| When going into these types of projects, you need to approach them with some caution. It's best if you have answers to the following questions. What were the weather conditions during construction? Was it cold or rainy? Where the outside walls capped and sealed during the wet spells? Was the mortar in the block or the concrete given adequate time to cure prior to applying the coating system (industry standards require 30 days of cure)? Knowing this may tell you ahead of time some of the problems that might exist such as a high level of moisture in the wall or a high pH level. Cold, damp weather will slow down the curing time of the concrete which increases the likelihood of moisture problems.
If you suspect the masonry surface may have a high level of moisture and a high pH content, you need to be very cautious about coating over it. Allow adequate time in warm or hot temperatures for the moisture to escape from the substrate. Make sure to test the pH of a given substrate, and get some indication that the surface has had adequate time to cure. Typically during new construction, cold, wet weather will exist at some time prior to coating the substrate. You need to be aware of the situation and protect yourself from the problems that can arise from this environment.
A typical scenario of new construction project would be; construction begins the middle of the summer and continues into the Fall season, maybe late Fall. During this construction there was excessive rain and cool temperatures. The wall caps where not in place prior to the rain, and the walls became saturated with moisture. The temperature turned cold and the moisture was not allowed to escape, also slowing down the cure process of the concrete. Now the General Contractor wants the building painted or waterproofed during the late fall season. He needs to get the job completed so that the business can open, and he can get his money. If at all possible, walk from this situation. If the owner of the building and the general contractor insist that the process of coating the building goes on, clear yourself of all responsibility in writing prior to the job beginning. If this building is coated within the parameters of this scenario, there is a good chance that late next summer you will see the coating delaminate or peel from the masonry surface. If you are forced into this situation, or you have a job where they just cannot allow 30 days of curing time prior to coating the substrate, there are surface conditioners available to resist or minimize the alkaline burn that may result. This alkaline burn in the concrete is what usually causes the peeling of the coating.
As a painting contractor, coating concrete is probably not the normal substrate that you typical work with. Concrete requires a coating system designed to give adequate protection to different substrates such as tight, smooth, "poured in place" concrete, dense block construction, split face block construction or haydite light weight block construction. Each substrate needs to be given special consideration when selecting a coating system.
Diamond Vogel Paints' typical recommendation for coating masonry surfaces is as follows:
Poured Concrete or Dense Block Substrate
1 ct. BU-1501 Sure Grip Acrylic Latex Primer
2 cts. MC-1531 Permaflex Elastomeric Waterproofing Coating or
2 cts. Permacryl Exterior Acrylic Latex.
In situations where there is a need for an alkaline surface conditioner on poured concrete or dense block, the surface conditioner maybe substituted for the BU-1501 Sure Grip.
Haydite Light Weight Block or Split Face Block
1 ct. BF-1501 Permafil Blockfiller
2 cts. MC-1531 Permaflex Elastomeric Waterproofing Coating or
2 cts. Permacryl Exterior Acrylic Latex
When high moisture or high pH levels exist on Haydite light weight block or split face block, Brad Perau, Corporate Product Manager with Diamond Vogel, recommends the surface conditioner prior to the blockfiller to give you some insurance against alkaline burn. Permafil is recommended for use on exterior porous concrete block construction because if moisture does exist in the concrete prior to application, or if moisture seeps in behind the coating after the application, Permafil will resist the rewetting of the blockfiller.
As a painting contractor, waterproofing exterior concrete is probably not a normal application you typically work with. There is a lot to consider when you're coating concrete. When you suspect high moisture levels or high pH levels, your Diamond Vogel representative can help you with the solution to these problems. Give your representative a call or call 1-800-387-8426 for more information.
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