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Stucco Over Concrete Block

What is the best way to prepare a concrete block wall to stucco over? Thanks, Dale

Re: Stucco Over Concrete Block

Stucco is mostly laid over Styrofoam this days. To limit on the telegraphing of the morter joints and for insulation purposes. If you are going over the block with a cementis topping it will need to be paint free and powerwashed with an application of bonding agent before the coating. and between coats and also in the mix. I have done block buildings this way using concrete overlays. It does require 3 coats min to hide the mortor joints tho. If the building is painted. I would recommend fastening Styrofoam as the hrs in labor to strip the paint will be way more then the expense of Styrofoam

Re: Stucco Over Concrete Block

Yep --- the stucco over a foam substrate would be a way to go. Although ----- I'm wondering about using a simple diamond lath attached to the wall? Saves a ton of extra work getting down to clear block and bonding agents or attaching the foam substrate--- also saves money on materials.

Hank Bauer
Re: Stucco Over Concrete Block
demurrah wrote:

What is the best way to prepare a concrete block wall to stucco over? Thanks, Dale

If it is New CMU apply the stucco direct to CMU.
Use a mixture of one part cement - one part sand and water to make a slurry dash on CMU with a large brush.
Than apply the stucco mixture.
If existing CMU has been painted as stated previous remove paint as for using a bonding agent MAKE sure that the selected bonding agent is not Re-Emulsifiable to use such will cause detachment in the future.
If you select to use the foam ( EPS ) board it will have to be installed 6 / 8 inches above grade.
If this stucco is for cosmetic reasons than check into a synthetic base with an acrylic finish.
For the synthetic system look at using products like STO Corp.After pressure washing apply STO Plex W Than STO RFP base coat with a STO finish as selected to include color there will be no block joint showing when the wall area is damp.You should be able to find about 35 manufacturer that have products Like STO.The total build out with a synthetic coatings will be in the range of 1/4 inch max.

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