Sunday 1 September 2013

How to Waterproof and Paint Exterior Walls

Tired of applying coat after coat of white cement on rain lashed walls and leakage still returns? Applied the most expensive decorative exterior paint and the leakage is still there? Contractor making a profit but building still not waterproof? Well the problem lies in the solution. The wrong solution. 

The common misconception among untrained contractors is that white cement is waterproof, which is not true. White cement being a form of cement, absorbs water and does not form a barrier against it, thus is not waterproof.
Also decorative paints that are commonly used on exterior walls are for mainly one purpose ... decoration, not waterproofing.

The proper solution is as follows.


Materials Required

. Acrylic polymer for repairs
. White cement (But why??, didn't you just say its not waterproof? Ans: It is used as a filler along with an acrylic repair polymer.)
. Acrylic Waterproof Coatings for Exterior Walls
. For new cement surfaces, Primer for  acrylic waterproof top coat.
. A good quality, large paint brush (100mm, 4")

Application

. Wash and saturate surface with water. All work should be taken up when surface is dry to touch (about 45mins later).
. Check for cracks and damage. Where there is cobweb cracking (cracks < 1mm), a mixture of 1part acrylic polymer for repairs : 2 part white cement by weight is prepared and applied by brush over the surface. The thus formed coating must be water cured twice a day for 2 days.
. Cracks > 1mm can be filled using an acrylic crack filler.
. Construction joints such joints between structural members and brick walls can be filled using a polyurethane construction sealant.
. Apply a coat of cement primer (as recommended by Acrylic waterproof top coat's product data sheet) diluted to the correct consistency on the entire surface using a paint brush.
. After about 4-5hours, apply the first coat of the acrylic top coat for walls by roller/brush; usually undiluted.
. 5-6hours later a second coat in the direction perpendicular to the first coat is applied. 

As can be seen, the above system is exactly the same as that followed when painting exterior walls with decorative paints. Thus adding no extra labour costs.

Advantages

. This system serves 3 purposes : 1. prolongs the life of the masonry (giving the property both life and value) 2. Gives an excellent finish 3. can be tinted to a shade of your choice; can be used as a decorative paint.
. The system is cost effective : can be done in the same cost of labour as decorative paints  
. The dry film thickness (DFT) of the system is usually > 130microns and gives excellent crack bridging.
. A heavy duty water barrier is formed keeping water out.
. Acrylic top coats give excellent anti-fungal and anti-algal performance.

So when you think of painting your exteriors, this system is an excellent option.

No comments:

Post a Comment