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Do-It-Yourself Chimney Repair

If you have a chimney as a part of your house, it is inevitable that it will eventually require some maintenance.

Although often overlooked, chimney maintenance is crucial for not only keeping your chimney functional but also for preventing fires and fumes from entering your house.

If left to deteriorate, a chimney can also easily become a point of structural weakness for the house. A collapsed chimney can bring down your walls, your roof, and anything else to which the chimney happens to be attached.

Luckily, it is easy to keep a chimney healthy through proactive inspection and cleaning. If your chimney is well looked after, issues that do pop up will be easy to solve, even on your own.

The following article will cover some advice for preventing your chimney from needing repairs, as well as how to approach any problems that come up.

Inspecting the Chimney: When Does a Chimney Need Repairs?

As a rule of thumb, it is a good idea to have your chimney professionally inspected at least every year, or more frequently if you use your chimney year round.

Inspectors can find and fix small problem areas such as minor cracks on the spot, which means that a frequently inspected chimney will need very infrequent repairs.

If your chimney is regularly inspected and is not giving you any issues, you are probably fine to continue using it as normal with no worries..

If you notice larger than normal cracks in any part of your chimney, if water or debris is getting into the flue, or if it isn’t venting properly, there is a larger issue that needs your attention. 

Basic Cleaning

The best way to keep your chimney healthy is simply to clean it regularly. Regular cleaning improves the smoke and gas ventilation, increases the heat efficiency, and reduces the risk of fire.

  • Tools
    • A steel chimney sweeping brush
    • A rope at least as long as the full chimney
    • A counterweight, such as a filled bottle of water
    • A good vacuum cleaner
  • Steps
    • First, secure the counterweight to one end of your steel brush. Secure the rope to the other end.
    • Lower the weighted brush down the chimney and hold it against the inside walls. Use the Full length of rope to drag the brush all the way up and down the sides, scraping off built up soot and creosote.
    • The debris will fall down your chimney and land in your fireplace and hearth. Use a heavy duty vacuum to clean the rest of the mess up.

Sealing Small Cracks

Small surface cracks are the most common damage you will see on a chimney. Hairline cracks, or so-called spider cracks, are typically not dangerous and can be easily fixed.

  • Tools
    • A ladder
    • Gardening gloves
    • Caulk
  • Steps
    • Use the ladder to get up to your chimney. Inject caulking into any visible cracks. Smooth the caulk. That’s it!

Repairing Mortar

The mortar is what holds the bricks of your chimney together. This mortar is made out of a much weaker substance than the bricks, so the mortar will have to be repaired more frequently than the bricks themselves.

  • Tools
    • A joint raker
    • A trowel
    • A set of gardening gloves or hand protection
    • Fresh mortar
    • A hose or power washer
    • You may also need:
      • A chisel
      • A ball peen hammer
  • Steps
    • Use the joint raker to scrape out the loosest and most deteriorated mortar from between the brick of your chimney. You shouldn’t have to scrape out all of it, just enough to expose whatever fresh mortar remains.
    • Use your hose or power washer to clean the bricks as thoroughly as you can. Make sure they are able to fully dry, at least 30 minutes, before continuing.
    • Put on your gloves and mix your mortar to the consistency of peanut butter. Use the trowel to scoop mortar into the gaps in the bricks and smooth it out. Make sure that the mortar isn’t spilling out from between the bricks.
    • If you find that you have some areas of mortar that have completely eroded and the bricks are coming loose, use a chisel and ball peen hammer to break off the old mortar from the bricks. Wash them and replace them with new mortar. Aim for a mortar thickness of about ½ inch, or match it to the rest of the chimney.

Repairing a Damaged Crown

The crown keeps water from running down the flue, as well as sheltering the stack from weather erosion. A damaged crown can let in water, which is disastrous for the well being on the chimney. 

  • Tools
    • A trowel
    • A wide Brush
    • Sealant
    • You also may need:
      • Chisel
      • Ball Peen Hammer
      • Caulk
  • Steps
    • If the crown of your chimney is cracked, you may simply use caulk to seal the cracks. If your crown has more extensive wear, you will need to redo the crown.
    • If necessary, use a chisel and ball peen hammer to pick away crumbling crown masonry.
    • Once the area is cleared of debris, apply sealant to the crown and use a wide brush to smooth the surface. Your crown must create a downward slope to direct water to the edge, and it must end in an overhang to keep the stack as dry as possible.

Broken and Cracked Bricks

If the actual bricks of the chimney are cracked, it isn’t worth it to try and repair them. They will always be a structural weakness, so must be completely replaced.

Luckily, you will likely only have to worry about the bricks which are actually damaged.

  • Tools
    • A trowel
    • Mortar
    • A chisel
    • A ball peen hammer
    • You may also need:
      • Power drill with a masonry bit
  • Steps
    • Use the chisel and ball peen hammer to chip the mortar around a broken brick to loosen and remove it. If the mortar is difficult to chip you may drill small holes into it first to make it easier to break.
    • Use the chisel and hammer to carefully chip off any residual mortar from the neighboring bricks.
    • Use your trowel to liberally apply mortar to all bricks neighboring the one to be replaced
    • Insert the new brick into the mortared gap. Push into place. Use your trowel to remove any excess mortar.

How to Repair Broken Flashing

The flashing covers the area where the chimney meets the roof. This area would be a structural weakness, allowing in water and becoming an easy point of erosion, if not for the protective flashing.

The flashing can come loose due to expansion and contraction of the materials from weather, rust erosion, or improper installation in the first place.

  • Tools
    • Replacement metal flashing
    • Mortar, sealant, and/or caulk
    • Trowel
    • Spare shingles
    • You may also need:
      • A powersaw to cut the sheet metal
      • A power tool to grind a groove into the chimney
      • Nails
  • Steps
    • Remove old flashing and clean the area of debris. You will need to cut new flashing first; if you have flashing prepared, continue
    • Remove shingles around chimney area
    • Carve a groove into the chimney
    • Insert one end of the flashing into the groove. Seal.
    • Lay the other end against the roof and reinstall shingles over top

How to Repair Broken Cap

The capis the topmost portion of the chimney. It is a little grate that sits on the opening to the flue, blocking rain from above and trapping out small animals, leaves, and other detritus from coming in.

  • Tools
    • Chimney cap
    • Screwdriver
    • Screws
  • Steps
    • You can buy a chimney cap already made. Pick up something that fits the dimensions of your chimney and that you like
    • The cap will have holes into which screws may be inserted. The flue may not have holes for screws. Screw the cap onto the flue through available holes, or directly screw the cap onto the flue if no holes are available.

When to Call a Professional

Chimney repairs have a broad range of difficulties and may require either very simple or very advanced tools.

However, sometimes the choice of DIY or professional help comes down to safety rather than convenience.

The circumstances listed below are ones in which it is almost always in your best interest to immediately call a professional.

  • Leaning Chimney
    • If your chimney is visibly leaning in any direction, it means the joints securing it to your house are coming loose. This poses a serious hazard as it means your chimney could collapse.
  • Split in Chimney
    • If your chimney is not cracked but fully split along the stack, it will need to be replaced.
  • Collapsed or Completely Crumbling Chimney
    • If your chimney is in such bad condition that it is completely coming down, either in collapse or by crumbling, it will need to be entirely replaced.

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