Chicken Wire

[Chobbs]

So I have progressed somewhat since my last post and the dome is complete!

I have now covered it in 3" of blanket and put some chicken wire over the top. I have started the Vcrete layer to add an extra inch of insulation but the chicken wire seems to be pushing it away from the blanket as its not tight enough. How did you guys keep it all tight? I seem to have a cm or two gap in several areas.

[david s]

I dislike the chicken wire over the blanket method because it takes so long and just end it sufficiently. straight over the blanket. You can tighten the chicken wire by grabbing a bit with the nose of a pair of pliers and giving it a 90 degree twist. Doing this a few times in the same area tight

[Chobbs]

Thanks I shall try that today. I hope the fact they are just laid over the top doesn’t stop them coming out of place though. Should I have fastened them by some means?

[david s]

Yes it needs to be fastened down somehow. The chicken wire layer would be more useful as a reinforcement in the outer shell IMO but even ther I find random fibres added to the mix a superior solution and less labour intensive.

[Chobbs]

Well I pushed on without fastening, as I had already started the Vcrete layer and so couldn’t do anything about it! I managed to tighten the wire with the twists you suggested. The Vcrete is a very different beast to anything I have handled before so I hope I managed to get the mixture right.

[david s]

As you’ve found the vermicrete is a strange beast. I recommend doing a run around the base, but only about 6” high with a flat top to take the next lot. If you let this set up for 24 hrs it can be easily carved back or added to. It does set up harder than you’d think. Also as you’ve found, it anchors the chicken wire, making it easier to tighten. This first ring gives you the confidence to do the same higher up the dome. It is the first vertical bit at the base that is the hardest. Once it starts to lean in it becomes easier and easier. Remember that the more cement you add the more it reduces insulating capacity and also increases drying time because the spaces between the grains are filled in more.
Make sure you wear rubber gloves.

[Chobbs]

I did something similar but found the Vcrete too unwieldy to form into a flat barrier.....maybe in doing something wrong? In the end is was just forcing it onto the dome shape in handfuls with the hope of it staying there. Not too much of a perfect dome shape but it will do for now. It is now covering the dome hardening so hopefully I did something right. I might add another inch with some sort of form if I don’t think it’s thick enough or finished well enough.

i was using a 1/10 or 1/8 ratio for the most part.

For now I’m going to leave it for 48hrs before starting the curing process and will see if it cracks.

[david s]

You will be able to easily shave its shape or add more where you need to after 24 hrs. I’d strongly recommend leaving it to dry for at least a week. Around 1/3 of the volume added is water so there’s lots to get rid of. When it turns white you’ll think it’s dry but it won’t be. Then you can start the drying fires. Leave doing the outer render until the vermicrete is completely dry.

[Chobbs]

Thanks for the advice! I’ll wait until next weekend to start the fires then.