Terrace area crack filling || Waterproofing

[hcsatish]

Hi,

I have attached quote given by one of the water proofing guy in mysore .

Regards,
Satish

[Nivas]

You have a quotation for Screed, the waterproofing admixture, I bet it is Pidilite LW+ or Fosroc Conplast XR421C or Roff equivalent, it will cost your contractor 2000 Rs for 10 liters which will suffice for 50 bags of cement . This admixture will be added to Slurry , Screed PCC and Plastering Mix . It is part of step c what I have indicated. The lignosulphonate class additive only breaks the capillary action to some extent. This does not ensure waterproofing. You need to ensure water proofing at different levels if you need a trouble proof roof for 15 years. Imagine your contractor is only spending 2000 Rs for waterproofing entire roof and giving a false guarantee of 10 years.


step A or step B, choose one of them

Step A : If you do not have 14 days prior to Screed or Step C nor if you do not have paddle mixer ( 500 rs Drill attachment or Rs 2500 for Machine with paddle), do not proceed. directly go to Step B.
Brush Bond TGP is available is 20kg packs for Rs 2000 approx , Coverage with Brush application : 1.5m2/kg, so for your roof you require three 20kg bags.
Surface preparation , Break Debris on top of slab,Scrub with wire brush , Vacuum clean or water jet , Clear Slab need to be exposed.
The surface must be saturated\damp before application , do not flood . If this is not done correctly this step is waste .
Mechanically mix 3 Parts TGP with 1 part water into a slurry, Always mix in batches not more than 30 min. It will set hard. Apply like paint with brush the entire area.
After application . You need to keep the surface moist (Never flood), either by gunny bags or with a sprayer attachment to pipe . 3 to 4 times a day. if this is not done properly the crystal does not grow proper into crevices. Maintain this for 7 days to 14 days. without any activity on slab except light walking for watering.

Total Material Cost : 6000 Rs . This step if done properly , will activate the chemical in presence of moisture and the waterproofing quality will grow with time.
However this step is optional , if this is too much for some one to implement one can safely proceed to B.

Step B : choose option 1 or option 2 (one of them)
option 1 :
fosroc brushbond : material required : six 23 kg pack = 15000 rs (approx 2500 per 23kg pack) .coverage 200sqft per 23kg pack for 2 coats. paddle mixer is required.
this is a 2 component system(powder + liquid), surface preparation is same as step A ,ensure the surface is damp\moist not ponded with water. divide the 23kg into 4 equal parts, ie
prepare slurry in 5.75kg powder + 1lit Liquid + 1 lit water.(do not add water more than this) Apply with brush on surface, this sets hard in no time, so do not mix all at once , prepare in batches. Apply 2 coats , ensure that the 2 nd coat is applied while 1 coat is tack dry not bone dry. While applying 2nd coat, sprinkle fine sand coarsley , so that it better bonds to screed. This needs to be done for patch to patch while the 2nd coat is wet.

Option 2 :
fosroc brushbond RFX : this is a better product ,material required : 9 packs of 15 kg , cost 40500 Rs ,(approx 4500 per 15 kg pack) . 150 sqft per 15kg pack
surface preparation and application same as indicated in Step B option 1. Batch preparation : 3.75kg powder + 1.2 liter Liquid + 750ml water.
Purchase a 100 rs spring balance and 50 rs plastic measuring mug.(mix in proper ratios) .


If you correctly implement the step C.
Step C1 : For Slurry, one need to add SBR Latex which is a polymer additive , bonding which avoids Surface Cracks. (Either Pidilite or Fosroc it costs you 400 to 600 Rs per liter) .
Dosage: For the slurry , the coverage of SBR Latex in slurry form 5m2/litre , so for your area you require 20 liters SBR for slurry itself. So the slurry is prepared
1 Volume of SBR : 3 Volumes of Cement : 1 Volume of Cement or in terms of Cement Bag : 5 Liters for 50kg cement bag.
This step will increase the bonding between the Screed and Roof Slab , ensuring water tightness.

Step C2 : Conplast XR421ic or Pidilite LW +, Cost Per liter : 200Rs approx , 125ml per 50kg Cement bag. Added to cement mixer with water. This is a plasticizer, do not add too much water to concrete. Buy 10 liters pack which will cost you Rs 2000, and keep using as and how cement bags are broken and put in mixer.

Step C3 : This is crucial , Addition of SBR to the plastering of screed will increase the Crack resistance\flaking and strength of top layer and water tighness. Add 5 liters per Cement bag + water. I guess you will require another 15 liters of SBR.

Total Step C Material cost : 35 liters of SBR + 10 liters of XR421c or LW+ = Rs 16000.


Step D: on top of screed
excel flexicool(thermal reflective + waterproof)
, pidilite new coat(water proofing only) , fosroc also has similar coating

for 2 coats for 1350sqft: six 20 liters drum : 2 m2/liter per coat total cost : 40000
i suggest


labour for step A or step D should not exceed 5000rs

[Nivas]

that was reply for hedge ,

hcsatish , i think organosilane\cement polymer coating for indoor \ bathroom is fine

elastomeric \cementious top coat is not uv resistant and for foot traffic , 1mm or 2mm coating may flake up in couple of years under intense sun. pricing is fine , check for uv resistance

[hcsatish]

Thanks Nivas for quick response.

The water proofing guy said it is uv resistant. The product name is Elastobar , the product page says excellent UV stability.

Regards,
Satish

[venk_pr]

Hi Nivas,

firstly I am a follower of your posts, thanks for sharing your knowledge and providing very good information on lot of subjects in this beautiful forum.

I am facing problem of fungus and cracks in the mould and water spotting in the room roof surface.
can u please provide me how to get the terrace fixed ?
I got a quotation of Rs 100/sqft chemically filling all the cracks and using bitumat membrane, my roof area is around 800 sqft.

The earlier solution given by you.
you can hire some painters to do the job , brush and vacuum clean \wet clean the surface and apply 3 coats at different angles. you can finish off with Brushbond cool roof for increased cooling . The PU \ UVR coatings are also available , these are more durable and expensive. anyways these coatings lasts long and are uv resistant. The coverage and quantity that need to be purchased is given in data sheets of these respective products .

my house was built 5 yrs back, already terrace have lot of cracks and mainly lot of hollow spots covering more than 30% of 800 sqft at random places bcos of filter sand, less quantity of cement and poor workmanship,
after consulting a engineer he mentioned to go from scratch, chip in the existing screed manually by labours not by machine, get cleaned neatly get brushbond waterproofing, after that lay screed with smooth cement finish or on top one weather coat paint layer,
for laying screed when i enquire with other mestri he quoted 80rs sqft for chipping old screed and cleaning and doing waterproof SW+ mixed slurry and then laying screed.
I am planning to do brush bond option 1 or 2, then laying screed from scratch for the entire surface.
one waterproofing guy given quotation of 40Rs sqft for brushbond.
in option 1, u have just mentioned fosroc brushbond only ( not anything like TGP or RFX) please specify.
And also is step C's compulsory to add additives to the slurry ?
please guide me to the correct course of action regarding this.
I appreciate your valuable guidance in advance.
if possible can you pm ur mob # for any further queries.
Thanks a lot
Venki

[Nivas]

the sequence of Aor B , i had given is for fresh slab, brushbond or TGP as described in Step A or Step B , is advisable on a clean \ fresh virgin surface free of debris. since you are removing the old screed , the removal will be incomplete , following step A or Step B in this situation would be waste or ineffective.

(Note : not that the slab can be cleared of debris and expose the slab, it is a elaborate procedure ,not something that your contractor will be ready to invest in, neither tools nor labor)

So after removing the screed and cleaning to a good extent , follow the step C in its entirety (C1,C2,C3) . Go for Step D after screed \ screed plaster is completely cured.This way , your screed it self will be sound and water tight for decades. For Screed, use M-sand and small aggregates , compulsory use a cement mixer.

Step A is crystalline water proofing , Step B , I have given 2 options , one Brushbond , other Brushbond RFX , See RFX has more solids and renders a thicker coating and is expensive. Brushbond has lesser solids and is economical.

[Nivas]

by the way the above procedures step A or step B or step c is same for sunken slab.
Step C can also be adopted for underground sumps or RCC tanks. Here screed mix is replaced by concrete mix for RCC casting.

if one needs ultimate protection of sumps, fosroc EP405 is a non toxic white Epoxy coating specifically designed for potable water .(this product may not be readily available order a fortnight before) it costs about 4500 per 4 liters , can be roller applied. (need 2 coats and coverage is given in data sheets) The cured epoxy resembles bone china.
Imagine your sump is covered with continuous white tile like material ,which is tougher than tile.

[venk_pr]

Hi Nivas,

Thanks for your quick feedback.

1) so even after removing old screed and doing a decent cleaning, Brushbond treatment is not necessary? is there any alternative or skip this procedure? or can v do later on top plastering(muddy)?
2) for Screed SBR latex 5litres/50 kg cement u have mentioned, our mestri told they require around 20 bags of cement, can u please elaborate the required quantity of cement and SBR latex for around 800sqft terrace?
3) myself and mestri are thinking of going for trichy or harihara sand(2 tractor loads) instead of M-Sand (reason bcos v don't get good M-sand)and small aggregates (batani jelly),
can u tell me the advantages of doing the screed using M-sand?
4) is cement mixer compulsory for the screed work? for 800sqft mestri said manual mix will suffice. how to add the right quantity of SBR latex in manual mixing?
5)excel flexicool(thermal reflective + waterproof) is there any other company equivalent products to this?( bcos only one excel distributor is in sanjayanagar i stay in RajaRajeshwari Nagar.
awaiting your reply
Thanks a lot in advance
Venki

[Nivas]

1) so even after removing old screed and doing a decent cleaning, Brushbond treatment is not necessary? is there any alternative or skip this procedure? or can v do later on top plastering(muddy)?

Yes , Decent cleaning is very subjective , it is hard to remove the adhered cement , unless you are blasting with water jet and scrubbing with wire brush for long. when your contractor cleans it , you will notice. Brushbond is surface coating , hence it will not be very effective. Having said that you can apply brushbond for your satisfaction. (whether to skip or not skip is entirely your choice) . Yes , on top of screed plastering also , you can coat RFX with a pretreatment of penetrating siloxane. ( this is a alternate to Step D).

2) for Screed SBR latex 5litres/50 kg cement u have mentioned, our mestri told they require around 20 bags of cement, can u please elaborate the required quantity of cement and SBR latex for around 800sqft terrace?

Yes sir , 5 liters of SBR Latex per bag of cement is recommended by the company or it is 1 Volume of SBR : 3 Volume of Cement : 1 Volume of water.
1 50kg Cement bag is 1.25 Cft , and 1 Cft of water is 28 liters , with a W/C ratio of 0.45 , you require roughly 0.45x1.25x28 aprox 15 liters of water per cement bag . ie you require 1 liter for every 3 liters of cement \ water slurry .ie 15/3 = 5 liters . Having said that if this is going to cost you , you can reduce to 4 liters per cement bag or 2 liters per cement bag. But that is deviation from recommended.
so in your case , if you mestri uses 20 bags , you require 20 x 4 liters of SBR . Totally 80 liters .. If you buy in bulk, the cost comes down... pidilite might sell for less.
3) myself and mestri are thinking of going for trichy or harihara sand(2 tractor loads) instead of M-Sand (reason bcos v don't get good M-sand)and small aggregates (batani jelly),
4) is cement mixer compulsory for the screed work? for 800sqft mestri said manual mix will suffice. how to add the right quantity of SBR latex in manual mixing?
Yes , mixing is the key deal in any concrete works, a homogeneous mixture is crucial for strength and properties . Imagine the fatigue of mixing manually However the sand and manual mixing is your choice. You can also order screed from reputed RMC , you can get light weight screed with addition of polystyrene balls or vermiculite or perlite .

5)excel flexicool(thermal reflective + waterproof) is there any other company equivalent products to this?( bcos only one excel distributor is in sanjayanagar i stay in RajaRajeshwari Nagar.
Yes fosroc, sika , pidilite, Berger, Ardex endura, MYK Laticrete, BASF all have similar products,. some companies may sell in sub components , you may have to order Nano Glass spheres product for thermal \ SRI seperately. Most of companies are based around mysore road area. Call up their customer care and contact sales for product specific details . Excel , Berger , Pidilite I know for sure , Fosroc has recently released a integrated product.

[Nivas]

sorry i forgot to answer ,how to add sbr to mix and few more tidbits.
add\dissolve sbr latex to water before adding to cement , not to cement directly. reduce the water by the same volume of sbr.
also maintaining optimum w/c ratio in concrete is crucial.
For Ex , if you need 15 liters water per cement bag and you decide to add 5 liters of SBR , you need to now limit water addition to only 10 liters.
Simply by forgetting above step , if one adds 5 liters of water more , your concrete mix will reduce roughly 1000 psi compressive strength.
So in any concrete works , if some one throws few liters of additional water to concrete ,so that it can be easily worked manually, you can easily reduce the strength by 50 %.

Now what do i get from adding SBR Latex to concrete , given I maintained correct w/c ratio.
By adding 3 liters of SBR to 1 cement bag , You will see , 20 % increase in flextural strength, and 35 % increase in Compressive stength
(Disclaimer : Not a absolute claim , but approximately).

pidilite refers it as URP.
(sbr means styrene butadiene rubber latex)
also note some companies sell in kg and some sell in litres, hence the price difference. (density is high)