Building Standards: Plastering and Brickwork

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Internal Plastering

Internal wall plaster is gypsum-based and is usually applied in 2 coats. The 1st coat is designed to fill and pretty much level the wall. The 2nd coat is the finishing coat and is smoother and finer. Normally each plaster coat is about 10mm (just less than 1/2 an inch).

With the residential property that I’ve seen being built in Perak it’s hard to tell if the walls got 2 decent coats of plaster. 

Generally, the internal plasterwork here seems to consist of a single coat of the coarser sand & cement that’s usually used outside (see below), with a very thin (3mm) coat of smoother gypsum plaster.

This is one of the major problems with property here and a considerable amount of time, effort and money is spent by folks trying to level-off and smooth-down the internal walls.

External Plastering

This is normally called render, or sand & cement plaster. It’s applied all over the external walls as an external finish, to fill-in the holes that got knocked-through when the electrician was chasing-in the conduit, and to generally cover-up the lack of full mortar joints. 

Render is normally applied in 2 coats. The first is called a scratch coat to level-up the wall, it’s about 10mm thick. The second is the finish coat, also about 10mm thick, and this is to smooth everything down. In good construction wire mess is placed over items like concrete beams and lintols where they meet the brickwork. It’s to provide a key for the render at the joints between materials.

In Malaysia there’s no 2 coating, or the use of wire mesh. The render is a single coat of varying thickness. This makes it coarse and uneven.

The more sand (cheaper) the rougher the finish, if that’s possible. The render gets a coat of external paint which reflects all the uneven bits. Better to go for a textured wall paint that will mask the poor finish.

regards, Scott

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Brickwork

This is probably more than you’ll ever want to know about brickwork.

A standard sized brick is (in inches) 9 long x 4.1/2 wide x 3 high or (in metric) 215 x 100 x 75. These are nominal sizes.

Bricks come in a large range with differing strengths, compositions, colours and uses. For example high-quality facing bricks for exposed brickwork, or blue engineering bricks for damp-proof courses. You can get special angled bricks for cills, wall tops, and corners.

The bricks are held together by mortar that is supposed to fully-fill the vertical and horizontal joints. Horizontal lines of brickwork are called courses.

Malaysia doesn’t have the quality or range of bricks available say, in the UK. Bricks here are seldom manufactured for loading or for appearance. They are for infill walls – to fill the spaces left by columns and beams. And then get covered on the inside with gypsum plaster, and outside with sand & cement plaster which is known as render.

If the 9 inch dimension is the thickness of the wall it is called a “1-brick wall.” If the 4.1/2 inch (width) dimension is the thickness of the wall then it’s a “½ brick wall.”  If the 3 inch dimension is the thickness of the wall it’s a very big mistake.

1-brick walls can be loadbearing, if the bricks meet certain strengths.

A ½ brick wall can’t be loadbearing by itself. However 2 skins of ½ brick walls together with a 2 inch cavity can be a loadbearing cavity wall if they are correctly, and skillfully, tied together with butterfly steel ties every 3 courses vertically and every 3 bricks horizontally.

You may not have seen this in Malaysia. There’s the skill issue but also the “why bother” issue.

Cavity wall construction was developed for temperate and rainy climates. The outer skin gets persistently wet and the moisture goes through the brick to drop down the cavity and out through weep holes left in the bottom mortar joints. As we know, in Malaysia it rains for a couple of hours, then the sun comes out and everything is dried up.

To Summarise:

1). 1/2 brick walls are the norm, used as non-loadbearing, infill walls to a concrete frame.

Because bricklaying is poor, there are often gaps rather than mortar between the bricks as well as wonky brick courses. The bricklayers also don’t adjust the size of the mortar joints in the brick courses to accommodate the height of the infill, so when they get to the top ... ? Usually the odd 2 inches is filled with brick chips. Or, if the space is larger then a sloping brick-on-edge is used, always with plenty of gaps.

Where the size of the opening (between floor, beam, and columns) is large some of these infill walls appear unstable, they look and are “thin.” They may not meet the “slenderness ratio” for brick walls. This is a ratio between height and thickness.

These walls are supposed to be tide-in on either side to the columns. Some are, some aren’t. Those that are often use a bit of reinforcement bar sticking out of the column, a bit at the bottom, and a bit at the top. Certainly not the “ties every 3 courses” that would be a good standard.

2). 1 brick walls can be loadbearing.

However, these walls provide a much stronger infill, and far less chance of toppling over with a good kick.  For the floor-to-ceiling space between columns, 1 brick walls meet the “slenderness ratio.”

Although the cost in bricks is doubled, the insulation and sound properties of the walls  increase by more than double. And the wall no longer looks “thin.” There’s enough width to have a small cill on the inside and another one outside. 

As 1 brick walls are stable in their own right, they can tolerate poor bricklaying, and a lack of metal ties to the columns.

3). Cavity walls are only fully utilised if they are loadbearing.

They need really skilled bricklayers. In Malaysia, the brickwork that I’ve seen is done badly (no not badly, chronically appalling more like) but concrete work (beams, columns, floors) seems OK.  I wouldn’t bother with cavity walls.

Hope this helps if your going to get your own place built, or if you’re buying and want to know what you’re getting. Or if you’re buying and can get in early enough to influence the construction and you don’t mind paying more for additional external wall thicknesses.

Please feel free to add your own comments.

regards, Scott

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Thanks for all this info Scott, have forwaded this link to my architect who is keeping an eye on our builders.

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Hello Scott,
Ever heard of Insulating Concrete Forms.

Please see the Google search.

http://www.google.com/search?q=insulated+concrete+forms&revid=483203943&sa=X&oi=revisions_inline&resnum=1&ct=revision&cd=1

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hi, Nathan,

Many thanks for the link. I had a quick look at icfhomes.com, and it's very interesting. I'm not familiar with this method of construction or the material so I'll need to spend some time reading up.

I like 1-brick walls because I'm familiar with them, most of Victorian London was built with them, and they have good thermal and acoustic properties.

As I haven't yet found a piece of land I have plenty of time to look at alternative construction methods.

regards, Scott

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One for Scott!

Polystyrene window frame shock for house buyers
By DERRICK VINESH
derrickvinesh@thestar.com.my

BUTTERWORTH: Several house buyers in Taman Ampang Jajar here had a rude shock when they checked the houses – the outer frames of their windows were made from polystyrene.

A buyer, Lee Kim Tatt, 35, claimed that the polystyrene pieces were covered with a thin layer of cement.

“What would happen if a person steps on the window sill, thinking that it was made of concrete?” he asked when Seberang Prai Municipal Council (MPSP) president Mokhtar Mohd Jait visited the project site yesterday.


Not sturdy: Lee showing the polystyrene used for his house in Taman Ampang Jajar in Butterworth, Penang, yesterday.

A representative for the project’s architect said the frames were merely decorative pieces that should not be stepped on.

Another buyer, Yan Wei Seong, 33, claimed the houses did not follow the original plan as per the sale and purchase agreement (S&P) signed in 2006.

“Some units in a particular row have double steps leading to the back lane while some in the same row only have one step, which shows that the ground is uneven,” he alleged.

Barisan Nasional’s Bagan parliamentary constituency co-ordinator David Chua, who was present, said he was surprised that the relevant departments and agencies had given the green light for the MPSP to issue the Certificate of Fitness (CF) to a majority of the units in 2008.

“How could the CF be given when some of the units are not in good condition?

“Access to these houses is also blocked with hoardings and there are no street lights in this area,” he said.

Mokhtar said the developer had agreed to extend the defect-liability period for the housing units by another two years.

“Disgruntled house buyers are advised to list down their grouses, so we can hold further discussion with the developer.

“We will try to come up with amicable solutions,” he added.

Mokhtar said of the 101 housing units, 22 units as well as 17 shophouses had yet to receive their CFs, pending approval from the relevant departments and agencies.

http://www.thestar.com.my/news/story.asp?file=/2010/5/11/nation/6232975&sec=nation

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hi, CA,

Many thanks for that, wow it's a new one. Cement covered polystyrene decorative feature. So all the window surrounds and ledges over the doors must be the same stuff. The contractor has glued on polystyrene around the doors and windows!

What's also noticeable on the photograph is the closeness of the 2 blocks. It's a narrow lane that'll become a rubbish tip.

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Polystyrene external edifices have been common in the building industry in Australia for at least twenty years. They are lightweight and allow for fancy edifices (particularly in renovations).
My understanding is that when coated with concrete and if properly annxed to the old structure they work very well aesthetically. I'm not able to comment on how they go from a weight bearing aspect.
Cheers