harney project

abdulwastecx:
Please take off this picture. The picture is a property of Harney project

This is a random picture. Neither the author nor the publisher have claimed ownership of the picture. It is basically for illustration.

jeftalene:


This is a random picture. Neither the author nor the publisher have claimed ownership of the picture. It is basically for illustration.

na "i too know" dey worry am

Booked

abdulwastecx:
Please take off this picture. The picture is a property of Harney project

are you for real??

[b][/b]brother are you writing biology.?

This argument over the picture used.....reminds me of a builder in this forum who uses watermarks on every picture he uploads.
That's the way to make pics exclusively yours.

www.engineerosaz..com is where you find latest prices of all building materials in Nigeria and lot of construction advice for your project from the contractor of first choice. Check it out

Op..nice info. What of the case of mixing sharp sand with that clayey sand.

Nice one


You can also render veneer bricks on the walls for Aesthetics and to minimize long term maintenance costs of the wall.

You really nailed it bro... I'm also a construction supervisor in need of a job and will appreciate it if you can help me out

Ddivino87:
Op..nice info. What of the case of mixing sharp sand with that clayey sand.

You wouldn't get a smooth surface so you may still have to screed with a pop

Oguaja 101

All this your grammer is nonsense to Oga Mason.
Just tell oga Mason what u want and he will deliver.

Nice one.

As a building technologist, cracks on rendered walls are not necessarily a result of bad jobs. Apart from the wrong mixing ratio, as stated, there are


1. Bad cement with too much gypsum

2. Bad fine aggregate which can be as a result of

a. Too many deliterious materials
b. Source of dredging
c. Bad sifting

3. Wrong choice of water in mixing

4. Nature of receiving surface

hmmmm

Ok

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Following Bro. This is my area of specialization

shortgun:
All this your grammer is nonsense to Oga Mason.
Just tell oga Mason what u want and he will deliver.

Huh ??

jeftalene:
Engr. Osaz' Enobakhare
Nigeria

‘Perfection’ is the word. ‘Smoothness’ is the feeling. ‘Mortar’ is the item. The wall is the receiver and we are the admirers. Everybody wants a perfectly smooth wall for their interiors but we sometimes get more than what we bargained for. Rough, uneven and not properly detailed wall plastering or rendering are some end results that stares us in the face because we somehow engaged the wrong hands. But that’s not the end of the road.

Rendering (or plastering) action on wall usually precede painting. It is the process of applying mortar made from a mix of cement, fine aggregates (or smooth sand) or Plaster of Paris and water to cover the surfaces of block, brick or concrete walls. This process if not properly handled can lead to a bad output. For instance there is often the problem of unevenness in the texture of the finish, flaking-off, breaking edges, cracking, etc. which hitherto affect overall aesthetics and durability. But not all cracks on walls are as a result of poor mortar or rendering work; sometimes it is a consequence of structural defects in the building. Sometimes when this happens, there is a temptation to simply cover it with paints or other finishing material; but that really doesn’t work. The effect of a bad plastering will still resurface with time.

Talking about getting the job done properly; it is important that the mason team understands the mix ratio for mortar in order to get the right output. They must also know how to use the trowel (or application device) and smoothing devices well. A cement-sand mix ratio of 1:6 -12mm thick is generally acceptable for walls; corresponding to about 3 wheelbarrows of smooth sand to 1 bag of cement. 12mm specified here represents the thickness of the layer on the wall after application.

The nature of sand is also important. The suitable grade of smooth sand for wall rendering is one that contains a good proportion of clay which gives it a tacky or gummy feel. This does not imply the use of pure laterite. The use of sharp sand for rendering should be avoided because overtime pores are generated within the layer that affects the surface texture of the wall. The moisture content in your mortar should be adequate; just enough to make the mix workable. There are special cements used to achieve quality rendering; they were produced with the required functional requirements good mortar/plaster in mind. It is good to make use of them rather than the general purpose cement so as to obtain great results. It is wrong to use mortar made for setting blocks or bricks to also render your walls. Naturally if you make a bad mortar, you can only expect a bad rendering.

Once there is a noticeable defect on a rendered wall, even if it has been painted; it is better to simply chip-off, prepare the surface and reapply properly so that it cures without cracks. Although it may cost more to chip-off old rendering layers before re-applying mortar or P.O.P, the durability potential often override the cost burden, hence making it a cost-effective approach to the alternatives. The use of filling materials to close-up voids in walls to create even texture without chipping off in walls is a welcome development but it is not often the best option; especially if the defect is on a large scale. If you must use filling materials some Experts advice that you drill tiny holes into sections of the wall (using a simple drilling device) to allow for a good grip to the wall; the hole is such as extends beyond the plastering layer well into the wall fabric. Special gums are sometimes used to fill the hole to enhance firmer grip; thereby improving stability.

Source: https://engineerosaz..com/2017/07/bad-rendering-or-plastering-of-your.html

Good write up!

[quote author=jeftalene post=60081402]

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Baba, is it advisable to screed a the inner part of a wall using POP, and cementing the outer part?......

...
..
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People here use the normal cement to plaster, then they screed with POP, so my question once again is that, will by buiding be ok if i screed the inner walls using POP only & not plaster with cement?.........
Ordo the outer part will be done with cement.....

informative post. There are increasing cracks in plastering these days.
screeding can be used to cover up the cracks and special modified paint filler can be applied and sand papered smooth.
The paint has the advantage of bonding well to the wall and giving a smooth finish.
The pictures below are that of the filler applied on a wall with cracks and the painted finish. Both materials supplied by me.

One bag of cement with 12mm thickness will cover how many sq meters?