Adding WFO to existing BBQ build

[gwmckay]

Thank you for that, I’m based in Northern Ireland but will certainly keep an eye on marketplace

[mikeb21]

Build has commenced, built the base layer and floor at weekend along with frame/former for the walls + cut a number of the heater bricks ready.

Put it together basically and doesn't look too bad, a little compromised due to the original base size but hopefully will turn out ok.

Going to take a few days leave over coming weeks to do some of the build, will post photos in due course!

[mikeb21]

A few photos of the build so far...

2nd hand fire bricks as an insulating layer on top of existing concrete plinth:





Layer of Skamotec calcium silicate insulation board and then heater bricks for the floor:




Mocking up the sides / insulation and frame:










Building up the sides:









Adding a layer of facing bricks to the outside of the insulation:





Mocking up the roof:




Roof frame built:





More mocking up using the frame:




Roof coming together with a layer of Home Brew for good measure:

















Using the BBQ again:

[mikeb21]

Still need to add a layer of ceramic fibre insulation over the roof then render and finish the front.

Question - how long should I wait for the homebrew over the roof to cure before adding the insulation.

[downunderdave]

Anything made with portland cement can have its strength enhanced if kept damp for a week. The homebrew needs to be pretty dry before covering over it with anything because sudden fire turning water to steam can damage it. In good drying conditions, depending how thick your layer is around a week of drying should remove most of the excess water. It is best to do the drying fires after insulation, but before sealing over the blanket.

[mikeb21]

Thanks have been keeping it damp for couple of days as want the home-brew to be strong enough to help support the roof from any movement.

I think I'll finish the front and then try and dry it all out before final covering!

[mikeb21]

Front roof/arch and chimney now fitted:

[mikeb21]

All the support structures removed and finished off the front including making a door to keep unwanted stuff out:





Lighting small fires now:

[mikeb21]

Well I've continued with the build and hopefully it will be OK as I didn't have or want to spend even more money on vermiculite for the roof.

Ceramic fibre insulation laid (two layers of 25mm) and held down with chicken wire:



First rough layer of homebrew to provide a solid surface:





Final render and shaping:



Just need to decide what to do each side of the arch, can't decide on leaving as is, just adding mortar to complete the arch or another yellow brick to finish.

[downunderdave]

You should do the drying fires before any final coat. This makes removing moisture easier.

[mikeb21]

Aug 4, 2020 19:27:14 GMT downunderdave said:

You should do the drying fires before any final coat. This makes removing moisture easier.

There is only about 10mm homebrew on the back of the fire bricks, did a series of drying fires over course of week to ensure this was dry before laying blanket.

The first layer onto the mesh was literally the thinnest of skims to provide a solid layer to render to, dried out over a couple of days before the render was done.  Will leave it the rest of week (keeping damp to help setting) and then do another series of drying fires.

Have left a few small holes in the top (out of sight) all the way through to blanket to allow any moisture to escape during drying which can be sealed later.

[mikeb21]

Small update, started a few more small drying fires and found that I was getting a lot of smoke out of the front (probably as chimney/flue is so close to front due to lack of depth as limited by original BBQ dimensions) with the door off and with the door on it was starving the fire, so added a £2.50 vent from screwfix into the door which is working perfectly to allow the oven to draw air in whilst keeping the door closed and any smoke out of the chimney/flue:



Had a fire burning for about 2.5 hours last night and checking the insulation...

Concrete slab under floor cold
Side walls were cold except for one slightly warm spot on each side
Roof was cold except for the top ridge which was slightly warm
Back wall was quite warm

So looks like the back wall insulation isn't perfect. However 12 hours later this morning the heater bricks are still holding heat.

Will give it a little longer before actually trying any cooking.

[downunderdave]

New ovens are notoriously smoky until properly dried so don’t go making any drastic changes. Also don’t be in a rush to get to pizza temperature too fast. Try roasting some chicken, you’ll never want to roast them any other way.

[mikeb21]

So with the rain finally coming after the last few days of heat I was wondering should I waterproof my render in some way?

Is this necessary if so any recommendations of waterproofing techniques / products?

[dave36]

Aug 13, 2020 20:59:22 GMT mikeb21 said:

So with the rain finally coming after the last few days of heat I was wondering should I waterproof my render in some way?

Is this necessary if so any recommendations of waterproofing techniques / products?

K-rend, easy to apply, comes in colours, breathable, nice finish. (I don’t work for k-rend btw). It is slightly dearer than making your own render, but you do save on the paint cost.

D