D105 Pre-Cut brick kit build in Tassie

[david s]

Re: D105 Pre-Cut brick kit build in Tassie

I think I have misunderstood your first post.

This was my thought process;

If there is moisture in the fire brick from the build or in future from rain on the hearth etc I assumed it would escape as steam into the air void between the bricks and the vermiculite render where the ceramic fibre blanket is - and you were suggesting it would be advantageous to put a vent in to allow the atmosphere in this space to equalise with the external atmosphere. That's why I was thinking to "drill a hole"

Ok, that would help to get the bricks and blanket dry, but there will be way more moisture in the vermicrete layer where it will collect from being pushed out of the bricks and the large amount that you added in the mix, that needs to be also removed. I cracked a couple of outer shells from not drying the vermicrete properly first, so I'm now really careful.
Remember that one litre of water will make over 1600 litres of steam. There's lots of free water ileft in the vermicrete not used in the hydration process.

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

Yes. But make sure you wear a mask, the stuff is dangerous to breathe. A 4" angle grinder with a diamond blade works ok but will not give you much depth of cut. A 5" one is much better and well worth getting if you haven't already.

Thanks - I have a range of grinders up to 230mm (9") - I will see what granite/stone I can find.

I work in the fibreglass construction industry and have access to all the PPE I could ever need

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

When the vermicrete has dried I like to do the curing fires to be sure there is no moisture in the insulation layer, before doing the cement render outer shell. You may want to consider putting in a vent so your insulation layer can communicate with the atmosphere to relieve steam pressure build up.

I can't see that a hole through your vermicrete layer will be of much benefit, as it is the moisture in the whole vermicrete layer that you are tiring to remove. When you start the fires the water moves away from the heat and the whole surface of vermicrete layer will be sweating it out. You should be able to feel the surface clamy, until it is completely dry. Try throwing some plastic over the oven to see if water is condensing under it. You need to have the vermicrete completely dry before doing the outer cement shell.

I think I have misunderstood your first post.

This was my thought process;

If there is moisture in the fire brick from the build or in future from rain on the hearth etc I assumed it would escape as steam into the air void between the bricks and the vermiculite render where the ceramic fibre blanket is - and you were suggesting it would be advantageous to put a vent in to allow the atmosphere in this space to equalise with the external atmosphere. That's why I was thinking to "drill a hole"

[david s]

Re: D105 Pre-Cut brick kit build in Tassie

Is it realistic to cut stone bench tops to shape/size myself for a landing using a cut-off wheel on an angle grinder - if I pick up some up 2nd hand from the local paper or Gumtree etc.

Yes. But make sure you wear a mask, the stuff is dangerous to breathe. A 4" angle grinder with a diamond blade works ok but will not give you much depth of cut. A 5" one is much better and well worth getting if you haven't already.

[david s]

Re: D105 Pre-Cut brick kit build in Tassie

I don't want a permanent vent, but I can understand the potential m3 of steam/gas that has to make its way out of the brickwork and insulation during the drying/curing stage.
If I drill a 8-10mm hole in the vermiculite render when I finish, and leave it open for the duration of the curing fires, I assume I could simply seal it up before applying the final coat of cement render and final seal coating?

I can't see that a hole through your vermicrete layer will be of much benefit, as it is the moisture in the whole vermicrete layer that you are tiring to remove. When you start the fires the water moves away from the heat and the whole surface of vermicrete layer will be sweating it out. You should be able to feel the surface clamy, until it is completely dry. Try throwing some plastic over the oven to see if water is condensing under it. You need to have the vermicrete completely dry before doing the outer cement shell.

[Greenman]

Re: D105 Pre-Cut brick kit build in Tassie

I don't want a permanent vent, but I can understand the potential m3 of steam/gas that has to make its way out of the brickwork and insulation during the drying/curing stage.
If I drill a 8-10mm hole in the vermiculite render when I finish, and leave it open for the duration of the curing fires, I assume I could simply seal it up before applying the final coat of cement render and final seal coating?

You could do that, it would work but I would make the hole a little larger. No big deal to render it later. A permanent vent would be handy should you be unfortunate enough to get the hearth soaked in the future but that is up to your preference.

I can not help with your benchtop cutting question. One for someone who knows.

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

Is it realistic to cut stone bench tops to shape/size myself for a landing using a cut-off wheel on an angle grinder - if I pick up some up 2nd hand from the local paper or Gumtree etc.

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

When the vermicrete has dried I like to do the curing fires to be sure there is no moisture in the insulation layer, before doing the cement render outer shell. You may want to consider putting in a vent so your insulation layer can communicate with the atmosphere to relieve steam pressure build up.

I don't want a permanent vent, but I can understand the potential m3 of steam/gas that has to make its way out of the brickwork and insulation during the drying/curing stage.
If I drill a 8-10mm hole in the vermiculite render when I finish, and leave it open for the duration of the curing fires, I assume I could simply seal it up before applying the final coat of cement render and final seal coating?

[david s]

Re: D105 Pre-Cut brick kit build in Tassie

When the vermicrete has dried I like to do the curing fires to be sure there is no moisture in the insulation layer, before doing the cement render outer shell. You may want to consider putting in a vent so your insulation layer can communicate with the atmosphere to relieve steam pressure build up.

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

Thanks Gulf - I am glad I asked as I hadn't considered it would trap the moisture.

[Gulf]

Re: D105 Pre-Cut brick kit build in Tassie

As it will be a number of weeks before I get to put another layer on, will I need to add bondcrete or a similar product to the mix or will the next layer stick ok?

Don't paint, mix, or add anything between "dried" layers of Vcrete. You don't want anything trapping moisture in the insulation layer. A good brushing with a dry paint brush or better yet, vacuuming with a shop vac to remove the loose dust is all that you need to do. Then with a paint brush, lightly dampen the surface before the next coat. You can lightly dampen the surface a little at a time, just staying a little ahead of the next application .

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

As it will be a number of weeks before I get to put another layer on, will I need to add bondcrete or a similar product to the mix or will the next layer stick ok?

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

My second vermiculite layer - Sunday 28-06-15

The first pic shows where I stuck my finger in the initial layer - twice..

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

First layer finished. Saturday 27-06-15

[Steady]

Re: D105 Pre-Cut brick kit build in Tassie

Applying the first layer of vermiculite render.