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If you can bear to wait, covering the slab to hold in the moisture can substantially increase its strength. The industry standard is 28 days, but at least a week can make a huge difference.
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Kindled with zeal and fired with passion. -
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Either of those should be fine. Ideally the whole thing is best sealed, but it may not be practical to seal up the underside, so just covering the top surface will stop sun and wind from drying it out.
This little chart explains the importance of damp curing and the relationship between moisture, time and strength.
Last edited by david s; 11-02-2026, 07:26 PM.Kindled with zeal and fired with passion.Comment
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So I’ve trimmed the template up to a 570mm radius giving a 44’ oven which leaves me with 110mm (not quite 4.5’) from soldier course to back wall . I will rebuild forms for oven opening to suit new 44’ WFO but at the moment front one is 140mm (5.5’) back from edge of hearth. Feel it will be a squeeze at the back come time for rendering. Have I left myself enough landing at the front?Comment
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Your oven size reduction should give you enough room now. A 44” oven requires an 8” (200mm) diameter flue pipe, so factor this into your plan for the entry and gallery.Kindled with zeal and fired with passion.Comment
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Laid out tiles to assist with water/moisture to wick away. After having no luck getting any response from nearest refractory to source cal-sail board and another charging the same price as materials for delivery I have decided to lay a insulated slab of perlite and vermiculite + cement mix . I took a trip to Bunnings and sourced some 100mm garden edge for the form and added a layer of aluminium fly screen as suggested on a post I read. Dropped into the local garden centre and picked up some 100Ltr bags of both perlite and vermiculite. All going to plan will mix some up tomorrow to get this WFO 1 step closer.Comment
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