formplyfa or plywood plus paper?

[Mats]

I was planning to cast a garden wall this summer. To make it simple for myself, it will be T-elements. I plan to cast these in two stages per element. The base first, and the next day I plan to cast the upper part.

The height will vary between 30 cm and 1.10 m, the length of each block will be 1 m. In total, it will probably be about 26 blocks. Now the question is whether I can be a bit frugal and skip the form plywood and use regular plywood for the mold instead. In that case, I was thinking of covering the plywood with plastic since I have plenty of vapor barrier plastic in surplus.

Good idea or just plain stingy?

 

[Johan Gunverth]

I was planning to cast a garden wall this summer. To make it easy for myself, it will be T-elements. I was thinking of casting these in two stages per element. Bottom first, and the day after I was planning to cast the top part.

The height will vary between 30 cm and 1.10m, the length of each block will be 1m. In total, there will be about 26 blocks. Now the question is whether one can be a bit frugal and skip the formwork plywood and use regular plywood for the mold instead. In that case, I was thinking of covering the plywood with plastic since I have plenty of diffusion plastic in surplus.

Good idea or just penny-pinching stupidity?

It will turn out great if you can pry up the mold and get the casting out. The concrete will be mirror smooth but will dull after a month. My grandfather made a couple hundred concrete slabs that way.

 

[Mats]

No problem with the form. If you look at it from above, the idea is like this

XXXXXXXXXXXXXXXXX
XBBBBBBBBBBB Y
YYYYYYYYYYYYY

That is, X is a horizontal L consisting of a long side and a short side. The same goes for y, and then I let the studs on the short sides overlap each other. I was thinking of drilling a hole through and putting a solid rebar as a pin. During demolition, you pull out the pins and split the form, leaving the concrete in the right place.