Chase Cover Replacement

Chase Cover Replacement

This page is about the replacement job itself, what gets made, to what specification, and what separates a cover that outlasts the house from one that rusts again in eight years. If you are still working out whether your cover needs replacing, or what the rust streaks on your siding mean, start with chase cover repair, which covers the diagnosis in detail.

Free estimates, no obligation. Call (888) 882-2070.

The Specification Is the Whole Job

A chase cover is a simple object: a metal pan with a turned-down edge, holes for the flue pipes, and a collar around each one. Because it is simple, the price differences between quotes almost never come from complexity, they come from specification. Four decisions determine whether the cover lasts a decade or a lifetime, and all four are invisible once it is installed and 25 feet up.

1. Material and grade

304-grade stainless steel is the sensible default. Unlike galvanized steel, it is not protected by a sacrificial zinc layer with a finite life, there is no countdown running from the day it goes on. Copper costs more, weathers to a patina and lasts a very long time; it is chosen for appearance as much as for durability. Galvanized is what most of these chases were built with, and it is why the replacement is happening.

Note that "stainless" alone is not a specification. Lower grades exist and were fitted on plenty of budget prefab systems. Ask for the grade.

2. Welded corners, not sealed ones

A pan can be assembled two ways: the corners can be welded, or they can be folded and filled with sealant. Sealant is a consumable, it hardens, shrinks and eventually opens, and Florida sun works through it faster than most climates. Welded corners have nothing to degrade. This is the single most common place a cheaper cover gives out first, and it is impossible to see from the ground.

3. A cross-break

A cross-break is a shallow ridge formed into the pan so water runs toward the edges rather than sitting in the middle. Without one the pan is flat, and a flat pan holds standing water after every storm. That is why covers often fail in the center rather than at a seam. Any pan large enough to hold water should have one.

4. Skirt depth and a drip edge

The skirt is the turned-down edge that laps over the top of the chase. Two inches is a reasonable minimum and deeper is better, because the skirt is what stops water tracking back under the pan and onto the framing. A formed drip edge at the bottom carries water clear of the siding instead of letting it run down the face, which is what produces the rust and dirt streaking you see on so many chases.

Why It Has to Be Measured

Stock covers exist in common sizes and they are cheaper. The problem is that a chase that is close to a stock size is not the same as a chase that is a stock size. A pan slightly too small leaves a gap at the skirt; one slightly too large sits proud and cannot seat evenly. Either way, wind-driven rain gets underneath, and in Florida, between June and November, wind-driven rain is the norm rather than the exception.

The measurements that matter are the outside dimensions of the chase top, the position of each flue penetration, and the outside diameter of each pipe. Get those wrong and the cover is wrong, regardless of how good the steel is.

Check Underneath Before You Order

This is the step most often skipped and the most expensive one to skip. If the old cover has been leaking, and if it is being replaced, it has, then water has been reaching the chase top plate and the framing below it. That wood needs looking at before a new cover is fabricated and fastened down, because finding soft framing afterwards means taking the new cover back off.

Florida humidity is what makes this urgent rather than academic. In a dry climate, framing that gets wet has a chance to dry out between rain events. Here it often does not, so rot progresses instead of pausing. A cover fitted over rotten framing is a good part on a failing structure.

Where damage has gone further than the top plate, the work moves into chimney frame repair or, if the sheathing and siding have gone, rotten wood chimney replacement.

What Drives the Cost

Two chase cover replacements can be very different jobs. The smallest is a modest chase top with one flue through it, a 304 stainless pan made to measure, one collar, sound framing underneath. The largest is a wide chase top with two or three penetrations, each needing its own opening and collar, in copper, a deep skirt formed all round, and a top plate that has to be rebuilt first. The pan is a simple object in both cases. Everything around it is not.

What the chimney decides

• The area of the chase top. The pan is cut and folded from sheet, so a wide chase costs more in material before any other decision. Chases vary more than people expect.
• How many pipes come through, and where. Each penetration is an opening in the pan and a collar sized to that pipe's outside diameter. Two flues is not one flue with a little extra.
• What is under the old cover. The top plate has been taking whatever the failed pan let through, and here wet wood stays wet. Where damage runs past it, this becomes frame repair rather than cover work.
• Getting a made pan up there. A cover for a large chase is an awkward thing to carry, and a steep or high roof adds equipment to the trip.

What you decide

• Material and grade. 304 stainless is the default and the reason the job is not repeated. Copper sits distinctly above it and is bought for appearance.
• Skirt depth. Two inches is the sensible minimum; deeper uses more sheet and more forming, and does more to stop wind-driven rain tracking underneath.
• How far the framing work goes, once you can see it. Making the top plate sound enough to carry the cover and putting the whole frame right are different pieces of work.

So the estimate is built from measurements. We take the outside dimensions of the chase top, the position of every penetration and the outside diameter of every pipe, and check the top plate first, because a pan made to the wrong numbers is scrap, and one fitted over soft wood comes off again. You get a free written, itemised estimate: material and grade, gauge, skirt depth, collars, and framing work on its own line. The two things that set the figure, the size of your chase top and the state of the wood beneath it, are the two nobody can read from the ground.

Comparing Two Quotes Properly

Two prices for "a new chase cover" can describe quite different objects. Before comparing numbers, get each quote to state:

• Material and grade, "stainless" is not an answer, "304" is
• Whether the corners are welded or sealed
• Whether the pan has a cross-break
• Skirt depth, and whether there is a formed drip edge
• Whether it is made to measure or a stock size
• Whether the storm collar is included
• Whether the chase interior and top plate have been inspected, and what was found

Ask us the same questions you ask anyone else. A contractor who cannot answer them has not specified the job, and a quote that does not state them is a number rather than a scope.

Free estimates, no obligation, call (888) 882-2070 and we will measure, check underneath, and put the specification in writing.