How to Fix a Sagging Floor in an Old House

It’s such a bummer when you find out your home has any kind of damage. From water damage to roof leaks to sagging wood floors, these are problems that require immediate attention for homeowners.

While some issues can be considered major, if you can detect the potential damage early enough, you can rectify it even on your own without having to pay much out of pocket.

For example, a sagging floor in your home can imply there is some damage to the wood underneath the floor. It can also predicate that there is a deterioration of the support or foundation of the home. Don’t go there just yet. This article will lay out the indications that your flooring is sagging and how to fix a sagging floor in an old house.

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Potential Causes of a Sagging Floor

According to home builder professionals, there are a few prevailing reasons your older home has sagging floors. Wood rot is a top cause. Where there are water leaks, wood is susceptible to wood rot and the wood will break down causing a floor dip in the middle of your given room.

Other reasons range from insects such as wood-hungry termites, and a poorly sized beam used in construction.

In some cases with homes that have a slab floor, the soil sometimes gets compressed, which causes the slab to shift. Also, pressure from the ground creates a shift in the slab causing it to crack, which then leads to a sinking floor above it.

Time to Inspect the Sagging Floor Problem

Take the time to walk through your home to inspect the various aspects of how your house was built. This way you can see where the problem lies and take the necessary action.

1. Beams

If your home is built over a basement, check out the support beams and posts. Beams are horizontal pieces that are essential to holding floors, walls, or roofs to the foundation walls. The goal of the beam is to provide an even and level surface. If your floor beams or posts look rotted or are damp, this is the area that might need fixing.

These supportive beams are more likely to become damaged when they sit directly on the dirt floor. If this is what is happening in your case, think about upgrading the footings to concrete pads.

2. Floor joists

Joists are similar to beams except that they consist of several smaller beams. Technically joists do the same job as a beam to support the flooring, etc. Take a look at the construction of these joists. Sometimes floor joists get low priority in the building stage. They may be cut in a way that is better for the install of piping, HVAC or wiring. Look for careless cuttings, improper holes, or notches. This could be an indication that the floor joists have become weakened or cracked over time.

Grab a tape measure to measure out the notches at the end of a joist. Here they shouldn’t be larger than ¼” of the depth of the joist. Center notches should be ⅙” or less of the depth. Holes should be no smaller than 2” from the joist’s top or bottom, or not larger than ⅓ “ depth.

3. Insect destruction

As mentioned earlier, wood-eating insects could be the problem to your sagging floors. There are a number of insects that like to feast on wood in homes. These small beasts include Termites, Carpenter Ants and Bees, Bark Beetles, and Powderpost Beetles. These critters gnaw their way through and travel via mud tunnels atop the foundation or beams. Exposing the deteriorating foundations or beams leaves the space ample opportunity to attract moisture. This then exposes your flooring to digs and sags.

Fixing the Sags and Dips

Without having to call a professional to come to your home for a fix, there are multiple techniques you can try on your own to fix that annoying sag in your home. These are not quick fixes potentially. It all depends on the independent circumstances.

1. Pour Self-Leveling Concrete.

Self-leveling concrete is one of those easier to use DIY home products when you want to flatten your existing flooring. These products will work on concrete, tile, and plywood. Created of a polymer, this concrete is a viscous liquid that lays flat atop the surface. In this case, you would make certain you are working with a clean floor (not carpet) and give the space the suggested curing time. This can be applied directly onto concrete, plywood, or subflooring. Reading the product directions thoroughly is a must. Self-leveling concrete can be purchased at most hardwood and home improvement stores.

2. Sistering the Joists

Sister the joists is one of the more effective and efficient ways to rid of those floor sags. This method in basic terms lifts the floor. You add an identical joist (piece of lumber) to the improper floor joist. Try to cut the same size as the damaged joist. You bond the two together with screws or nails. Thus, the new joist supports the older one diminishing the sagging.

Another idea is to sister the existing joist to one or two flitch plates. These ¼” – ½” pieces of steel or engineered wood can be secured to the joist. Match up the steel or wood flitch plate to the existing joist. These plates can be secured with bolts on both sides of a joist.

3. Screw Jacks

You’ll need a screw jack. The screw jack offers support to actually lift underneath the damaged sagging joist. This job isn’t for the weary. There are a lot of heavy pieces and equipment involved. Both screw jack and hydraulic jacks are used to lift the heavy joists. Once jacked up, you can sister the joists (see above), which will reinforce the joist.

This type of DIY activity may require more help. You can always consult with a structural engineer who may help you avoid any mishaps or permanent damage to your home.

4. New Hardwood

Probably the more expensive option, you may opt for laying down new hardwood flooring. This can be accomplished by placing it on top of your existing floor. Before you consider this choice research your current subfloor. You want to be certain the joists can handle more weight. And, if the joists or beams need additional support you can sister the joists and add adjustable columns (the vertical piece in your foundation).

Older homes come with a history. Shifts in the home’s foundation are also part of its story. Floors take a hit with age. And, while some homeowners refer to their sagging floors as a home with character, others want to fix the problem ASAP. It takes a bit of detective work to nail down what is the problem. A journey into your home’s crawl space can give you the answers you need. Once you diagnose the problem several DIY actions are in your reach. Hopefully, now you can enjoy your living space without those unnecessary dips on the floor.

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