How To Repair Cracks

 
Cracks must be repaired immediately when observed otherwise the life of structure will reduce causing structural failure. They not only weaken the building but spoil the beauty of walls also. This write up tells you about repair of cracks in plaster, RCC member, Brick walls, Floor and Fine Cracks.  
 
The cracks can be prevented at the time of construction. To know more about prevention of cracks during construction, click at the link below.

 

Repair Cracks in Plaster

 
Two types of cracks are found on surface of plaster i.e. A. Crack with hollow sound in plaster.  B. Crack with no hollow sound in plaster. Hollow sound can be checked by striking the plaster. 

A. Repair cracks giving hollow sound

Remove plaster applying proper cut

Defective plaster should be removed and the edges should be slightly cut in square or rectangular shape to provide a neat joint.

Prepare the surface thoroughly

Clean the surface with wire brushes and wash it. Wet the surface 24 hours before application of cement mortar.

Apply fresh cement mortar and finish the surface

Defective portion should be filled in with cement mortar. Keep the surface wet at least for 3 days. When surface is dry, finish it according to adjoining area on the wall.

B. Repair cracks if it is solid without hollow sound

Clean cracked portion of all loose materials and fill crack seal sealants in cracked portion. Finally finish the surface according to adjoining area. 
 

Cracks in plastered surface

 

Cracks in plaster

Prepare surface for Crack Repair

 

Repair Cracks in plastred Surface

 
NOTE: Plastering is done after cleaning. To know the process of ‘Plastering’ click on the link
 
 

Repair Cracks on RCC Surface

Clean cracked portion and apply guniting

The cracked portion should be widen gently and be cleaned of all loose materials.  Fill the cracked portion by pressure grouting or ‘guniting’. The material for such grouting can be epoxy or cement (with suitable admixture).

Apply epoxy and finish the surface

Epoxy has more strength and adhesion than cement and can go into very thin cracks as fine as 0.1 mm. The surface should be finished according to adjacent area on the wall.
Note: The cracks in RCC members/ structural members should be repaired immediately with consultation form structural engineer/professional.

Repair Cracks on face of plaster

When two components having different elastic properties such as RCC slab and brick work abating each other, the crack on face of plaster is formed between these components due to their thermal expansion. 
 

Remove plaster and old material

The plaster should be removed from cracked portion. The joints should be widened at least 20 mm to 25 mm in thickness. Clean old material by washing and brushing.

Apply cut and prepare the surface

Apply slight cut on edges in straight line to provide neat joint. Make the surface damp 24 hours before application of new plaster.

Apply cement mortar

Cement mortar should be applied on defective portion. Make 20 mm wide and 25 mm thick groove at the junction of two materials/components.

Do curing and finishing

Keep the surface wet at least for 3 days. When surface is dry, finish it according to adjacent area on wall. 

Cracks in RCC surface


Repair cracks in RCC surface


Repair Cracks in Masonry Walls

Two types of cracks are seen in masonry walls i.e.  A. Crack in mortar joints of walls.  B. Crack in bricks/Diagonal Cracks  

A. Repair cracks in mortar joints of walls

Remove mortar

The mortar should be removed from cracked joint with the help of iron tools at least up to 25 mm depth. All loose material should be cleaned from cracked portion.

Wet the surface and apply cement mortar

Cracked portion must be kept moist at least for 24 hours before doing repair. Fill in the joints with cement mortar of coarse sand in 1:4.

Do curing and finishing

After filling the joints with cement mortar, keep the repaired surface wet at least for 3 days. After drying the surface, finish the repaired area according to the adjoining area.
 
 

Crack in Wall

 

B. Repair cracks in bricks/diagonal cracks 

Remove broken bricks

Before doing any repair of cracks, make sure that the cracks are stabilized and are not widening further. Remove broken bricks by scratching cement mortar from the joints gently.
 

Prepare the surface

All loose material should be cleaned from the portion by brushing and washing. Wet the surface 24 hours before application of new plaster.

Fix new bricks thoroughly

Lay fresh cement mortar with coarse sand in 1:4 and fix new bricks. Fill all joints around bricks with mortar tightly with the help of iron tools. 
 

Do curing and finishing

The repaired surface should be kept moist up to 7 days.  When surface is dry, it should be finished according to adjoining area. 

 

Repair Cracks in Floor  

Remove loose material and apply mortar

Create V shape groove in cracked portion and remove all loose material by washing and brushing. Fill in the groove with polymer modified mortar (for wide cracks) or with polymer modified cement grout (for thin cracks).

Remove cracked panel or material

If there are many cracks in the floor, remove cracked panels and old materials.

Prepare the surface and lay new panel

Clean the panel by washing and brushing. Prepare floor material according to the existing floor and lay new panel.
 
Note: To know more on ‘How to Lay Floor’ in detail, you can click at the link given below on our website. 

 

Repair Hair Cracks in plaster

Broaden the crack gently

Widen the crack about ¼ inches with chisel and remove all loose plaster from the cracked portion.  

Apply vinyl spackle compound

Use vinyl spackle compound to fill the cracked portion. Press the vinyl spackle into the crack and let it dry. Sand or sponge the surface smooth.

Seal the patch and finish the surface

Seal the patch with proper priming coat and finish it with proper shade according to the adjoining area.

Repair Fine cracks

  • Apply surface water proof coating on the entire area having very fine cracks (especially on roof) where filling /sealing of each individual crack is not possible. 
  • Do proper curing of repaired area at least for 3 days.
 
28  Comment(s)
Pradeep Ahi
By Pradeep Ahi -  On  6/29/2014 12:48:49 AM
Hi Sir,
My house is 16 year old RCC construction and one of its central single bricked wall has a approx 8mm wide crack wich seems quite deep, please suggest a remedy
 
Anonymous
By Anonymous - On 1/4/2013 12:20:26 PM
very very good thk u
 
Anonymous
By Anonymous - On 10/16/2012 1:21:02 PM
these days fiber glass net of differnt thickness is available .u just open the crack area and fix this wiremesh with the help of cement.its rustproof and more strenght and easy to install.use it and plaster again. area will remain crackless for life time.
 
Anonymous
By Anonymous - On 9/14/2012 12:49:50 PM
It is really helpful, the explanation with diagram is really very good. My house is totally cracked and damped, I want to repair it thoroughly. Can I get any help?

Thank you
Gautam.
 
s p gandher
By s p gandher -  On  12/13/2011 8:38:55 PM
I would like to know the reasons for cracks in marble flooring and the method of repairing.
 
Anonymous
By Anonymous - On 6/23/2011 7:08:58 PM
very useful articles,how can we know about walltile joints,(today some are others using for walltile vitryfied tiles also)
 
Anonymous
By Anonymous - On 6/1/2011 4:30:23 PM
dear sir
i have looking your home repair wall photo . i have understand your problem if you mind i have visit your site than we have dissed how can soul f your problem . i have request please send you site address . i have come .
my self sumit i have interior contracter
 
S L Gupta
By S L Gupta -  On  5/30/2011 4:41:23 PM
1. Brick wall joint: Improper bonding of cross wall with main walls by not leaving proper keys in the main wall. In this case main and cross walls should be properly bonded by proper toothing.
2. Cracks in the RCC may occur due to;
i. Inadequate cover in reinforcement.
ii. Permeable and porous concrete.
iii. Carbonation
iv. Alkali aggregate reaction.
v. Sulphate attack.
Vi continuous dampness and seepage in concrete.
Vii. use of cacl as accelerator.
viii. Passage of electric current through concrete.
ix. Use of water having chlorides and sulphates.
 
Anonymous
By Anonymous - On 5/30/2011 2:37:24 PM
very useful and knowledgable.
 
MAHESH SALUNKHE
By MAHESH SALUNKHE -  On  5/28/2011 6:34:11 PM
This article given me info. regarding repairs but i want to know what care should i taken to avoid repair works like rcc wall & brick wall joint.
 
chotto
By chotto -  On  5/27/2011 11:31:40 PM
One way of plaster repair is to use wire gauze on plaster surface which will hold the plaster and will let let it crack.

I have use this technique in all most all the old plaster crack repair, which have given neat look as well.
 
Anonymous
By Anonymous - On 3/31/2011 7:03:14 PM
Its helpful thanx...& i hv sum another prob also plz suggest me.
 
Anonymous
By Anonymous - On 2/20/2011 8:43:23 PM
wonderful,thank you very much
 
Anonymous
By Anonymous - On 8/4/2010 9:48:31 PM
above this articles for good experience teching to quality engineers
 
Anonymous
By Anonymous - On 7/2/2010 6:42:13 PM
thanks for information.i m buying a new house. but house is many crack by black cotten soil pl give me information.
 
juhi
By juhi -  On  5/6/2010 5:36:53 PM
hi sunil dutt,
The cracks occur due to carelessness of contractor, mason, and ignorance of house owner and using of inferior materials in construction. If the cracks happen after all preventions, they must be repaired as soon as you observe them. Cracks threaten structural stability of the building.
These cracks are very dangerous and repaired immediately.
for further details you can read articles at www.gharexpert.com website.
and article link is:


http://www.gharexpert.com/articles/Cracks-1468/How-To-Repair-Cracks_0.aspx



http://www.gharexpert.com/home/HOW_TO_PREVENT_CRACKS_IN_BUILDING.aspx
http://www.gharexpert.com/category/1371/Cracks-0.aspx?CatID=1371
bye
take care..

 
S L Gupta (Civil Engg)
By S L Gupta (Civil Engg) -  On  5/6/2010 5:16:03 PM
Dear Sunil,

Before doing any repair of cracks, make sure that the cracks are stabilized or not i.e. widening further. Remove broken bricks by scratching cement mortar from the joints gently. All loose materials should be cleaned from the portion by brushing and washing. Wet the surface 24 hours before doing the necessary repairs. Now lay RCC (cement conc. with 2 no steel bars) in one coarse height then laid the bricks tightly with fresh cement mortar with coarse sand in 1:4 ratios and repeat this process. Fill all joints around bricks with mortar tightly with the help of iron tools. Finish the area with plaster and do curing at least for 7 days. Employ expert mason for the repair work.  

Regards
S.L.Gupta
 

 
suni dutt panwar
By suni dutt panwar -  On  5/6/2010 12:31:22 AM
In my area there is Black cotton soil. so we fce a problem of cracks in newly or old building .we rectifed sevral times with many new compounds but same problem occurs with in two or three days even at time of const we removed all black cotton soil up to 1.5 mt deep refill that area with CNS soil . so please give suggestion to rectified all craks.
 
deepak
By deepak -  On  11/23/2009 4:01:21 PM
good
 
Girish
By Girish -  On  11/16/2009 12:43:30 PM
A single component high strength fibre reinforced structural repair mortar can be used for repairs to honeycombing and other defects in all strctural elements such as beams, columns , walls and slabs in high rise buildings.


Readymade products are available with BASF, Foscroc, HENKEL polybit ranges

Example : for 3 mm crack , cut grooves and apply Emaco S22NB from BASF

it can be installed by hand or trowel.
 
Bob Christo
By Bob Christo -  On  11/13/2009 5:43:10 PM
Thanks for the useful information.
 
Jitendra
By Jitendra -  On  11/6/2009 3:20:18 PM
This is important information for new homeowners when they have to make a case to builders to come back to repair foundation cracks.
This is something builders do not like to do, since it would be an admission that they poured a poor slab.
Homeowners need to repair these cracks prior to the ending of homebuilders warranty. Failure to do this can possibly harm a future resale of the house, when prospective purchaser sees unsightly and unrepaired cracks.


 
Anonymous
By Anonymous - On 10/17/2009 10:47:10 PM
Very good article. There are cases in Kerala for such cracks due to verious techanical reasons. Some peoples having insurances policies atributes to it. For such normal crakcs the estimates comes for demolishing and reconstructing.
 
Anonymous
By Anonymous - On 3/30/2009 3:28:47 PM
I have built a 2 storied building 2 years back. upto 1st floor constructed with steel reinforcement and 2 nd floor partly with brick work and partly with reinforcement. In last few months the walls, without reinforcement has undergone many horizontal cracks and at the corners of windows has undergone oblique cracks. Kindly tell me the probable reason and necessary maintenance, I should take care.
 
Anonymous
By Anonymous - On 2/12/2009 6:22:23 PM
Please send me some information about reason of hair crack by e-mail
 
Kishore Kumar Dutta
By Kishore Kumar Dutta -  On  5/18/2008 9:15:49 AM
Its a very very importet infomation.All consultent civil engineer ,builder and house owner will be benifited.
 
kirk Lumsden
By kirk Lumsden -  On  4/29/2008 7:58:49 AM
This is important information for new homeowners when they have to make a case to builders to come back to repair foundation cracks.
This is something builders do not like to do, since it would be an admission that they poured a poor slab.
Homeowners need to repair these cracks prior to the ending of homebuilders warranty. Failure to do this can possibly harm a future resale of the house, when prospective purchaser sees unsightly and unrepaired cracks.
 
Anand Shethna
By Anand Shethna -  On  2/23/2008 2:23:03 PM
Very useful details. Pls keep mailing such informations.
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