Ceiling Thoughts

That is what the north end of the cottage looks like at the moment. Much of the block is simply stacked so I can look at how things go together and what the resulting spaces are like. It’s a lot like playing with 43 lb Lego bricks and a wonderful workout on a cold winter day.

I’m thinking a lot about ceilings these days. I’ve been reading about plastering, which I’ve never done aside from installing and fixing sheetrock. Sheetrock is something I’ve done a lot of before but I’m not going to be doing that for the tiny cottage project.

One of my goals is to not paint inside the house, although someone has recently told me about mineral paints so I’m looking into those. I do not want to be repainting paint walls, ceilings, trim, etc and then watching them peel. This is a health, aesthetics and maintenance issue. Thus I would like to go with stone, plaster, stucco and light colored concrete for surfaces.

I did the roof of the tiny cottage using a technique like MXSteve’s barrel vaults such that I have a very nice rough interior from the concrete that came through the expanded metal lath. I plan to do a light colored cement onto and then perhaps a coat of plaster.

I have three more areas to do that will produce a ceiling – front room, bathroom and bedroom. I’m about to pour those areas and I’m thinking of how I can do the ceiling plaster and cement pour all in one shot.

First there is the bathroom which is about 30 sq-ft. I’m planning a flat ceiling in the bathroom. I have setup the scaffolding for this and when I pour the bathroom ceiling I’ll be also creating the floor of the utility space above the bathroom for the hot water heater and such. I’ve been wondering about using a white PVA fiber reinforced concrete for durability.

Finding white sand has been, shall we say, challenging. I’m in Vermont near Montpelier. Any ideas on sources? I’ve been looking around for local sources of marble dust but struck out so far. I have some very nice pieces of white marble I pulled out of the loads of junk rock piles but grinding it up is a challenge! Some of the pieces are 4″x4″x96″ – just think marble fence posts! Others are bench and step sized pieces as well as some huge ones (e.g., 10’x8″x4′). Unfortunately, my stashed granite and marble is currently buried under 4′ of snow.

Ideally I would like to buy a truck load of white sand if I can find it. That way I’ll have enough to do all of the plaster and parge work and it will be far cheaper than buying small quantities. Any excess can become the beach on the upper pond. The bathroom is small enough that if necessary I might buy bagged white sand ($$$!!!). I’ve also been experimenting with adding lime to whiten the grey cement. Finding reasonably priced white cement is difficult. I have found one source of white Portland cement (STGriswold) but it is expensive at $28.75 for a 94lb Bag and Lee white sand in a 50lb bag is $6.99. I may bite the bullet and get some of that to use sparingly. I had thought of doing plaster in the bathroom but fear it won’t be long lasting enough in the presence of the water from the shower and other wet room moisture. I would be interested in hearing from anyone who’s done this…

The next ceiling is the master bedroom which is about 43 sq-ft. Again I’m going to go with a flat ceiling and that is the floor of the storage attic. Here I was thinking of doing a 1/2″ layer of plaster on top of forms leaving the upper surface rough and then as soon as it stiffens a little I would like to pour PVA fiber reinforced concrete which will make the actual attic floor.

Lastly is the kids loft in the front which makes the 71 sq-ft ceiling of the entry and dining area. I’m thinking of doing that as possibly a lightly arched ceiling poured into a mold. Again I would like to do a plaster layer which will be slightly more tricky with the arch – the reason I’ll do that one last. Aside from the arch it would be the same technique as the bedroom.

I already have setup the scaffolding for each of these spaces. I’m planning to place 2″ pink foam board on top and join them together with PVC tape. Edges of the concrete will lock to the existing walls with #4 rebar pins and rest on top of the partition block walls forming the bond beam for the top of the partitions.

I have thought of doing a shrink wrap plastic layer on the top of the foam to get a perfectly smooth surface. The foam alone gives a pretty smooth surface and oiling the foam helps with release. My next step is to make up several test casts with layered plaster and concrete over various forms. Results will be coming in a bit.

Alternatively I’ve thought of doing shallow vaults on all three ceilings just like the roof leaving a rough surface for plastering. That means then doing a lot more plastering over my head. Doable but a pain in the neck. The reason I’m doing the various ceilings in different ways is in part because this house is highly experimental.

Our existing house is a >200 year old wooden farm house. Each winter I read about house fires in the newspaper. Not a pleasant thought. This morning’s story was a mobile home where they owner had been thawing pipes with a heat gun and burned down the house. Usually it is chimney fires. We heat with wood and will continue to do so since we are able to harvest our own wood. Having a very fireproof house is important as that is probably our highest risk factor. Concrete, stone, ferrocement, plaster are all appealing from that point of view – low flammability. That means a minimum of wood, fabric, canvas, burlap, plastic, paper, etc in both the structure and in the contents. I have a revulsion to the idea of my family being cooked in a fire of my own making.

While I’ve put up a lot of sheetrock over the years and am quite good at it I don’t want to do any in this new house if I can avoid it. I’ve seen too much mildew in many different houses. Besides, I am feeling like doing something more adventurous and new, thus plaster, stone and concrete finishes instead of sheetrock.

I’ve also done acoustic ceiling tiles. They went up well but look rather institutional. I would rather go with something more hand crafted. Since I’m doing such a small space I’ve got the opportunity to think different(ly).

Sooo… all of you plaster buffs out there… Any thoughts?

Outdoors: 20°F/10°F 1″ Snow lightly all day, Partially Sunny
Farm House: 60°F/48°F six log
Tiny Cottage: 53°F/45°F block work, plaster research