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Re: Chimney extension
The mortar btw chimney and house could be normal from how they built it but you have to suspect the chimney is not tied to the house and is pulling away. I see it is crooked as a dog's hind leg. The wide head joints and smaller footprint than the original tells me these bricks are probably nominal in size while the lower originals are true 8", thus the way it truncates in at the cold joint. I recommend those footings be probed to see how far out they extend. That starter course has already had problems so what's up there? Water pulling up from the ground? Weak mortar mix/ cure?
David, the joint btw masonry and frame construction is always a joke. The code calls for a 1" clearance to combustibles. Finally, the IRC realized there was no way to literally comply with this so they came up with an allowance of minimal material touching the chimney inside and out to form a weather seal. However, you cannot pack this joint with insulation. Since it is not really properly flashed, it will forever be a potential water intrusion point. You have two ways to build a chimney on an exterior wall: frame a gash in the side of the house and fill it with brick & mortar or frame out an opening but sheath over the exterior wall then run your brick up the outside trying to maintain your 1" airspace to the frame construction. If this is done, how do you seal the lower edge of the frame out at the header so it meets the energy code with clearance to combustibles? This joint is a major source of air infiltration. With warm moist air entering this interstitial space, you have a major propensity for condensation in the wall cavity. It is an energy hog, water intrusion threat and fire hazard all designed by code. That's what minimum stds. will get you.
how was the flashing and crown wash? Those are two of the usual water intrusion suspects.
Good job!
Bob
__________________
Keep the fire inside the fireplace!
IAFCI Regional Director & Certified Fireplace Inspector
Certified Master Hearth Professional & HPBA BoD
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