Fudge Factor for Painting Block Walls

I'm purchasing a condo in the mountains at a ski resort that needs a total repaint due to past owners poor color choices. The common walls of the condo that separate the units and also act as a fire stop are solid block set on end such that the narrow edge is visible with deep mortar groves. Wall has been previously painted (either orange of yellow) and I want to take it to a more neutral off white/beige. Given the nature of block, and the deep grooves, how much should I discount the amount of coverage per gallon to account the odd wall make up. Really struggling on estimating paint needs and what amount of coverage I should expect per gallon. I'm also struggling on painting by brush or spraying - either way, there is concern about major drip marks from all the relief of the walls.

Here is picture one of the bedrooms

 

I gave 'er a quick flip.

Those almost look like bricks.
Is the seam painted the same color ?

 

The grooves are painted as well. They were big Virginia Tech Hokie fans - can you tell?

Brick or block, I got the gut feel of block, but either way, a challenge to paint.

 

Irregular surfaces are always a little difficult to estimate coverage. A lot depends on how rough/smooth it is, how well sealed it is by the previous paint and how deep the grooves are. I'd guess about 300 sq ft per gallon ...... your mileage may vary

I rarely ever spray in a finished dwelling. Any time saved is ate up by the cover up and clean up time. I'd roll the walls with a 1.5" roller cover. Slop the paint on so it runs into all the grooves and then once the roller cover is low on paint, back roll. You might need to back roll twice to get rid of any runs.

 

I'm wondering if I take a 2 roller approach to this -one to put on the paint and then a dry one to back roll. Yep complete with vaulted ceilings and all, ugh!

Fortunately, we looked at several other condos in this same complex and know first hand what a difference it will make painted neutral. Yep, I got my work cut out for me in this one. Not quite ready to delve into the other planned upgrades. Will take me a while to get it worthy to enjoy.

 

Personally I'd just use one roller, no need to have to clean up two. Once you get the hang of it - not a big deal to back roll with the roller once most of the paint is used up. A completely dry cover would be prone to pull the paint off of the wall

 

This is probably the most prep work I have ever done to paint a single wall.

Thoughts going through my head while painting:

-A what point do you just decide that you are brush painting the whole wall?
-Its not really brushing more as it is rubbing paint into the grooves.
-No one will see this section, it will be behind the headboard of the bed.
-Maybe orange is not such a bad color...
-I hate block walls.
-Maybe easier to sheet rock over this.
-Wonder what white face with orange grout lines would look like?
-In this case, prep is 95% of the job.
-Oh good, its gonna take 2 coats.
-Only 6 more walls to go.
-Gonna need more paint.

 

You're making the job harder than it needs to be. Use a heavy nap roller [1"-1.5"] and just slop it on the wall and then dress it up as the roller gets light on paint. Applying a lot of paint lets the paint run into the grooves/joints, then it's just a matter of rolling it again to wipe out the runs. The only places you should need a brush is for the cut in and at the bottom where you have to roll the paint on lighter to keep it off of the floor.

 

Those grooves are about 3/8' - 1/2" deep, and struck square, aren't they? I can see why you did it that way. What a pain.

I recently had to paint a room that was about the same color... had to prime it first just to block the old color before applying the new one. Otherwise the top coat would have been a funny hue.

 

Yep, 3/8" and square. I used a 3/4" nap and couldn't have touched the grooves if I tried. I even had a difficult time with a brush getting into the grooves.

 

A bigger nap will help but the 3/4" should work as long as you apply the paint heavy enough for it to run into the joints.