Hairline Cracks In Rendering

[gdhm]

Hi All,

My new house of 7 months has accumulated some 90 hairlinecracks (some very short) in the outer rendering. All hairline and tapping does not suggest a live plaster situation.

The bricks used were Qcon AAC 10cm blocks. My builder I know was much too generous with the Qcon mortar between the blocks (similar to half normal mortar thickness between blocks, which I was very angry about, as it dilutes the AAC insulation properties and was supposed to be glue like thin.

We have checked out as lager crack that occurred inside and outside of the wall and was in the same position (1 case only) I was convinced somehow the Qcon Block had cracked BUT THIS was NOT the case it was solid.

We use the Qcon rendering.

The lower half of the house with a light pinkish brown acrylic exterior emulsion is showing all the hairline crack but (AS FAR AS I CAN SEE from the ground) the light lemon coloured upper floor exterior wall seems almost entirely without hairline cracks

Both floors have very sound supporting pillars and concrete bases and flooring so I cannot believe it is a load reason as the downstairs non load bearing walls are the same height to concrete floor as the upper non load bearing walls are to ceiling.

My questions:

1) Is there anything I have said that suggests why so many hairline cracks (still increasing slightly) have occurred?

2) A French friend has said "do not bother with repairs until 1 year has passed as that should see the end of the hairline cracks and any tiny or climatic expanding contracting that may cause hairline cracks. assuming no structural problems" (which I am sure is not the case)

IS this sound advice?. If not how long and what repair basis should I proceed with?

3) Are Qcon AAC blocks and their special mortar and rendering more prone to this problem. I ask because the normal concrete block, normal mortar and rendering on our all round 2 to 3 metre high perimeter wall has only 3 or 4 cracks in TOTAL

4) Some hairline repairs done by our builder have after a month or so reopened (NO worse but as if the hairline crack did was not big enough to adhere to the surface).

Any suggestions?

Could the wrong filler have been used (it did say it was for such cracks)?

What is BEST for hairline cracks and then NOT reopening in Thailand very hot and wet/humid the Monsoon climate?

Is it better to dig out even hairline cracks and fill in to get a permanent non opening repair. If so what should be used to fill in the dug out rendering? and should that be sealed or covered before painting

5) I am worried about appearance after repairs and painting. At present where the builder did some the repair areas are visibly smoother than the un-repaired areas making it look like a patchwork in some lights

In experts opinion will it be an easy job for a repairer and re painter to ensure identical texturing

6) is there any value when I repaint is getting an exterior paint that is supposed to be a little flexible to cope with hairline cracks (or are hairline cracks too much for it to cope with.

What paint would be recommended please.

(CANNOT SAY HOW UNHAPPY I am with my Wife's family builder Uncle's finishing. Structure seems good and he has cut no corners but he has cut every money saving corner on his finishing and later used workmen (when eh ran out of money and I said an extra 450,000 Baht was all I could give him to complete house. Anyway that is different PAST issue). I have 4 out 5 bathroom sloped toward the drain holes (rather than in the wrong directions and 7 doors reseated (as best could be done after the fact without a complete re-framing and re-dooring)

My intention with you Guys and Gals good/expert advice to to ensure I do not allow repeat of poor or botched finishing or by using low quality very cheap materials as false economy. I am seeking permanent solutions not makeshift or good for a few years regarding the cracks. When I repair/repaint be it 6 months 1 or 2 years I wish the hairline cracks, evidence or repair to be things of the past.

Thanks for reading and hopefully being able to advise me.

Regards

Dave

[ignis]

Hairline cracks are normal........

If you had a house build in the UK your would be advised to paint the wall only, then decorate after 9 - 12 months because of hairline cracking.

Re here my house was the same after about 6 months, I repainted it using elastic waterproof paint, Thai friend had there house painted as soon as built with elastic waterproof paint, and appears fine 2 years later..

It is all about costs... elastic waterproof paint is far more expensive, the same as metal work, all mine is painted in 'Hammer Rite' which is 5x the price of normal metal paint. Mine all looks fine 5 years on, others in the Village have had there metal work repainted at least twice..

So I would take a sample of the colour of your walls to somewhere like Home Pro and get them to mix the same colour in elastic waterproof paint

[trogers]

When cracks appear, you first should try identifying the types of cracks:

1. Shrinkage cracks - crack lines appear random and spread in all direction, like a web

2. Cracks due to movement of support structure - shear cracks (usually at an angle to the X-Y axis), tension cracks (usually vertical), and compression cracks (usually horizontal).

Your friend is right in saying you should wait out a year to allow the building to settle a year (on firm ground), or 3 years if on soft ground like Bangkok.

In the meantime, if you want to cover the cracks, use the elastic wall paint of Nippon paint.

Edited May 2, 2009 by trogers

[johnnyk]

It may well be simply house settling, lots of soft ground here. Keep an eye on the cracks though. Everything should be settled after a year or full rainy/dry season cycle.

[gdhm]

It may well be simply house settling, lots of soft ground here. Keep an eye on the cracks though. Everything should be settled after a year or full rainy/dry season cycle.

Thanks Johnny, will do.

I would expect the long reinforced pylons that were driven into the ground to deal with the very soft .75 metre new top soil and possible soft soil to be honest.

The Site was left as a banana and undergrowth site for at least 5 years and probably similar forever. Of course monsoon weather keeps it damp for many months in the year.

I am sure the land is essentially Isaan Clay. Thank goodness houses here are built with pylons and non supporting walls and NOT as SE London Houses were built on clay in pre 70s.

Dave

[Rimmer]

Hairline cracks are nothing to worry about, just very annoying every time you pass by them right?

Probable causes:

The cement screed was too thin.

The cement screed was too wet.

The cement screed was too dry.

The cement screed dried too quickly in the hot sun.

Wait for a year then paint over the cracks with something like Nippon three in one paint that covers the cracks (only comes in white) Then either paint over the crack or paint the section if the paint does not match.

Settling cracks go all the way through and will break the Q Con blocks.

As a matter of interest I have exactly the same problem over exactly the same O Con blocks with exactly the same Q Con rendering.

The correct way to apply a screed on walls is to use an elastic ad mixture mixed in with the cement but of course cost constraints will often prohibit the builder doing this.

Edited May 2, 2009 by Rimmer

[gdhm]

When cracks appear, you first should try identifying the types of cracks:

1. Shrinkage cracks - crack lines appear random and spread in all direction, like a web

2. Cracks due to movement of support structure - shear cracks (usually at an angle to the X-Y axis), tension cracks (usually vertical), and compression cracks (usually horizontal).

Your friend is right in saying you should wait out a year to allow the building to settle a year (on firm ground), or 3 years if on soft ground like Bangkok.

In the meantime, if you want to cover the cracks, use the elastic wall paint of Nippon paint.

Hi trogers

Very interesting info. Had to go and have another look

NOT 1

one is a .5 metre horse shoe shape

The other cracks I suppose are commonly 75% vertical and 25% at angles a few bend.

NONE are more than hairline (diagonal slightly wider but definitely still hairline still).

There is no sign of the render surface either one side of any cracks ridging at different levels to each other (if you know what I mean).

Many are only .3 mtr and difficult to see others can be 1 or 2 meters. NONE look structural (except one horizontal on in a brick added on hollow brick column hiding upstairs plumbing pipes. We have had that dug out and re-cemented a week ago and expect that to have been resolved. I ma sure that was vertical stress as the level either side of the crack were slightly different.

Two we checked out completely as they seemed more suspicious in walls where they were no windows or consequential lentils.

One was vertical, one diagonal and both were emulated (approx. on the interior side of the wall. However when taking the rendering back to the QCon blocks neither revealed any cracks in the Qcon AAC blocks or mortar binding them. This confused me as I expected there to be something.

Some areas can have very faint hairline cracks about .5 to 1m every 1 metre or so so apart all stop of course at the horizontal concrete lentils which the builder (as most do) has built around the house above and below window placement level (seems to be for placing windows between instead of individual lentils and I assume this is a normal Thai practice).

The vast majority of hairline cracks are between ground and the first lentil and do not continue above it. In the front of the house we have horizontal style foundation between the upright pylons. Th rendering on the visible two sides have hairline cracks on their 20 cm vertical and 20 cm flat horizontal surfaces.

I have no idea how or why any of these could be load bearing or structural faults as there is SO LITTLE load bearing. We have a really solid pillar based with reinforced concrete sections under all ground floor walls and and 2 all around house lentils for below and above windows on ground upper floor Plus the concrete floor the upper floor is built on. The Architects stipulated thick pylons and the several workmen commented that they were thicker than used on projects they had worked on. Additionally AFTER the architects calculations I decided to use 10 cm Qcon blocks for ALL walls which would have hugely reduced his anticipated loads based up a Thai brick based construction.

Except our garage area store room at it back (which has no windows or lentils) no Qcon block is more than approx 2 metres in height between foundation, lentils or upper concrete floor. Very little room for load bearing stress cracks I would have thought. BUT I am no builder so I only understand the basics

From what you and others say it look like around 1 to 1½ years is a good time to consider crack repairs and repaint. I assume Thailand cool dry season after the Monsoon season is best for repair and painting as dry and not so hot and humid.

Thanks for the Nippon paint recommendation.

Regards

Dave

[gdhm]

Hairline cracks are normal........

If you had a house build in the UK your would be advised to paint the wall only, then decorate after 9 - 12 months because of hairline cracking.

Re here my house was the same after about 6 months, I repainted it using elastic waterproof paint, Thai friend had there house painted as soon as built with elastic waterproof paint, and appears fine 2 years later..

It is all about costs... elastic waterproof paint is far more expensive, the same as metal work, all mine is painted in 'Hammer Rite' which is 5x the price of normal metal paint. Mine all looks fine 5 years on, others in the Village have had there metal work repainted at least twice..

So I would take a sample of the colour of your walls to somewhere like Home Pro and get them to mix the same colour in elastic waterproof paint

HI Ignis ,

Sure agree with you on the Hammerite. A great paint and in my opinion worth the extra if the metal work is valuable and important enough as over time it will pay for itself and look better for much longer.

Can one get textured elasticated waterproof paint which would hide up smooth repaired cracks and original less smooth exterior wall finish?

I know for sure our paint is cheap and certainly not elastic (builder' choice and as I had spent so much due over his stupid fairy tail quotation I could not afford better. Even though I appreciated the false economy issue, I needed to spread my costs over time (must protect the Visa financial reqts and allow for an awful GBP ER). I just underestimated the number of hairline cracks as had none of this with my new Spanish home when built (but different method and materials) (pebble dash type exterior wall and interior walls were soft rendering (I could push a thin nail in to the brick with my thumb - not great for picture pins )

Maybe not using elastic paint is I why I think my walls and number or hairline cracks are unusual compared to project houses and some others that maybe used the elastic paints thus hiding unimportant hairline cracking.

I do suspect the QCon AAC blocks are a factor as well (or the type of special rendering needed) because my boundary wall rendering on ordinary concrete blocks are not hairline cracking anything like as much. Maybe the heat expansion of Qcon blocks is greater or the special rendering less robust to vibration or heat expansion/contraction. or the heat expansion/contraction qualities of Qcon and its rendering do not match as well.

Regards

Dave

[gdhm]

Hairline cracks are nothing to worry about, just very annoying every time you pass by them right?

Probable causes:

The cement screed was too thin.

The cement screed was too wet.

The cement screed was too dry.

The cement screed dried too quickly in the hot sun.

Wait for a year then paint over the cracks with something like Nippon three in one paint that covers the cracks (only comes in white) Then either paint over the crack or paint the section if the paint does not match.

Settling cracks go all the way through and will break the Q Con blocks.

As a matter of interest I have exactly the same problem over exactly the same O Con blocks with exactly the same Q Con rendering.

The correct way to apply a screed on walls is to use an elastic ad mixture mixed in with the cement but of course cost constraints will often prohibit the builder doing this.

Hi Rimmer,

You help me again Thanks.

Seems Nippon paint has the preferred vote. I will note that. We used all Qcon materials Qcon AAC blocks, Qcon mortar and Qcon rendering.

As I have just said to Ignis I wonder on Qcon s AAC and it rendering matching each others heat expansion/contraction properties. Very interesting you report similar.

"Hairline cracks are nothing to worry about, just very annoying every time you pass by them right?"

Too true mate You are a mind reader.

Problem with a new house is that the Farang owner sees everything through a microscope (not my wife she is too happy and accepts poor standards as norm and acceptable). Once flaws are noticed its Bl**dy annoying. Especially when nearly all my capital went into a promised up to West standard home. Now I cannot easily find funds at present to rectify the most annoying. Also one gets many visitors and one imagines they will notice all the cracks and think lovely ruined by finishing.

I am not a vain person but obviously when one has a new "toy" one wants it to look perfect (or nearly).

Also I worry about what it will look like in 1 to 2 years. Thankfully I do not think the finishing limitations of the house (which are many) are important and the structure was well attended to.

During the finishing days our builder had labourers walking away and people doing tasks they are not trained to do. Late in the day I found out he was working elsewhere to pay salaries and some were towards the end of house building on ONLY 70 baht a day.

Hence some very poor finishing in places.

[trogers]

When cracks appear, you first should try identifying the types of cracks:

1. Shrinkage cracks - crack lines appear random and spread in all direction, like a web

2. Cracks due to movement of support structure - shear cracks (usually at an angle to the X-Y axis), tension cracks (usually vertical), and compression cracks (usually horizontal).

Your friend is right in saying you should wait out a year to allow the building to settle a year (on firm ground), or 3 years if on soft ground like Bangkok.

In the meantime, if you want to cover the cracks, use the elastic wall paint of Nippon paint.

Hi trogers

Very interesting info. Had to go and have another look

NOT 1

one is a .5 metre horse shoe shape

The other cracks I suppose are commonly 75% vertical and 25% at angles a few bend.

NONE are more than hairline (diagonal slightly wider but definitely still hairline still).

There is no sign of the render surface either one side of any cracks ridging at different levels to each other (if you know what I mean).

Many are only .3 mtr and difficult to see others can be 1 or 2 meters. NONE look structural (except one horizontal on in a brick added on hollow brick column hiding upstairs plumbing pipes. We have had that dug out and re-cemented a week ago and expect that to have been resolved. I ma sure that was vertical stress as the level either side of the crack were slightly different.

Two we checked out completely as they seemed more suspicious in walls where they were no windows or consequential lentils.

One was vertical, one diagonal and both were emulated (approx. on the interior side of the wall. However when taking the rendering back to the QCon blocks neither revealed any cracks in the Qcon AAC blocks or mortar binding them. This confused me as I expected there to be something.

Some areas can have very faint hairline cracks about .5 to 1m every 1 metre or so so apart all stop of course at the horizontal concrete lentils which the builder (as most do) has built around the house above and below window placement level (seems to be for placing windows between instead of individual lentils and I assume this is a normal Thai practice).

The vast majority of hairline cracks are between ground and the first lentil and do not continue above it. In the front of the house we have horizontal style foundation between the upright pylons. Th rendering on the visible two sides have hairline cracks on their 20 cm vertical and 20 cm flat horizontal surfaces.

I have no idea how or why any of these could be load bearing or structural faults as there is SO LITTLE load bearing. We have a really solid pillar based with reinforced concrete sections under all ground floor walls and and 2 all around house lentils for below and above windows on ground upper floor Plus the concrete floor the upper floor is built on. The Architects stipulated thick pylons and the several workmen commented that they were thicker than used on projects they had worked on. Additionally AFTER the architects calculations I decided to use 10 cm Qcon blocks for ALL walls which would have hugely reduced his anticipated loads based up a Thai brick based construction.

Except our garage area store room at it back (which has no windows or lentils) no Qcon block is more than approx 2 metres in height between foundation, lentils or upper concrete floor. Very little room for load bearing stress cracks I would have thought. BUT I am no builder so I only understand the basics

From what you and others say it look like around 1 to 1½ years is a good time to consider crack repairs and repaint. I assume Thailand cool dry season after the Monsoon season is best for repair and painting as dry and not so hot and humid.

Thanks for the Nippon paint recommendation.

Regards

Dave

Sounds like the cracks are due to structural movement. Such movements can be due to 2 different reasons: depth of piles (not size) insufficient, or excessive deflection of floor slab.

Walls sitting along a beam should not have any cracks, unless a column supporting the beam sinks due to sinking piles. In such a case, watch out for any cracks in the structural members - column, beam and floor slab. Plaster cracks in such a case are angular to the X-Y axis.

Walls built across a beam will have vertical tension cracks as the beam (under the walls near its mid span) will be stiffer than the thin floor slabs along the 2 ends.

If you have 2 walls built at right angles to 2 beams and the walls meet near the middle of the floor slab, you will get vertical tension cracks above the beams, and possibly a horizontal compression crack 25-30cm above the corner where the 2 walls meet.

I have seen such cracks on QCON walls built on to a 45-storey steel structure.

Edited May 2, 2009 by trogers

[trogers]

I might add, it is generally a good practice to complete the floor layout of a house (or condo) before designing the structural support. This will ensure the walls are adequately supported by beams so that there is with minimum defection.

The problem at the 45-storey steel structure was that the structure was constructed using drawings revision D while the wall positions were shifted and constructed to drawings revision G. So most internal walls were not supported by beams, and in many cases, were placed across constructed beams.

Edited May 2, 2009 by trogers

[gouda]

hello,

just wondering about the possiblity of sinking piles as mentioned by trogers...

how long are the piles? did they go all the way down e.g. 1.5m below the top soil when they were driven or did they hit firm ground before that and could no longer by driven down?

[gdhm]

hello,

just wondering about the possiblity of sinking piles as mentioned by trogers...

how long are the piles? did they go all the way down e.g. 1.5m below the top soil when they were driven or did they hit firm ground before that and could no longer by driven down?

How deep did they go. Now you are asking. It was a year ago and I have no photos.

The impression I got at the time ws that they were 4 or 5 metres (they were long not much shorter than the pile driver (photo shown) ( They were all successfully driven all were driven all the way into the ground (of which the first 0.75mtr was new top soil so no support) by the huge and high hammer machine

The above ground reinforced pillars were built and formed on site. However, The more substantial reinforced concrete primary ones (that were dirven below ground) were bought in and were longer and thicker and had a pyramid point at the bottom (no doing to aid penetration into the ground. All pylons were same thickness (except the two that were going to support the garage patio roof front columns which were thinner.

Here are some pics I DID take (for what they are worth)

[attach

ment=82556:IMG_0015.jpg]

Regards, Dave

[trogers]

From the photos, your house is not situated near Bangkok. If you are in NE Thailand, adequate pile lengths will probably be 12-14m, unless the land is near to a canal or river.

The angular hairline cracks are due probably to small differential settlement between pile foundations. This would be minimal about a year after you have moved in and load the floors with furniture.

To check for cracks due to deflection of floor slab, superimpose the floor layout drawing that shows wall positions on to the strutural drawing that shows beam positions and see if your walls are sitting along beams or not.

[gdhm]

From the photos, your house is not situated near Bangkok. If you are in NE Thailand, adequate pile lengths will probably be 12-14m, unless the land is near to a canal or river.

The angular hairline cracks are due probably to small differential settlement between pile foundations. This would be minimal about a year after you have moved in and load the floors with furniture.

To check for cracks due to deflection of floor slab, superimpose the floor layout drawing that shows wall positions on to the strutural drawing that shows beam positions and see if your walls are sitting along beams or not.

Hi trogers

I live in Khon Kaen City, Isaan and the soil I think is reddish clay. Sure looks like the sort of clay I lived on in Greater London area.

All walls are on the horizontal reinforced concrete beams are between pillars that are above the pylons driven deply into the ground

Except the small bathroom entrance walls (which contain the door) (even the store room (at the back of the car port is built upon 3 pylons driven into the ground.

The widest measurement between pylons driven into the ground is 5.5 metres many are less 4 metres

For yours and others interest. Here is a plan of ground floor (Every square pillar location on the ground floor plan have a thicker pylon driven into the ground below them. Despite the porch ones looking bigger this is just thicker decoration around them for effect. All top floor pillar rest directly above the ground floor pillars which rest on the driven into ground pylons. As I said earlier ONLY the 2 front car port pylons were thinner than all the rest as the pillars above only support the car port roof).

I would be genuinely astonished if the structural integrity of our house was in question as htis was a very important factor in my requirements being aware of soft ground or clay ground problems.

Yes I know it's a huge house for only 3 but I expected an extended family of up to 4 additional people. Many things changed over the year plus of building (not falling out, just different directions of and desires of the extended family -wish I had known before I built our house but that's life)

Regards

Dave

Edited May 3, 2009 by gdhm

[trogers]

What floor structure was used in the construction of the ground floor? I see precast slabs used on the 2nd floor. Was the same being used on the ground floor?

The largest spans of beams are in the reception room, below the large balcony - 7.0m x 5.4m. I do not see the 2 columns at the window in the floor plan. They were added later to shorten the span of the beam holding the balcony. Problem could be that these columns are just transferring the upper loads to the 7.0m beam below the windows, but there are no additional pile supports for these 2 new columns. The beam would be deflecting more than calculated for, and cracks appearing at the wall sitting on this beam.

post_a82551_19_Stairs_of_House_01_06_08_.jpg.html

post_a82552_2nd_Reception_room_08_08_08_.jpg.html

post_a82576_08a_Downstairs_831_x_634_.jpg.html

[gdhm]

What floor structure was used in the construction of the ground floor? I see precast slabs used on the 2nd floor. Was the same being used on the ground floor?

The area between the raised reinforced bases (below the ground walls walls were part filled with soil or sand and then covered with wire mesh and concrete

All pylons driven into the soil were topped by a reinforced concrete square block approx. 1 sqm block, maybe .75mtr (as can be seen in one of my photos above)

The largest spans of beams are in the reception room, below the large balcony - 7.0m x 5.4m. I do not see the 2 columns at the window in the floor plan. They were added later to shorten the span of the beam holding the balcony. Problem could be that these columns are just transferring the upper loads to the 7.0m beam below the windows, but there are no additional pile supports for these 2 new columns. The beam would be deflecting more than calculated for, and cracks appearing at the wall sitting on this beam.

Reinforced concrete Pre-cast beams were used for the upper floor area except for the bathrooms. Our builder felt for them steel,mesh and concrete was preferable for more certain leak proofing.

I have searched through my photos and found one partial shot of the reinforced pre-cast beams above the front lounge you refer to trogers. The pre-cast beam were laid horizontally to the house EXCEPT above the front lounge you refer to where they were laid across the shorter (back to front) length which is 5.4 metres (incl. wall). The internal measurement is 5.03m.

As you say the two columns either side of the front windows are not supported below and seem to be more window trims than true support.

Therefore the upper floor of the front lounge is supported with reinforced cross beams between (at the back) 3 primary columns above underground pylons (gaps 2.5m and 4.5m) but at the front of the lounge are only two and the gap is 7m. However the front only has an un-roofed patio above it with a short balcony wall, and, whereas the back has a bedroom and landing walls and roof on top of that.

Would not the front of the lounge need much less support due the the lack of weight above it trogers?

Regards, Dave

[trogers]

What floor structure was used in the construction of the ground floor? I see precast slabs used on the 2nd floor. Was the same being used on the ground floor?

The area between the raised reinforced bases (below the ground walls walls were part filled with soil or sand and then covered with wire mesh and concrete

That means there are no beams supporting the ground floor, only a thin reinforced concrete slab (probably 15-18cm thick) sitting on compacted soil/sand and cast over the pile caps. Should the soil/sand below this floor be washed away by water penetration, or settle over a period of time (up to 10 years), the slab will deflect and the walls (and any hard floor finishes like tiles or marble) sitting on the slab will develop cracks. The longer the span between pile caps, the more the deflection.

All pylons driven into the soil were topped by a reinforced concrete square block approx. 1 sqm block, maybe .75mtr (as can be seen in one of my photos above)

This 1 m2 reinforced concrete block is the pile cap.

The largest spans of beams are in the reception room, below the large balcony - 7.0m x 5.4m. I do not see the 2 columns at the window in the floor plan. They were added later to shorten the span of the beam holding the balcony. Problem could be that these columns are just transferring the upper loads to the 7.0m beam below the windows, but there are no additional pile supports for these 2 new columns. The beam would be deflecting more than calculated for, and cracks appearing at the wall sitting on this beam.

Reinforced concrete Pre-cast beams were used for the upper floor area except for the bathrooms. Our builder felt for them steel,mesh and concrete was preferable for more certain leak proofing.

Only the slab of the bathroom is in cast in-situ concrete, the rest are precast slabs, resting on in-situ concrete beams as seen from the photo).

I have searched through my photos and found one partial shot of the reinforced pre-cast beams above the front lounge you refer to trogers. The pre-cast beam were laid horizontally to the house EXCEPT above the front lounge you refer to where they were laid across the shorter (back to front) length which is 5.4 metres (incl. wall). The internal measurement is 5.03m.

The precast slabs for the upper floor have lengths of 4 to 5 metres. Those above the lounge span across the shorter width of 5.4 metres

Standard

As you say the two columns either side of the front windows are not supported below and seem to be more window trims than true support.

If they are not built of concrete (but from bricks or blocks), they are non-structural and only trims.

Therefore the upper floor of the front lounge is supported with reinforced cross beams between (at the back) 3 primary columns above underground pylons (gaps 2.5m and 4.5m) but at the front of the lounge are only two and the gap is 7m. However the front only has an un-roofed patio above it with a short balcony wall, and, whereas the back has a bedroom and landing walls and roof on top of that.

Would not the front of the lounge need much less support due the the lack of weight above it trogers?

All beams and slabs are calculated based on 3 kinds of loads on them: dead load (meaning their own self weight), superimposed dead load (meaning weight of walls and floor finishes), and live load (meaning weight of furniture, equipment and human occupants). The weight difference between a an open balcony and an enclosed room is the weight of walls. But since there is no additional column, the load of the upper floor is not transferred to the structure below.

Regards, Dave

So the question now is, are the hairline cracks on the walls due to the ground floor slab deflecting? And will deflection get worse over time? These are questions you have to ask your designer.

One thing to watch out for: make sure any water pipe under the floor is water tight. Any erosion of the soil under the slab by leaking water will make matters worse.

[gdhm]

Thanks trogers very helpful and interesting:D

I assume if the ground floor reinforced concrete base was suffering with gaps forming under it that the floor tiles would star to crack as a warning of this.

Water pipes under the house:

Well I am sure the incoming water pipes are not leaking because the water pump would keep engaging when not in use as pressure dropped (unless minute). Cannot speak for outgoing pipes of course as would not easily be known.

To be honest I am not going to get too stressed over these hairline cracks (unless they never cease) or show signs of being more than hairline. The underground pylons are pretty big and long beasts and the ground reinforced cross beam foundations above and between all the pillars where walls are built upon are about 0.5 to .75 metres in depth (did not note exactly and can only go by memory and photos).

In answer to your question about concrete lengths around windows sides and above and below. All that look like concrete lengths in the walls are concrete and NOT bricks covered with concrete.

Regards and thanks for all your help and advice

Dave

[trogers]

Thanks trogers very helpful and interesting:D

I assume if the ground floor reinforced concrete base was suffering with gaps forming under it that the floor tiles would star to crack as a warning of this.

Water pipes under the house:

Well I am sure the incoming water pipes are not leaking because the water pump would keep engaging when not in use as pressure dropped (unless minute). Cannot speak for outgoing pipes of course as would not easily be known.

To be honest I am not going to get too stressed over these hairline cracks (unless they never cease) or show signs of being more than hairline. The underground pylons are pretty big and long beasts and the ground reinforced cross beam foundations above and between all the pillars where walls are built upon are about 0.5 to .75 metres in depth (did not note exactly and can only go by memory and photos).

In answer to your question about concrete lengths around windows sides and above and below. All that look like concrete lengths in the walls are concrete and NOT bricks covered with concrete.

Regards and thanks for all your help and advice

Dave

This means there are concrete beams supporting the floor slab, just that the floor slab is cast in-situ concrete instead of precast slabs.

Then the problem with sinking earth is not critical. At first I thought your ground floor was constructed like a concrete road with no support beams. And you know roads sink over time in soft soil...

If the floor finish of the ground floor slab is not yet constructed, I recommend you get your contractor to apply a coat of cement-based waterproof layer (trade name 'Brushcrete') before placing the floor finishes. This will prevent moisture penetration from under the house through to your living areas.

Edited May 4, 2009 by trogers

[gdhm]

.....If the floor finish of the ground floor slab is not yet constructed, I recommend you get your contractor to apply a coat of cement-based waterproof layer (trade name 'Brushcrete') before placing the floor finishes. This will prevent moisture penetration from under the house through to your living areas.

Afraid that is too late trogers. The house was finally finished Jan (we moved in Nov).

Found one pic that shows the cross beams between pillars (pre concreting)

For your interest and others here is the finished article

Regards Dave

[extexthai]

I have found that dealing with rendering cracks, just add one table spoon of apathy to your bowl of oatmeal every morning. Like most things done here in Thailand...nothing or anyone goes by what the directions for making a working chap (rendering) would entail....to them, it is just a slurry mixed by eye and easy for them to apply...to cover the bricks or ACC block, or what have you. The wall it is going on needs to be wetted first, then apply....I had this one lazy bast*rd (after we had already been through the way I demanded it be done )try and put in on one wall without pre-wetting it and made him tear it all out and redo it and then ran his ass off at the end of the day. You have to be in charge and watch them or it won't get done correctly. If they think they can get one over on the farang, then it's their point. I am going to let my house settle some more and then start the repair process. If I had it all to do over again, I would go with interior metal studs and sheetrock. ett