Oven Rebuild Ireland

[benji]

My favourite pizzeria was giving away their old oven. Well some of it. The steel base and the dome were all that survived. It's a Pavesi RPM 120.

Here are some photos of the build.

I live in Ireland and it rains a lot, so water is a big concern for me. I know this oven will retain water, its inevitable. So I needed to think about drainage. We drilled weep holes and added tiles to the base. Thanks to the forums for these great tips! I raised my Calsium Silicate board up from the tile with a layer of Vermicucrete. I hope this clearance from the steel will help with moisture retention.

I still need to dry out, then paint the oven. Rather than going for a waterproof finish I will try to cover the oven with a pergola. The humidity is so high here that this oven will inevitably suck in moisture and I need to make it as easy as possible for that moisture to escape.

If anyone has any tips or advice for waterproofing(or anything else) I would love to hear them.

[SableSprings]

You've done a great job so far Benji! I think you are very wise to build a pergola over your oven rather than search for a "magical" waterproofing paint. Over the years, we have seen lots of different approaches and sadly, most fail over time. There is a reasonably good additive to help make water resistant cement, but water and time seem to always win . I built a 16'x16' around my oven so that I could enjoy cover from the rainy days and screened it so it became a no fly zone (or yellow jackets. mosquitoes, etc.). Your extended roofing system is really the only thing that seems to consistently provide adequate protection from water entering the oven's insulation via the cracks & crevices that always appear in any render. Locations with high humidity will always are affected with the creeping damp just via the air.

So even covered, you'll want to continue to use it on a semi-regular schedule if at all possible or be prepared to have a couple low fires after a month or more of inactivity to dry it out again. Usually not a problem using your oven year round once you discover how good a roasted chicken, pork loin, or even simple roasted veggies are in your WFO...and not to mention the bread (and none of these require pizza temps!)

p.s. You've probably seen the tip about covering your oven with some clear plastic during the later curing/drying fires...the plastic over the oven will show you if moisture is still escaping (as it condenses on the plastic).

Good luck & make sure to continue this thread so we can watch your progress...so much fun & enjoyment coming your way!

[david s]

Plus one to your comments , Mike. To help prevent water pooling around the base of the outer shell, a slight fall from that point to the outside perimeter of the supporting slab goes a long way to discouraging water from sitting up against the base of the outer dome. This is best done when pouring the slab, but is more tricky than making it dead level.
A product developed to reduce leaks from the ridge caps on tiled roofs, that was developed in the 70’s is a very flexible acrylic and designed to be high build by the addition of fine sand. The idea is to trowel a coating over the mortar that holds the ridge caps in place. Because a tiled roof is constantly expanding and contracting, a flexible, waterproof material is called for. Even if the mortar cracks a little this flexible coating will bridge fine cracks. Experienced old tilers confirm that prior to this invention they regularly had to re-mortar ridge caps. Now they never do. I thought that as our ovens are also subjected to continual expansion/contraction cycling, with the resulting problem of cracks developing, it would be an ideal product for our application. I’ve now been using it for the past 16 years on ovens, but to make application easier I water it down 20% so it can be applied by brush. 3 coats results in a layer around 1mm thick and works extremely well. In Australia the product is called Flexible Pointing.
one other point to make is that adding more cement to a render mix simply makes it more brittle and prone to cracking. A good mix is 4:1;1:1 fine sand, general purpose cement, hydrated lime. (lime imparts some elasticity as well as crack healing properties).This mix reinforced with AR (alkaline resistant) glass fibres does a wonderful job to reinforce the outer shell. I make this outer layer only 12-15mm thick and don’t have problems with cracking.