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How to Build a Paintcrete Roof Outhouse


Latex Cement Roof
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I need an outhouse at the land if I am ever going to have workshops and classes. Additionally I have been wanting to find a cheap and durable roofing material. I have lots of plans for domes that defy traditional construction. To this end, I decided to build an outhouse and perform a Pantcrete Roof Experiment to kill two birds with one cheap stone. This is also called latex cement

I first learned about latex roofs while researching ferrocement. While I still like ferrocement as a building material, this particular technique is a little better suited to roofs. The Dept. of Civil and Environmental Engineering, Notre Dame University did an experiment on disposing of latex paint inside of cement to replace the water.

They found the compressive strength of the cement slightly increased at relatively low latex paint rates. I am not worried about strength, I am wanting the flexibility and slight waterproofing aspects the paint brings.

What I used to Make the Paintcrete Roof

For this experiment I actually used type s mortar and some 100 acrylic waste paint. I started with a quart of mis-mixed paint I got on sale, but quickly ran out and had to use some once frozen bathroom ceiling paint with a anti-mold additive. I didn’t mind using the old paint, except it was frozen and did not mix well. You can see some small balls of unmixed paint in the “semi” finished product.

I bought a few 8 and 10 foot 2×4’s and build a 4×4 frame and then a 5×4 foot frame. The ends of the 5×4 frame were beveled so that the ends were perpendicular to the ground as the actual frame was at a slight angle.

The slope is enough to shed water, but not so steep that I cannot come back and retrofit a green roof over the top if I still desire.

How I Put the Latex Cement on the Roof

I mixed the paint into the mortar and making a pretty high slump mix. For those with even less construction knowledge than me – it was soupier that normal. It could be poured – but it was not soupy.

I spread it over fiberglass window screen that was stapled tightly over the wooden frame. Next, I used 3 rolls of 36×84 fiberglass screen to ensure no area had only a single layer of screen.

I poured this mix on and spread it lightly with an old broom. I found that pouring it on, lightly brushing it down and pouring new mix over covered mesh and pulling down in batches worked better than trying to fill a section completely in one try. The older mix got into a few holes and held the next pour better.

After about 2/3 of an 80 pound bag and a gallon and a quart of paint completely filled the roof. The last few layers were much more soupy and served to coat the mortar mix already on the screen. It pretty much self leveled – with the bits of old balls of frozen latex making small bubbles that I imagine will cause problems later.

Remeber this is an experiment in feasibility and will be the roof of an outhouse. Perfection was not the object – to see how easy and cheap this can be while achieving some strength and basic waterproofing is what I am looking for.

In the event you want more information to try top do this Besides the book above, and the paper I linked to, below is a document from the US Army Corps of Engineers.

Latex Admixtures for Portland Cement Concrete and Mortar.

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Underside of the Paintcrete Roof


In working with my concrete experiments, I figured I should show the latex cement underside of my outhouse roof. You can see the effects of mixing paints.  However, it does not seem to impact the strength of the roof.

None of the original latex cement dripped through the screen.  There were places where my staples and the bottom layers of window screen were not fully contained inside the cement.

It is my plan to make a thin mix of paint and cement (probably the PVA Primer because it is the cheapest and seems to be the best) and paint over the bottom. This will give a more finished look and hopefully will be one final bit of water proofing.

I am pretty happy with the project so far, I was planning on finishing the base this weekend, but the local habitat for humanity store was out of doors. I have all the wood I just need a door.

As a side note, I plan on trying out the forever floor concept found in backwoods home magazine as a cheap and durable floor covering.

 Update on the Latex Cement Roof


I wanted to give a . It has dried and is in good shape. While it can’t quite hold my weight, it does hold the kid’s weight well.

It is light enough that two people can easily place it on the outhouse structure.

Using thick mortar mix worked well. It did not drip through the screen like my wife expected it to. I did use a lot of mortar and a fair bit of paint. However, it was not so much as to be excessive or overly expensive.

I still need to build the outhouse frame.  However, I could not decide if I wanted to continue with the paintcrete theme for the walls. In the end I will probably go with  board and batten siding.  I have some logs, I just need to get out my sawmill and cut the siding

Right now, I am waiting to see how my paintcrete over bed sheets experiment works on my rabbit hutch before I decide how to finish the outhouse.

I am not in a hurry to finish the outhouse as local thieves have broken into my shipping container again. This time they took the time and energy to use a grinder rather than a bolt cutter. Since they did not break the lock to my gate, the only way I can see for them to bring in a truck to steal is by coming through my neighbors yard.

He just got back out of prison and hasn’t found a job. So I don’t know why he didn’t tell me someone was stealing small and easily sold items from my property…. I do know the lady that lives with him yelled at me for calling the police over the theft- which I think is odd.


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