How To Fill A Large Gap Between Patio And House

If you have a significant gap between your house and your concrete patio, it’s essential to consider filling it up. That way, you can prevent water leakages that may end up inside your house, causing water damage. In this article, we’ll guide you on how to fill a large gap between your house and patio affordably.

How Do I Seal the Gap Between My House and the Patio?

When a slab of concrete is laid between a concrete patio or a concrete step and your house, it is usually called an expansion joint. These joints are installed before concrete is poured into areas such as gardens, driveways, basements, and between your house and concrete patio or any other area where a concrete slab meets another slab.

This allows two different slabs to expand and contract effortlessly during hot weather conditions to prevent water from running into the gap. A paving slab or concrete outside your house gets direct sunlight, which heats it up, while the slab on the inside of your house sits in the shade. This means that the rate of expansion and contraction of the two concrete slabs is different because the concrete slab expands and contracts more than the paving slab. 

Large Gap Between Patio And House
Large Gap Between Patio And House

Filling the gap requires using a flexible material that won’t crack. That is why using cement and gravel to fill the gap is not the best option, as the concrete will crack after some time and allow water to seep through into your house.

Having a gap between your patio and the house can cause serious damage to your property down the road. Therefore, you must have it filled at the right time. It would be best if you don’t do it immediately after you finish the construction project because the house is bound to shift as it settles slightly. So, it would be best if you started thinking about filling the gap at the right time. 

If you’re a handy person, you can purchase polyurethane caulk and use the right construction tools to seal the gap between your house and the patio without the help of a contractor. But, if you want to finish the job perfectly and get it right the first time, consider hiring a licensed professional contractor.

Here is a quick video to show you how to fill a large gap between your house and patio:

What Should I Put Between the House and the Patio? 

Urethane caulk is a great material for sealing the gap between your house and the patio. The material is like a concrete joint sealant or the driveway caulk that most homeowners often apply on their driveways to seal cracks. However, installing expansion joints to fill the gap between the house and the patio can end up messy if you don’t execute the project carefully.

There are three effective ways to add a joint to a concrete slab. If you plan to add expansion joints to your concrete slab when it is still hot, simply slip some joint material between the slab sections and position it along the edge of the form. Use exceptional asphalt, cork, plastic joint materials, or a backer rod. If you choose to use expansion joints, ensure that the joints extend across the entire width and depth of the concrete slab.

A second method is to use a joint trowel to extend the width of your slab to allow it to expand. When you pour your slab, create a slight space between the slab sections by using a joint trowel. The disadvantage of this option is that it does not allow you to install a concrete expansion joint fully on the entire thickness of the concrete slab. The expansion and contraction of your slab will still happen due to the space above your slab. That is why the second option is suitable for narrow surfaces such as sidewalks.

Thirdly, you can choose to add expansion joints on top of a concrete slab that was already poured and cured using a concrete saw. This method of creating expansion joints requires you to cut through the concrete slab using a concrete saw. You need to accurately mark the depth and width of the joint that will be added before you cut it to get it right.

How Do You Fill a Large Gap in a Concrete Patio?

Caulking is the most effective way of sealing the gap between your patio and house. It’s an easy DIY project that you can handle without too much difficulty. Buy the right caulking material, and you’re good to get started.

A Step-by-step Guide On Filling a Large Gap Between Patio and House

Here is a step-by-step process of filling a gap between your house and patio:

  • Step One: Assess the extent of the problem
  • Step Two: Thoroughly clean the gap. Make sure you take out all the old fiber boards that were used in encasing the concrete and get the correct measurements of how much you need to seal the gap. Removing any porous material (other than the soil) will allow you to seal the space more effectively. 
  • Step three: Find out what size the gap is. It would be best if you also determined how thick your backer rod will need to be installed and how much sealant you will need to use to fill the gap. 
  • Step four: Install your backer rod. Trim the rod based on the gap size using a pair of scissors and place it into the gap. You can also apply a layer of sand to seal the gap. 
  • Step Five: Apply the sealant. The sealant will help seal the gap between the patio and the wall. Apply a urethane caulk or crack sealant to the area around the gap. Smoothen the area with sandpaper. It’s advisable to use a crack sealant and a urethane caulk if you want to create a nice-looking concave lip that is waterproof between your patio and your house.
  • Step Six: Level the sealant evenly in the gap. Caulk the small cracks in the walls and floor that are narrow. Cracks that are only 14 inches wide can be sealed completely without using a backer rod. Caulk the crack carefully by placing the caulk gun down along the crack and smoothing the caulking over the area.


What is causing my house to sink? 

If the ground on which your house sits can easily allow it to sink, you may have serious foundation issues. Your best approach is to re-seal your foundation. Ensure all the cracks in the walls or window frames and walls are properly re-sealed. If you have a poor foundation, ensure it’s reworked to ensure your house doesn’t get ruined. Some signs that you may be experiencing if the house has a potential problem include cracked bricks, stuck windows, noises when the house is settling, and drywall cracks.

What are the suitable materials for filling up concrete joints?

Epoxy foam backing is one of the best materials you can use when you want to fill holes or gaps in concrete expansion joints. Polyurethane caulk is best for fixing the gap between your patio and house. Avoid using a mix of cement and gravel as it will crack with time and cause leakages. Backer rods can be used to fill voids that are in concrete slabs to prevent them from cracking. They also provide a good seal for the concrete pad. This helps to prevent water from leaking from joints in concrete, especially if the rod is positioned to sit under a concrete slab.

How deep should I cut the expansion joints of my concrete slab? 

Saw cuts should meet the specifications of an experienced structural engineer. It is ideal to cut your expansion joints 14 to 13 times as thick as the slab. If you are using 6 inches of concrete, the expansion joints of your house will need to be cut at least 1.5 to 2 inches apart. Making very shallow cuts is likely to cause cracks. On the other hand, if you go too deep, aggregate interlocking will not be sufficient to transfer loads effectively.

How often should I put expansion joints in my concrete?

It is common for concrete expansion joints to be spaced 24 to 30 times the thickness of the concrete. Any joint that extends over 15 feet needs a load-bearing device, such as a dowel or a diamond plate. It is important that the joints of your concrete slabs are as square as possible and should have a ratio of length to width of 1.5 to 1.

Why do I need to cut lines in my concrete slabs?

When a contractor cuts a line in concrete, it causes the concrete to move downward. Cracks in the concrete will be able to follow the path of the forming lines. Contraction joints or sidewalk lines are the lines that are cut into the concrete slabs to allow for easier access to the walkways. So, you need to cut the lines to avoid any random cracks in your concrete that can cause your slabs to separate. Contraction joints should be cut in fresh concrete when it is still wet. Otherwise, it will be very difficult to cut through. You can see where cracks are formed from cutting vertical lines in your concrete slabs that are almost similar to the lines that you may have cut for contraction joints.

Wrapping Up

Maintaining your home’s integrity is vital. It’s critical to allow a gap between the concrete slabs that connect your house and your patio. This allows your slabs to expand and contract depending on weather conditions. For this purpose, appropriate material should be used to fill the gap between the patio and house walls to prevent water from causing damage to your property. There are different effective methods that you can employ when installing expansion joints in your concrete slab. The type of method you opt for depends on the thickness of your concrete slab and the stage of the project at which you want to install these joints.

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