After deflating and removing the tube, the full smoke chamber is visible. There are some rough edges that will need to be smoothed out. Supaflu is much more difficult to carve after it has hardened overnight.
Carving with chisels and files yields a streamlined smoke chamber. Because the throat of the chimney is so narrow, the tube touched a few spots directly above the lintel. So, it's not quite perfect, but a considerable improvement over what it was.
Supaflu is a very effective insulator, so this flue will warm up rapidly, not leaving cool spots that will allow flue gases to condense as soot or creosote.
Plastic sheeting makes a bond break at the top of the chimney so our concrete will not be connected to the chimney structure. Foam sill insulation wrapped around the flue tiles makes a 1/4" expansion joint. Flue tiles grow larger when heated and will damage a crown if there is no room for them to expand.
After the standing water evaporates from the concrete, we trowel it smooth and use a concrete edger to compress and round the edges to make them stronger.
We filled them in with mortar repair caulk. ChimneySaver water repellent was then applied to the chimney, but it is invisible after applied, so you can't see it.
Hot southern days breed thunderstorms, so we covered the chimney with a tarp to protect the wet concrete.
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The Supaflu had hardened overnight, so it was time for the finishing touches. The tube was deflated and removed from the flue, revealing the new Supaflu liner.
The smoke chamber needed some smoothing, and after some quality time with wood chisels and rasps, it looks pretty good.
After the smoke chamber was finished up, we poured a concrete crown at the top of the chimney, filled in some open mortar joints on the chimney exterior, and applied ChimneySaver Water Repellent.
It’s been a very warm week in the mountains of Western North Carolina with temperatures in the high 90s and the Heat Index around 107°. This kind of weather is really fun to work in, and it also breeds thunderstorms in the afternoon. With thunder rumbling in the distance, we covered the chimney with a tarp to protect the fresh concrete on top of it.
