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Greg Hoedl
Uncovered Chimney concern

Outside at the top of my chimney there are to openings exposed to rain. Do I need to cover them and why. I have never had problems with water, but I am concerned living in a very rainy area as to where the rain that does get in goes. My observation of other chimneys in the area is that some have various covers, others do not. Do I NEED to spend the money to cover them or is the chimney designed to take on rain?

Re: Uncovered Chimney concern

I assume we're talking about a brick, masonry or stone chimney with two flue liners protruding an inch or two out the top.

Yes, stainless steel chimney cap for both flues recommended for several reasons.

A brick, stone or masonry chimney is a product of previous centuries; they are rarely being installed any more in new housing because of cost, liklihood of weather deterioration & slight movement separate from the building---all of which will eventually cause small cracks & leakage---unlike the newer stainless steel chimneys that don't have these problems, masonry chimneys need periodic inspection & maintenance to prevent water leakage.

Not only will water get into the bottom of the chimney & cause problems with rusting the firebox and any damper present, but more important, there is a concrete MORTAR CROWN at the very top of the chimney that provides a seal between the flue liner and the top run of bricks that prevents deteriorating water from getting in between the flue liner & brick course to work its way into the attic & cause ceiling leaks and damage.

Wind, rain & sleet will eventually wear away the seal on most masonry chimneys to create hairline cracks, which are all that's needed to cause water leakage into the house.

Other reasons for a cap include keeping birds, squirrels & other critters out of the flue---birds in particular perch right over the flue in cold weather to "steal the heat" & inhale the carbon monoxide, pass out, & fall into the flue to cause a blockage.

This can be done as a diy project if you have a low roof and the proper ladders & safety equipment; however, if you don't feel comfortable going up on a roof, consult the Yellow Pages under "Chimney Builders & Repair" or "Roofing" to get several estimates for the job.

To maintain a chimney in good condition, the top & side mortar joints should be inspected at least once a year to determine if any mortar has been lost from the mortar crown, as well as the mortar joints on the rest of the chimney; "pointing" refers to the process of chiseling out any mortar deterioration & applying fresh mortar to the deteriorated joints.

The box stores carry the standard chimney caps for a 9" X 9" or 9" X 14" flue ($45-$50 typical stainless); go to a roofing supply wholesale house to get different sizes also in stainless steel; most will sell to a homeowner at wholesale (Yellow Pages: "Roofing Supplies).

Don't even THINK of buying a painted steel chimney cap---always buy a STAINLESS STEEL cap that will last a long time & won't rust out in 6 months and create an ugly rust stain on the chimney and roof shingles; never install any steel or painted steel parts on top of a chimney---they will only rust out in a short time & cause ugly rust stains.

If there is not enough flue liner sticking out of the chimney to bolt the base of the chimney cap to (think of losing the cap in high winds), drill some holes (with a masonry drill bit) on the 4 corners of the top brick course (brick is very soft to drill), cement in some stainless steel bolts, & attach the cap to the bolts with copper or stainless steel wire.

At the site below, in the left-hand column, click onto "Why do I need a chimney cap?"


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