You know your square footage of a room however.
Should you bid floor space or wall space for painting.
In either case there are problems with this approach.
Given the information above the paint sells for 29 a gallon when purchased in a 5 gallon pale.
Two to three coats of a sealant may be necessary.
Instead of apply paint why not use a plastic vapor barrier over the block wall in the crawl space.
One home has a lot more detail than the other home.
As one would require more prep more labor and more paint.
You can measure the perimeter of a room to calculate the wall area but if you already know the floor area of the room from floor plans for example it may be quicker to calculate the wall area based on that number if your room is square or round.
To paint wallpaper or panel a wall you must know the total area of the wall so you can buy the appropriate amount of finish.
In both cases they might use about the same amount of materials.
30 feet of chair rail.
You could loose allot of money bidding like that.
Sometimes contractors will talk about square footage about floor space and other times it will be about wall space.
Do you know how long it takes you to paint 200 square feet of wall space.
Unless of course you are painting the floors with porch floor paint then that makes sense.
Imagine you have 2 homes that are both 2500 square feet.
I agree that measuring the floor space only would make your estimate inaccurate.
If you know your production rates you can bid by square footage.
Crawl space foundations are easily waterproofed by gluing a thick sheet of plastic to the ground and walls.
A 10 10 8 room would be a different price from a 10 10 12.
With an open floor plan the same large space typically has windows with different exposures.
If you re using a single paint color on all of the walls make sure the paint looks the same on each.
Cutting in and rolling.
Do you know how long it takes you to paint a chair rail.
So you invest 145 to cover 500 square feet for 1 coat and 290 for 2 coats and 435 for 3 coats which is most likely the appropriate amount to apply.
Interior basement walls should be scrubbed free of mildew or mold and then primed with a waterproofing paint that is suitable for the surface.
For example if the concrete wall has a three inch drain pipe running along its face build the new wall 3 5 inches from the concrete wall.
I only give a bid for the floor footage after seeing the plans for the homes.