Thread: Wooden Cap

Anybody ever seen this before? It's a masonry firebox and chimney. I've never seen plywood below the mortar cap?????

Aaron

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Aaron, is the chimney sealed shut? It's hard to tell from the partial pic.

If it is sealed, the plywood will only last so long before water gets in and rots the wood. If the fireplace is operable, then it's even worse.

No, it's presently in use. Why would there be plywood there in the first place? I've overseen the building of a few masonry chimneys in my time and there was never plywood involed save for forms in the crawl space.

Aaron

Originally Posted by Aaron Miller

No, it's presently in use. Why would there be plywood there in the first place? I've overseen the building of a few masonry chimneys in my time and there was never plywood involed save for forms in the crawl space.

Aaron

I think most masons would use corrugated galvanized steel. Some masons use to be carpenters and just can not get away. But wood takes on humidity and cracks the cap. Should be no wood in that area anyway. Could also be a homeowner special

It likely had a full metal cap at one time that was replaced with what is there now.

They used plywood to form/set the concrete.

Shouldn't they have used flashing instead of plywood?

Aaron

This is typically done when the chimney is built as a one wythe outer shell and no fill to the flue. It looks like a brick chase with terra cotta flue tiles. When you get to the top, the mason sets plywood to hold a mortar crown.

This should get a leve III inspection: remove the crown and combustible plywood, inspect the interior and develop a game plan. If it is a chase with more than 4" air space around those flue tiles, a total rebuild would have to be considered or possibly a liner.

Bob

Originally Posted by Bob Harper

This is typically done when the chimney is built as a one wythe outer shell and no fill to the flue. It looks like a brick chase with terra cotta flue tiles. When you get to the top, the mason sets plywood to hold a mortar crown.

And, if I recall correctly ... plywood burns ... doesn't it?

Yes... that plywood is set in place for the mortar cap as a form. That's all. That sucker should not be there.

Wood should be burned in the fireplace... not on top of the chimney.

rr

Thanks to everyone for confirming my doubt that this was a legitimate installation. As EC Jerry said - wood burns. As Richard said - should be burned in the firebox, not at the top of the chimney. As Bob said, I ordered a level III inspection.

Thanks again,

Aaron