Tips to prepare fire damaged walls for redecoration
After a house fire, you’ll want to get your home back to its pre-blaze state as soon as possible. Fire can cause many problems to the fabric of your home, including damaging and cracking walls. Damage assessment and repair is part of the restoration process after a fire.
In this article, you’ll learn about the severity of damage that walls suffer because of fire, and how to fix cracks in walls caused by fire damage.
Spalling – what is it, and how is it caused?
Spalling is the term used to describe the pitting and chipping that fire causes to brick, block, and concrete. It’s a sign that the concrete has lost strength, and is caused by heat expanding the concrete one way while the mass of the wall pulls it the other.
This type of heat stress can cause concrete to crack. If this happens, it’s likely that the crack will be penetrated by soot. The acidity of the soot could, in turn, affect the wall’s steel reinforcing. Therefore, before attempting any repairs, it’s essential that you have your building assessed by a structural engineer or other experienced and competent person.
Clean walls before repairing them
Smoke damaged walls will need to be cleaned. How to do so depends upon how badly damaged your walls are:
- Light damage requires dry sponging, vacuuming, and washing with a mild detergent.
- Moderate damage may need sponging, vacuuming, and power washing.
- Heavy damage may also require degreasing, and soda blasting.
For a comprehensive (but concise) guide to cleaning after a fire, see my blogs:
And remember this important tip: never fill in cracks in walls before cleaning.
Different walls = different crack repairs
It may be that certain walling will need to be replaced. Again, this depends upon the severity of the fire. Here are the methods to fix cracks in three different types of wall:
Drywall
- Cut a ¼ inch v-shaped notch along the crack
- Vacuum away any loose material
- Cover the crack with joint tape
- Apply a thin layer of joint compound, extending 1 to 2 inches beyond the width of the crack
- Allow to dry, before applying a second coat of joint compound feather to 5 to 6 inches beyond the width of the crack
- Allow to dry thoroughly
- Sand smooth
- If the plaster is moving away from the lathe, first shore up the wall by:
- Drilling holes every 3 inches along the length of the crack. Penetrate the plaster, but not the lathe.
- Remove debris from the holes.
- Inject adhesive into each hole, and clean excessive adhesive away.
- Attach plaster rings to pull the plaster against the wall.
- Allow to cure and then remove the rings
- Use joint compound to fill the holes and the crack
- Sand smooth
- Tap 3-inch nails into the crack every 12 inches
- Mix an epoxy and apply injection ports, before attaching them to each nail
- Spread epoxy over the crack, extending to a width of 1 inch either side of the crack
- Allow the epoxy to cure
- Inject liquid concrete into the ports, and plug
- Allow to cure for at least five days, before cutting flush to the wall
Plaster wall
- If the plaster is moving away from the lathe, first shore up the wall by:
- Drilling holes every 3 inches along the length of the crack. Penetrate the plaster, but not the lathe.
- Remove debris from the holes.
- Inject adhesive into each hole, and clean excessive adhesive away.
- Attach plaster rings to pull the plaster against the wall.
- Allow to cure and then remove the rings
- Use joint compound to fill the holes and the crack
- Sand smooth
Concrete walls
- Tap 3-inch nails into the crack every 12 inches
- Mix an epoxy and apply injection ports, before attaching them to each nail
- Spread epoxy over the crack, extending to a width of 1 inch either side of the crack
- Allow the epoxy to cure
- Inject liquid concrete into the ports, and plug
- Allow to cure for at least five days, before cutting flush to the wall
If the cracks are deeper than ¼ inch, we recommend that you have them professionally repaired. The structure and solidity of the wall may have been impaired, and it is always best to err on the side of caution. Once all cracks have been repaired, you can then start the process of redecoration as your home and life returns to normal.
Contact Porter’s Cleaning today – we’ll be happy to provide a no obligation quote for any clean-up and restoration work that may be needed after a fire.