Open cell foam does stop most of the airflow, and it costs a bit less than closed cell foam; however, it is spongy and can retain moisture. There are at least two ways that moisture can get inside the wall. Water vapor can migrate into the wall, which a properly-installed vapor barrier should prevent. The second way moisture can be present in the wall is via condensation. The warm air from inside the home will meet the cold air from the outside somewhere within the wall cavity. Where the two temperatures meet, moisture is created. When one uses only open cell foam, the condensation will form within the foam, but won't be able to dry out because the airflow has been cut off, potentially leaving wet insulation which could lead to unhealthy mold. Building science offers that, if a home is heated during the winter months, the best way to prevent condensation from forming in a wall is to be sure that 50% of the R-value in the wall is closed cell foam. The remainder of the cavity can be filled with open cell foam, fiberglass, or any other insulation. Because the cells of closed cell foam are solid, they can't hold moisture. By following the 50% rule in external walls, the hot and cold temperatures will be forced to meet within the closed cell foam, condensation will be neutralized, and you'll have a wall that is air-tight and moisture-free, making the use of closed cell foam as the first line of defense against Mother Nature well worth the investment. Linda - Foam It Green http://www.sprayfoamkit.com/videos-a-how-tos/insulating-a-2x6-wall

KS...are you a GC? That price is very good. I'm shocked it's that low. Curious....was the company that did the work union? The last time I got a quote for sheetrock in this area(SE) it was around .75/sf but that was 9 yrs ago. Just did a search and found a web site that you can put in your zip and get an estimate of what it is in your area, it says around $1.70/sf here now. I would much prefer plaster but I really don't think anyone in the SE even knows how to apply it. I think it's really a trait that's very specific in local areas in the country. My wife grew up in a house that had plaster walls that was built in the early 1900's. Those were the first plaster walls I ever saw and haven't seen any since.

Well, I LOVE my recently added knockdown ceilings. Ya wanna know why? because I had POPCORN ceilings before! DH and I did all the popcorn removal ourselves. It was torture, but well worth it. We had a company come out and do the knockdown..DH really wanted smooth ceilings but yes, our ceiling was all wavy and would have to be "floated"and would cost a lot more...so we went with knockdown. We had it sprayed and troweled so it is very big "blobs" (for lack of a better word...you know what I mean, I am sure). This is a 1970's ranch we just purchased a few months ago and are totally renovating. In my last house I had popcorn...and in the house I grew up in? POPCORN. Geez, I hate that stuff! I just did the 1st coat (primer) on the knockdown and yes, it is hard...I have to apply pressure on the roller to make it in all the little grooves and whatnot. My shoulders were bunched up in knots at the end of the day. I guess I don't have it so bad cuz my house is small (2000 sq ft) and the celings are low (8 ft) but I am not looking forward to doing the paint. I keep putting it off. I actually like the look of KD on walls, but my DH hates it so we didn't add it to the house. My DH was a builder and said just what you did...knockdown (and popcorn) is used to disguise shoddy workmanship. We needed it on the ceiling, but not on the walls. Good luck, I am sure your rooms will be GORGEOUS when you are done!

All the walls in my home are smooth except for my downstairs basement living area that we finished ourselves and did the texture ourselves. It a more casual room, tv and kids play room. We did the knockdown texture ourselves with a thing that splattered the texture on then smoothed down. It's more random than orange peel but about the same "depth". It's more randomness makes it easy to repair any damage. I wouldn't want it my whole home but like it in that one room. I probably would dislike it immensely if in every room. But..if you ever want to do wall paper don't get it. Texture was in alot of new homes in Texas where we lived for a while, bathrooms too. I knew of several people who wanted wall paper later and spent weeks trying to smooth out the walls, yuck. The finish I have is looks like the skip trowel technique on this YouTube video, skip to end of video. https://youtu.be/C_cUnSEXnrM