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DIY Waterproofing Basement Walls

Learn how to help waterproof cinderblock in your basement using MasterSeal 581.

before closet that needs waterproofing with arrow showing after craft closet.

What is MasterSeal 581?

MasterSeal 581 (Formerly Thoroseal)is a non-fibrate, water-based bitumen emulsion powder product that mixes with MasterEmaco A660 in order to help waterproof a basement. The finished film makes a vapor-proof barrier. 

*Disclosure: I only recommend products I would use myself and all opinions expressed here are our own. This post may contain affiliate links that at no additional cost to you, I may earn a small commission. Read our full privacy policy.

In this post, we will talk about how our use of and review MasterSeal 581 and MasterEmaco A660 in order to improve your basement.

Why did we need to waterproof?

We had concrete masonry units (CMU/Cinderblocks) in our basement that needed a new coating of waterproofing. Therefore, we chose to use these products to help create a waterproof barrier. You can see how we were able to use this product in order to prep some walls in basement closets that needed a little help.

chip CMU cinder block in basement

Who should use MasterSeal 581 and MasterEmaco A660?

This product is best for people who aren’t afraid of a little DIY. We definitely felt that this product was worth purchasing. You will need a few tools in order to use this product successfully.

Masterseal 581 and MasterSeal Emaco A 660

What does this Masterseal do?

Masterseal 581 when mixed with MasterEmaco A660 makes a vapor barrier. We used this product to help fixed cinderblocks in our basement. I am sure it would work to coat new cinderblocks, but we used it to repair cinderblocks in our basement wall.

If you don’t want to try to pay a huge waterproofing company, then this product may help you. One thing to note, if you are having major water damage issues, then you need to find out why this happening. Don’t just use Masterseal 581 to put a bandaid on the problem.

How to Use Masterseal 581 and MasterEmaco A660?

There are detailed instructions from the MasterSeal 581 datasheet on how to use mix this product. You will want to follow these. Here are the steps we took in images.

Note: You can always rent the spade handle mixer from Home Depot, Lowe’s or your local hardware or rental supply store.

How To Mix Masterseal Waterproofing Product

Step 1: Clean Cinderblock

Use a wire brush to remove extra loose pieces on your cinderblock wall.

Use a wire brush to clean cinderblock in basement

Step 2: Pour Liquid Into Powder

Follow mixing instructions to get the proper measurements or powder (Masterseal 581) with diluted liquid (water + Masterseal Emaco A 660).

Slowly add the liquid to the powder and mix in a 5-gallon bucket.

Measuring Masterseal Emaco A 660

Step 3: Use Spade Mixer

Here is the consistency you are striving for.

Mixing Masterseal products to waterproof basement

Step 4: Get Even Consistency

You are going for a thick pancake batter pictured below. Make sure to fully mix both parts together.

Mixed Masterseal 581 and Masterseal Emaco A 660

Step 5: Apply To Walls

Let it sit, then use a masonry brush to apply to the walls.

Masonry Brush Applying Waterproofing on CInderblock in Basement


  • This product is pretty easy to apply. Once the product is mixed, you are able to apply it rather quickly.
  • The white color may not even need to be painted, depending on where you are putting the waterproof material.
  • Great for fixing some areas in your basement. This is way less expensive than having a company come and do this for you.


  • This product requires a few extra tools for mixing.
  • MasterSeal 581 mixed with MasterEmaco A660 is slightly messy to apply. For our basement closets, this wasn’t that big of a deal as we weren’t so attached to keeping the floor clean. 
  • You have to work quickly when applying the mixture before it will dry.
Mess from masterseal product when dry

Where can you buy Masterseal waterproofing?

We always recommend shopping around for the best price. You can even order these products from specialty hardware or supply companies. Here are common places you may want to check the price.

You can even purchase MasterSeal 581 and Master Emaco A660 at different hardware stores. I was shocked that you could have is shipped from Amazon.

You can even pick up the masonry brush needed in one order.

How much footage will be covered with the 50 lb. bag of MasterSeal 581?

For our closet touch-ups, we used one 50 lb bag with the proper diluted Master Emaco A660 mixture. According to the website, one 50 lb. bag mixed will cover 225 ft squared-450 ft squared depending on how thick you apply the base or topcoat.

Finished closet after using Masterseal products

Final Thoughts

We love that we were able to rewater proof areas that seemed to be chipping off after 30 years. We feel pretty lucky that in our basement we only had a few spots to redo.  

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Other Basement and Closet DIY Home Ideas

Our nice-looking closet is proof that this DIY home project is a great, functional product. We will have to revisit this post and review it each year to update how the waterproof barrier is holding up.

Soon we will be finishing our basement room into an awesome homeschool and craft room for our children. I can’t wait until this is finished and we can get this closet organized.

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